Tuesday, June 20, 2017

New National Hurricane Center Advisory Policy in Play this Week

For days meteorologists have been watching a disturbance in the Gulf of Mexico. Today that disturbance became Tropical Storm Cindy, the third storm of this young season and concurrent with T.S. Brett in the Caribbean. This year the National Hurricane Center has the option of issuing the full range of advisories, watches, and warnings for disturbances that not yet a tropical cyclone but which  pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours. Under previous longstanding NWS policy, it was not been permitted to issue a hurricane or tropical storm watch or warning until after a tropical cyclone had formed. The purpose of these potential tropical cyclone advisories, watches, and warnings is to provide more lead time to those that will be impacted, hopefully minimizing injuries and saving lives.

Monday at 4:00 p.m. CDT the first advisory was issued for Potential Tropical Cyclone Three, now Tropical Storm Cindy. That advisory, which included a tropical storm warning and watch, was issued 18 hours earlier than would have been allowed in previous years.

Here is the forecast track of the storm as of 10:00 p.m. CDT. As the graphic states, hazardous conditions can occur outside the probable path of the storm. Typically with systems like this one, heavy rainfall and flooding is the biggest threat. 

To give you an idea of the extent of the storm, here is the Quantitative Precipitation Forecast for the next five days. Note that the heavy rain and likely most of the impacts, including some storm surge, will be well east of the storm track.

Over the next 72 hours the heaviest rain is expected over the Mississippi and southwest Alabama coast.

A complicating factor for the southeast is a frontal system which will likely slow to a crawl or stall out as it moves into the Tennessee Valley late in the week providing additional lift in the moisture-laden atmosphere associated with the remnants of Cindy. CoCoRaHS observers from eastern Texas to West Virginia will be busy measuring rain the rest of this week.

Forecast surface weather map for 7:00 a.m. CDT Saturday, June 24, 2017.

Only three previous Atlantic hurricane seasons on record have had two concurrent named storms in June prior to this year: 1909, 1959, 1968, and now 2017. In addition, T.S. Bret and T.S. Cindy became named storms only 21 hours apart, the shortest time between two June named storm formations in Atlantic on record. Late this afternoon Brett was downgraded to a tropical depression.

Tuesday, May 9, 2017

April Showers Bring Some Flowers and Lots of Flooding


As CoCoRaHS observers know, it's often a "feast or famine" situation. Heavy rain occurred the last few days of April and the first days of May from the southern Plains into the Ohio Valley. The reason was a slow-moving upper level system tapping into abundant moisture flowing northward from the Gulf of Mexico.

500 millibar map (~20,000 ft) for 7:00 a.m. CDT May 1, 2017
Over the six-day period from April 27-May 2 periods of heavy rain pounded an area from Oklahoma through the Ozarks of Missouri and Arkansas into the Ohio Valley.

Rainfall exceeded 12 inches in some locations with widespread 5-inch plus amounts. The axis of the heaviest amounts extended over the rolling terrain of the Ozarks in southern Missouri and northern Arkansas. A broad band of 10-inch totals extended through this area producing widespread flooding.

On the outskirts of St. Louis the Meramec River was pushed to a new record-flood level, last set less than two years ago on December 31, 2015. Preliminary data indicate the the river crested at Eureka, MO at 46.11 feet, compared to 46.05 feet in December 2015. In Valley Park, MO the river crested at 43.9 feet, just inches below the record crest of 44.1 feet set on December 31, 2015.

River stage on the Meramec River at Valley Park on May 2 and the forecast stages (dotted line)

Location of Valley Park, MO

I-44 and MO 141 at Valley Park, MO on May 2, 2017
Photo credit: KSDK on Facebook

The flooding near St. Louis closed portions of Interstates 44 and 55, at one time cutting off access to crossing the river. The flooding closed numerous roads and in some cases washed out large sections of pavement that will have to be replaced.

