Tuesday, December 29, 2009

Current US Snow Cover - Pretty Extensive

Wednesday, December 23, 2009

AMAZING Storm Warnings; Tornado to Flood To Winter Storm

Mature Nature Will Grant White Christmas Wishes For Many

A very complex and far-reaching winter storm will take shape today across the center of the nation. It will produce widespread winter weather, and may grant wishes of a white Christmas to millions.

Snow is a guarantee across the northern and central plains states this Christmas, and it will be measured in feet across some locations such as Minnesota.

Snow is becoming more and more of a possibility in places like Oklahoma City, Tulsa and Springfield, MO.

There may even be some flakes as far south as central Arkansas and Memphis by Christmas Day.

Before the flakes potentially fly in the lower Mississippi River valley, we'll first have to contend with the potential for a few severe storms today. Areas in and around the Arklatex (Arkansas-Louisiana-Texas) will be under the gun for some storms. Even extreme southern Missouri.

Very heavy rain is also expected across Arkansas and portions of the mid-south.

Monday, December 21, 2009

Christmas Travel Woes Ahead

Well it was an absolutely amazing storm over the weekend - my friends on Long Island recorded 2 feet of snow. Numerous records were set for either snowiest day, snowiest storm, or snowiest December across the mid-Atlantic and northeast.

A new storm is moving onshore today and it will have a pretty significant impact on travel plans Wednesday through Friday across the center of the nation.

Snow will fly on the northside of the system and severe storms will rumble on the southside across Arkansas and Louisiana.

In the middle, we may see an ice storm in the middle.

Stay tuned!

Saturday, December 19, 2009

Epic Eastern Winter Storm

Just look at this area of low pressure. 29.22 mb of pressure on the outer banks of North Carolina at Kill Devil Hills. That is pretty deep in weather man terms. Those lines around the low are called isobars, or lines of equal pressure. The closer the lines, the stronger the low. Close lines of equal pressure, also referred to as tightly packed isobars, translates into windy conditions. No wonder there are blizzard warnings out in and around the Baltimore/Washington DC vicinity.
When this weekend is over, I think there will be numerous new snowfall records across the mid-Atlantic and coastal New England areas. Folks along the mountains of western Virginia, North Carolina, eastern Tennessee and West Virginia have already seen between 14 and 20 inches of snow.

I saw a report that said the record 2-day snow event for Washington D.C. is 12 inches dating back to the 1930s. For Baltimore it is 14 inches dating back to the 1960s. Both records could fall this weekend.

Thursday, December 17, 2009

Kinda Quiet Now, Maybe Not This Weekend

The weather maps are fairly quiet right now. No huge storms really.

There are some occasional lake effect snows around the Great Lakes, some sub-zero temperatures from time to time along the Canadian border, and some pockets of rain in the west and south with occasional mountain snow in the Rockies, Sierras and Cascades.

This is all to be expected this time of the year.

There could be a potential eastern snowstorm as we head into the weekend. Forecasters are watching the areas from the mountain of Tennessee and North Carolina across the mid-Atlantic and into New England.

Winter storm watches have already been posted for upstate South Carolina, extreme eastern Tennessee, southwest Virginia and much of western and central North Carolina, including Charlotte and Raleigh/Durham.

If wintry precipitation develops across this area, we are talking early Friday and lasting into the day on Saturday - so keep abreast of the latest if you either live in that region or have holiday travel plans there.

Tuesday, December 15, 2009

Chilly Upper Midwest

Much if not most of North Dakota, South Dakota, Minnesota, Iowa and Nebraska are below zero this morning as a large bubble of arctic air sits across the region.

Anticipate one more day of the bitter cold before warmer air moves in to end the week.

On Monday, some isolated severe storms struck the central Gulf Coast region with a few tornadoes even reported around southeast Alabama.

This morning some more showers and thunderstorms are rumbling across Louisiana and southern Mississippi.

And an article recently published by NOAA warns of the dangers posed by both nighttime tornadoes and winter tornadoes.

Click here to read more.

Thursday, December 10, 2009

Current US Snowcover

Wow look how much of the country has snow on the ground today!

Wednesday, December 9, 2009

Blizzards, High Waves, Below Zero Temps Oh My!

What a fun day to recap the national weather scene -- actually I don't have time to effectively give it justice so much amazing weather is happening today.

Let's start way out west -- in Hawaii.

Portions of that state are waiting on high waves --- possibly in the 40 to 50 feet range! It has prompted a surf competition that only happens when waves top 20 feet. Surfers from all over the globe are flying in to "catch a wave" in Hawaii. This contest is so rare it has only happened 8 other times.

In the Rockies, we're warming up finally after a huge bubble of bitterly cold air dominated the weather for a few days. Here in Denver, we have been below 11 degrees for nearly 3 days, bottoming out at 17 below zero with a wind chill of 36 below zero just after sunrise Wednesday morning.

Locations across Wyoming dropped into the 20s below, with 30s and even a 40 below zero reading in the central valleys of that state.

The blizzard in the midwest has all but crippled much of the state of Iowa. Many locations are sitting under a foot of snow with drifts to 3 and 4 feet common.

Heavy snow has also fell across portions of Kansas, Nebraska, northern Missouri. Wisconsin has also been hard hit by the snow and wind.

All that is shifting into New England where many will see in excess of 6 inches of snow before all is said and done. Huge travel delays are being reported in the major northeast airports, esp. in and round New York City.

In the south, it is a contrast of 2 seasons -- with 18 degrees and snow flurries in Fayetteville, Ark., as reported to me by my childhood friend Kristin.

Meanwhile there was a tornado threat overnight across Mississippi, Alabama and Georgia. Now that threat has shifted into the Carolinas and far east Georgia.

Tuesday, December 8, 2009

Amazing Map -- U.S. Warnings

What an amazing map -- the large winter storm and huge cold air mass is evident with all the blues and reds from the Rockies to the Great Lakes.

Ahead of the storm, you can see some tornado warnings and a tornado watch in the southeast.

Bitter Cold Accompanies Winter Blast

Portions of northwest Montana and the adjacent areas of Canada awoke to temperatures between 30 and 40 degrees BELOW ZERO this morning!

Most of the rest of Montana is between 0 and 25 degrees BELOW ZERO.

Negative numbers can also be found in Wyoming, North Dakota, portions of Colorado, South Dakota and northwest Minnesota.

The storm system currently across the lower 48 states is impacting many with cold and frozen precipitation.

Many major cities are experiencing winter today, including Denver, Kansas City, Chicago and Minneapolis.

On the south side of the storm, heavy rain is falling across the mid-south, from Louisiana to Mississippi and Alabama.

There have been reports of flooding this morning in Louisiana.

Severe weather is also possible today across the Gulf Coast states as warm and moist air is drawn up into the storm system.

