3/7/09 FCST: OK, KS, AR, MO

[Bob Hartig]

Let me start by saying that after a long northern winter, I'm willing to read tea leaves in order to find my first chase opportunity for 2009. That being understood, I've been following the long-range GFS for a few days, and I'm seeing consistency in pulling moisture north into the plains late next week. Since I'm coming to Norman to attend Tim's severe Wx forecasting workshop, I'm keeping an eye on Saturday.

Anyone else watching this system? Here are a few things I see for 18z on March 7, based on the 06z GFS: ample dewpoints from the mid-fifties up into the sixties; Theta-e ridge nosing up through Tulsa into SE KS; decent lapse rates (7.5); backing surface winds veering nicely up to 500 mb, and so forth. Best forecast sounding is by Coffeyville, KS.

Right, it'll all change. I just figured I'd get the discussion rolling, since I doubt I'm the only one who's been eyeballing next week.

 

[Matthew Harding]

The 12z GFS shows what would appear to be some elevated convection at 12z Sat 3/7/9 and gives atleast an indication of some precip in C & E MO at 0z Sun 3/8/9. To be honest, with the event being ~200 hours out, a lot can and will change. It is something worthy of keeping an eye on. I have also noticed by looking at the GFS 0 and 12z runs the last few days that there is an indication of things getting more active as we move toward the 2nd week of March.

 

[Chris Wilburn]

I too have been watching the models for late next week. Moisture return begins on Wednesday, however the huge downfall is the 850mb winds and 500mb winds "veer" too much. The 850mb winds are more southwesterly this time period and the 500mb winds are due westerly for the most part. I know it is still 9-10 days out so that may change. Something to watch I guess and see what happens if anything. Sunday the 8th the trough digs in a bit more and 500mb winds are southwest and the 850mb winds more southerly with still some moisture to work with.

 

[Matt Gingery]

I have been watching this play out for some time. GFS has gone back and forth, originally showing a well defined negatively tilted system pushing in. Now it appears as if GFS wants to show a less aggressive system, but I think it will have enough ingredients to give us a chase opportunity. I personally will take advantage of any weekend event.

http://msustormchase.ning.com/

 

[Gabe Garfield]

Obviously, it's much too early to talk about specifics, but the GFS forecasts the potential for a chase next weekend -- as has been mentioned already.

The pattern looks generally favorable for the onset of severe weather, with a few exceptions. First, the upper-level ridge that is forecast to develop in the eastern U.S. is configured such that the surface high extends quite far to the south. Unfortunately, this will likely lead to unfavorable trajectories, keeping the richest moisture -- in the western Caribbean -- from advecting into the Southern Plains. Second, the vorticity maximum is forecast to be slightly cut off to the north; this lowers its predicability. We could see a nice negatively tilted system, or just a sheared out piece of junk. On the other hand, this feature will likely move slowly, so that could be beneficial in keeping the forcing for convection at a minimum and allowing for more discrete convection. At this point, of course, this is all in the realm of conjecture.

A quick glance at the Euro -- the most reliable long-range model -- shows a pattern similar to the GFS. At this point, it doesn't look that impressive, but I suppose I'll take what I can get.

Can you tell this fellow is raring to go out?

 

[Darren Addy]

This forecast thread validates what I've been watching as well (which means I'm learning!) Could be interesting as early as Fri. night if current model would verify. Moisture would appear to be confined to eastern OK, SE KS and points east (and south). Same area appears to have CIN concerns, however. As always, timing this far out is questionable. Hope it isn't a mainly-after-dark event.

 

[Connor McCrorey]

The 12Z GFS is much more favorable than the 0Z was last night. Moisture still a little lacking, but that can change. I loved seeing the 850mb winds go from southwesterly on the 0Z to southerly on the 12Z. Come on, Spring!

 

[Shane Adams]

Looks like 11th-hour return flow (shallow), and blown out east within 12 hours (bring a chain-saw).

Perhaps I've been in this mindset so long now that I'm just being a pessimist, but IMO the S Plains are in trouble as far as quality chaseable events, at least through the next several weeks. And without some type of significant precipitation event, I just don't see the remedy, no matter how far into the future I look.

 

[Mike Hollingshead]

Looks like 11th-hour return flow (shallow), and blown out east within 12 hours (bring a chain-saw).

