Starting February with Snow & Ice

There has been a lot of talk in the one to two weeks about a colossal storm heading for the Midwest this week.  A lot of the talk and hype has been extremely irresponsible, but that is a discussion for a different day.  It does appear a storm will impact the Midwest Tuesday and Wednesday.

One of the reasons I have been relatively quiet about the storm and its potential is due to the many different solutions computer models were coming up with.  Some had it as a HUGE ice storm, others as a HUGE snow storm and most had it somewhere in between.

Patience is a virtue sometimes when it comes to weather forecasting.  Let the models battle it out for a while and then start to come up with a somewhat unified solution to what the storm could do.

This is a storm that is going to develop over far southern New Mexico, western Texas and northern Mexico.  As it matures, moisture will become plentiful as it taps in to the Gulf of Mexico Tuesday.

Here is a solution the latest run of NOAA's Global Forecast model has come up with.  The image depicts 6pm CT Tuesday.

0z GFS - 6pm CT Tuesday
(Click image to see larger version.)

This is a classic winter storm for the Midwest.  The surface center of low pressure is tracking from around Monroe, Louisiana to just south of Nashville, Tennessee by Tuesday evening.  We're talking snow along and north of I-44 in Missouri and roughly along I-70 in Illinois.  This also means the rain/snow line is at play for southeast Missouri, southern Illinois and western Kentucky.

At this time, I do think all forms of winter precipitation will be possible for southeast Missouri, extreme southern Illinois and western Kentucky.  The primary nuisance will be rain, freezing rain and sleet.  There will probably be a change over to a little snow towards the end of the event.  The exact location of the rain/snow line is a little difficult to pinpoint this far out.  As you often hear meteorologists say, "The track of the storm will be extremely important." and this will be the case this time.  A change in just 40-miles will have a huge impact on what type of precipitation falls.

Right now, for places like Cape Girardeau, Paducah, and Poplar Bluff, I think rain, freezing rain and sleet will be the primary types of precipitation.  Icing could potentially be a concern, but let me say right now... This is NOT anything like the ice storm of 2009.  NO WHERE CLOSE.

TALKING SNOW

Let's talk a little snow for the Midwest.  I have gone through and looked at several computer model runs and have come up with a snow matrix.  Looking at the matrix can give you an idea of the range computer models are suggesting could happen through Wednesday night.  The data includes tonight's runs of the NAM and GFS and also Sunday morning's run of the European forecast agency's computer model as well as the 23-member SREF ensemble.

Missouri/Illinois Snow Matrix
(Click image to see larger version.)

Indiana Snow Matrix
(Click image to see larger version.)

Colorado Snow Matrix
(Click image to see larger version.)

As you can see, there is some variation between the computer models, but I must say, they are coming in to line with each other.

For many, the storm is still out 36 to 48 hours but I'll go ahead and throw out some ball park numbers.  I hope to update my blog tomorrow evening (time permitting) with fine tuned numbers.  Although, if you have followed my blog for a while, you know that my initially numbers usually only get slightly tweaked.  Think of it as a very time course correction.  But do know, these numbers can adjust as we get closer to the event.

COLORADO: (Monday night through Wednesday afternoon)

• Colorado Springs:  3"-5"
• Lamar:  5"-9"
• Pueblo:  2"-4"
• Springfield:  4"-6"

ILLINOIS: (Tuesday through Wednesday night)

• Mt. Vernon:  2"-5"

INDIANA: (Tuesday through Wednesday night)

• Columbus:  4"-8"
• Indianapolis:  6"-8"
• Lafayette:  5"-9"

MISSOURI: (Tuesday through Wednesday night)

• Cape Girardeau:  Up to 1"
• Poplar Bluff:  Up to 2"
• St. Louis:  3"-5"

FREAK-OUT-METER

COLORADO:

• Colorado Springs: 2
• Lamar: 5
• Pueblo: 2
• Springfield: 4

ILLINOIS:

• Mt. Vernon: 5

INDIANA:

• Columbus: 5
• Indianapolis: 5
• Lafayette: 5

MISSOURI:

• Cape Girardeau: 4
• Poplar Bluff: 4
• St. Louis: 3

For those that don't know what my Freak Out Meter is, it is a number I give out that attempts to quantify how big of a deal the upcoming weather event will be. It is based on a 0-10 scale. Zero being the lowest, "not a deal at all", and 10 being "get all the bread, milk and eggs and lock yourself in the basement". The score is 100% subjective and it's an attempt to have a little fun.

For more frequent updates, be sure to follow me on Twitter at @johndissauer.

End of Week Winter Storm

Things could start getting active this week in the winter weather department.  Bitterly cold air will be on the move from Alaska/Canada and moisture could be coming north through the Mississippi River/Ohio River valleys.

Before I get too far in to this I want to remind you that the items I am going to discuss are still MANY days away.  Things can and likely will change in the forecast.  The data I am going to show you is not the actual forecast but instead a weather computer model projection of what could happen.

Ok, now that all of that is out of the way lets talk about later this week, specifically in Missouri, Illinois, Kentucky and Indiana.

