Here it Comes!

Monday, March 3 -- 4:30PM

Winter Storm Warning until Tuesday evening....

What may be the most significant winter storm in a number of years will effect the STL region tonight and Tuesday. All signs point to an axis of heavy snow extending from southwest Missouri into southern Illinois, with STL smack-dab in the middle. We might even see thundersnow!

http://www.crh.noaa.gov/wxstory.php?site=lsx

The one thing that worries me is the rule "Don't forecast major snow until you see the flakes falling from the sky." With this system, we are relying on a "trowal" (a TRough of WArm air aLoft) to develop, and that will be the trigger for the heavy snow. That has not formed yet, but all of the models are predicting it to happen. That is why I have this much confidence.

As this is the case, I am going to go along with the NWS and predict heavy snow.

Drop Dead Prediction:
60% chance - 6+ inches of snow
20% chance - 0-5"
20% chance - sleet/snow/freezing rain not amounting to much

There is a better than average chance that we will get somewhat more than the 6 inches of snow in my prediction. Dare I say 12 inches? If so, it would qualify as one of the top ten 24 hour snowfalls of all time in STL.

Could it happen???

Think Snow!!!

-WD

Winter Storm Tuesday

Monday, March 3 -- 8:30AM

Winter Storm Warning from noon Monday through 6PM Tuesday....

A complicated weather scenario is taking shape over the midsection of the country. We started the morning with mild temperatures and rain, and by Tuesday afternoon it is entirely possible we will have 6+ inches of snow on the ground.

I love March! In like a Lion, out like a Lamb, as the old saying goes.

So, will we get the 6+ inches of snow? I am thinking yes. The various models have had extraordinary run-to-run consistency, as well as good concurrence. Here is the good news:

1. Plenty of moisture to work with in the low levels of the atmosphere. This is constantly a problem in our part of the world. How many times has a forecast called for snow, only to have it be so dry outside that all of the snow evaporates before ever reaching the ground? Shoudn't be an issue with this storm.
2. Cold air intrusion appears to be on track.
3. Low pressure over New Mexico forecasted to move our way. This is the classic "Southwestern storm" scenario. This kind of storm track is the one where we get the most snow in the STL region.
4. The "Farmington Rule." One of my rules is "Don't predict snow for STL if they are not predicting snow for Farmington." The thinking behind this rule is that forecasters have a habit of over-predicting the southward push of cold air. So the fact that 4-6" of snow is in the forecast for Farmington is good news for us.
5. As it is early March, thundersnow is a real possibility. The dynamics for this storm are right for it. If we do get thundersnow, the total accumulation will be high. So 6+ inches is not a stretch.

Now the bad news:

1. Time horizon. This will be a long storm that starts off slowly, with only a minor nuisance of wintry weather Monday, and ends with a BANG. The major portion of this storm will not begin until Tuesday morning. Will schools close Tuesday before any snow starts? Especially since many school districts feel like they got burned recently by closing when the wintry weather failed to materialize? I only predict the weather; I don't predict how humans will behave.
2. Models prone to error. Only a slight change in the storm track can alter the entire weather picture for us. But like I said, the models have mostly been predicting the same scenario for numerous consecutive runs.

I want one more model run before I make my Drop Dead prediction. But it is looking good to me!

Think Snow!

-WD