Ending February with a Bang

Mother Nature may have a plan to end February, and Meteorological Winter, with a bang. However, more of a spring-like bang than a winter-like bang.

A strong storm system is expected to move across the United States over the next 60 hours. Currently, the upper-level low is located a couple hundred miles off the west coast. It is expected to be in the Rocky Mountains Tuesday morning and over Nebraska/Kansas Tuesday evening.

Ahead of the storm, winds will turn back around to the south and begin to transport moisture (and warmer temperatures) in the lower portions of the atmosphere to the middle Mississippi Valley.

Forecast models are bringing strong jet stream winds through the Plains and Midwest early Wednesday morning.


Pictured above is the wind forecast at 300mb (the jet stream) at 6am CT Wednesday morning as predicted by the NAM forecast model. A strong jet streak (wind maximum) is located from northwest Illinois through northwest Oklahoma.

This model is showing an area of diverging winds setting up over southeast Missouri, southern Illinois and western Kentucky at the forecast time (6am CT).

The NAM also has a decent amount of instability forecast to move through the Mississippi Valley and Ohio Valley Wednesday morning.

On the flip side, the GFS model is a little more bearish on the threat of severe weather. The model is suggesting there will be very little instability.

I should say that the NAM has been a little overboard with systems the last couple weeks so I am hesitant to get too excited.

The Storm Prediction Center is keeping an eye on it. They have southeast Missouri, southern Illinois, western Kentucky, northwest Tennessee, northeast Arkansas included in a "Slight Risk" for Tuesday night through Wednesday morning in their latest Day 2 Outlook.

Day 2 Outlook

They include a big portion of southern Indiana, Ohio, Kentucky and Tennessee in their Day 3 Outlook which covers the time from 6am CT Wednesday through 6am CT Thursday.

Day 3 Outlook

Right now it appears to me that a line of thunderstorms, capable of producing damaging winds, hail and perhaps a tornado will develop during the overnight hours Tuesday-Wednesday. The line will quickly move to the east at 50mph-60mph.

To be honest, I have not completely bought in to the severe weather threat yet. Something feels "off" about the setup. To me it feels like the jet streak isn't lining up where I would like to see it for big severe weather. That being said, this morning's NAM is much closer to where I'd want to see the jet streak located.

Models are also suggesting a large cloud shield moving in for Tuesday. This isn't one of those storms where we need to see a lot of sunshine to make things more unstable, but sun would definitely help make things more unstable.

I am also questioning the amount of moisture that will be able to return to the area. As of 11am CT this morning, dew points were ranging from the 20's to lower 30's. We will need to see the dew points get back to the 50's to make it work out.

Bottom Line...

• Will there be thunderstorms overnight Tuesday/Wednesday? Yes
• Will there be a watch issued? It is a little too early to say with certainty, but I'd guess "yes" at this point.
• Will this be a wide spread severe weather outbreak? At this point I'd say "not likely".
  

Even though I am slightly downplaying the severe weather threat one concern is that it will likely move through southeast Missouri, southern Illinois and western Kentucky during the overnight hours. That means people will be asleep which is always a concern. When storms move through overnight people are less likely to be aware if a warning is issued.

Be sure to turn on your NOAA weather radio before you go to bed. If a warning is issued, you will know about it and you can take appropriate action. Having said that, be sure to check the batteries in your radio. Is your radio still working? Just give it a once over today so you don't have to do it tomorrow.

For those of you in Indiana, it looks like the threat will move through as a thin line of storms mid-morning Wednesday. The main threat would be damaging winds and perhaps a quick spin up tornado. My gut feelings are much the same as I posted for the other areas above. I don't think everything has lined up just yet.

Freak-Out-Meter:

• southeast Missouri - 4
  
• southern Illinois - 4
  
• western Kentucky - 4
  
• central Indiana - 2
• southern Indiana - 3
  

Tornado Watch Possible

The Storm Prediction Center is keeping an eye on parts of southeastern Illinois, western Kentucky and southern Indiana for the possibility of issuing a Tornado Watch. They expect storms to begin to fire up over the next 2-4 hours.