Perhaps I've been in this mindset so long now that I'm just being a pessimist, but IMO the S Plains are in trouble as far as quality chaseable events, at least through the next several weeks. And without some type of significant precipitation event, I just don't see the remedy, no matter how far into the future I look.

http://drought.unl.edu/DM/DM_state.htm?OK
http://drought.unl.edu/DM/DM_state.htm?TX

Thought these were posted in here but don't see them now for some reason.

 

[Bob Hartig]

You guys are breakin' my heart. I thought evapotranspiration wasn't much of a factor until later in the season. At this point, my thought is that Arkansas and Dixie Alley will bear the brunt of this system. But I'm keeping my fingers crossed.

 

[afischer]

I'm watching the long range models with optimism along with everyone else. With regard to the severe drought conditions over much of TX and southern OK, they sure didn't keep relatively impressive moisture from surviving to the I-35 corridor for the Feb 10 event. Surface dewpoints for the Lone Grove tornado were around 64F with mean boundary layer dewpoints near 61F... pretty impressive (though not unheard of) for the depths of winter in the southern Plains. I'm not exactly sure how drought conditions effect the quality of boundary layer moisture as it advects N from the Gulf of Mexico, especially in the cool season with little evapotranspiration taking place, but maybe the Feb 10 event offers some hope.

 

[Ted Keller]

This time of year, I like to see at least 3-4 days in a row (at a minimum) without a cool front into the Gulf which appears possible this time.

Of course, I thought this last week for this past weekend and we ended up with screaming northerly winds!

12Z GFS shows the first wave lifting across the Plains and upper Midwest Saturday with the main energy hanging back until Sunday.

I wonder if a 3/8/09 FCST thread will be needed?

 

[AndyGabrielson]

When this system started showing up I was thinking the third or fourth, now it looks like the seventh or eigth... This appears to have potential (and i watch with hope and anticipation) but I think your going to be looking more along the lines of MO,AR,IL,KY,TN... I don't think it has anything to do with the drought conditions in TX/OK it just has to do with the fact the dp will return stronger along the mississippi river at least what i saw when i last checked the models. This can all change though. To answer the question about whether an 8th forecast may be needed, a 7th through the 11th forecast may be needed... It just seems to me with as much as this system has changed over the last few days, it is going to be too hard to pinpoint something until maybe Wednesday or Thursday at the earliest...

 

[Shane Adams]

I'm watching the long range models with optimism along with everyone else. With regard to the severe drought conditions over much of TX and southern OK, they sure didn't keep relatively impressive moisture from surviving to the I-35 corridor for the Feb 10 event. Surface dewpoints for the Lone Grove tornado were around 64F with mean boundary layer dewpoints near 61F... pretty impressive (though not unheard of) for the depths of winter in the southern Plains. I'm not exactly sure how drought conditions effect the quality of boundary layer moisture as it advects N from the Gulf of Mexico, especially in the cool season with little evapotranspiration taking place, but maybe the Feb 10 event offers some hope.

That was one system, and it was the first thing down the pike in quite a while...meaning there was no previous system to scour the gulf and limit return. Since Feb 10, we've been in a very dynamic upper-air pattern, with lots of fronts and all that jazz sweeping through every few days. The gulf is getting its ass handed to it every few days, and this leaves little to zero time for a return flow to even have a shot at making the next system. That's the problem with a dynamic pattern but no moisture, it just keeps feeding itself.

 

[Rich Thompson]

I'm watching the long range models with optimism along with everyone else. With regard to the severe drought conditions over much of TX and southern OK, they sure didn't keep relatively impressive moisture from surviving to the I-35 corridor for the Feb 10 event. Surface dewpoints for the Lone Grove tornado were around 64F with mean boundary layer dewpoints near 61F... pretty impressive (though not unheard of) for the depths of winter in the southern Plains. I'm not exactly sure how drought conditions effect the quality of boundary layer moisture as it advects N from the Gulf of Mexico, especially in the cool season with little evapotranspiration taking place, but maybe the Feb 10 event offers some hope.

The impact of the drought will become more pronounced as surface temperatures warm across TX through the spring. Drier ground, more rapid surface heating, no evaporation, little transpiration from trees/grass, and deeper mixing all add up to more challenges in the moisture return department (think "moisture holes" during the afternoon in central TX). A strong synoptic wave can overwhelm the local drought impacts on moisture return, but the drought gives us less leeway in each situation. More importantly, if the drought persists/intensifies, it means we're likely stuck with the same lousy pattern that got us in this mess in the first place!

Rich T.