We shouldn't experience a wide spread outbreak, but a few isolated storms can't be ruled out.

Take a look at the national CoCoRaHS "new snow" map - for today. As you can see, snow was reported nearly coast to coast on Monday. The heaviest totals were reported in the San Juan Mountains of southwestern Colorado, near Wolf Creek Pass. Heavy snow was also reported in the mountains of northern Arizona, near Flagstaff.

Monday, December 7, 2009

Winter Gripping Nation

Wow the past several days have been really something in terms of wild weather.

Late last week we saw snow fall almost all the way to the Gulf Coast in some cases. Houston, Corpus Christi, the northern edges of New Orleans, Jackson and Meridian were just a few of the places that saw snow flying from the skies.

This week there is a major cold blast impacting the lower 48 states with temperatures in the negative numbers across a large chunk of the northern Rockies and high plains.

Some places in northwest Montana will be in the 20s to 30s BELOW zero.

A large swath of snow is expected from the higher terrain of southern California all the way to the Great Lakes. Places like Flagstaff, Denver, Kansas City, Omaha, Chicago and Detroit are all anticipating snow to fly.

It will be heavy in the central Rockies of Colorado, for example, with 2 to 4 feet between now and Wednesday.

Some places in the central plains are looking at potentially a foot of snow, such as Omaha.

Denver may see several inches of snow because the snow density is so light. Just a few hundredths of moisture will translate to an inch of snow. So if we see a quarter inch of moisture, that might mean 6 to 12 inches of snow!

The great thing about that type of snow is you can shovel it with a broom -- so light and fluffy!!

Wednesday, December 2, 2009

Jet Stream Bringing Active Weather To Nation

Good morning from snowy and chilly Denver, Colorado! It's hovering around 13 to 15 degrees with light snow. The commute has been aweful today.

So although the official start to winter is still a little under 3 weeks away, the climatological/meteorological winter began yesterday, Dec. 1.

And boy does it feel like winter in many locations. Temperatures are in the mid 30s to lower 40s as far south as northern Mississippi and southern Arkansas.

Ahead of the cold air, we have seen some strong to severe thunderstorms across the Florida panhandle, southern Alabama and southern Georgia today. There has been 1 tornado reported on Eglin Air Force Base.

Meanwhile, areas in and around the Great Lakes have seen snow over the past 36 hours, including around Buffalo, NY where 6 inches fell.

And some bitter cold can be found in the mountains of Montana today where readings are between 0 and 20 degrees below. Some of that cold air is sliding down the spine of the Rockies with near zero temperatures expected in Cheyenne, WY and Denver, CO tonight.

Dry and mild weather can be found across the deserts of the southwest.

And looking ahead, a few of the forecast models indicate a chance for some light snow as far south as central Texas by Friday night. We'll have to watch and see how this evolves.

Tuesday, December 1, 2009

2009 Atlantic Hurricane Season Ends, Most Quiet Since 1997

Yesterday marked the official end of the hurriacne season. It was the calmest season in over a decade thanks to El Nino.

Although not common, we can still see a stray tropical system in the first few weeks of December.

Click here for a link to a story about the season released yesterday by NOAA.

Monday, November 30, 2009

Low Bringing Winter To Desert Southwest

Here is a map you don't see everyday....winter storm warnings along the US/Mexico border, including the city of El Paso, Texas!

This is being caused by an area of low pressure that is slowly drifting across the region. It has a pocket of cold air associated with it and just the right dynamics in place to produce snow -- in some cases to the valley floor.

Up to 4 inches could accumulate in the deserts before all is said and done, with up to a foot across the higher elevations of this area.

The low will slowly drift east and eventually move along the Gulf Coast by the weekend, producing heavy rain from Brownsville, TX to Pensacola, FL.

Elsewhere, most everyone is quiet with the exception of rain along a front that extends from east Texas to Maine.

A new storm is churning in the Gulf of Alaska and is expected to spread very high wind and heavy rain or snow across southern Alaska. This is expected in two waves -- one today and tomorrow with another round by the weekend and early next week.

Wednesday, November 25, 2009

Alaska Chill Not Unusual

The recent string of below zero weather across Alaska was a little longer than normal, but certainly nothing unusual.

Fairbanks dropped below zero on Nov. 15 and stayed there through Nov. 22 before once again rising above 0 degrees.

Back in 2006 there was a 16-day below zero cold snap in Fairbanks.

It has been drier than normal at Fairbanks with 6 inches of snow so far this month. November is the snowiest month on average in Fairbanks with about 14 inches on average.

Tuesday, November 24, 2009

Nation's Icebox Not So Cold

Yesterday (Monday) was the 240th day in a row where the high temperature at International Falls, MN, was above freezing. This is the 4th longest stretch at International Falls followed behind the 246 string of days in 1958, 244 days in 2001 and 241 days in 2005.

International Falls is known as the "icebox of the nation" because when it does get cold there -- it gets cold!

It was the 236th day in a row with above freezing high temperatures in Duluth. The record number of consecutive days above freezing in Duluth is 257, held by 1878.

The last time a high temperature failed to go above 32 degrees at either city was on March 28, 2009 where the high temperature was 31 degrees at Interantional Falls and 26 degrees at Duluth.

High temperatures are expected to be above freezing through at least mid-week and may last into next weekend which will threaten to tie or break the record at International Falls.

Monday, November 23, 2009

Cold Days Ahead?

Cold air can still be found today over much of interior Alaska and northwest Canada....but it is nothing like a few days ago when we saw widespread negative numbers in the 30s and 40s below zero!

That cold air is on the move and will spill south -- bringing a few days of below normal weather to much of the nation as we round out November and head into December.

Of course it will moderate some before reaching the lower latitudes but still -- it will be chilly!

Thursday, November 19, 2009

Cut-Off Low Drifting Slowly

Those of you in the midwest have had several days of cloudy and damp weather, all thanks to an area of low pressure cut-off from the main flow of jet stream winds aloft.

The result has been this low just kind of spinning along, minding its own business....but bringing those under the low pressure system a dreary week.  (i.e. St. Louis)

In the northwest, a new storm is onshore and it is spreading plenty of rain and wind to the region. One of my good friends called yesterday from the car ferry on Puget Sound saying it was a rough ride!

Portions of Alaska's interior are well below zero this morning. Such as 46 below in Bettles! Compared to that, it is a balmy 9 below in Fairbanks with snow this morning.

Tuesday, November 17, 2009

Brrrrr -- It's Chilly In Alaska

Much below normal temperatures continue to grip Alaska this morning with minuses showing up from Anchorage to Bettles!

As of this blog posting, it was -6 in Anchorage and -14 in Fairbanks -- both stations were reporting snow.

It really gets cold in the interior with -43 at Bettles and -42 at Tanana.