Temperatures are increasing across the region as a deepening area of low pressure is moving through southern Missouri this afternoon. At 2pm CT temperatures are in the lower to middle 70's over southeast Missouri, southern Illinois and western Kentucky.

There is also decent amount of wind shear in the atmosphere. When I say wind shear I mean winds are turning with height. For example winds at the surface are out of the southeast. Winds 1,000-2,000 feet up are out of the south. Winds at 15,000 feet are out of the southwest and winds at 30,000 feet are out of the west. If you think about the direction of those winds, you can get a sense of how there is inherent rotation setting up in the atmosphere.

There is one thing that is severely lacking for some areas. Moisture. Dew points are low across southern Indiana (30°s and 40°s). There is substantially higher moisture levels at the surface in western Kentucky where the dew points are in the lower to middle 50°s which can easily sustain thunderstorms.

As far as Indiana is concerned, I think the "big storms" stay south of a line from Jeffersonville to Princeton.

It is interesting to look at a visible satellite image of the area. Look at all the clear skies out there! No wonder temperatures are so warm today.


The interesting thing about the above satellite image. Look in western Kentucky. There is a thin little line of clouds that has developed from roughly Reidland, KY to Water Valley, KY. I will be curious to see if we see storm initiation along this line.

Once storms fire, they should move quickly to the ENE at around 45mph-50mph. The main threat will likely be damaging winds and large hail but a few tornadoes can not be ruled out. However, I think the threat for tornadoes is relative limited west of Murray, KY to Calvert City, KY.

2:45pm Weather Update; Watching Boiling Water

What's the old saying, "A watched pot never boils"? That's how it is today but instead of watching the pot everyone is watching the radar.

One of the most difficult things when it comes to forecasting is sitting back and waiting for things to play out as you forecast. That's the position I am now. Waiting for snow to start to accumulate. The thing I have to remember is that I figured the snow would start to arrive in the St. Louis metro area between 2:00pm and 4:00pm. There is snow falling, but nothing is sticking yet. It's basically "heavy flurries" right now.

At 2:00pm CT, temperatures were sitting right at or slightly above freezing. St. Louis (Lambert Airport) 34°, Chesterfield 32°, St. Charles 32°, Cape Girardeau 32°. Go a little further southwest and temperatures drop below freezing and there are reports of snow. Farmington (Mo) 28°, Poplar Bluff 32­°.

Everyone is looking at the radar this afternoon. If you click on the "Radar" link above and look back over southwest Missouri you might be thinking "There's nothing out there. We're almost done with the snow." That isn't entirely true.

(Click the image to see a larger version.)

The National Weather Service doppler radar in Springfield is down for maintenance today. That means the mosaic/composite radar that everyone uses to show the "National Radar" or the radar imagery that shows rain, mix and snow is missing some important data. The way the composite radar works is by looking at all of the individual doppler radar sites around the country and then, in simple terms, averages them all together to come up with a "big picture" radar view. When there is data missing from an area that is seeing precipitation, it is like taking away a big piece of the puzzle.

It is even more important to have all the radar data possible when there is snow as snow doesn't show up very well at far distances.

In cases when there isn't radar available it is important to look at surface observations to get a sense of what is falling from the sky. At 2pm, moderate snow was reported in Springfield as is the case in West Plains and Rolla.

Bottom line... Even thought it isn't doing much right now, give it time. There is still moisture to move through and a lot of it should fall as snow.

11:45am Weather Update

Just a quick update to the current weather picture.

You may be looking out your window and wondering where all of the snow is at. If you've been following along here on the blog you know that I am not expecting the featured event to get started until later this afternoon and this evening in Missouri/Illinois/Kentucky and overnight for central Indiana.

Here's a look at the latest satellite imagery.

(Click the image to see a larger version.)

I have drawn on a couple features to help point things out. First you can see the surface low drawn on with the red "L". Ahead of that I have two areas circled in yellow. I expect the areas circled to start to fill in and eventually bring some snow our way.

High resolution computer models are suggesting that snow will arrive in the St. Louis metro area around 2pm this afternoon. The area that will bring us the 2pm snow is right yellow circle.