One basic concept we need to discuss before going any further.  Cold air is denser/heavier than warm air.  Hence, hot air balloons rise.

All computer forecast data is indicating COLD air will be on the move through the central United States late Wednesday and Thursday.

Projected Surface Temperature - 6am CT Thursday
(Click image to see larger version.)

The cold front will be somewhere near the Ohio River by Thursday morning.  Again, keep in mind that cold air sinks, so the cold air will undercut warmer air, which will reside a few thousand feet in the sky.

Temperatures at the surface will be dropping and it will be cold at the end of the week and cold for the weekend.  Here is a look at forecast temperatures from the European forecast agency's computer model for Friday afternoon.

Projected Surface Temperature - 12pm CT Friday
(Click image to see larger version.)

Computer models also project a couple waves of energy riding up and over the cold front.  The moisture will be riding in the warmer layer above the ground.  As the moisture falls it will encounter the below freezing air.  Depending on how thick the layer of warm layer and cold layer is will determine what type of precipitation it could be.  In other words, we could be talking a cold rain, freezing rain, sleet and/or snow.

At this point, it is too difficult to say with any certainty the form will be.  We are talking about trying to determine the temperature in a layer of air along with how thick the layer will be (A few hundred feet or thousands of feet?) for something that is 96-120 hours away.  That being said, at this time, I think there potential for snow and/or freezing rain.

What could make this interesting is there could be a couple waves of moisture and there could be ample moisture to work with.

Here is a look at the National Weather Service’s Global Forecast model, the GFS, using a program called BUFKIT.  Specifically, the data is for Cape Girardeau.  Keep in mind when looking at the data, the timeline runs from right to left.

12z Sunday GFS for Cape Girardeau
(Click the image for larger version.)

The colored bars indicate what the program is projecting what form the moisture will fall.  Green = rain | Orange = sleet | Red = freezing rain | Blue = snow.  See all the green and blue?  Right, neither do I.  It is showing up as red.  That means the software/computer model is suggesting it could be falling in the form of freezing rain.

I mentioned "ample moisture".  The GFS is projecting 0.4" to 0.8" of liquid Thursday through early Friday morning for much of southeast Missouri, southern Illinois and western Kentucky.  The European computer model is also putting down some decent moisture (0.5" to 0.8") for the same areas through Friday afternoon.  The one difference is the European model is suggesting it would fall as snow, especially north of the Missouri bootheel and western Kentucky

Also to note, there are hints of another round of moisture coming up through the area Sunday in to Monday.

At this point this is nothing to get concerned over.  My "Freak-Out-Meter" is at maybe a 2 out of 10.  However, I point out the possibilities for later in the week to try and get you to pay attention to the forecast over the coming days.  As more data becomes available, as the computer models are able to sample more of the atmosphere, we will start to get a better idea of what may happen.  As I like to say... Stay tuned.

Bottom line... It is going to turn much colder for the end of the week and the weekend.  There is potential for rain, snow, and freezing rain.

HPC Puts On Their Skates

Taking a quick glance of data this morning concerning Sunday-Monday and the possibility of freezing rain.  Last night’s European computer model (ECMWF) continues to be bullish on the potential whereas NOAA’s global forecast model (GFS) is downplaying the icing side.

One thing the models are in agreement about, rain, heavy at times, will fall Saturday night through early Sunday morning.  A cold front will be slowly moving through Missouri, Illinois and Indiana at the time.  There will be shallow cold air behind the cold front while a few thousand feet up in the atmosphere winds out of the southwest will keep temperatures above freezing.  There are two big questions at this time:

1. How long will water be available?
2. Where will be the location of the cold front?

Most likely, just north of the front will see freezing rain.

The Hydrometeorological Prediction Center is getting in on some of the freezing rain chatter.  There latest Day 3 Freezing Rain Probability Forecast and Day 3 Freezing Rain Accumulation Forecast is out and includes parts of Arkansas, Missouri, Illinois and Indiana.  The images below look at the Saturday night through Sunday morning time frame.

24-Hour Probability of Freezing Rain Accumulation 0.01”+:

Click the image to see larger version.

24-Hour Probability of Freezing Rain Accumulation 0.25”+:

Click image to see larger version.

48-Hour Freezing Rain Accumulation – 95^th Percentile:

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Notice how HPC keeps the freezing rain out of western Kentucky, southern Indiana and northeast Arkansas.  The European computer model has the freezing rain going further south in to those areas.

Will the models continue the way of the GFS, keeping the freezing rain away, or will they lean towards the Euro, hinting at an ice storm?  We’ll have to wait and see what the runs come in with over the coming days.

FREAK-OUT-METER:

• Southeast Missouri: 3
• Southern Illinois: 3
• Western Kentucky: 2
• Central Indiana: 2
• St. Louis metro: 3

Wet and Slick Weather Ahead

Quite a few weather “things” coming to the Midwest over the next five to six days and there are still a lot of question marks as to what will hit the ground.  One thing is for sure, there will be a significant and beneficial amount of rain falling at least through Sunday.  In some instances, upwards of 6” of rain could fall in parts of Missouri, Illinois and Kentucky.