A strong cold front has blew through portions of Washington and Oregon with strong winds overnight. Gusts to 70 mph at Hoquiam and 58 mph at Bellingham were reported. Seattle saw winds near 40 mph.

Crystal Mountain, Wash. saw wind gusts clock in at 115 mph!

Astoria, Ore. saw 2.71 inches of rain on Monday setting a new daily record. From what I just looked at on the extended forecast models...there might be several more daily records falling across the Pacific Northwest in the days to come. A wet pattern looks to be setting up now through Thanksgiving.

Monday, November 16, 2009

Mid-November Weather

It was a busy weekend here in Colorado with below normal temperatures and another decent snowfall. That puts us over 2 feet so far this season....some parts of the city close to 3 feet!

Today there is a small pocket of wintry weather across northeast Kansas, northwest Missouri, southwest Iowa and southeast Nebraska.

It is still very cold over Alaska with sub-zero readings expected this week in the interior.

Hawaii has been dealing with record rain and extremely high surf with waves over 15 feet. Hilo saw over 4 inches of rain in one day last week.

The week is off to a stormy start in the Pacific Northwest with plenty of wind and rain as well as mountain snow. Heavy totals are possible from northern California through western Oregon and Washington this week.

Thursday, November 12, 2009

Wicked Storm East, New Storm West

Wow the CoCoRaHS maps have really tracked the progress of Tropical Storm Ida and  the remnants since making landfall along the Gulf Coast earlier this week.

The map above is from 2 days ago when the storm was dumping heavy rain over north Georgia and the western Carolinas. What a nice footprint!

Today more heavy rain, high surf and blowing sand will pelt the coastal areas of the mid-Atlantic as the coastal low (remnants of Ida) slowly move north.

Much of the western US will see a cool and unsettled weekend ahead as a storm system impacts the region.

Our facebook page for CoCoRaHS has been busy the past few days with a lot of chit chat among members! That is excellent!

Observer NC-CL-01 has seen a lot of impact from the coastal low -- with nearly 5.00 inches of rain as of his post on Facebook yesterday -- I am sure that number is still climbing!

Station FL-ES-2 also checked in on Facebook before Ida made landfall -- she was expecting alot of rain just 6 miles east of the Alabama and Florida state line in the far western panhandle.

 Welcome to a few new stations who checked in on our Facebook page....Matt from Custer County, Montana and Karen from Maine!

I was not able to process my pictures from the new weather station dedication yesterday in Denver but will hopefully tonight and try to post tomorrow!

Wednesday, November 11, 2009

Wednesday Weather Wrap

Well Ida is no more, but the remnants are making waves (literally) along the eastern coast of the United States.

A coastal low has formed off the Carolinas and will bring a lot of wind and rain to the eastern seaboard over the next 48 hours.

Coastal flooding is expected from the onshore winds and heavy rain.

In the northwest, a new storm system is moving into Washington, Oregon and the mountains of Idaho, Montana and Wyoming.

And cold air continues to build over Alaska -- something to watch in the days ahead.

Tuesday, November 10, 2009

Ida Makes First Landfall

Tropical Storm Ida officially made landfall around 5:40 a.m. Tuesday along the shores of Dauphin Island, Alabama.

As I type this blog, the storm has crossed the island and is now over Mobile Bay -- and will make a second landfall soon on the U.S. mainland.

I just checked the latest observation out of Mobile and they have a sustained wind from the North at 28 mph gusting to 44 mph. They've seen over 3 inches of rain in the area during the past 30 hours.

Thanks to CoCoRaHS observations -- we see a few isolated pockets of 5 to 7 inches.

Elsewhere around the nation -- things are really starting to chill down across Alaska. Over the next several weeks we'll have to start paying attention to what is happening up there as we often see large masses of cold air develop -- and then spill down the Rockies and across much of the lower 48.

It has been fairly mild across much of Alaska in recent weeks, but things are now chilling down enough that rivers and lakes are freezing up for the winter.

There is a flood advisory in and around the Fairbanks vicinity due to potential flooding along the Tanana River because of ice jams.

The forecast over the next 5 days has high dropping to near zero with lows falling into the 20s below zero around Fairbanks so that river willl freeze up nice and solid and the threat for flooding will come to an end.

Monday, November 9, 2009

Ida Downgraded, Still Poses Danger

Ida is no longer a hurricane, but will still make landfall as a potent storm system and will definitely be a threat to the southeast U.S. -- more and more in the form of heavy rain versus wind.

Below is a picture sent to me by Marilue -- one of our CoCoRaHS observers along the Gulf Coast. The picture is from Seagrove Beach, Florida.

November Hurricane History

If Hurricane Ida can maintain "hurricane status" all the way to the coastline, it will be one of only a handful of tropical systems to do so during the month of November.

Below are the few Nov. hurricanes on record that struck the U.S. coastline.

Hurricane 4 of 1925 -- struck Sarasota during the night on Nov. 30. The hurricane caused damage to Florida's citrus crops. High winds knocked down power lines and damaged homes. Several deaths were reported on the open waters as ships sank. A ship carrying 2,000 cases of liquor and a crew of six sank near Daytona Beach. The storm made a second landfall as a tropical storm along the North Carolina coast.

Hurricane 6 of 1935 -- struck the Miami area on Nov. 4, moved into the Gulf of Mexico and lost strength before curving back east and hitting near the Tampa area as a tropical depression. The storm killed 19 people and caused widespread damage. The hurricane's unusual approach toward Florida and late arrival earned it the nickname of the Yankee Hurricane.

Hurricane Kate of 1985 -- struck Florida's panhandle on Nov. 21 as a weak Category 2 storm with flooding rain, power outages and beach erosion. The storm was blamed for five deaths.

Some historical summaries show a fourth November hurricane hit Florida in 1916. But research by the National Hurricane Center shows this storm actually lost tropical characteristics between Cancun and Key West, but did move over the Florida Keys as an extratropical cyclone.

Thursday, November 5, 2009

Wednesday, November 4, 2009

Tropics Come To Life, Giant Crack Found In Africa

Well after several days of quiet, the Atlantic side of the tropical season has come to life with a tropical depression forming on the coast of Nicaragua.

The disturbed area weather is expected to organized and make a northwest trek into Nicaragua before turning north and moving across Honduras.

Forecasters currently think the area of low pressure will continue moving north, off the northern coast of Honduras and reform into a tropical storm once it gets back over the warm waters.

The map below shows the potential track and status -- potentially threatening the Yucatan of Mexcio by early next week.

And in some very interesting world news, my grandma sent this to me on email the other day.

She found an article that talks about a huge crack found in the African deserts of Ethiopia.

Scientists think the 35-mile rift will eventually become a new ocean.

Click here to read more.