Within the second circle (left), I expect to see that begin to fill in with clouds and eventually moisture in the next couple of hours. This area should bring the "heaviest" snow to the St. Louis area between 6pm and 9pm this evening.

The Hi-res computer models are also picking up on a "blob" of moisture moving in to southern parts of southeast Missouri (Poplar Bluff, Dexter, Sikeston, New Madrid and bootheel) starting around 4pm.

Temperatures have risen above freezing (33° - 34°) in southeast Missouri, southern Illinois, western Kentucky and the St. Louis metro area. Temperatures are expected to drop a couple of degrees starting around 5pm in St. Louis and temperatures will hold stead in southeast Missouri, southern Illinois and western Kentucky.

6:45am Weather Update

As expected radar displays are lighting up this morning. However, even though the radars may be showing snow, that doesn't mean the snow is reaching the ground. The air is still relatively dry at the surface. Dew points ahead of where the snow is reaching the ground is in the single digits. Where snow is falling, dew points have climbed in to the 20's. We'll need to see the dew points increase to those levels (20's) before the snow makes it to the ground.

Not too much has changed with overnight computer model runs. Although one thing did peek my interest this morning... The European forecast agency's computer model has come in a little wetter compared to all of the other models. It is also cooler at the surface which could mean more snow for areas in southeast Missouri, southern Illinois and western Kentucky. Specifically, the European model is hinting at a 1" to 2.5" snow for those areas. I'm going to keep the forecast I put out last night but I am going to raise the snowfall amounts just a little bit for southeast Missouri, southern Illinois and western Kentucky.

(Click the image to see a larger version.)

St. Louis metro area:
Generally speaking around the St. Louis metro I am expecting 2" to 3" of snow to fall. There will likely be a few spits of snow through late morning but I don't expect the accumulating snow to begin until mid-afternoon and it should end by 2am Tuesday. Snow showers will be possible Tuesday morning (rush hour +) but shouldn't add to the totals.

Southeast Missouri/Southern Illinois/Western Kentucky:
The forecast will be a little trickier for this area as there will likely be a mix of snow, sleet and freezing rain north to south across the area.

• Places like Cape Girardeau, Perryville, Sikeston, Poplar Bluff, Carbondale, Marion (IL) and Harrisburg there could be 0.5" of snow to 1.5". Towards the end of the event, the snow is likely to change over to sleet or a little freezing rain.

• Places like New Madrid, Paducah, Mayfield, Murray and south will mainly see light sleet/freezing rain. There could be a little snow mixed in for Paducah but it should be no more than 1"

Central Indiana:
I think we are looking at anywhere from 1" to as much as 3" of snow. I think the 3" amounts will be northwest of Indianapolis.

Here is a look at what the other overnight forecast models are suggesting for the Midwest.

First we start with the NAM.

(Click the image to see a larger version.)

Now let's look at the GFS.

(Click the image to see a larger version.)

I have also mentioned the possibility of a little freezing rain for northeast Arkansas and parts of southeast Missouri and western Kentucky. Here is what the GFS is showing for freezing rain accumulation.

(Click the image to see a larger version.)

Again, any freezing rain will be light so don't get too concerned, although even the smallest amount can make roads slick.

Freak Out Meter - Feb. 13

I just realized in my snow forecast post that I forgot to give out my "Freak-Out-Meter" for the different locations concerning today's/Tuesday's snow.
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.
Freak-Out-Meter:

St. Louis Metro area: 3 out of 10 (This could be the largest snow of the winter. Let's hope the roads don't become as much of an issue as the 1.5" snow in January.)

Southeast Missouri, Southern Illinois, Western Kentucky: 3 out of 10. (Not so much because of the snow but because of the potential of sleet and freezing rain.)

Central Indiana: 2 out of 10 (Only because you may have to shovel.)

Bottom line, this isn't going to be a huge winter storm for the Midwest but it may be the biggest we have seen all winter for 2 out of the 3 locations listed above.
If you are looking for more specifics concerning the forecast (i.e. snow totals), check my previous blog post.
- Posted from my iPhone

8:00pm Snow Forecast

Here is my snow forecast for Monday through Tuesday for the St. Louis metro area.

