3/30/06 FCST: IA/NE southward to central TX/LA

[Mikey Gribble]

I like the central to northern Oklahoma target as of now. Relatively speaking, the only thing the surface low target has going for it is more backed surface winds. Central to northern Oklahoma should have stronger instability and better deep layer and low level shear. My primary concerns are moisture and cloud cover. If we can get good insolation along the dryline(in OK.) and realize something close to the 60 dewpoints the NAM is calling for, then I think tornadic supercells are a reasonable possibilty.

 

[Bill Tabor]

12z to 0z forecast only: Looks to me like a definite tornado day at this point. I'd say probably moderate risk, potential high especially if more higher quality air can get up further north closer to the sfc and mid level low. I prefer the dryline - probably eastern KS, or north eastern OK, but with strong 850 jet in place MO will definitely be under the gun toward the end of the day and throughout night with potential strong tornadoes and long track supercells. Potentially tornadic areas: eastern OK, ne AR, all MO, eastern KS, parts of eastern NE, southern IA.

I do note in some ways this is similar to last weeks big system, but coming in a bit more north, and right now a bit further west. As I recall the last system had better dewpoints too (anyone remember?) I'm thinking it was 60's whereas many northern areas here are showing 50's. The dynamics do look similarly very strong though.

Either way even if then northern area with big dynamics (edit: and lower dewpoints) bust a bit, I don't see how the southern area along the dryline such as ne OK could. The last run of the NAM shows the sfc low positioned a bit further east than previous influencing MO quicker. We'll see how the dance of the models goes in the hours ahead.

EDIT: Thinking about this I may have given a bit too much credit to the northern areas showing 50's dewpoints. I think they will still have some torn potential, but this will be diminished some because of lack of moisture. I'm still thinking at least a moderate risk though. For my area (based this far out and subject to change), I'd probably be tempted to go down into the juicier air with 60's dews rather than right on top of the sfc low and mid-upper level forcing direct pathway; however this might still end up being eastern KS, and ne OK. SPC now mentions change for early forcing to cause convection early with possible stabilization and outflow boundary conditions. It will be interesting to see how this plays out. I'll have to look a bit further into Jeff's idea of northern Tx - that of course would be more preferred for me since closer to home. I haven't yet checked today 12 run, but may comment further in a bit.

EDIT2: Also I mention MO and chance for long track supercells and torns....hmm with lower dewpoints this maybe a bit questionable, but perhaps still possible. Areas further south may find it possible also. I'll have to look closer as this thing approaches; however MO and night torns - seems to go together.

EDIT3: Wow looking at forecast ehi for thur is surprising - it is all along the red Tx/Ok (se OK and ne TX). With so little further north this may impact my forecast and drag me further south.

 

[beau_gjerdingen]

Well assuming we can clear out the precipitation the synoptic setup is actually quite similar to the November 12th outbreak of last year. I plan on playing near the triple point, and if that looks to bust fall a little further south onto the dry line, however I do think that the big show for "surprise" tors will fall just east of the Surface low. Looking at 21z output from the 00z NAM shows a far more than ample 1500j of sbcape! Of course this all depends on clearing out of morning convection. For fun though, just compare the synopic setup advertised by ETA with this SPC storm data from November 12th....

http://www.spc.noaa.gov/exper/archive/even...1112/index.html

 

[Jeff Snyder]

As a relatively quick note, I'm actually liking the area in northern TX better on Thursday than areas to the north. The 0z NAM has sped up the progress of the vort max on Thursday, such that I could see relatively widespread convection initiating by early afternoon as the intense vort max slams into the warm sector. Farther to the south, the southern end of the strongest forcing aloft should skirt northern TX and southern OK. The 0z NAM indicates ~65-67F tds down there (I'm highly suspicious of that, but it's a signal nonetheless), which will help boost CAPE a bit. Low-level and deep-layer shear shouldn't be a problem anywhere given the strong, veering winds in the vertical, but the slightly weaker mid-level flow in northern TX will favor slower, more manageable storm motions (Bunker's motion of 40-45kts in that area), while still maintaining 50-55kts deeplayer shear. Depending upon how insolation goes up north, I'm concerned with both the intensity of the forcing aloft and the relatively marginal instability.