Tuesday, November 3, 2009

Continued Quiet....For Now

The first few days of November remain on the quiet side for much of the lower 48. There is some active weather in Alaska with both some wind, rain and snow as well as cold temperatures (0 to 20 below zero in the northern interior)

This will change next week as the pattern turns more active across the nation.

The first storm system will start impacting the northwest as we head into the weekend and the central Rockies by early next week.

It will then sweep across the country and will be followed by another storm system a few days later according to current models.

Our most recent poll ended with 41 responses. Of those, 53% didn't realize CoCoRaHS was on Facebook while the rest said they are already friends with CoCoRaHS on Facebook.

Sunday, November 1, 2009

November Arrives Quietly

Aside from last week's storm exiting the east coast today, and a small disturbance moving over Minnesota, it is really quiet and seasonal for many locations.

That trend should take us into the first few days of the 11th month -- November.

October 2009 will go down in the record books for many locations and won't soon be forgotten.

It was the wettest month on record for St. Louis, MO -- Little Rock, AR -- and Shreveport, LA.

It was the coldest month on record for Cheyenne, WY -- and Tulsa, OK. 2nd coldest for Denver, CO -- and Oklahoma City, OK.

It was the hottest October on record for Miami, FL.

It was the snowiest on record for Cheyenne, WY and North Platte, NE.

Saturday, October 31, 2009

U.S. Snow Cover

Below is a map that shows what this week's western winter storm left behind. That is quite a bit of snow!

Friday, October 30, 2009

Severe Flooding Hits Mid-South

I catpured this snapshot last night off the web -- it shows flash flood warnings (in the maroon color) that were in effect along the line of heavy rain producing thunderstorms that extended from Missouri to Texas.

Those storms put down a lot of water -- as much as 5 to 7 inches in just a few hours across the Little Rock and Shreveport metro areas.

Little Rock has now seen its wettest October on record with 15.92 inches thus far in the gauge. The previous record was 15.29 inches during October 1984.

This is the 4th wettest month in recorded histroy for Arkansas' capital city.

Little Rock suburbs were hit hard, as well as downtown. A high water rescue took place at 10 pm last night on 7th street in downtown Little Rock.

The northern suburb of Sherwood took on a lot of water, including my mom's neighborhood. The two pictures below are her street. Luckily the road crests at her house, so she was ok. But there was flooding on either side that prevented her from going to work today.

In Louisiana, it is a similar story around Shreveport.

And ontop of the water, there was at least 7 tornadoes in the region on Thursday that prodcued damage.

Below is a map of yesterday's national precip. You can definitely see the rain footprint across Louisiana and Arkansas -- but it would be so much better with more spotters!

We need to do some heavy recruiting across the entire CoCoRaHS network -- but especially in this part of the world.

I survived the snow, but still don't have my driveway clean. See picture below. Anybody wanna come help? ;-)

Thursday, October 29, 2009

Squall Line Develops Ahead of Winter Storm

Good morning from snowy Denver, Colorado! It is 1 am and I need to get in bed, but I am too excited over the weather.

I am fortunate to have the opportunity to do a little free-lancing for KMGH-TV in Denver since I am home in the snow and unable to go to my regular job.

So I spent the evening writing a few weather stories. Check them out!

Click here for the one I wrote about CoCoRaHS and here for the one that compares the current storm to one that struck about the same time back in 1997.

Meanwhile I just checked radar and a narrow, but long line of thunderstorms has developed from south-central Kansas into northwest Texas.

You can see this on the 1 am national radar image below.

Out ahead of the storms a tornado watch has been issued for southeast Oklahoma and northeast Texas.

I grew up in Arkansas and have to admit I hate overnight storms, especially when a tornado watch is in effect.

Weather will be a big headline all around the nation today from heavy snow in the Rockies to severe weather in the southern plains to more rain expected in the water-logged southeast.

Wednesday, October 28, 2009

Western Storm Still Organizing

Well the western storm is still organizing today, and let me just tell you first hand, it is packing a punch!

Sitting at about 7 inches of snow on the ground here at my house in the southeast Denver metro area. I should easily be able to add another 6 to 12 inches to that before all is said and done tomorrow.

On the west side of town, in the foothills, the snow has accumulated to over a foot in many locations.

On Tuesday, as the low pressure formed over the Great Basin, it brought incredible wind to the southwestern US.

Flights into places like Phoenix, Las Vegas and Los Angeles were what I like to call "white-knuckled" for lack of a better term -- meaning passengers likely had a tight grip on the arm rests!!

Gusts to over 70 mph were reported on Whittier Peak just outside of L.A., and across the higher terrain of Nevada.

As you can imagine, the winds produced several dust storms that hampered ground travel.

As the storm pulls east today, there is the chance for a little bit of severe weather across the high plains of Texas and Oklahoma, outlined below.

Elsewhere, it's wet today across upstate New York with blinding rain at times along the New York State Throughway.

Residents of the south are catching a small break in the action before more rain moves in to end the work week.

And for many in the Rockies and across the High Plains, it is winter! Just look at the slew of watches, warnings and advisories in place on the map below.

Tuesday, October 27, 2009

Soggy South, Wintry West -- Get Those Gauges Ready

Wow the CoCoRaHS maps are going to be colorful over the next few days as the rain gauges get a workout all across the nation.

Let's start in the south.

A very soggy air mass is in place with widespread heavy rain today from Arkansas to Georgia.

In the panhandle of Florida, severe weather is possible through the afternoon hours. The Storms Prediction Center has issued a tornado watch until 6 pm.

Heavy rain has been falling across the Atlanta metro this morning, especially on the west and northwest side of the city, which was hit so hard by epic flooding during September.

There are numerous flash flood warnings in effect for the region.

In the south today, remember the very important safety rule: TURN AROUND, DON'T DROWN!

It just isn't worth driving through a flooded road because you never know if the road is still there -- and even if it is and you can see it -- it might not be stable.

Heavy rain fell across Texas on Monday. Several places from Austin and San Antonio to Dallas and Houston saw flash flooding.

Along with the heavy rain came some cooler temperatures -- with many locations reporting 50s and even some chilly 40s this morning.

In addition to the south, it's wet in the northeast today such as in and around New York City.

And looking out west, the big storm that will sweep across the nation over the next 5 days is starting to take shape this morning.

It will start with a lot of wind for the western US, in particular, in and around the Las Vegas vicinity and across southern California. Red flag warnings for high fire danger cover much of Arizona.

As the low pressure strengthens and starts a slow trek to the east across northern Arizona and northern New Mexico tonight, snow will begin to fly across Colorado and much of the central Rockies.

It will likely be measured in feet in a lot of places before all is said and done Thursday.

A 2-day snow event is always fun -- one reason why I love living in Denver!