(Click image to see a larger version.)

Generally speaking around the St. Louis metro I am expecting 2" to 3" of snow to fall. There will likely be a few spits of snow through late morning but I don't expect the accumulating snow to begin until mid-afternoon and it should end by 2am Tuesday. Snow showers will be possible Tuesday morning (rush hour +) but shouldn't add to the totals.

Southeast Missouri/Southern Illinois/Western Kentucky:
The forecast will be a little trickier for this area as there will likely be a mix of snow, sleet and freezing rain north to south across the area.

• Places like Cape Girardeau, Perryville, Sikeston, Carbondale, Marion (IL) and Harrisburg there could be 0.5" of snow to at the high end 1". Towards the end of the event, the snow is likely to change over to sleet or a little freezing rain.

• Places like Poplar Bluff, New Madrid, Paducah, Mayfield, Murray and south will mainly see light sleet/freezing rain. There could be a little snow mixed in for Poplar Bluff and Paducah but it should be no more than 0.25"

Central Indiana:
I think we are looking at anywhere from 1" to as much as 3" of snow. I think the 3" amounts will be northwest of Indianapolis.

5:15pm Weather Update

More data has come in and that means there is more information to digest. Earlier today I showed you what the NAM computer forecast model now let's take a look at what NOAA's global forecast model is suggesting for Monday's "storm".

Here is a bigger picture of the amount of snow the GFS is suggesting.

(Click image to see a larger version.)

Looking at the above image and comparing to the NAM's forecast from earlier today, both models seem to be relatively consistent. There also appears to be a northward shift, not by a lot, in the models. This means that there could be less snow for parts of southeast Missouri, western Kentucky and southern Illinois.

Here's a closer look in to the St. Louis metro area.

(Click image to see a larger version.)

Similar to the NAM and the previous thinking, the GFS puts the higher snowfall totals over central Missouri. It also supports the idea of 3"-5" of snow.

I am hearing a lot of chatter about snow moving in by late morning for the St. Louis area. I'm not buying that idea just yet. The air is extremely dry. Dew points are currently in the single digits to just below 0°. Moisture is going to have to fall for several hours to bring up the humidity in the air to support moisture reaching the ground. This means we are likely to see a lot of snow appearing on the radar, but nothing reaching the ground. This means the accumulating snow won't start to reach the ground until afternoon (2pm - 4pm).

Here's a look at the southeast Missouri, southern Illinois and western Kentucky area.

(Click image to see a larger version.)

Unfortunately, if you are wanting snow, the shift to the north in the models is taking the snow away from southeast Missouri, southern Illinois and western Kentucky. The GFS is suggesting a general dusting to 1" of snow with a few pockets of 2". This is partly due to the model suggesting more sleet and freezing rain mixed in as warmer air a few thousand feet move in.

Here is a closer look at central Indiana.

(Click image to see a larger version.)

The GFS is suggesting 1"-3" of snow for central Indiana with the higher totals northwest of Indianapolis.

I mentioned that there could be sleet and freezing rain mixed in with this system. Models are suggesting that initially the precipitation falling from this system will be snow but eventually warmer air will move in a few thousand feet in the atmosphere. This would change to snow over to sleet and depending on how deep the warm layer is, it could fall as freezing rain.

Below is a look at the how much freezing rain could fall (and where) according to the GFS.

(Click image to see a larger version.)

Yes, I do think there could be some freezing rain mixed in for southeast Missouri and especially in northeast Arkansas. Don't get too concerned, it doesn't look like it will amount to a thick coating of ice. But as we all know, even a tiny bit of ice can make driving difficult.

It should also be noted that looking at this morning's European forecast agency's computer model, it has decreased the amount of moisture available for the storm from previous runs. For instance, yesterday's run had 0.19" (liquid) for St. Louis. This morning's run had 0.12". However, it did increase the amount for Cape Girardeau, Farmington and Paducah. This is due to the model shifting the track of the system a little further south.