Section of I-44 at Hazelgreen.
Credit: MO DOT
Missouri road closures from flooding on May 2, 2017

Preliminary data suggest that the month will rank as the wettest April on record, with a statewide average just short of 10 inches of precipitation. That amounts to about one quarter of Missouri’s annual average.

In Arkansas flooding along the Black River and the White River is estimated to have caused in excess of $21 million in damage, and losses to agriculture, where some farmland was under four to eight feet of water, are estimated at $65 million. 36 Arkansas counties were declared disaster areas by Governor Asa Hutchinson

The upper level trough that brought the rain to the central U.S. then turned its attention to Canada as it lifted northeast and deepened.

500 millibar map for 7:00 a.m. CDT on May 6, 2017

Several days of heavy rain in southern Ontario, Quebec, and the Maritimes resulted in widespread flooding there. A number of cities, including Montreal, declared a state of emergency due to the flooding. One of the hardest hit areas was Gatineau, Quebec near the border of Ontario. Government offices were closed early this week with numerous roads flooded,.

The affects of the rain and flooding will continue for some time in the Mississippi and Ohio River Valleys. Flood crests are moving down the smaller rivers into the Mississippi and Ohio Rivers.

River stages in the Midwest as of 5/9/2017

Thursday, April 27, 2017

Can You Say "Pattern Change"?

Most of this spring east of the Rockies has been warm, coming on the heels of a mild winter. The growing season is running two to three weeks ahead of normal, but now Mother Nature is messing with us.

This week saw a lot of snow in the Rockies, not all that unusual even this late in spring. This morning flakes were flying in Minnesota and Wisconsin in the wake of a strong low and associated cold front.

Surface weather map at 1:00 p.m. CDT April 27. 2017

More snow is expected throughout the Rockies this weekend as cold air plunges south behind an intensifying low pressure system in the central Plains. This storm will be associated with an upper level closed low over the central U.S., one that will move very slowly over the weekend and early next week.

500  millibar level chart for 7:00 a.m. CDT Sunday, April 30, 2017

Heavy rain is expected this weekend from the Missouri Ozarks northeast through Illinois and Indiana. Severe weather is also likely from the southern Plains northeast into the Ohio River Valley. Flash flood watches are already in effect

Watches, warnings, and advisories in effect as of 9:00 p.m. April 27, 2017.

For the next week to ten days, and perhaps longer, the overall upper level pattern will be characterized by high pressure ridges off the west coast and the east coast, and a broad trough in the middle part of the country. That sets the stage for a cold, wet period for most of the U.S. east of the Mississippi River.

6-10 day temperature (left) and precipitation (right) outlooks from the Climate Prediction Center.

The next week is going to be a challenging one with heavy rainfall expected in the central U.S. CoCoRaHS rain gauges will get quite a workout from Oklahoma to Michigan and Nebraska east to Ohio. One thing to keep in mind when looking at these QPF maps is that this is a broad generalization of precipitation. The heavy amounts aren't uniformly distributed as these maps might indicate. "Precipitation doesn't fall the same on all."  (CoCoRaHS proverb). It certainly conveys the potential, however.

Quantitative Precipitation Forecast for the 7-day period ending 7:00 p.m. Thursday, May 4

After this weekend's system lifts out, another closed low is forecast to develop in the central U.S. late next week by one model.

500  millibar level chart for 7:00 a.m. CDT Friday, May 5, 2017

Wednesday, April 19, 2017

Weather Radio - A Must for Every Home

2017 severe weather reports.
We have already had a good bit of severe weather this season. Radar technology has improved with the advent of dual Doppler capabilities, and lead times for warnings have improved as well. Yet, there have already been 27 fatalities from tornadoes this year, and we are just getting into the peak of the season.

In the aftermath of storms we often see people interviewed who say "It struck without warning". What that statement usually means is "I wasn't aware of a warning", because in most cases a warning was not only issued, but issued with enough time to take shelter.  Everything from the forecast to the warning can be perfect, but if people aren't receiving the information then that information can't help them.

Outdoor warning sirens are exactly that. Their purpose is to warn people outside of impending severe weather, and are not intended to alert folks who are at home with the windows closed, the AC running, and the TV turned up.