And looking down the road, severe weather is likely to be with us Wednesday through Saturday -- starting in Texas and moving east ahead of this large winter storm that is currently developing across the west.

We are entering the second severe weather season in the lower 48. It usually starts sometime in October and peaks later in November or December as the air masses once again battle it out -- just like in the spring.

The biggest difference between severe weather in the fall versus the spring months is it usually isn't as widespread, mostly confined to the Gulf Coast states.

Monday, October 26, 2009

Dynamic Storm To Sweep Nation This Week

A new storm system is moving into the Pacific Northwest today with clouds, rain, wind and high elevation snow.

Winter storm warnings are in effect for the mountains of Washington state, northern Idaho and western Montana.

The storm will initially dive south and carve out a large trough of low pressure across the Great Basin of the western United States tonight and into the day on Tuesday.

As the storm system develops, it will be quite the wind maker across the deserts of southern California, Nevada, southern Utah and northwest Arizona.

If your travel plans take you into Las Vegas on Tuesday get ready for one bumpy ride!

Later in the day on Tuesday the storm will begin a slow crawl to the east. It is expected to bring heavy snow into Colorado and northern New Mexico, both across higher and lower elevations.

If the low takes the right track, residents of Denver could be shoveling 1 to 2 feet of snow by Thursday morning.

Late Thursday, but especially into Friday and Saturday, we could be looking at a severe weather outbreak in the areas outlined on the map below.

It will all depend on just how this storm system evolves over the next 36 hours and the exact track it takes.

Sunday, October 25, 2009

New England Soaked Saturday

Widespread moderate to heavy rain doused much of New England on Saturday, with particularly heavy amounts reported across New Hampshire, southern Vermont and east-central upstate New York.

There were plenty of observer comments from the region on Saturday, reporting everything from thuder to rainfall rates topping 1-inch per hour.

With the intense rainfall area waterways are running high so use caution if out and about in that part of the nation today.

One observer in New Hampshire filled the inner tube too fast and lost some rainfall on the table! Oh I have done that before -- it is just horrible!

The observer near Saratoga Springs, New York, reported such intense rainfall that he had to take an alternate route home making for a nearly 90 minute commute from Albany.

An observer in Vermont described the roar of a nearby brook as deafening at times during the heavy rain bands.

Saturday, October 24, 2009

Unsettled Week Ahead

Below you are looking at the current "threats outlook" from the Climate Prediction Center for the upcoming week.

This is based off current forecast information and could certainly be tweaked a little as we move through the weekend.

Regardless of how the exact details play out, there is one thing we can say for certain and that is get ready for an active week ahead -- in particular across the western United States.

Some places may be really active such as the Front Range of the Rockies where the current outlook for mid-week is to have a pretty good snowstorm!

The southeast US may see an increasing threat for heavy rain with a plume of tropical moisture currently moving across the Bahamas.

Friday, October 23, 2009

Heavy Rain In Midwest

Wow did you see all the heavy rain reports today on the CoCoRaHS map?

Dozens of reports in the 2 to 4 inch range from Texas to southern Wisconsin.

In Louisiana, severe weather broke out on Thursday with at least 6 tornado reports in Cameron and Jefferson Davis parishes.

One report included cars flipped over on Interstate 10 at the town of Jennings as the tornado passed by.

Damage was also reported in the town of Elton.

Today the heavy rain has shifted a little east into the Tennessee and Ohio River valleys.

A new storm system is moving into the Pacific Northwest.

Thursday, October 22, 2009

Hurricane Neki Parallels Hawaii

Hurricane Neki continues to churn up the waters in and around Hawaii and the storm moves north-northeast with winds of 120 mph.

The center was located about 500 miles west of Honolulu at last advisory.

Hurricane warnings are in effect for the Papahanaumokuakea National Monument and from Nihoa Island to French Frigate Shoals to Maro Reef.

Right now it appears the biggest impact to our 50th state from the hurricane will be higher-than-normal, and rougher-than-normal surf. Some increased showers and windy conditions may also be possible, especially on the northern end of the island chain.

Ok...so after reading the hurricane warning for Papahanaumokuakea National Monument, I had to do a little research to see what that is -- I've never heard of it.

It is the largest marine conservation area in the world, covering more than 139,000 square miles of the Pacific Ocean.

It was created by Presidential proclamtion on June 15, 2006.

Click here to learn more by visiting their web site.

Wednesday, October 21, 2009

Forecasters Say El Nino To Make Return

The most recent ocean data and trends show a return to El Niño climate conditions for the upcoming winter.

Click here to view a PDF file of the latest forecast information.

Typically, El Niño creates warmer-than-average winters in the upper Midwest states and the Northeast.

Central and southern California, northwest Mexico and the southwestern U.S. are usually wetter-than-normal.

The northern Gulf of Mexico states and northeast Mexico are usually both wetter and cooler than average.

If you are up for some reading, here is a lot more info on El Niño.

Tuesday, October 20, 2009

Hurricane Rick Weakens, Checking On Alaska

Once the second most powerful hurricane ever observed in the eastern Pacific, Hurricane Rick is no more.

The storm encountered conditions during that day on Monday that weakened it from a category 3 hurricane down to a strong Tropical Storm.

It is still expected to move in a northeast manner over the next 36 hours and give the southern Baja of California a glancing blow.

Meanwhile, let's look up toward Alaska and see what is happening right now. There are no signs of arctic air building which is good news.

We often look toward Alaska during the fall and winter months to see if large bubbles of cold air are in place. Many times these eventually break off and move south toward the lower 48.

We keep a very close eye on Alaska between December and February.

Right now, Alaska has been running above normal in terms of temperatures. Some places in the southeast US have been seeing weather similar to what has been observed in Fairbanks over recent days.

Things are cooling off in Fairbanks to more normal readings for late October, which means their highs will be in the upper 20s and lower 30s with lows in the teens.

Lately highs have been as high as the mid 50s if you can believe that!

The CoCoRaHS map for Monday, October 19, can be seen above. It was one of the most quiet national maps I have seen in quite some time.

Wet on the edges with a little bit of spotty precip here and there, such as across the inter-mountain west.

But other than that, dry for most observers.

That will change in the days ahead as a new storm system moves onshore in the west and enters the Rockies for mid-week!

My latest poll closed on Monday with 74 votes. The question was when do you think the first widespread arctic outbreak will sweep across the lower 48 states.

37% think before Halloween, 44% think during November and the rest say sometime in December.

A new poll is up so check it out!

Monday, October 19, 2009

Super Hurricane Rick, Winter Outlook

Wow what a monster! Hurricane Rick peaked with winds at 180 mph over the weekend not too far off the Mexican coastline.

That makes Rick the second strongest hurricane ever recorded in the eastern Pacific. The strongest on record was Hurricane Linda back in 1997 with 185 mph winds.

