3/19/09

 

Well it still looks very interesting for the Monday-Tuesday time frame.  I'll focus on Tuesday since it's the only day I'll be able to chase, unfortunately.

 

Anyway there's a huge difference between the GFS and the Euro/UKMET models from 12z.  The Euro and the UK remain more consistent in evolving a much stronger and negatively tilted storm out of Nebraska and move it into Minnesota by Tuesday night.  The GFS on the other hand has a much weaker (by about 10mb) storm and therefore a further south track.  It places the low way down in southeast Nebraska later Tuesday. 

 

The Euro has been an outstanding model in the mid-range lately, so I think it'd be very smart to stick with that.  Plus, as mentioned above it's been more consistent.  The Euro has been a bit slower than the GFS in moving this storm out, but the GFS is catching onto that.  GFS has slowed this storm up a bit in the past few runs, and the trend might continue a bit.  Taking that into account, the best chance for severe on Tuesday looks to be from western Nebraska/western Iowa, down into eastern Kansas and western Missouri.  If the trend continues most of the action could remain west of the Missouri River.  The good news is severe weather looks very likely.  Very good moisture supply, and strong upper dynamics should make for some healthy storms.  The Euro has a fairly impressive amount of wind shear as well.  With a deeper surface low and a further NW track, this would keep the winds largely backed out ahead of the main trough.  That's a good thing.

 

The GFS model has a narrow ribbon of >750j/kg mixed layer CAPE later Tuesday near the Missouri River.  By looking at it's surface temp/dewpoint forecast, I'd say it's underdoing the amount of warmth ahead of the trough, so these CAPE values may be a bit underestimated here.

First chase of the season brewing?

 

It's now March 18th and we've yet to chase.  I guess that's not too unusual since it is still pretty early in the season.  We had hoped to chase a week or so ago, but at the last minute the parameters sort of "crapped out" on us.  Next week we hope things will be different.

 

Although it's still quite a ways away, most of the models have converged on a very stormy situation starting Monday of next week, and lasting till at least Tuesday.  Monday's chase will be out in the high plains of Nebraska, and stretch down into Oklahoma.  By Tuesday, the setup will shift eastward towards the Midwest.  The GFS model (shown in the picture) is the quickest of the two more reliable mid range models I prefer.  The ECMWF model is a bit slower, and would keep the best severe further west close to the Plains on Tuesday.  In either case, Monday and Tuesday look like great chasing days. 

 

I'll be in Chicago on Monday, so a Great Plains chase is out for me, but what I'm really eyeing is the Tuesday setup.  Fantastic moisture availability, (due to several days of uninterrupted Gulf of Mexico feed), tremendous jet support, and modest instability point towards widespread severe weather on Tuesday.  Question is, will any of this be tornadic?  Right now it would look like Monday could be the best day for tornadoes.  By Tuesday winds aloft somewhat back, or become a bit more southerly as opposed to southwesterly.  That may cut down on directional shear a bit, but there's still a sufficient amount to initiate supercells the way it looks now.

 

Over the next several days you can be sure we'll be analyzing the models and following the trend of this upcoming event.  Stay tuned!

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