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.

Taking Aim at the Long Range

It is always interesting and fun to see what computer models are suggesting for the long range.  I'm not talking five to eight days out, instead twenty to thirty days out.

There are a couple computer models that try to stick their arms waaaaaay out to look that far.  One of the forecast models, the European Forecast Agency's computer model, is a model that attempts to look out thirty days.  I have access to data that updates once a week.  Going forward I am going to try to take a look at the model and post observations here on "New at Dis Hour".

Here are a few observations from last week's run of the European.

• Above normal temperatures for Colorado Sept 14-20.
• Below normal temperatures for the Midwest September 12-14 and September 16-20.
• Northwest flow dominates weather pattern September 25-28 from the Rocky Mountains to the Midwest.  (Northwest flow often means there could be storms developing in the NW US and they would quickly dive to the SE.  Also often produces below normal temperatures.)
• Heat builds back in to Colorado October 1-3.

Keep in mind, the model is just that.  A computer model.  The farther out the model looks, the higher the error rate.  The key to looking at this kind of data is to not look at specifics but instead trends and long wave patterns.

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

Looking Back at Meteorological Fall 2012

Meteorologists break the year up to in four equal segments for spring, summer, fall and winter.  This makes it easier when looking at seasons.

(Click to see larger version.)

Meteorological Seasons:

• Spring – March 1 – May 31
• Summer – June 1 – August 31
• Fall – September 1 – November 30
• Winter – December 1 – February 28/29

METEOROLOGICAL FALL 2012

Most of 2012 has gone in to the books above normal, however Meteorological Fall bucked the trend.  In the Midwest, fall went in to the books below normal.

 

Below is a breakdown of the monthly temperatures for Cape Girardeau, Carbondale, Indianapolis and St. Louis.
  

CITY	SEPTEMBER	OCTOBER	NOVEMBER
Cape Girardeau	-0.6°	-1.9°	-1.9°
Carbondale	-0.6°	-2.3°	-2.4°
Indianapolis	-1.7°	-2.3°	-2.2°
St. Louis	-1.0°	-1.9°	-0.8°

Interestingly, for all four cities listed above, the last time any of the cities had three consecutive months below normal was December 2009, January 2010 and February 2010.

Below is a breakdown of the number of days each month below normal.

 

METEOROLOGICAL FALL 2012
CITY	SEPTEMBER	OCTOBER	NOVEMBER	TOTAL
Cape Girardeau	14	18	18	50 (55% of days)
Indianapolis	17	20	18	55 (60% of days)
St. Louis	15	19	18	52 (57% of days)

As you can see, the majority of days during the three months were below normal.

Its Sweating Time

It is going to be a story you hear talked about on the national news for a couple of days. It is getting hot outside! Temperatures across the Midwest this afternoon are climbing to the middle 90's to 100° while the heat index climbs above the century mark.

High temperatures of the day:

• St. Louis: 100°
• Cape Girardeau*: 98°
• Marion, IL*: 97°
• Paducah*: 97°
• Louisville*: 96°
• Indianapolis*: 95°
• Columbus, IN*: 95°

*Temperatures are indicating hourly observation high temperatures. Official highs for the day will come in later this evening.

Along with the high temperatures, dew points have climbed in to middle 70's (even 80° around Louisville). This is creating heat indices (the feel like temperature) in the 110°-115° range across much of the Midwest. Remember that the dew point is a specific measure of the moisture in the air. Dew point is much more accurate at depicting how humid it is compared to the relative humidity. I know, it sounds weird but its true.

A cold front will slowly move south across the Midwest Tuesday. It should allow for some slightly cooler, less humid air to move in to central Indiana and the St. Louis metro area. However, places like southeast Missouri, western Kentucky and places further south may see a slight increase in temperatures tomorrow as the air is compressed along the front. Typically, air just along and ahead of the front will get warmer than forecast models indicate.