Thankfully Rick has weakened down to a Category 3 storm with winds of 115 mph. That is still extremely dangerous -- but much better than what it was over the weekend.

The storm is moving toward the resort town of Cabo San Lucas, and will make a landfall on the southern tip of the Baja Peninsula late Tuesday or early Wednesday.

Click here to visit the National Hurricane Center for the latest forecast information.

Looking ahead to the winter, it looks like El Nino will have an influence on the weather pattern over the next several months, according to the latest forecast from the National Weather Service.

Click here for a breakdown of the forecast by region.

If this forecast verifies, it will be some good news for California as they are potentially going to be wetter-than-normal.

Saturday, October 17, 2009

Chilly East, Mild To Hot West

The eastern US remains chilly this weekend with below normal temperatures behind a strong cold front that has now pushed all the way into southern Florida.

Highs will only be in the 40s across much of the northern tier with lower 50s into places like Atlanta and Memphis.

Some places in New England may not even reach 40 degrees.

Only mid-70s are expected over the next few days as far south as Miami with overnight lows as low as 50 degrees in some outlying areas of the metropolitan area.

Signs of this chilly air mass can be seen in the US map above with numerous frost and freeze advisories and watches in place.

Meanwhile, out west...it is mild and hot. Highs will climb into the 70s and even lower 80s along the Front Range of the Rockies.

In the deserts of Arizona, temperatures will push 100 degrees!

Historically, the last 100-degree day of the year happens around September 28 on average in the Phoenix vicinity.

The latest 100-degree event on record was October 23, 2003.

Here is a neat write-up about the last 100-degree day trend in Phoenix.

Off the teach a CoCoRaHS training class in Brighton, Colorado. Hoping for a good turn-out!

Friday, October 16, 2009

PA Snow Sets New Record

The eastern half of the US is under a very large airmass full of clouds and cold air.

All the blue and red dots indicate mostly cloudy to overcast sky conditions.

And in some of that cold air, snow is falling.

State College, Pennsylvania, saw the earliest snow on record. The previous record stood since October 18, 1901.

Nearly a half-foot fell in the college town.

Snow was also flying across southern New York and across much of the rest of northern and central Pennsylvania.

This type of weather is anywhere from 2 to 4 weeks ahead of schedule.

More snow is in store this weekend along the mountains of Pennsylvania and New York, and possibly extending down into the highest elevations of Virginia and West Virginia.

Wednesday, October 14, 2009

CoCoRaHS Workout In California, Unusual Record Set

A huge storm slammed into California on Tuesday with hurricane force winds across the higher elevations and heavy rain across both high and low elevations.

Locations in and around Los Angeles saw anywhere from 1 to 3 inches of rain. Some foothill locations in Ventura County and the Santa Barbara Mountains saw over 10 inches of rain.

Rocky Butte in San Luis Obispo County saw over a foot of rain!

Trees and powerlines were down in places like Merced and Fresno, while there was flooding in Hanford.

The winds created a dust storm that resulted in a multi-car pileup that killed 3 and injured 6 others on I-5, just north of State Road 119 in Kern County.

Power was out to over 250,000 California residents at the peak of the storm.

Here is a record you don't see everyday...Sacramento had a record low pressure reading for the month of October recorded at 3:44 pm. The air pressure was 29.39 inches.

So if you live in that area and felt poorly in body, that may have had something to do with it.

The CoCoRaHS observer in Santa Clara County, 6.1 miles south of Los Gatos, challenged the limits of the rain gauge with a 24-hour total of 11.09 inches!!!

That was the highest CoCoRaHS total in the nation on Wednesday.

Los Gatos is in the foothills of the Santa Cruz mountains so there was definitely precipitation enhancement due to the terrain. In meteorology, we call this orographic lifting -- that is simply where the winds, which in this case were blowing on shore and up the mountain chain, force the air to rise and squeeze out all the moisture it can -- thus enhancing the amount of precipitation.

October is usually a dry month for the region. The rainy season starts in November but really gets going in late December through early March.

Nearby in Santa Cruz County, the observer 1.2 miles SSE of Ben Lomond was close behind with 10.76 inches of rain in 24-hours.

This area is located on the central California coast, south of the San Francisco Bay area.

California needed this precipitation -- maybe just not so heavy all at once.

The rainy season is still ahead so let's hope they get a lot of much needed moisture.

Tuesday, October 13, 2009

October 1969 -- A Year To Remember

I wasn't around in October 1969, but if you were, chances are that you might recall the unusual weather it brought.

On this date in 1969, a bitterly cold air mass was spilling south from the Arctic. It brought single-digit temperatures and widespread snow to the northern Rockies and high plains.

Meanwhile, record heat was found on the west side of the storm system with mid 60s as far north as central Alaska.

It was a stagnant weather pattern with much of the month cooler and wetter than normal for the lower 48 states.

In fact, for Denver, it was the coldest, wettest and snowiest October on record. And those records still stand today.

The cause for the unusual weather was the jet stream pattern. There was a huge ridge over the western US with a large trough of low pressure covering the rest of the country.

There was a great paper written about the weather pattern and the resulting weather that October.

Click here to read it.

The paper has charts, maps and detailed analysis of the scenario.

Monday, October 12, 2009

More Southern Rain, Chilly Midwest

More rain is on tap (no pun intended) for portions of the south, from southern Arkansas over to the Atlanta area.

Atlanta has seen just over 46" of rain so far this year. The 30-year average for the period of January through December is just over 50 inches so they are pretty much on track to have a normal year.

The problem is after a dry start Mother Nature decided to play catch-up with a very wet late summer that brought epic flooding.

Click here to read about the epic floods that hit Atlanta in September.

It was a cold weekend along the eastern Rockies and across the northern plains. Here in Denver we never left the 20s during the day on Saturday.

It was cold!

We received some snow but nothing too serious -- I didn't even have to break out the shovel. However in extreme northern Colorado, portions of southeast Wyoming and stretching over into Nebraska -- shovels were required over the weekend as up to a foot of snow fell.

Some places even saw more than a foot - breaking a record at North Platte that has stood since 1896.

Click here to read more about the heavy snow.

Friday, October 9, 2009

First Time Gauge Reader Overflows

I have such a great story about a girl I went to kindergarten with at Bayou Meto Elementary in Jacksonville, Arkansas.

She and I found each other on Facebook a few months back and she learned that I was a meteorologist. She shared with me that she was a die hard weather buff and had started following CoCoRaHS and my blog.

This past week she signed up to be an observer and her gauge arrived this week. Her husband installed it yesterday just in time to catch rain from an overnight squall line that moved through central Arkansas.

Guess what?

Her first report was 2.60 inches! So lucky to overflow on her very first day of measuring for CoCoRaHS!