The rapid development in phone technology means that those with cell phones can receive alerts of severe weather, provided the phone is on and you have it with you. What about in the middle of the night when you are sound asleep and a severe thunderstorm or tornado warning is issued?  The most reliable means of getting those warnings in time to take cover is a weather alert radio.

The NOAA Weather Radio All Hazards web page contains everything you need to know about NOAA Weather Radio, including consumer information about the radios, how to program your radio, and listing of radio frequencies and their status by county for every state. NOAA weather radio is even established in Puerto Rico, America Samoa, the U.S. Virgin Islands, Guam, and the N. Mariana Islands.

Weather radios come in portable models that you can take with you to outdoor events or other activities like hiking or camping. Some have crank and/or solar recharging capabilities. Desk models run on AC power with battery backup.  The prices of radios range from $25 to $135, with most desk models in the $40 to $75 range. One feature you should seriously consider is a radio with SAME (Specific Area Message Encoding) capability.  This allows users to receive messages only for their designated county or counties of interest rather than the entire broadcast area. This is especially nice at night, as your radio alert will not be activated for areas you have not selected. On the basic radios without SAME, any alert issued for any area covered by a specific transmitter will be triggered on the radio. Note that the weather radio program is officially the NOAA All Hazards Weather Radio. In addition to severe weather, NWR also broadcasts warning and post-event information for all types of natural, environmental, and public safety hazards.
My weather radio - ready and waiting.

There are only seven VHF frequencies used for NOAA Weather Radio transmissions in the U.S.

Weather radio frequencies in the U.S.

NOAA All Hazards Weather Radio coverage in the U.S.

NOAA Weather Radio broadcasts are also available via live streaming over the web.  A group of home weather station operators, website owners, CoCoRaHS volunteers, and spotters have developed a web site to live stream NOAA weather radio broadcasts across the country. This will not replace a weather radio in your home since there is no alerting capability, but it is a convenient way to access the broadcasts for other parts of your state or the country. The list of stations also include three from Canada. Visit http://noaaweatherradio.org/ for more information and to listen to live streams.

NOAA Weather Radio stations current available for live streaming on noaaweatherradio.org

Weather radio receivers will also work in Canada. Environment Canada, the government agency responsible for producing official forecasts, operates a network of "Weatheradio" transmitters which generally operate on the same frequencies as the U.S. NOAA Weather Radio network. More information on weather radio in Canada can be found here.

A weather radio should be in every home, just like a smoke detector. It should be located in a spot where you can hear it at night, preferably in the bedroom. Without being too dramatic - you're life could depend on it.

Thursday, April 13, 2017

Hail - It's in Our Name

CoCoRaHS' annual Hail Week is coming to a close. If you have been following this week's messages of the day you have seen how to measure hail, report it, and how to make a hail pad. Hail is a fascinating phenomena and there is a lot of information available if you want to learn more about it. The CoCoRaHS Hail page  has some information, and you can find a lot more information at Living With Weather- Hail on the Midwestern Regional Climate Center website.

This year's hail season was off to an early start with quite a few large hail events from late February on. Normally probabilities for significant hail very low at the end of February and only begin to ramp up in mid-March to early April. Here are the climatological probabilities for significant hail from the the NOAA Storm Prediction Center. The center of the high probabilities moves north through April and May, reaching a peak in late May. By early August probabilities are diminished and continue to diminish into early fall.

This year, hail has been frequent. So far CoCoRaHS observers have submitted hail reports on 65 of 102 days so far this year,just slightly ahead of last year's pace.  This map is a compilation of hail reports for the year to date from the Storm Prediction Center.

There have been some impressive and damaging storms so far this spring. What's caught my attention are the number of significant hail events (hail 2 inches or more) that have been reported.

There have been some impressive and damaging storms so far this spring. What's caught my attention are the number of significant hail events (hail 2 inches or more) that have been reported.

Hail photo credit Keri Bentley

 More baseballs in Texas on March 26.

