Wintry Weather Showing Up On Maps

Well, it's that time of year for more and more of the country. Here in Colorado, we have already seen wintry weather a few times since late September, but that is normal for us.

Now wintry weather is showing up in places like upstate New York.

There were several reports from Monday of sleet and a few flakes of snow as showers moved off Lake Ontario.

In addition, the first killing freeze hit the area putting an end to the growing season across portions of the northeast.

Before too long, we'll see the first winter storm of the year move across the northern tier of the US -- November is fair game for this.

Tropical Storm Noel continues to ravage Hispanola. Nearly 2 dozen have died from the heavy rain and flash flooding/mudslides.

South Florida is still on alert as this slow moving storm churns erratically to the north.

Noel Update; Welcome Alabama, Kentucky

Tropical Storm Noel is moving over western Cuba and is dropping extremely heavy rainfall over Hispanola.

The storm has been moving a bit further west than previously anticipated, which means once it emerges over water and takes a northerly turn, it could graze south Florida over the next 48 hours.

We'll wait and see.

There are about a dozen or so CoCoRaHS observers along the southeast Florida coast so if Noel does move in, we should see some great precipitation data.

Meanwhile, speaking of data, we are now getting reports from both Alabama and Kentcuky. Welcome observers!

The weather is quiet nationwide, with most reporting stations dry yesterday and today. That is actually pretty typical of this time of the year, but it won't be long before the jet stream arrives in the US and hangs around for several weeks, bringing active winter weather, including the wet season to southern California.

It is getting cooler and cooler with each passing day. I noticed there were frost and freeze advisories scattered around the nation this morning, including across portions of Tennessee and North Carolina.

Tropical Storm Noel Forms in Carribbean

Tropical Storm Noel formed over the weekend from an area of disturbed weather south of Hispanola.

The storm peaked with winds gusting over 50 mph late Sunday, but now are dropping back a bit as the center moves over land.

Although minimal in terms of winds, this storm is going to drop life-threatening rainfall over Haiti and the island of Hispanola.

Some places could see 10 to 20 inches of rain with isolated amounts up to 30 inches.

Due to the mountainous terrain, mudslides are likely.

I am sure Noel will make a few headlines over the next day or so.

The storm is expected to move north toward the Bahamas, but current forecasts suggest it will curve eastward away from Florida and the USA.

In some aspects it'd be nice if Noel could stay minimal but move into the southeast United States because they so desperately need the rain.

US Weather Summary

Rain and unsettled weather will continue across the southeast states today. Some locations in the drought stricken states of Alabama, Georgia and Tennessee have seen 2 days in a row with rainfall.

Meanwhile, a new storm system is set to come onshore in the Pacific Northwest in the next 24 hours.

It will sweep across the country over the weekend and into early next week with cooler weather and some precipitation.

In southern California, winds are slowly weakening and the humidity is coming up -- GREAT news for the fire fighters!

There are unfortunately still several days of fire fighting ahead -- but at least conditions are showing signs of improvement -- which is the best news we have heard in several days.

Skies Open In Drought Plagued Areas

My goodness -- today's CoCoRaHS reports must be some kind of record. I'll have to email Nolan to ask.

There were just over 350 reports of 1.00" or more as of 10:30 am MDT today -- 356 to be exact.

And what is so wonderful is many of those reports are from Tennessee and Alabama.

In fact, 216 of those reports were from Tennessee alone! Rain gauges were hard at work on Monday and that is a GOOD THING for this drought stricken state.

Two stations in Montgomery County picked up over 6.00 inches of rain yesterday, and one in Humphreys did too.

One observer in Davidson County, Tennessee said it best in the daily comment reports --- WHOOPEE!!!

Another observer near Spring Hill, Tennessee said there is water in the pond again -- my goodness that is great news.

Much Needed Rain Heading For The S.E. States

Good morning from a chilly Octo - brrrrrrr morning in Denver. Lows here ranged from 20 degrees over the southeast metro where the most snow fell to about 27 degrees downtown and out at the international airport.