Congratulations Shannon -- so glad our paths have crossed again after all these years and really glad to have you as part of the extended CoCoRaHS family!

Thursday, October 8, 2009

Henri Downgraded, Large Fall Strom Moving In

Tropical Storm Henri is now just a depression as it slowly drifts west. It will skirt across the northern shore of Puerto Rico and continue moving west toward Hispanola.

Meanwhile, the center of the nation is cool and damp as a large autumn storm system moves across the region.

It will spread widespread showers across portions of Kansas and Missouri. Behind that, in the cooler air, anything from freezing fog and drizzle to some light snow is possible from Denver to North Dakota.

Flash flood watches are out from Texas to central Indiana as this storm system moves further south and east over the next 24 hours.

Freeze warnings cover all of North Dakota, portions of South Dakota and western Minnesota. Temperatures will fall into the lower teens in some places.

Rain will move into the southeat states and New England before the week is over.

If you want some dry weather, head west. From San Diego to Seattle the next few days looks dry.

Wednesday, October 7, 2009

Tracking Henri, Preparing For Winter Blast

Well believe it or not, the tropics have flared up just a bit with Tropical Storm Henri spinning to the northeast of Puerto Rico.

It is a very weak storm and is expected to be downgraded to either a depression or just simply an area of low pressure.

However, it will bring some unsettled weather to the area north of Puerto Rico and east of the Bahamas.

It does need to be monitored since it is fairly close to home.

Elsewhere, a strong cold front is now pushing into the northern plains. Montana and North Dakota are already feeling the effects with temperatures in the 30s and falling.

It will sag south over the next 2 days along and east of the Rockies. Let's just say the middle of the country is setting up for a cold and wet weekend. Here is the Friday forecast map.

There are already some flood watches out around eastern Kansas and across much of Missouri, eastern Oklahoma and northern Arkansas in advance of the storm system.

Tuesday, October 6, 2009

Taste Of Winter For Some

Parts of southwest North Dakota received the first accumulating snow of the season Monday with 1 to as much as 4 inches in a few locations.

More snow could be in store this weekend as a chilly storm system moves into the northern Rockies and high plains.

Perhaps chilly is an understatement -- maybe I should have said very cold! Temperatures across portions of North Dakota could drop as low as 15 degrees with the new storm system.

In fact, the Climate Prediction Center is outlining a huge portion of the middle US for below normal temperatures this coming weekend, along with some wet weather.

So let's wait and see just how this weekend weather system unfolds!

Here is another installment from our Hawaiian blogger....Ben Black.

Take a look at NOAA’s Northern Pacific weather maps at http://www.prh.noaa.gov/hnl/graphics/npac.gif and you’ll see that for much of the year, one or more high pressure areas align in a “convoy” near the 40th parallel north of Hawaii and glide slowly in succession toward North America.

The rotation around these “highs” reinforce the trade wind flow toward Hawaii to the south, and add impetus to the movement of storms in the north Pacific and Alaska. When a low is introduced to the tropics south of these high pressure areas or slips into traffic between the highs, interesting dynamics develop that can stop or reverse the trade wind flow around Hawaii. Depending on the location of the low, Hawaii might see a localized reversal of the direction of prevailing winds that we call “Kona” winds. These can draw up even warmer, more humid air from the equator. When a Kona storm or Kona winds move in, they can make the westerly sides of the islands rainier and leave the eastern sides dry and sunny.

Here’s a weather map from 9/29/09 that shows a low that’s worked into the line of high pressure areas. Compare the with this detail from the GOES-11 satellite photo to see the gorgeous pinwheel effect that spins out of this low pressure area.

Friday, October 2, 2009

CoCoRaHS Important To Hawaii

On the island of Kaua`i, Mount Wai`ale`ale (“rippling water”) is purported to be the wettest spot on earth. This eroded volcanic core rises nearly vertically to just shy of a mile above sea level.

Rainfall records at the summit of Wai`ale`ale have been kept intermittently since 1910. The average rainfall since 1910 is 426 inches of rain a year, with 680 inches being the greatest annual rainfall recorded there (1982).

You’d need a 57-foot tall rain gauge that year to collect the entire year’s catch before emptying the gauge. Meanwhile the great sand dunes at Polehale on the leeward side of Kaua`i get an annual average rainfall of only 8 inches.

On O`ahu, the official 30-year average annual rainfall for Honolulu (on the leeward side) is 18.29 inches. On the wet, windward side of O`ahu, the tradewinds bring 60 to 280 inches to the mountain ridges.

On the big island of Hawai`i, rainfall on the east slopes of Mauna Kea can be nearly 300 inches, while on the west slopes, rainfall is unreliable and less than 10 inches per year. During a three-day rainfall in 2008, Hilo recorded just under 40 inches of precipitation.

Most rain comes in the form of isolated showers that come and go in a few minutes. When major storms bring heavy rain to Hawai`i, they’re pervasive and easy to identify.

But, the rainfall amounts vary greatly by locality.

On any given day, you can be standing in the sun while across the street your neighbor is getting a shower. When heavy rain hits, rapidly changing elevation, air currents, land formations, and other factors can mean that the amount of rainfall varies incredibly from place to place, even between localities that aren’t widely separated.

At the same time, its hard to get excited about reading the rain gauge on the dry sides of the island when it’s dry for weeks or months at a time. But when it rains, the effects on vegetation, stream beds, reefs and wildlife are so dramatic that the rain report is vital data.

Let’s proudly report those zeroes!

Thanks to Ben Black for the great entry.

Thursday, October 1, 2009

Welcome To October-rrrrrrr, More On Hawaii

Well good morning from windy and chilly Denver, Colorado! We have dropped into the upper 30s after mid 70s to lower 80s yesterday. It's a great welcome to the 10th month of the year.

Our first freeze of the season is due tonight, about 6 days ahead of schedule. Normal first freeze in Denver is around October 7.

Some fall severe weather is possible today from northeast Texas, across Arkansas and into southern Missouri.

The map below outlines the area where wind and hail is likely with storms that develop. There is only a 2% chance for an isolated tornado across the area.

There is a campaign currently in progress by NOAA to raise the awareness over tsunamis. As you have been following in the world headlines a series of tsunamis hit the Somoan Islands this week.

Click here to learn more about identifying the signs of an impending tsunami and what to do if you are in one.

The USA has two tsunami warning centers, one located in Alaska and the other in Hawaii.

Speaking of Hawaii, here is today's installment by Ben Black.

Is it going to rain today?

Singer and songwriter Stan Rogers said of the farmer on the Canadian prairie that on his tractor, he could watch the rain coming for miles. In large areas of the western and central United States, you look to the west or south to see what change in the weather may be headed your way.