Hail in Double Oak, TX on March 26.
Credit: @WxChaserBryan on Twitter

A nice assortment of hail sizes in eastern Illinois on March 20 .

Finally, not all hail falls as nice round balls. Here is a photo of some spiked hail that fell in Bolivar, TN on March 27.

Hail in Bolivar, TN on March 27.
Photo by Cynthia Thrasher Dickerson

Measuring hail is a core mission of CoCoRaHS, and the separate hail reports on the CoCoRaHS web site allow you to submit your hail information. There are a few things you need to know before measuring hail, and you can find that information in our "Measuring Hail" training animation. Here is a hail size reference and measuring guide you can download, print, and laminate for use. The rule on the bottom is to scale and fits on a 3x5 card. Make multiple copies and keep one at home, in the car, or at work.  

Monday, March 27, 2017

Web Page with GOES-16 Images - COD NexLab

Since my post last week about the GOES-16 satellite I became aware of a web site that features the latest images from this satellite. The College of DuPage (IL) NexLab site has an experimental page where you can view the latest images from GOES-16, including looping of images.

The NEXLAB Experimental Satellite page opens with the latest visible image displayed. So, if you are opening this at night there won't be anything to see. You can select one of the other images (Water Vapor, Infrared) to view. You can also select one of the sectors list on the left-hand side of the screen to view. The sector images for the visible images are at 0.5 km resolution, while the  resolution for the remaining images are 2 km.

Here is the visible image of the continental U.S. Sunday afternoon at 12:52 p.m. CDT.

Here is the corresponding surface weather map for 1:00 p.m. CDT Sunday.


You can clearly see the circulation around the low pressure system over the Midwest.If you look at the enlarged satellite image (click on image to open full view) you can see the thunderstorms developing along the warm front in Oklahoma.

Note that at this time you can only access this page by the direct link above. There is no link from the NexLab main page or the Satellite/Radar Products page though I was told that there will be a link in the near future. While you're at it check out some of the other weather analysis tools on the web site.

Wednesday, March 22, 2017

A New Weather Eye in the Sky

GOES-16, atop a Atlas V booster, leaves the launch pad.
Credit: NOAA
Last fall members of the meteorological community anxiously awaited the launch of a new weather satellite, one that could revolutionize weather satellite science. Dubbed the GOES-R at that time the satellite was equipped with state-of-the-art imaging equipment and array of sensors. GOES-R was originally scheduled to launch on November 4, 2016. We collectively held our breath in early October when Hurricane Matthew clobbered eastern Florida as it moved north just off the coast. Hurricane Matthew had a close encounter with the Kennedy Space Center. The satellite was safely secured and escaped harm, but damage to Cape Canaveral and at the Kennedy Space Center forced the launch date to November 16. On November 3 the launch date was pushed to November 19 because of a minor issue with the Atlas V booster. Finally at 6:42 p.m. EST on November 19 the GOES-R was launched into space.

Credit: NOAA
On November 29 GOES-R reached geostationary orbit at an altitude of 22,000 miles and officially designated GOES-16. Testing and calibration of the satellite systems began at that point and is continuing. Though not yet officially operational (data is preliminary and undergoing validation), GOES-16 images and products seen so far are nothing short of spectacular.

Not only is GOES-16 monitoring our terrestrial weather, it is also monitoring space weather. There are sensors on board for observing solar flares (Ultraviolet and X-Ray Irradiance Sensors, the Solar Ultraviolet Imager (SUVI), monitoring the flux of charged particles associated with the Aurora Borealis (Environment In-Situ Suite (SEISS), and a new, faster magnetometer for monitoring the earth's magnetic field.

The cool stuff related to terrestrial weather includes the Geostationary Lightning Mapper (GLM), the first lightning detector in geostationary orbit. It monitors for lightning flashes in the Western Hemisphere, both in-cloud lightning strikes and cloud-to-ground strikes.