Here is the Hydrometeorological Prediction Center’s precipitation forecast for the next five days.

Click image to see larger version.

If the computer models are correct, the numbers on the map (above) might be on the low side of reality.  Just through Friday, a four computer model average for rainfall is:

• Cape Girardeau:  0.96”
• Indianapolis: 0.89”
• Paducah: 1.32”
• St. Louis: 0.96”

Considering much of the area is still well below normal (precipitation), the rains will definitely be beneficial.

CLEAR SLICK STUFF

Now  the main reason for writing this post… What comes Sunday/Monday.

In the next 24-48 hours I think you are going to start to hear television meteorologists/weather-peeps starting to mention “freezing rain” (a.k.a. ice).  Freezing rain isn’t fun as it only takes a very small amount to make things slick.

The temperature profile of the atmosphere will be a HUGE factor in determining what type of winter weather will reach the ground.  It is the changing temperatures with height that makes winter forecasting the most difficult.

Instead of going in to detail how each type of winter precipitation is formed, check out the following links for tutorials from the University of Illinois on how the various winter weather types are formed.

• Snow
• Sleet
• Freezing Rain

Ok, now that you have a better understanding of how the different precipitation types form, let’s take a look at what some of the computer models are advertising for a few select locations.  (Note:  This is just an overview of what a few locations could see.  The data used is coming straight from computer models and is not the forecast.  It is also subject to change, and likely will.)

For the last couple of runs, computer models are hinting at cold shallow air to be in much of the Midwest.  The cold air is scheduled to arrive late Saturday night through Sunday depending on your location.  The models have temperatures slightly above freezing at 5,000 feet and  how thick that “warm” layer is will determine the type of precipitation hitting the ground.

This is a meteogram for St. Louis.  Each line is a representation of a different run of a computer model’s prediction of freezing rain accumulation.

Click image to see larger version.

The light blue line shows the amount of freezing rain accumulation from this morning’s run of NOAA’s global forecast model, the GFS.  Disregard the dark blue line (comes from the 6z GFS which I hold little faith in).

Not shown in the above meteogram is the European forecast agency’s computer model, the ECMWF.  The Euro is suggesting 0.59” of rain may fall while temperatures at the surface are below 32°F.  (Keep in mind that not all precipitation falling accumulates.  That is a reason for difference in numbers.)

Here are meteograms for a few other locations along with how much precipitation is projected to fall by the Euro.

Cape Girardeau, Mo:   Euro – 0.63”

Click image to see larger version.

Indianapolis, In:  Euro – 0.60”

Click image to see larger version.

As we get closer to Sunday the models should get better at predicting the minute details needed for determining precipitation type. 

Bottom Line… What I want you to take away from all of this is that there is a chance we could see freezing rain Sunday in to early Monday morning (timing varies by location).  It could also fall as all rain or sleet.  There are still considerable uncertainty as to what will fall.

I know many are skittish after the 2009 ice storm but as of today I do not think this will be anywhere near that storm.  As you will see below in my “Freak-Out-Meter”, I don’t think you should be freaking out nor should you be stocking up supplies to go weeks without power.  Instead, what I think you should do is keep an eye on the forecast over the next couple of days, maybe beat the lines and grab a can of deicer and a few batteries.  Worst case (for me anyway), this doesn’t pan out and you’ve got an extra can of deicer and batteries.

FREAK-OUT-METER:

• Southeast Missouri: 2
• Southern Illinois: 2
• Western Kentucky: 2
• Northeast Arkansas: 2
• St. Louis Metro: 3
• Central Indiana: 2

4:30pm Weather Update - Winter Weather

A quick look ahead at what a couple of national government forecast agencies are showing for Christmas Eve and the Post-Christmas Storm I mentioned in my previous blog post.

First Sunday night through Christmas Eve.  There is potential for parts of Missouri to central Indiana will encounter some light moisture being spread up from the south.  The moisture will encounter cold air near the surface.  Whenever you mix warm air a few thousand feet up and cold air at the surface you can get freezing rain.  This may be the case Sunday - Monday.

The Hydrometeorological Prediction Center has put out their probability forecast for freezing rain that covers 6pm CT Sunday through 6pm CT Monday.

(Click the image to see larger version.)

HPC indicates a heightened probability of freezing rain from roughly St. Louis to Indianapolis along and north of I-70.  Not great for travelers during that time period along a major interstate.

The one bit of "good" news is that it should be light.  Generally less than 0.10".  However, it doesn't take much to make driving "interesting".  This isn't set in stone so if you plan on traveling be sure to check the latest forecast.

Also want to show you what the Climate Prediction Center has highlighted in the Day 3-7 U.S. Hazardous Weather Outlook.

(Click image to see larger version.)

They are highlighting an area of "heavy snow" December 25 through December 26.  So it looks like they are on board with the Post-Christmas Snow Storm.  Although, this is subject to change and likely will wiggle around as computer models crunch the numbers.