Winter Storm Update

I have been monitoring data coming in from Wednesday night's and Thursday morning's computer model runs and it still looks like a winter storm will have a significant impact on the Ohio River Valley.

The upper-level energy for the storm is still located off the southwest coast of California.  It will be better once it is overland and models can get a better sampling of what is happening in atmosphere.  That being said, the NOAA Hurricane Hunters - the pilots and scientists that fly in to hurricanes to collect data - started to fly missions in to the storm over the Pacific earlier this week.  Another mission is scheduled for Thursday evening.  I can't emphasize enough how important is that they collect.  The data goes straight in to the computer models we use to forecast weather.

In Wednesday's update I talked about how much water there will be to work with over the region.  Wednesday night's computer model runs, and Thursday morning's, increased the projected water available.

A 34-computer model average suggests the following liquid equivalent 7am ET Saturday - 7am ET Monday along with the range in data.

INDIANA 

• Bloomington: 0.82" (0.58" - 1.02")
• Columbus: 0.86" (0.61" - 1.05")
• Indianapolis: 0.67" (0.47" - 0.86")
• Shelbyville: 0.76" (0.58" - 0.91"

MISSOURI

• Cape Girardeau: 1.01" (0.82" - 1.22")
• St. Louis: 0.63" (0.43" - 0.83")

ILLINOIS

• Carbondale: 0.91" (0.70 - 1.10"

KENTUCKY

• Paducah: 1.16 (0.88" - 1.55")

Needless to say, that is a LOT of water for a winter storm.  Especially when most locations - north of the Ohio River - will be mainly all snow.

Having enough cold air to create snow will not be a problem with this storm.  (There will be some, mainly along and south of the Ohio River, that may have a little bit of warm air in the atmospheric column which would create sleet, at times.)

Air will be cold enough for higher than normal snow to liquid ratios.  A good rule of thumb is for a 10 to 1 (10:1) ratio.  With the cold air expected to be in place, ratios could go from 12:1 to as much as 18:1.  

This is when the fun begins.  You - or your kids that know how to multiply - can start doing the math on how much snow that could potentially produce.  Multiply the water amount to the snow to liquid ratio.  Example:  0.86 x 14 = 12.0"

Areas that have sleet mixed in will drastically reduce the numbers.  Sometimes by as much as 40%+.

There is a little more massaging of the data that goes in to producing the snow forecast, but this can give you a rough idea.

If the models don't come in overnight/tomorrow suggesting much lower water amounts, this will likely be a "doozy" of a winter storm for many in Missouri, Illinois, Indiana, and Kentucky.  And that isn't talking about the BIG ice storm that will happen further south.

Let's see what Friday's information brings and that could warrant me issuing Freak-Out-Meters for several locations in Missouri, Illinois, Kentucky, and Indiana.  Stay tuned...

Winter Storm for Mother's Day

Still need to get mom a gift for Mother's Day?  Well, Mother Nature may be able to help you get something useful.  If you're in eastern Colorado you could get her a shovel.  She may need it Sunday and Monday.

An area of low pressure is moving through the Gulf of Alaska off the northwest coast of the United States.  (See the satellite loop below taken Friday morning.)

Computer models project the low/energy will move southeast in to the Rocky Mountains Saturday.  Once in the mountains, a surface low is expected to develop over southeast Colorado Saturday afternoon.  As the low moves east, cold air will begin to filter in from the north/northwest.

Almost all of the data suggests moisture will begin to fall in the central mountains of Colorado Saturday.  The moisture is expected to move east and southeast over eastern Colorado Sunday afternoon.  Both medium-range computer models, the GFS and European forecast agency's model, suggest that moisture will remain in place over eastern Colorado through mid-day Monday.

Overall, the computer models are very bullish with the amount of moisture falling from this system.  Here is a look at a 27-computer model average of how much moisture will fall for locations in southeast Colorado through 6pm Monday MT.

• Colorado Springs: 0.70"
• Monument Hill: 1.03"
• La Junta: 0.48"
• Lamar: 0.37"
• Pueblo: 0.61"

Initially, moisture will likely fall as rain but in some locations it will change over to snow.  Places that get snow, could got a lot of snow.  Here is a look at the 27-computer model average of moisture that computer models project will fall as all snow through 6pm Monday MT.

• Colorado Springs: 0.52"
• Monument Hill: 0.76"
• La Junta: 0.08"
• Lamar: 0.01"
• Pueblo: 0.13"

As you can see, data is suggesting higher amounts across El Paso County and north.  This also likely suggests higher snow amounts in the higher elevations west of I-25 (Teller/Fremont counties).

Keep in mind this is still a couple days away from happening.  Computer models will get a better handle on the storm, the amount of moisture and the timing once it gets better sampling over the land.

Winter Storm Watch (in blue) Saturday night
through Monday morning.

In the meantime, the National Weather Service in Pueblo has issued a Winter Storm Watch for areas west of I-25 Saturday night through Monday morning.  I'll be in throughout the weekend and will have further updates on KOAA-TV, on Twitter, and time permitting, my blog.

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.

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.

1:30pm Weather Update - Updated Numbers

Trying to keep everyone updated as far as what the weather data is showing.  I had been waiting for the morning run of the European forecast model to come in.  It is now in and I've added it to the snow matrix.  You can now see a snowfall number derived from a 5-computer model average (some cases 3 or 4-computer model average).

First, I wanted to show you a larger picture snowfall map.  This is a projection from NOAA's global forecast model, the GFS.  This is valid from now through 6am CT Saturday.

 (Click the image to see larger version.)

CITY	12z NAM	12z GFS	12z RPM	12z EURO	AVG
Cedar Rapids, IA	8.2”	10.3”		12.0”	10.2”
Columbus, IN			0.3”	1.1”	0.7”
Bloomington, IN	2.2”		1.3”	1.4”	1.7”
Indianapolis	1.4”	0.6”	0.7”	2.3”	1.3”
Lafayette, IN	1.4”	0.9”	0.2”	2.5”	1.2”
Moline, IL	3.8”	2.3”		3.4”	3.2”
Muncie, IN	1.7”	1.5”	0.8”	3.0”	1.6”
St. Louis	0.0”	0.1”	0.1”	1.0”	0.2”

1:45pm Update: One thing I am still a little leery of with the numbers listed above for central Indiana and St. Louis, I still think we could see a dry slot develop behind the cold front.  The intrusion of dry air would diminish snow amounts as it would "soak up" the moisture.

Measuring snow will also be difficult as winds are expected to be 30-40 mph with gusts to 50mph throughout the day Thursday.