Very Heavy Snow Now in Nebraska and Kansas

As expected, the heaviest snows (rates of 1-2″ per hour) have shifted into northern Kansas and southern Nebraska. The Mayor of Lincoln has declared a state of emergency effective at 6am Saturday.

Click to enlarge. AccuWeather regional weather. 

In Texas, a damaging tornado has occurred in the Bryan-College Station area. Don’t have details as yet.

1:40pm Friday Storm Update

A tornado watch has been issued for north central Texas and parts of southern Oklahoma until 8pm.

Strong thunderstorms are now developing SSE of Wichita Falls.

As much as 36″ of snow have fallen in some of the suburbs west of Denver with about a foot at the Denver Airport.

The forecasts below are the probabilities  of 2″ or more of snow accumulating starting at 6pm this (Friday) evening through 6pm Sunday evening.

And, below, is the probability of 8″ or more accumulating during that period. It does not include snow that has already fallen.

Please take these forecasts into consideration when planning your travel!

One More Update

Lots going on that is important.

Courtesy of Dr. Ryan Maue, here is the 6pm snow cover this evening:

And, the forecast snow cover at 6am Sunday, scale at right. There is a small spot of 20″ along I-80 in south central Nebraska! Please take these forecasts into account if you are planning travel!

click to enlarge

Immediately below is the 10:03pm radar showing a thunderstorm with large hail moving ENE across northern Oklahoma toward southern Kansas.

Finally, there are at least a half dozen severe thunderstorm warnings for large hail farther southwest:

The above AccuWeather regional radar shows the extent of the thunderstorms that are moving ENE to NE.
Below, is the summary of watches and warnings (see below for color code) at 10:03pm. The amber colors in west Texas and Oklahoma are severe thunderstorm warnings.

Last update of the night — honest this time!!

Latest Weather Update

The high-resolution model from the National Weather Service shows 8 to 12″ of snow by Colorado sunrise (6am MST):

The swipe from Lubbock to Wichita that shows up as snow is the model sensing hail. Yes, there could be hail overnight. Below is the forecast radar for 1am CDT:

The current (7:30pm CST) AccuWeather winterized regional radar shows thunderstorms developing in the Texas Panhandle that could cause large hail overnight as they move northeast.

 The strongest storms right now are the ones just west of Amarillo.

UPDATE: 7:40PM. National Weather Service has issued a severe thunderstorm watch for large hail and damaging winds until 3am. 

Blizzard Warning and Tornado Threat

Orange = blizzard warning. Lime green = blizzard watch. Pink = winter storm warning. Dark blue = winter  storm watch.

Here is AccuWeather’s snowfall forecast. Many roads will become impassible in these areas. Note: It will continue so snow near the Mississippi River past the time of this map.

Finally, there is a small area with a significant tornado threat late this afternoon and tonight:

NWS Storm Prediction Center Forecast. 5% is considered significant. 

While any tornadoes are certainly unwelcome, the moisture from this system in the winter wheat belt will be welcome indeed. This is the 5-day precipitation amount forecast from the NWS.

The Amazingly Good Forecasts of the Boxing Day Blizzard of 2010

My AccuWeather colleague, Jesse Ferrell, just tweeted copies of our forecast maps for the 2010 record Boxing Day Blizzard.  Here is what we forecast on December 22 for a storm that began in the NYC area Christmas evening.

And, here is what occurred:

Forecast from LAST YEAR at this time. Not a current forecast.

Jesse tells the full story of our forecasts here.

A frequent theme of this blog is how reliable forecasts of all types of major storms have become. We (and, in this case, Mayor Bloomberg) ignore them at our peril!

Fortunately, nothing like this is in our forecasts for the contiguous 48 states for Christmas, 2011.’

NOTE: I had an incorrect graphic up earlier. Fixed now. Apologize for the error.

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How Good, or Bad, Were the Blizzard Forecasts? Part 1.

One way meteorologists get better at what they do is by holding themselves accountable for their forecasts by validating them after the fact.

Here is the National Weather Service’s total snowfall map as of midnight CST this morning.

click to enlarge

And, here is a detailed map of the High Plains where the heaviest snows fell.

The dark blue area in southeast Colorado is more than twenty inches.

