3/23/09 FCST: NE, KS, OK

[Beau.Gjerdingen]

Honestly, pending Monday morning's vis sat, if I was close enough, I would consider playing a Cold Core setup in N/NE NE.

My thoughts exactly! I have been wanting to target the southern areas all the way up until today. It is becoming increasingly apparent that moisture will be meager from northern Oklahoma all the way through Nebraska. The best way to sneak instability out of this setup appears to be under the cold core further north over Nebraska where the lapse rates will be much more extreme. Of course the main con will be the much stronger forcing and the attendant quick transition to a linear arc of storms (Small window of opportunity).

As it stands now though I am abandoning KS/OK for NE unless I see a substantial difference in the moisture return.

Good luck to all who venture out...wherever you end up!

 

[William Reid]

Based on a quick look at the 00Z Sunday NAM valid for Monday afternoon, the most favored area for tornado formation would appear to be right in front of the Nebraska surface low ---- surprise, surprise. This would be around Lake Andes, SD around 4 p.m. CDT to about Mitchell, SD around 7 p.m. Surface winds are very nicely backed on Monday afternoon over southeast SD. Of course, the details will change between now and Monday afternoon.

My secondary target area is between Great Bend and Salina, KS. If I were based in ICT or OKC, I doubt that I would make the drive to NE/SD...but I don't have to decide because I'll be watching from California.

Bill R.

 

[Tom Tackett]

As of 0500Z, Sun., 3/22/09, Td's are still only the upper 40's to lower 50's across North Texas Reporting Stations. In watching the Western Gulf of Mexico today, there is an area of 65+ Dewpoints out there, although it has not expanded in size much during the day.

Since the best opportunity for surface-based thunderstorms appears to be near or more likely after 00Z Tuesday across the Red River Valley of North Texas/Southern Oklahoma, I will likely watch this one from the comforts of my home base.

 

[Andrew Stoller]

Well, after checking out some NAM forecast skew Ts, there's a glimmer of hope. Wichita had 1,300 J/JG CAPE at 00z, but the hodograph wasn't very pretty, and the cold front pushes through from northwest to southeast right after 00z. Points further southeast like Bartlsville - only 800 J/KG CAPE, but the hodograph is a thing of beauty.

If my home base was in the area, I'd be all over it. But a 12 hour drive for a fairly marginal setup? I dunno...

 

[Eric Treece]

I am having a hard time buying into this. If I were going to chase, and the door is just slightly cracked at this point, I would probably target near Kearney and points north with the cold core part of the system. I am probably going to watch this from home tomorrow as this is has just not really entrigued me enough to chase it. I like how the dryline has the slight bulge on the eta at 18Z, but I wish there were a little more CAPE to make it more appetizing. Unless something drastically changes on the next couple of runs, I am probably going to armchair quarterback this one and wait for my May/June vacation. Good luck to all those venturing out!

 

[cdcollura]

Good day all,

It appears as if this will be a cold-core setup nirth of Kansas and into Nebraska with a dry-line (linear forced) southward into Oklahoma, so two "targets" might apply. The moisture return will be the biggest player on the southern target / backing of low-level flow.

 

[Jason Young]

I feel like the odd one here . Dew point's here are in the upper 50's and the Nam ( per twisterdata ) is showing CAPE of 1000 around 7 pm. As of this time , due to working until 4:30 , I will be targeting the Lawton area . Good luck to you guy's up north .

 

[Donald Giuliano]

The moisture situation for Monday is looking up this morning as per both morning obs and the NAM forecast. Soundings this morning show decent moisture already established in FWD, with better moisture already on the way:

Dallas sounding
Brownsville sounding

The NAM seems to be picking up on this, and is forecasting a much larger area of decent CAPE with no CIN Monday afternoon, leading to some pretty nice forecast soundings (I've chosen ones somewhat ahead of the dryline a little northeast of El Dorado, KS and near Norman, OK):

NAM Forecast CAPE
NAM Forecast CIN
El Dorado Forecast Sounding
Norman Forecast Sounding

During the course of the evening the soundings/hodographs improve even further as the system swings through and the nocturnal LLJ intensifies. It should be noted, though, that the GFS has much more severe capping, partly due to slightly less BL moisture and partly due to warmer mid-level temps.

In short, there's still a long way to go with this system, but I'm at least more interested now than I was yesterday--especially since today's moisture situation is much better than initially forecast. Some of this will mix out of course, but given that BL moisture in Brownsville is above 12 g/kg (though fairly shallow), it doesn't seem unreasonable that it would mix out to something more like 11 g/kg as it advects further north (as depicted by the NAM). This is especially so if we have 850 mb moisture advection from the west on Monday to help stem the tide of daytime mixing as the moisture slug forecast to back up against the higher terrain this afternoon/tonight shifts back east. At any rate, I'll be very interested to see this evening's soundings.

 

[Chris Wilburn]

Forecasting sounding for Stillwater valid 7pm Monday (00z) looks very nice. CAPE 1,496 with an EHI of 4.1 and and LI of -4.8. Also, 0-1 SRH is 230 and 0-3 SRH is over 500. Of course this is only one sounding, but near 1,500 CAPE sure would be nice. The forecasted moisture and instability increase as storms move further off the dryline, therefore storms may take a while to mature once they initially fire. Add this with moisture and instability still increasing in the evening and it could be a very nice day, esp. later on and just after sunset. Of course there will be some mixing of the dews, but if we can actually get say 58-60 td's with CAPE above say 1,200 or so there may be a shot at a few tornadoes, esp. with the insane amount of shear. Of course like any early spring setup storm will be moving rather quickly at around 40kts. It sure would be nice to have td's in the low 60's and CAPE actually reach 1,500-2,000 but you can't have everything I guess. At least there is some very nice wind shear, however like many have said before I haven't had the best of luck with low instability and high shear setups. I guess we will see what tonights run of the NAM looks like.