I was just looking at the forecast for some southern cities, including Atlanta, Little Rock, Memphis, Birmingham and Mobile.

They all have a 100% chance of rain and thunderstorms in the forecast!! This is excellent news for these drought stricken locations.

I am not sure how much of a chance you get to follow the news, but some of these areas are close to just having a few months of water supply left, according to reports.

It will take days of rain to put a dent in the drought there, but at this point -- every single drop counts!!

One area that is expecting heavy rain, but doesn't need it, is the Pensacola area. Just last week they saw up to 12 inches of rain.

It will be interesting to watch the CoCoRaHS maps for both Florida and Tennessee over the next few days.

Alabama will be coming online soon enough -- I believe November 1.

Fall In The Rockies

Fall in the Rockies means rapidly changing weather, in addition to other things like the beautiful changing aspen, hibernating bears, etc.

Less than 24 hours ago I was riding my bike around a suburban Denver metro area park enjoying a high of 80 degrees.

Now I am sitting at my computer on Sunday morning watching it snow outside.

The snow in Denver is almost right on time -- our average first snow falls on October 19. Today is the 21st.

The beauty is it will be leave almost as fast as it came with sunny skies and a return into the 50s by tomorrow.

My family in Arkansas says oh my gosh, how do you deal with that. We'd be stuck in the house, maybe for a few days!! It's true, just mention the word flurry in the forecast there and the store's shelves go bare. ;-)

Skies Open Over NW Florida

Wow-we-wow! Did you see the Florida maps today?

Not only did a tornado touch down on Thursday and move right through downtown Pensacola, but heavy rains hammered the region too.

Over a dozen stations picked up over a half-foot of rain on Thursday, with station FL-ES-2 recording a whopping 12.10 inches of rain for the observation period.

That is more than an entire year's worth of rain for many locations here in the interior west!

Elsewhere, it was an active day for severe weather once again. Hail hammered the Chicagoland area during rush hour and tornadoes moved through portions of Michigan and Kentucky.

Nice Job CoCoRaHS Observers

WOW -- there were several intense precipitation reports filed on Wednesday from the midwestern states. GREAT JOB!

One Missouri station saw almost an inch of rain in just 15 minutes!

As I am writing this blog at 1:04 am Thursday, the radar is lit up like a Christmas tree in the Ohio River Valley -- I bet there are some rain gauges in Illinois and Indiana overflowing into the outer cylinder even as I type!

I wish I were there.

Wednesday was a violent day with severe weather -- nearly 200 reports of hail and wind. There was over a dozen tornadoes, with the most touchdowns in southwest Missouri. Damage was reported in and around the Springfield vicinity.

2.5" hail fell near Medicine Lodge, Kansas.

74 mph winds screamed through Muskogee, Oklahoma.

More severe weather is expected today in the Ohio River Valley.

On the backside of the storm system, highs winds and chilly temperatures can be found in the Rockies, along with some snow along the Continental Divide of the Rockies.

Fall Severe Weather Outbreak

WOW! Take a look at the regional surface map for the southern plains today. (the link is down in yesterday's blog entry)

Southeast winds have transported copious amounts of moisture into the southern plains. Dewpoint temperatures (a measure of the moisture available) are in the upper 60s to middle 70s.

Above the ground at jet stream level, winds are blowing out of the southwest as a storm system moves in along with a cold front.

This change of direction in the wind as you go up in height is called wind shear (southeast at the surface to southwest aloft).

Severe thunderstorms in this area will potentially rotate due to this wind shear and thus there is a pretty good chance for tornadoes today in Oklahoma, Arkansas, Kansas and Oklahoma.

As of 8 am there is already a huge line of showers and storms from Kansas City, MO to Oklahoma City, OK -- as well as a Tornado Watch for most of central OK.

There has already been one intense rain report filed this morning from Butler County, Kansas. The observer 7.5 SW of Leon saw 0.88 inches of rain in one hour with more moving in according to the report. Remember you can look at intense rain or hail reports too by clicking on View Data at the top of the CoCoRaHS page. Then scroll down and click on the report of your choice.