This blog provided its first alert of a major winter storm in the Plains at 7:52pm Friday evening by linking to Mike Umschied’s blog. I followed up with my own analysis of the potential storm at 9:18pm. It included this graphic for up to 11″ that you can compare it to the NWS graphic (above) of actual snowfall.

This initial forecast, about 48 hours before the snow started falling in New Mexico, isn’t too bad but is too far southeast. Because of the holiday travel period, I saw this posting mostly as a “heads up.” My sense is it served its purpose.

The next update was 9:11am Saturday. Because of the uncertainty over the path of the storm, I presented probability maps so readers could gauge their risk as I thought it was too early to plot out an exact path.

I posted an update at 3:19pm Saturday, here is a reproduction of the most important part (click to enlarge):

I presented the northwesternmost and southeasternmost models and provided a list of roads (immediately above) with advice. This turned out to be exactly correct: All of the listed roads were closed.

Sunday evening, I posted the following:

As Interstate 70 was indeed closed between Salina and Colby (actually, WaKeeney to Colby), this was a very good forecast as was the forecast map. I was late catching on to the heaviest snow actually falling in southeast Colorado and the final map over forecast the amount of snow in parts of western Kansas by several inches.

The snow started in New Mexico shortly after the above “storm total” map was posted. So, from this point on, I was updating and nowcasting (short term forecasting) the storm. The above was the final map depicting the amount of snow. You can compare it to what actually fell. I believe they compare quite well but please form your own opinion.

In Part 2, I’ll discuss the response to the forecasts.

Blizzard Update – What to Do if Stuck

The orange area is where the blizzard warning continues. Essentially all roads are closed within the blizzard warning area.

Pink is a winter storm warning and blue is a winter weather advisory (a lesser condition). 
If you are on the internet, stuck in the snow, here is what to do.
The map below is the forecast additional accumulations from 5am this morning to 3pm this afternoon:

Wind gusts between 30 and 35 mph are now common with a few gusts to 40 mph.  
Believe it or not, more snow could occur later in the week in these areas. More on that late today.

The Storm at 6pm

Here is the AccuWeather regional radar at 6pm:

A line thunderstorms is moving east across eastern Texas. Strong winds are possible with a few of the strong thunderstorms. The purple is the transition zone from rain (east) to snow (shades of light blue, west). Very heavy rains are occurring over eastern Kansas.

The blizzard is in full force from northeast New Mexico to central Kansas. Orange = blizzard warning on the map below.

Pink = winter storm warning. Blue = winter weather advisory meaning inconvenient, but not dangerous, winter weather.

Winds are gusting to 50 mph from the north in southeast Colorado, far southwest Kansas, the western Oklahoma Panhandle, and northeast New Mexico.

The map below is the expected snow accumulation from 3pm this afternoon until 5pm Tuesday morning. Note: This does not include snow that fell prior to 3pm. There are very heavy amounts of around a foot between Salina and WaKeeney, KS on Interstate 70.

This will be the last storm update this evening.

Snowfall from 11am until 11pm

Here is the predicted snowfall from 11am this morning (note: snow began earlier than that in New Mexico and southeast Colorado) to 11pm tonight. You can use this for travel planning purposes. This is showing 6″ or so along Interstate 70 which accumulations accelerating after about 4pm as temperatures begin to cool. Yes, that is 12-15″ inches centered in southeast Colorado in just 12 hours!

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Blizzard Now in Kansas

Conditions in western Kansas are deteriorating very rapidly as shown by the light blue snow echoes on AccuWeather:

1:30pm CST

Compare to two hours ago (below).

11:30am CST

You can see on the upper image the purples/greens/yellows have changed to the light blue snow colors. Whiteout conditions are being reported in parts of west central Kansas and road conditions are worsening.

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Monday Morning Winter Storm Update

As indicated in yesterday evening’s update, the threat of major blizzard conditions (orange) now extends farther north in Kansas with blizzard warnings that now include Interstate 70.

Pink is winter storm warnings and blue is winter weather advisories.
The threat for tornadoes, large hail, and damaging thunderstorm winds exists in southeast and parts of central Texas today and tonight. Please keep up on the local weather in these areas.
And, here is the AccuWeather regional radar as of 7:25am:
Note the moderate to heavy snow falling in New Mexico along Interstates 40 and 25.