The Advanced Baseline Imager (ABI) is the primary imaging instrument on GOES-16. It will provide three times more spectral information, four times the spatial resolution, and more than five times faster temporal coverage than the current system. The increase of both speed and resolution will be a huge advantage to forecasters. Mesoscale (1000 x 1000 km) spatial resolution will be 2 kilometers, with updates as often as every 30 seconds. This will have a tremendous positive impact on the ability of forecasters to monitor and respond to developing weather situations.

You may have already seen images from GOES-16 on the web. The difference on visible images is astounding, like the difference between your old TV and the latest HD TV image. Here is one of those images.

Visible image from GOES-16 on the morning of March 7, 2017. This is one image captured from a loop.
Credit: CIRA/RAMMB at Colorado State University

This image is one from a loop of images assembled by the Cooperative Institute for Research in the Atmosphere (CIRA)/Regional and Mesoscale Modeling Branch at Colorado State University in Fort Collins. The amount of detail is amazing. These high resolution images from GOES-16 have even captured the smoke from small wildfires. For a full-size high resolution of this image and the image loop, click here.

NOAA emphasizes that "the GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing." The switch to operational status should occur this summer or in the fall.

If you would like to view the different types of GOES-16 satellite images there is a nice sampling of GOES-16 images and videos at this link.

Wednesday, March 1, 2017

Winter 2016-2017 Recap: The Winter that Mostly Wasn't

We put the wraps on climatological winter (December-February) yesterday, although winter weather is not out of the question in many parts of the country over the next two to four weeks. Climatological winter was capped off by very springlike weather, including a severe weather outbreak in the central U.S.

We can take a quick look at what winter has been like across the country using the latest map of the Accumulated Winter Season Severity Index. Most of the country has experienced a mild winter, with the only notable exception the northwestern U.S. and far northern New England. Omaha, NE and Des Moines, IA are on track for record mild winters. Note that the AWSSI continues to be accumulated until the last day with a maximum temperature of 32°F, the last day with measurable snow, or the last day with measurable snow on the ground. The factors that are keeping other locations from having record mild winters are snow early in the season and several periods of cold weather in December and January.

The Accumulated Winter Severity Index as of March 1, 2017.
The maps of the average temperature departure from normal for December through January depict very much the same pattern. Average temperatures for the period were above normal from the Plains to the east coast. Colder than normal temperatures occurred in the northwestern quarter of the country.

The map of maximum temperature departures mimics the mean temperature map, but the map of minimum temperature departures shows a larger area of warmer than normal temperatures, particularly in the southwestern U.S.

On a monthly basis it's clear that February was a huge contributor to the warmer than normal winter. Final numbers aren't all in yet, but many locations in the central and eastern U.S. will find that this February will be the warmest on record.

Click on map to see larger version

The precipitation map does not contain too many surprises. Precipitation in most of the western U.S. was much above normal. It was a much drier than normal winter in a bulls-eye in the central U.S. extending from northern Arkansas through Missouri and Illinois. It was also dry in the mid-Atlantic and Florida.

Snowfall during climatological winter was well above normal from the northern Plains to the Sierras, and near to above normal in much of New England. Snow season (July 1- June 30) is not yet over and many locations could yet see some substantial snowfall in the spring. There definitely has been a snow drought in much of the central U.S. Chicago did not have any snow cover in January or February for the first time in the 146 years.

CoCoRaHS observations were included in both the precipitation and snowfall maps.

Ice cover on the Great Lakes is only 10 percent of what it usually is on this date. The average coverage on March 1 is about 43 percent, and as of today it was 4.5 percent.

Ice cover on the Great Lakes as of 2/28/2017

The warm weather in February, especially the last ten days of the month, is particularly problematic for vegetation this spring. The warm weather coaxed trees and bushes to bud and plants to emerge from the soil much earlier than normal. The U.S. National Phenology Network data shows that "spring" is almost three weeks ahead of schedule as far north as the Ohio Valley. The risk of freezing weather is pretty much a sure thing for the next several weeks, and the possibility of damage to emerged vegetation is rather high.