COCORAHS OBSERVER ALERT: Our observers in Missouri, Kansas and esp. Oklahoma need to be alert to changing weather conditions today and if you can safely do so, be prepared to file intense rain and hail reports via CoCoRaHS. Deploy all hailpads in these areas and make sure the rain gauge is ready to measure! Tomorrow this threat may shift to our observers in Illinois and Indiana.

As exciting as the weather can be, and as much as we want any and all repots, please only do so if you can safely.

Moderate Risk For Severe Weather

A new storm system will cross the Rockies over the next 36 hours and move into the southern plains by Wednesday.

It is anticipated that it will generate a pretty big outbreak of severe weather across eastern Kansas and Oklahoma, extending into southern Missouri and portions of Arkansas.

The severe weather threat will then shift into the Ohio River Valley by Thursday.

If you live in these areas, you may want to keep an eye on the Storms Prediction Center Web site by clicking here.

Look under convective outlook (listed as Conv. Outlook) in the menu across the top of the page to see the highest threat areas.

Here is another nice resource on the internet to see the current weather observations on a regional basis. Click here.

One that window opens, there should be a map of the US with all kinds of dots representing the most recently reoprted weather conditions at that location.

Green dots mean clear skies, where the blue and red dots are clustered -- well that is where the clouds are.

You will see a few locations are highlighted, such as Little Rock (LIT) and Wichita (ITC). Click one of those and it will bring up a regional map of current weather.

These maps are helpful because you can see the overall flow of wind through the wind vectors. Check out the southern plains states today -- a huge flow of southerly and southwesterly winds overall (at least when I checked while writing this blog Tuesday morning).

Those winds are transporting low and mid-level moisture up into the severe weather target zone on Wednesday.

First Snow Of The Season

Do you know the average date of first snowfall for your community? Here in Denver, we typically see our first snowfall by October 19.

If you don't know, check online (usually your National Weather Service office) has this information on the climate page for major reporting stations in your area.

Take some time to find out and then hold a little fun contest with your friends, family or co-workers to see who can guess the when the first snow of the season will fall.

Hail In West Texas

There were about a dozen reports of hail in west Texas on Thursday. Some of it was quite large, esp. near the town of Maple along the New Mexico state line.

I love reading the daily comment reports on CoCoRaHS -- I see another Maryland observer seeing the first rainfall in 26 days.

There is also a Tennessee observer reporting their catfish are beaching themselves and dying due to the drought. That is so sad, but also a great piece of information to document the extent of this drought in the southeast.

And probably my most favorite from Friday include this report from the observer IL-DP-32 near Lisle, Illinois.

"Still dry my last record of rain was on Aug.25,07 That's 48 days of no rain. Noway near what folks in the southeast are living with but our dryness is putting stress on many plant species. Don't think I would have noticed if I wasn't reading percepitation for CoCoRaHS."

It is great to see so many of you using the CoCoRaHS website interactively. I hope you enjoy the blog! See you Monday.

It's Cooling Down

A taste of fall has swept much of the nation. Some observers in northern Indiana and Illinois reported a few flakes of snow this morning. Quite the change from the record breaking, summer-like heat of this past weekend!

While observers in Florida are reporting lower humidity for the first time in quite a while.

Folks in Maryland are saying they can't recall the last time there were 2 days of precipitation.

And some observers in southeast Colorado reported near zero visibility due to fog on Thursday morning.

Isn't this a fun time of the year! The weather change is absolutely awesome.

Check out the daily comment reports for more.

Dry Times

October is usually a dry month for many parts of the country, and Tuesday was no exception.

Out of over 2000 CoCoRahS reports, only about 25% saw any precipitation.

Most of the totals were on the light side, but there was a few drenchers. 4 stations saw between 2 and 3 inches of rain. Those were in Pennsylvania and extreme sotuh Texas.

Two observers in Cameron County, Texas were able to file intense rain reports. One of those reported 0.90 inches of rain in 30 minutes! That was just northeast of Los Fresnos.