AccuWeather’s snow forecast is here

Late Evening Winter Storm Update

The winter storm continues to develop and warnings are being extended. As always, let’s start with the forecast precipitation with this storm:

Click to enlarge all graphics.

Severe Thunderstorm and Tornado Risk
While certainly not a situation where major tornadoes are likely to occur, tornadoes and thunderstorms with damaging winds are possible in the area marked “slight” risk. I suggest residents of these areas monitor the weather tomorrow for possible watches and warnings.

Blizzard and Winter Storm
Here is a map of the winter weather warnings and watches as of 8:50pm. The orange is a blizzard warning. Travel is strongly discouraged in these areas. Pink is a winter storm warning. Turquoise is a winter storm watch (mainly northeast Kansas) and the blue is a winter weather advisory.

This much is clear: Do not think about driving through the blizzard warning area — roads will likely be closed and/or impassable. You could get stranded!  The amounts over southwest Kansas will be in excess of a foot with wind gusts of 35 mph. Note the blizzard warning now extends over a small part of Interstate 70 between Oakley and Ellsworth, KS.

The ARM model shows giant snowfalls over southwest Kansas and adjacent areas of Colorado and Oklahoma. This big issue with this storm is how far south and how fast the cold air will move. This model has six inches in Wichita because it shows the cold air moving just a little south of the other models. In theory, this should be the better model. 

How, the new NAM model this evening has the whole area of snow farther north. Scale same as above.

This model shows almost no snow falling in Wichita. I’m leaning toward the amounts and locations on this model. The important thing about this model, if I am right and it is the more accurate forecast, is that Interstate 70 would receive very heavy snow between roughly Salina and Colby, KS. 

Another way to play this is to consider the probability of snow accumulation thresholds at your location. These combine a variety of the models. So, here are the probability maps, the first is the probability of 2″ or more:

This is the probability of 8 inches or more:

So, this update has been based on the very latest information. If you live in the area where heavy snow is forecast, please take this storm seriously.

So, where is the storm at 9:30pm? Via AccuWeather regional radar, it is over the Southwest. Note the bright red echoes (thunderstorms) W and SW of El Paso. This indicates it is a strong storm in the upper atmosphere.

Finally, thunderstorms have developed rapidly in southern Oklahoma which demonstrates that very moist air (more than adequate moisture for heavy snow as the air mass moves northwest) is in place and the instability exists for big thunderstorms tomorrow.

Sunday Morning Winter Storm Update

As promised, here is the latest information on the looming winter storm in the Central U.S.

Amounts of moisture in the drought areas will be helpful. Father east, where the ground is saturated, amounts will be lighter. Everybody wins!

click to enlarge this and the other graphics in this posting

There is also the likelihood of thunderstorms in the south central U.S. with severe thunderstorms (large hail, damaging winds) and, maybe, a tornado or two in southeast Texas between 6am Monday and 6am Tuesday.

The above forecasts are reasonably straightforward.

Winter Storm
Here is a map of current watches and warnings from the National Weather Service. Pink is a winter storm warning, meaning the winter storm is likely.  Light green are blizzard warnings watches while the blue are winter storm warnings watches. A watch means the there is an elevated chance of a winter storm and preliminary preparations should be made. Purple counties are winter weather advisories, meaning that accumulating snow will occur of an inconvenience nature.

The blizzard watch is to be taken very seriously. Here are two multi-model graphics pertaining to Dodge City and Garden City, Kansas (click to enlarge). While the most likely amounts are 13-14″, a foot and a half, or more, is not out of the question along with high winds. As I said yesterday afternoon, this region will get nailed — roads will be impassible. Once advantage of these graphs is you can see when the snow begins and compare depths to times for planning purposes.

Courtesy: Mike Umschied

What about the rest of the region?

Some of the models want to move the band of heaviest snow slightly farther north in central Kansas. Two postings below you can see how that can make a huge difference in amounts at a give location. However, the statistical model, keeps the heaviest snows farther south. So, let me present the statistical graphs: You can pick your location and determine your chances. Maps valid 6am Monday to 6am Wednesday.

Probability of two inches or more:

Probability of six inches or more:

Probability of eight inches or more:

I’m avoiding posting a specific amount map because, for now, the statistical approach is the better way to go.