The recent dprog/dt from the NAM is a little interesting, since there's a general bias for models to bring systems out of the southwestern US too quickly, which is the opposite of the recent NAM trend from 12z-0z runs. I'm very interested in seeing what the WRF has to show, since it's done pretty well, IMO, this season.

EDIT: There are some similarities to the overall pattern from 11-12, but this one will be several 100 miles south of 11-12 in terms of the low aloft. In addition, the midlevel flow on 11-12 wasn't closed, while it appears that we'll be dealing with a closed low this time around.

EDIT2: I should say that since I'm basing out of OUN / Central OK, I'm not planning on heading to play the triple point to the north unless is looks a LOT better than areas nearer me, which doesn't appear to be the case right now. So, don't take my discussion to be a big discouragement for areas nearer the sfc low, but I do like the southern target better based on current model output.

 

[Mikey Gribble]

After taking a closer look at the 00Z ETA I have to jump on board with Jeff. The Red River area looks better than points farther North. I am sure things will change again, but right now Ardmore looks good.

 

[Ryan McGinnis]

One thing that must be mentioned and which those who don't live up here might not realize is that we still have a significant snowpack up here from the 17-28 inch snowstorm that blanketed more or less all of Nebraska and northern Kansas last week. I'm not sure that it will all be melted by Thursday... I somehow doubt it. I reckon that will depress the temps here a bit. Dunno what that will do to the chances of surface based convection, but it sure can't help.

 

[Jason A.C. Brock]

Im with Jeff as well. Unless things change and NC OKlahoma NE towards SE Kansas begins to look better I will be looking at an area anywhere from OKC South Towards Gainesville Texas (hopefully even a bit further west of this) on Thursday. We havent had a real good dryline set up in this area yet this season but now is the time to start. I also think moisture return in this area is more likley than points North. This will be a good area to chase also after chasing what could be a bust due to the cap along the Texas Oklahoma border on 3/29. Hopefully not and we will get 2 days of Supercells for Oklahoma and or North Texas.
Im also hopng things can fire early enough for a few good hours of chasing and no more of this storms firing at 5pm or later. Depending on Moisture return and cloud cover I could see a moderate risk along the dryline over a fairly large area Thursday from SE Kansas accross the Eastern Half of Oklahoma and into North Central & NE Texas. Anyways jsut my 2 cents.

 

[Todd Rasmuson]

i also have to say iam in agreement with everyone on this issue looks like the prime
target region will be the i-35 area okc to maybe the denton,tx area on thursday, dryline
setup as we all know though will be key to this, so iam saying at this point i-44 east
with best area rightnow for me being i-35 area... also i do see a mod risk day possible
on thursday, with the chance there of a couple large long lived tornadoes in my opinion
if this pans out right, esp along the red river valley area of sc ok into nc tx...

Edit 1: Just also to add looking at some of the latest models i think this could be even
a bit further east then we were thinking but we will just have to see... which would put
most of the svr wx e of okc to e of adm in ok but iam not so sure of this idea i have
a feeling the dryline will stall and we will have a good setup from sw ok into central ok up
along i-44 to close to interstate 35.. could be wrong but thats way i feel.. think models
are proggin it to the east abit to fast but we shall see =) i still think we have a good shot
of something big but still attm have my doubts, gotta see some more runs before i get to
locked in

 

[Chris Lott]

61 td in Waco at 10:45 with a temp of 64. I think higher dewpoints by Thursday might come into play this time. Gfs is still showing LI values around -4 along the Red River for Thursday, with some 0-3 km srh values in the 250-350 range.

 

[Scott Lincoln]

One thing that must be mentioned and which those who don't live up here might not realize is that we still have a significant snowpack up here from the 17-28 inch snowstorm that blanketed more or less all of Nebraska and northern Kansas last week. I'm not sure that it will all be melted by Thursday... I somehow doubt it. I reckon that will depress the temps here a bit. Dunno what that will do to the chances of surface based convection, but it sure can't help.
[/b]

We had a differential heating boundary here in central Iowa on November 12th and that was likely the cause of the sudden turn from non-tornadic supercells into tornadic supercells with large tornadoes.
Lots of things may come into play here than some may not be looking at. The dynamics near the low have been looking better with passing runs. This is similar to the Nov 12th event when people were saying OK and that area for that day, then it kinda pulled a surprise on everyone.
Its the big scale stuff that gives us the greatest potential for chasable storms, but its the almost unforecastable subtle things that turn that potential into reality.