In Hawai`i, we generally look eastward to see what showers are coming across the miles of ocean on trade winds. Because the trade wind flow dominates our weather so much of the year, we readily refer the windward (or rainy side) and leeward (or dry side) of each island.

After crossing thousands of miles of open water, many clouds can’t wait to precipitate, and are shedding rain well before making landfall at Hawai`i.

The windward sides of the mountains tease and squeeze showers out of the approaching clouds. The showers bless the windward sides with rainfall to produce luxuriant vegetation over the dramatically eroded mountainsides that appear as glorious green folds on postcards and travel brochures.

So, is it going to rain today in Hawai`i? Yes -- somewhere.

Weather History

And on this date in weather history in 1752, a hurricane hit the Carolinas for the second time in 2 weeks. It caused major damage to Onslow County Courthouse and Beacon Island disappeared.

In 1893, a hurricane hit the Mississippi Delta region drowning more than 1,000 people.

In 1987, winter struck northern Minnesota with snow in Duluth, while it was topping out in the upper 80s and lower 90s from Seattle to Portland during a heat wave.

In 1988, severe storms developed and brought large hail to Troy, Park Springs and Nocona, Texas.

And in 1989, a severe weather outbreak produced nearly a dozen tornadoes in the southeast, with Georgia and Florida hardest hit. Two people were killed near Moultrie, Georgia.

Wednesday, September 30, 2009

Let The Change Begin, Restarting State Climate Series

I am blogging to the sound of wind whistling past my back door and watching a huge bank of clouds billow up over the Continental Divide.

Living on the southeast side of Denver with a full western exposure offers some wonderful views!

It's all part of a huge weather change sweeping across the region today. After topping out in the upper 80s on Tuesday, residents of Salt Lake City are waking up to foggy conditions with rain and temperatures holding in the lower to mid 40s.

A few severe storms are possible today across northeast Colorado, western Kansas and western Nebraska. Right now the thinking is that storms will be isolated, but the ones that do form could be potent.

Back in May I attempted to start a climate series where we'd talk about all the states in detail over a series of days in the blog.

Tennessee was first, followed by Washington, Missouri and Vermont. In late July I got so busy with work and summer that I just couldn't put the time into researching more states.

Well thanks to Ben Black, CoCoRaHS observer and volunteer recruiter for Hawaii, I am happy to announce the climate series is back and will start with information courtesy of Ben!

Hawaii Climate Intro

Hawai`i has joined the lower 48 states in contributing rainfall data to CoCoRaHS! They are actively building a network of volunteers across the settled islands of the 50th state.

Yes, Hawai`i is an island state, but it’s really also a mountain state. The great volcanic peaks that formed the island chain rise from the ocean floor over 20,000 feet just to break the surface of the water, then as much as another 13,796 feet to face off against the oncoming weather born here by the westerly flow of the trade winds.

The trade winds carry weather generally from offshore of Mexico and Baja to Hawai`i on their way toward Asia. This prevailing weather pattern is the delivery service for much of the precipitation that keeps this outpost in the Pacific green and inviting to residents and visitors.

Click here to read more about the global circulation of wind patterns and the trade winds.

Another source to learn more about trade winds.

Tuesday, September 29, 2009

Low Pressure Developing Over Western US

A large area of low pressure will form and intensify over the western US today and tonight. It will kick up the winds across a broad area, as seen in the US watch/warning/advisory map below -- with all the fire weather watches in place from Arizona to Montana.

As that low pressure begins to move east on Thursday, it will have the potential to kick up quite a fairly large severe weather outbreak in the middle of the country.

Meanwhile it is chilly around the Great Lakes as an area of low pressure pulls cold air south out of Canada.

Sunday, September 27, 2009

Active Days Ahead As Omega Block Sets Up

Well the first big taste of fall will sweep into the northern tier of the United States this week as a large area of low pressure moves out of Ontario, Canada and into the Great Lakes vicinity.

That low pressure will bring cool, unsettled and very windy weather to that region. In fact, waves on the open waters of Lake Superior could reach as high as 20-25 feet.

A second area of low pressure will move into the Pacific Northwest and bring fall weather to the inter-mountain region as well as some below normal temperatures.

In the middle, we will find a small ridge of high pressure.

There is a special type of weather pattern created when you have low, high, low as you look from west to east. It is visually represented below in a picture from the GFS forecast model that was ran on Sunday night at 6 pm.

The picture is a forecast of what the jet stream is predicted to look like at 500 millibars, or approximately 20,000 feet, on Tuesday night at 6 pm.

Look at the pattern of low pressure, high pressure, low pressure -- going from west to east...does it look like anything you might know...think Greek letters.

This type of pattern in the upper atmosphere is called an Omega Block because it looks like the greek letter Omega.

It is important for a meteorologist to notice this type of pattern in the upper atmosphere because it can create weather patterns that persist for several days.

Below is a picture from the same model run where I took the snapshot above...but this picture is for 180 hours out into the future -- which would be Sunday night at 6 pm. We are still looking at 500 mb, which is the jet stream level at approximately 20,000 feet.

It still shows an Omega Block -- only the ridge in the middle has flattened out just a bit. This could be a sign that the flow above wants to open up and the low pressures that have been sitting in place may move out.

So what does this mean exactly?

In the short term, areas under the troughs, or low pressure, will be cool and unsettled. The area under the high pressure, which is the ridge in the middle of the first picture, will be mostly on the quiet and mild side.

And if you are on the edges of the low pressure, it will be windy due to the pressure difference, or gradient, between the low pressures over the east and west and the high pressure in the middle.

So if this forecast verifies, it will be turning cooler, unsettled and windy for places like Salt Lake City, Denver, Chicago, Minneapolis, Detroit and New York this week.

While it should be fairly quiet and seasonal in places like Wichita, Kansas City, Dallas, Oklahoma City and Little Rock this week -- with the exception of Thursday when we will see the chance for a severe weather outbreak in the middle of the nation as the low pressure intensifies over the Rockies.

Stay tuned to the forecast over the next several days to see how this Omega block pattern plays out. Sometimes it resolves quickly and sometimes it can keep the flow in the upper atmosphere stagnant for several days.

Thursday, September 24, 2009

Jet Stream Turning Active?

Well taking a look at a few weather models, it looks like the jet stream, which has been parked over southern Canada for several days now, will start to dip south as we head into the month of October.

The first signs of this will come early next week as an area of low pressure develops over the Great Lakes.

It should bring some very windy conditions to the western Great Lakes by early next week.

Behind that low pressure will be an even bigger area of disturbed weather, or a trough, moving onshore in the Pacific Northwest by the 1st of October.

This should bring some cooler and unsettled weather into the Rockies for the first few days of October.

It looks like the southwest and western US will stay hot and dry under a ridge of high pressure. This isn't good for the fire conditions, especially across California.