I expect winter storm warnings to be issued into Kansas this afternoon and I’ll plan on posting my forecast that maps exact snow amounts this evening. And, I expect to lose more hair over this.

Throughout the day, AccuWeather will be providing updates. You might want to check there from time to time.

I hope this coverage is helpful. If you live in the areas where 8″ or more of snow is forecast, I urge you to take this storm seriously and prepare accordingly.

Winter Storms — or — Why I Have So Little Hair Left

Here is the latest snow forecast generated from the NWS North American Model this evening via a display system from Earl Barker. I want to use this to illustrate a point. People often perceive snow amount forecasts as not very accurate because what they get at their home may be somewhat (or a great deal) different than forecast.

Take a look at the gradient in snow amounts from the NAM model over central Kansas (purple ovals).

The lower left oval is over the City of Wichita. If the NAM is making a perfect forecast, the northwest part of the city will receive 10″ while the southeast part of the city will get an inch or less. The gradient is even tighter along the northeast oval: Ten inches in 12 miles!

While I am confident there will be a major winter storm in central Kansas, I’m not confident the band of snow will lay out exactly as shown.

Meanwhile, the two gray areas (yellow arrows) are forecast by this model to get a foot and a half!

If the storm shifts just 50 miles north or south, it could be the difference between nothing and getting buried.

In the afternoon update (below), I depict a probabilistic way of looking at this. For now, it is the best approach.

Meanwhile, the green area in New Mexico is a blizzard watch and the navy blue is a winter storm watch, both from the NWS:

I’ll another comprehensive update tomorrow morning.

UPDATE: 9am Sunday. The comprehensive update is posted, scroll up. One new model, the ARM, has 10″ at my home on north Rock Rd. in Wichita. In far south Wichita, along Rock Rd. the forecast amount is zero! The forecast snowfall gradient is even tighter on that model. More hair is falling out as I try to make sense of this for blog readers.  :-)

Major Early Winter Storm Developing — Travelers Beware

Things look a bit worse than this morning. Here are the latest advisories from the National Weather Service. Graphic updated at 4:47pm CDT. 

Orange indicates blizzard warnings over a good part of eastern Colorado, northwest Kansas, and far southwest Nebraska. This includes Interstates 70, 76, and 25, parts of which will likely be closed by the storm. Addition 4:47pm: Essentially, a blizzard warning is in effect along I-70 from Denver International Airport east to Colby, KS. 

The pink is a winter storm warning which includes Denver International Airport that will get high winds and 4-8 inches of snow. Delays and/or cancelled flights are likely! Here is my Airline Survival Guide.

For the timing, here are some experimental simulated winterized radar products from Dr. Ryan Maue:

The blues = snow and the lighter the blue, the heavier the snow.  This chart is valid at 6am MDT tomorrow morning.

By tomorrow afternoon at 4pm CDT, the snow — quite heavy — moves out into the High Plains. Given the recent warm ground temperatures (it is currently 74° in Wichita and 67° in Garden City, KS) it is questionable how much will stick but visibility will be low in heavy falling and blowing snow.

AccuWeather has even more on this developing storm.

Because it has been so warm lately, I’m concerned this is going to be a sucker punch to the region. If you have friends or relatives planning to travel into these areas, please let them know so they can make an informed decision whether to risk it. I wouldn’t.

I-70 Closed Due to Blizzard Conditions

…west of WaKeeney, Kansas, into Colorado.

UPDATE 10:20am: Power is out (duration unknown) in much of the blizzard area of northwest Kansas.

Winds have been clocked in western Kansas gusting up to 67 mph!  Travel discouraged in southwest Kansas and strongly discouraged in northwest Kansas.

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Winter Hangs On

Pink = winter storm warning. Orange = blizzard warning. All of the green areas are various flood warnings due, in part, to the heavy snow cover which will grow a little deeper today.

If Jim Had Been Reading This Blog, He Would Not Have Been Surprised!

If you scroll down, you see the coverage of the thunderstorms rolling into Chicago, including an AccuWeather lightning chart. If Jim had been reading this blog or getting his weather from AccuWeather, he wouldn’t have been surprised!

Lightning lights up the storm coverage!

Watch the video here.

UPDATE 9:05pm Wednesday: Because we always strive to be accurate, please see the comment below. Jim apparently HAD mentioned the potential for snow thunderstorms.