The days leading up to Nov 12, it was looking like a cold core low scenario, then changed as it got closer. What we have is a strong low pressure area with lots of support and dynamics for intensification, that with minor changes could cause severe weather in a number of places.

 

[Simon Brewer]

By the current model forecasts: Southeastern Nebraska still looks like a possible good target, and the possible target in Central OK looks to have shifted a little to the southeast.

Way too many factors are still up in the air for Thursday; speed and path of shortwave, morning convection/precip, position of warmfront and outflow boundaries, orientation and position of dryline and/or cold front, etc.

With strong shortwaves like this one there are many rapidly changing variables, which can turn a potentially good area into a 'bust' area.


I probably will not commit to a target area until around midnight in the early morning hours Thursday, but I have a feeling I'll be heading to Lincoln, NE.

 

[Melanie Metz]

After a brief analysis of morning runs, I like Omaha and ENE from there (at least for the Northern target...since I am in MN after all). Depends on the track of the surface and 500 mb Lows. Eta shows the surface Low in SW MN by 00Z Fri. If that's the case and enough moisture advects north maybe I won't have to travel too far from home! I won't be playing the dryline this day simply because I'm coming from the northeast.

I'll look at more details as the day approaches.

Melanie

 

[Scott Lincoln]

After doing some analysis in BUFKIT, i think the best area along the dryline for severe storms would be the area from Tulsa, OK to Kansas City, MO. At least this seems to have the most favorable overlay of wind dynamics and CAPE during the 3pm-6pm time frame. So if storms form that far east, they'll have some favorable things to work with. The area near the low is kinda looking iffy still dynamically, and still not sure what the models are doing with the mid level moisture/temps. If i were to say follow the surface low, i would aim for the area between Omaha, Lincoln, and St Joseph as a starting point.
Now something i found interesting in BUFKIT was the "forward propagation" feature. I've used it before and it seems to be similar to the storm motion that you'll see with the storms, but i think i might be doing something wrong there. It has the storms in the north moving at like 50-60kts which isn't too insane, but says storms near Tulsa would be moving 70-80kts.
Anyone else using BUFKIT know what i might be doing wrong that can send me a PM or something?

 

[Ryan Pfannkuch]

I know this has been brought up a few times already within the last day, but after perusing the 12z NAM data the synoptic similarities between Thursday and 11-12-05 look even more remarkable given that the NAM shows a more northerly surface low track into northwest IA during the day.

On 11-12 there was a big question as to whether convection would be linear or cellular, and cellular won out with 2 distinct tornadic supercells over central IA roughly 100-150 miles southeast of the surface low.

With both the GFS and NAM both showing the surface low somewhere between the Lincoln NE and Estherville IA areas at 0z Friday, I am liking the 4-state border area of KS, MO, IA, NE more and more. 12z NAM is showing a nice mid-level dry slot punching into this area during the day which would be crucial, especially if the models are over-doing moisture return as many theorize.

As if its not obvious, I am probably being the "opposite" of Jeff here showing my "northern bias" but this bears watching for those of us within a few hours drive of the surface low.

 

[Bill Tabor]

After reviewing the 12z run today it appears once again the sfc low is shifted east a bit more and substantially north as well by 0Z. This will pull the area of interest north into more difficult chase terrain of MO, etc and may thin out dewpoints even more up there while veering the sfc to 850 flow (not desirable). Based on this I have to shift my area south. Large dynamics and probably cold core will be at play further north, but I'm not interested in playing cold core in NE/IA with low dews or taking my chances on a lower dew dryline run in MO (trees/hills). Stronger instability and SRM combo are to be had south near the Red (that is model continues moving sfc low off like this). Still going moderate with some potentially strong tornadoes in areas of stronger instability that can take advantage of mid level and upper level dynamics and perhaps additionally any outflow boundaries if left from earlier. A day of bright sunshine will intensify this situation (obviously).