Finally, the severe weather season got off to an early start in the Midwest yesterday with an outbreak of severe weather across the Midwest. Several strong tornadoes caused significant damage and several fatalities in Illinois, Missouri, and Indiana. The severe threat moved east today with severe weather from new York south through Alabama.

Wednesday, February 22, 2017

A February Like No Other?

This week of unseasonably and crazy warm weather is like kryptonite to a winter fan like myself. It paralyzes me from doing much at all. The calendar says February, but outside it's all April. It's not just one day which you briefly enjoy before the reality of winter sets in again. It's been a whole week, and we have two more days to go here (at least in the Midwest). Outdoor projects that were suspended in late fall are trying to pull me outside but I'm still in winter mode and trying to resist. Fortunately, or unfortunately depending on your viewpoint, it's all coming to an end soon.

This stretch of warm weather has been unusual not just in its intensity and duration. For a large portion of the central U.S. to have warm and sunny days in winter is very unusual. Typical warm-ups in winter tend to occur in advance of large weather systems moving out of the Rockies. Strong southerly winds will pull warm air well northward at times, but it is often moisture-laden and we end up with mild but  cloudy or partly cloudy days. Combine that with stiff winds and yes, it's mild, but not the kind of days we have enjoyed this week. This week of late fall-like (or spring-like, if you prefer) is clearly something most of us have never experienced in February.

Earlier this month it was downright hot in the southern Plains. High temperatures in northern Texas and southwestern Oklahoma were in the 90s, and it was confirmed one location topped out at 99°F! In February!

Maximum temperatures across Oklahoma on February 11, 2017.
Credit: Oklahoma Mesonet

Record high temperatures were recorded from New Mexico to the southeast coast. While that was occurring, New England was digging out of another snowstorm.

The exceptional warmth is not limited to the central part of the country, of course. Even Florida has been relatively warm. Miami, FL has not yet recorded a single day below 50° since December 1. This has never happened in the Miami period of record which dates back to 1896. (Thanks to John Morales, Chief Meteorologist at WTVJ NBC-6 in Miami for tweeting this fact.)

This current warm spell began late last week in the central and southern Plains and then expanded east  over the weekend and this week. The animation below shows the temperature map at 2:00 p..m CST starting on Friday, February 16 through today.  The area of green (55°F contour) was associated with the upper level system that moved across the southern U.S. last weekend.

 Here is the temperature map for 2:00 p.m. CST today. Note that it was warmer in Milwaukee, WI (69°F) than in Miami, FL (67°F)!

This map shows where record highs had occurred or were close to occurring today as of 2:00 p.m. CST.

While the warm weather is most welcome by many people, it's not without some problems. The very early warmth and its duration is coaxing plants to respond well before we are out of the danger for freezing weather.

The USA National Phenology Network, which like CoCoRaHS utilizes volunteers observers, tracks the start of the spring season across the country using models called the Spring Leaf and Bloom Indices. The Spring Leaf Index is a synthetic measure of these early season events in plants, based on recent temperature conditions. The index allows the NPN to track the progress of spring across the country.

The latest Spring Leaf Index map shows that the changes seen with the warm weather are about two to three weeks ahead of normal. It's still February, and much of the country is a long way from seeing the last freezing temperatures.

This maps below shows the distribution of the date of the earliest last freeze in the spring, and the median date of the last freeze in the spring.

Ten years ago, in the spring of 2007, much of the central U.S. experienced a very warm end to March and first days of April, with numerous record high temperatures and record high minimum temperatures recorded. High temperatures in the low to mid 80s were measured as far north as central Wisconsin. Unfortunately a major winter storm the first week of April pulled in cold air that resulted in a hard freeze across most of the Midwest. Subzero readings occurred in northern Minnesota. Many plants and fruit trees had budded in the warm March weather, and the hard freeze ended up extensively damaging fruit trees, grapes, and other plants. You can read more about the weather the first week of April 2007 here.

Enjoy this unusual warm weather while it lasts.

Meanwhile, noon temperatures today in west-central Alaska ranged from -10°F to -40°F.