Yesterday I talked about a cold front sweeping across the nation. It looks like another one will move into the northwest later this week.

I know here in Denver we are looking at 70s all week, falling into the 50s by Sunday with light rain showers. That means light snow is once again possible for the mountains.

Time will tell how much progress that front makes across the country as we head into next week.

Record Highs, October Chill

One of the first major cold fronts of the fall season is sweeping across the nation today.

Here in Denver, highs reached well into the 80s on Saturday. I was out to dinner in the evening when FROPA happened.

FROPA means Frontal Passage in meteorology lingo.

I literally arrived to the restaurant around 8:15 pm or so and was walking toward the open area to meet a friend. We were both on cell phones walking toward each other.

All of a sudden the wind kicked up, the visibility lowered and the temperature dropped like a rock. I said wow, there was the cold front!

I went back to look at my car thermometer and it had went from the upper 70s when I arrived to the upper 50s.

After dinner, it was down to 43 degrees and overnight we bottomed out between 28 and 32 degrees around town.

I love this time of year!

Other cities probably have like stories, though maybe not quite as dramatic. That is one of the beautiful things about Colorado weather. The changes are usually very abrupt.

Back east, other midwest cities saw major cool downs. Places like Minneapolis and Chicago went from record highs in the 80s to near 90 degrees over the weekend to highs only in the 50s and 60s.

Extreme northern Minnesota even saw a little light snow Monday night.

More About Dew

A CoCoRaHS observer left me a comment yesterday asking if dew contributes much to the water table over the long run? And Does it decrease evaporation so that water already IN the soil is not touched?

The answers are both no.

Dew is not precipitation -- meaning it doesn't fall from the clouds. It is a process that happens at the surface. What you are seeing is the process of a gas (water vapor) condensing into a liquid (dew or if it is cold enough -- frost)

Dew forms on surfaces that do not receive heat conducted from the soils of the earth. (roof tops, car tops, grass, plants, etc.)

SO while it does benefit the surfaces it forms on (meaning it is a brief little drink of water for plants and grass) -- the key words are brief and little.

The dew or frost forms during the coldest part of the night (just prior to and at sunrise) and goes away almost as fast as it forms. As soon as the sun gets above the horizon and begins to warm the air temperature a bit, dew and frost will go back into a gas (water vapor).

So it is a fast and short-lived process, and there really isn't enough of it to make a difference in the water table, and because it is just on the surface, it comes and goes so fast that it doesn't really slow down the normal processes of evaporation.

Now having said that, if you are seeing a lot of frost and dew -- you are probably in a climate that is somewhat moist overall -- so evaporation is going to be slower than in a drier climate.

Let me explain...

As a kid growing up in Arkansas, dew or frost seemed to be a part of almost every single day. And it would stay on the ground through a good chunk of the morning -- say until 10 am. But Arkansas is a very moist climate overall.

Here in Colorado, we don't see dew or frost all that often. And when we do, it evaporates within minutes of the sun rising. We are a very arid climate overall.

It all ties back to the climate. The less moisture (or water vapor) in the air, the less the dew or frost potential will be.

You can gauge how much water vapor is in the air by either looking at the humidity or dewpoint value on your local weather report.

If that isn't available, something else you can look at for a gauge is simply the daily high and low for a location.

The greater the difference in your temperatures between day and night -- the drier the air. The closer the daily high and low temperature are, the more moist the air is.

Dry air cools and warms much much faster than moist air.

That is why places here in the west have such a large spread in daily temperature. That is called the diurnal range. Denver often sees a daily temperature spread of 35 to 50 degrees. Yesterday our high was 83 and the low was 39. That is a 44 degree spread. A great example of our very dry climate.

Back east -- let's say Nashville, Tennessee -- their high was 85 and the low was 71. A difference of only 14 degrees. A great example of a humid and wetter climate.