 

[jshields]

i've decided that i am going to go out tomorrow afternoon up in ne nebraska with the cold core setup. hopefully we get some clearing in the afternoon tomorrow! the 12z Nam shows cape of about 1000 j/kg with temps in the low 70's and 55-60 degree dewpts and the omaha wfo talks about a window of opportunity for a few tornadoes between 21Z and 0Z. i'm not hoping for a lot but maybe i'll get lucky

 

[Mikey Gribble]

here is part of my forecast post from my blog this morning...

I’ve spent a little while going over models and current conditions this morning and I am a little more optimistic about the chances of a few tornadoes tomorrow.
Morning soundings show that moisture is adequately deep across a large portion of eastern and southern texas. This moist tounge is about half way across Texas now (going off >55 td). Trajectories will remain very favorable for further moisture advection and my best guess is that we will get dewpoints in the 58 degree range near the KS-OK border. If dewpoints are at or above 58 degrees it will be adequate for a respectable tornado threat with any discrete, persistent supercell.
There isn’t much to say that I haven’t gone over already. The keys to this setup is getting the quality moisture up to the KS-OK border, getting some clearing over the warm sector ahead of the dryline to allow for destabilization and getting a persistent supercell off the dryline near the KS-OK border or a little south of the border. The sweet spot for tornadoes is northeast of the Cherokee-Medicine Lodge area, so any storms developing in that area should track through the best environment and would have a good chance of going tornadic IMO. The location of the dryline is still uncertain, so these targets I’ve mentioned could shift east or west tomorrow based on where the dryline sets up.
My target as of now would be the KS-OK border straight south of Medicine Lodge. I am hoping for a storm to fire south of there and track northeast. On fast storm motion days like tomorrow you always want to cheat downstream of your actual target area. Because of that I will probably set up shop in Medicine Lodge. Remember it is a hell of a lot easier to catch a storm that is moving at you than one that is moving away from you, so make sure you cheat north of your actual target area.
I will post updates through the day on how moisture advection is going and on anything else that I may pick up on when I work on my forecasting. Below is a map showing the area that I think has the highest tornado probability tomorrow. Remember this could shift east or west based on the location of the dryline.

I have a map highlighting the highest tornado risk area on my blog too, but I don't know how to paste that here and the forecast post before this one on my blog goes a little more in-depth if you're interested here is the link http://loadedgunchasing.com/blog1/

 

[Jeff Richardson]

Didn't surprise me that a moderate risk area was added on the Day 2 update. Considering that I'll be sitting this one out, I'm sure it's bound to be a good show. Forecast shear profiles are good for OK & KS, just like to see an improved moisture return. Going to be a "computer chase" for me...best of luck to those who are headed out...be safe.

 

[nickgrillo]

Of course the main con will be the much stronger forcing and the attendant quick transition to a linear arc of storms (Small window of opportunity).

Exactly. Infact, the degree of deep-layer forcing looks to be the biggest problem for tomorrow, in my opinion. Now, assuming we do get discrete convection developing further down the dryline in southcentral KS/northcentral OK, then the ambient low-level/deep-layer shear will easily support a strong supercell (NAM forecast hodographs in southcentral and southeastern KS show defined cyclonic curvature given the backing boundary layer flow). CINH for a surface-based parcel rapidly erodes after 21z in response to the mid-level cooling associated with the shortwave trough at 500mb. This, of course, will lead to the rapid development of DMC. The best window of opportunity for an isolated tornadic supercell would be in southcentral KS/northcentral OK between 21z and 00z. If we can get a surface-based supercell to remain semi-discrete for a while, then the favorable boundary layer kinematic and thermodynamic profiles will support the development of low-level mesocyclones and potential tornadoes; LCL heights are very low in the warm sector (less than 800 m AGL in some areas).

If I was chasing tomorrow, then I'd be heading for ICT.

 

[Chris C Sanner]

Tonights soundings are going to be very important to figure out the depth of the moisture. We have been slowly mixing down here in Oklahoma all day as we started out the day with TDs in the upper 50s and we've mixed down into the lower 50s. The mid-50s dewpoints are sitting down well south in Texas, but I'm sure tonight's LLJ will probably give us rapid moistening, definitely back into the upper 50s by morning.

I'm thinking we are going to be battling with moisture depth all day tomorrow, we had a day very similar to this last year which the shallow moisture completely fizzled out by evening and we ended up with a blue sky bust with the only good storm occurring south of the Red River.

The upper air pattern is definitely favorable, but we are going to be fighting time as far as discrete storms go. Systems that are this dynamic tend to produce a lot of storms, and the SPC outlook definitely reads they are expecting this as well. I'm just worried we are going to have too much of a good thing as far as dynamics and it's going to kill our chances if the moisture isn't deep enough.

However, given sufficient moisture return, which I think is a toss-up at this point, we could be looking at a 4-5 hour window of discrete storms with manageable motions tomorrow in the southern target. That would be good enough for a cluster of tornado reports. However, we could just as easily end up with a severe complex with a bunch of hail and wind reports. No target yet, going to wait until tomorrow morning for that.

EDIT: Third paragraph, yeah...that's what I get for not really checking the models until the 0z run before the event I was basing that off of much earlier runs...but I do still believe my comments about the highly dynamic nature of the system (and the loads of forcing) leading to numerous storms is still a major concern

 

[Benjamin Rock]

I've been planning on the OK/KS border myself for the last 36 hours and now seeing the MOD risk pop up, the CAPE at or slightly above 1000 j/kg, my biggest concern is moisture and the fact that is looking to be a cold core system with dew pts varely reaching the 60s. Sit and wait is the game tomorrow.