With nothing more than a daily high and low temperature for a city, you can tell a lot about the weather and climate. The closer the high and low, the more moisture there is. There was probably morning dew and filtered sunshine throughout the day due to passing clouds in Nashville yesterday. Maybe even some patchy overnight fog!

In Denver, just looking at that temperature spread -- you can pretty much bet there were clear skies, maybe a few high passing clouds, and plenty of sun! It was darn dry.

The Temperature & Dewpoint

Thursday morning was a foggy start for many in the midwest, Great Lakes and northeast. There were also several reports of heavy dew in the comments today.

You can be your own forecaster if you will at deciding if you have a good chance of seeing morning fog or heavy dew by checking the latest weather observation for your area before going to bed.

What you will want to do is look at the temperature and the dewpoint temperature. The closer they are, the higher the chance for fog and dew. If they are equal, that means to air is completely saturated and you will likely have total cloud cover.

There are definitely some other factors involved, namely wind.

If wind is present, it keeps the atmosphere stirred up and would inhibit fog formation.

Here is an example: If the dewpoint is 51 degrees at 10 pm, and you are expecting an overnight low of 52 -- as long as drier air doesn't move in overnight (meaning the dewpoint temperature doesn't fall) and the wind is calm, then you will probably wake up to a muggy, damp morning with dew and fog.

If you have that same scenario with a decent breeze, you will wake up to a grey morning with a deck of clouds overhead, but the wind will prevent the fog from forming most likely at the surface.

But say the low drops to 52 and drier air moves in during the night taking the dewpoint to 40 degrees, you will probably wake up to a sunny morning with just some scattered clouds.

The dewpoint temperature will never be higher than the air temperature -- that would be called super-saturation and it doesn't happen.

More Florida Rains

Wow, take a look at the maps for Florida today! In Nolan's most recent email, he said that this state would be one of the most interesting in terms of precipitation patterns and by golly, I think he is right!

An area of low pressure off the east coast dumped tremendous amounts of rainfall in the Jacksonville area on Tuesday.

One station 8.4 miles SSE of Jacksonville picked up a whopping 7.83 inches of rain!

Those of us here in west would have to build an arc to survive that kind of rainfall.

Heavy rain also fell in the Tampa vicinity.

Meanwhile, in the midwest, some CoCoRaHS observers were too close for comfort as severe weather kicked off over a dozen tornadoes -- mostly in Missouri, but a few in Iowa and Illinois.

There was damage and injuries unfortunately from the outbreak.

If you have time, go to View Data at the top of the CoCoRaHS page and then daily comment reports. Choose Missouri and read through some of the comments. A few observers give a play by play report of the precipitation and storms, including times.

It almost makes you feel like you were there watching it unfold.

Gully Washer In Florida

Check out today's map of precipitation reports from Florida.

Look along the east coast in Brevard County -- the observer 2.6 miles SSE of Palm Bay picked up 5.70 inches of rain -- saying it was the most rain since the hurricanes of 2004.

Even with only 2 reports coming from the county of Brevard, this is a PERFECT example of how awesome the CoCoRaHS network is at showing the footprints left behind from weather, and just how isolated weather can be.

Just a matter of miles up the coast from the 5.70 inch rainfall in the same county, the local observer reported less than an inch of rain.

I am sure you have seen examples of this where you live, and if you haven't -- try and make it a point to check the local maps where you live the next time you have precipitation -- you will be in awe every single time at what Mother Nature can do!

Severe Storms Move Across Plains

I was in southern Missouri on Sunday afternoon, and although I left before the severe storms moved through, I did see the clouds moving in from the southwest and felt the gusty winds at the surface from the southeast.

Some of the remnants from those storms actually moved through central Arkansas around sunrise this morning. It was fun waking up to the sound of moderate rain. It took me back to when I was a kid.

(It is so rare to wake up to moderate rain or thundershowers in Colorado!)

Portions of Missouri and Iowa saw over an inch of rain on Sunday, as did a few stations in Wisconsin, Florida, Texas, Illinois and South Dakota.

I am heading back to Denver this afternoon so will be able to do a little bit better job of posting once I am back home and in my routine.