2011-05-19 FCST: CO/TX/OK/KS

[samuel stone]

primarily regarding the 0z nam

with the 0z nam out, the only potential inhibbiting factor to me continues to be the quality and width of the instability axis. wind fields continues to be favorable at all levels of the atmosphere. nothing catches my attention as quickly as hard backed surface through 850 mb winds. which continues to be progged, cross over from 850 to 500mb should be nearly at a 90 degree angle so thats more than sufficient for supercell modes along the dryline and triple point in central/south central kansas and nw oklahoma. the only thing kinematically id like to possibly see get better is a harder push from the upper level speed maximum but i cant complain about the wswerlys above 300 mb. i didnt look too much at the gfs since i despise it but it appeared mid and upper level winds tended to have a slightly more meridional compenent to them so we'll see how that shakes out. for the one of the first times all year it apears there may be just enough of a cap but not too much as the main chunk of forcing for ascent is progged to hang back to the west hopefully just enough so that a 4-14-11 doesnt happen. keep fingers crossed on that that though as the models will likely waver still being 48 hrs out.

right now id say atleast a handfull of tornadoes appear probable over c/sc ks and nw ok, IF descent mid lvl lapse rates can push in in time, and a good deal of insolation
can take place along the dryline

monitoring visible satellite for breaks in a probable stratus deck during the early afternoon thursday will prove crucial. that will likely determine which areas along the dryline in sc ks/nw ok i will end up targeting. since Hutchinson is my home ill likely have plenty of time to monitor things. couldnt ask for a better setup geographically.

will be interesting to see which models gives in to the other over the next 36 hours but im taking the nam right now. hence this post.

Note; experiencing a thunderstorm in Hutchinson right now. this is the first thunderstorm weve had all year!!

 

[Ryan McGinnis]

Right now it seems to me like the WRF progs the better shear near and just south of the triple point (along the DL), due to the LLJ and the surface winds backing into the surface low. There is a precip signal there, too, at 0Z.

As has been noted before, though, the WRF renders the CAPE axis really, really skinny that far north.

 

[Michael Riedl]

Morning NAM is in, and it again has different placement of the SLP then the GFS does. I am not sure that is going to change the over all potency of the set up, because both the NAM and GFS have strong SE flow at the surface, but geographically it certainly changes things. This needs to be considered when trying to figure out a triple point play, as this option is looking more and more like a strong place to consider. Russel Sounding from this Mornings NAM . Exceptional veering with height and the 0-1 KM Helicity reflects that.

Both this Mornings NAM and GFS come in with almost identical Dryline placement (roughly along US 281) and a very good consensus with the location of the Jet Streak and trough. Also they are both showing a strong SErly LLJ. LCL heights will not be a problem, but again soundings from both models show almost moist adiabatic lapse rates, and morning stratus appears to be an issue when checking the RH charts. Thermodynamically this setup might not be the best, but I am certainly hoping and expecting the great directional shear to over come this and produce.

My current plan is to start out somewhere along US 281, as this provides Dryline and Triple Point access.

 

[Jeff Duda]

I'm just going to say that I hope the GFS verifies. It has slightly cooler mid-level temps and thus is progging SBCAPE to be a tad higher and the axis a bit more widespread (although some of that extra width could be due to model resolution). However, the GFS has the warm front draped farther north, even getting up to the SC NE-NC KS border by 00Z. Slightly better 500 mb flow makes it a little farther east in the GFS as well, thus upping deep layer shear near and east of I-35 (although the triggering mechanism for convection east of the dryline will be very weak or negligible, so the dryline clearly looks like the best play). The warm front may be able to kick off a rogue storm at or north of I-70, thus northeast of Salina.

Oh, if only surface temps would increase a bit. That's about all that's still keeping me from pulling the trigger at this point. I went to Pratt last week. Why not do the same tomorrow?

 

[samuel stone]

it all depends on what the stratus deck does tommorow. as well as the velocity of the pre-850mb winds. those are going to be the two biggest things ill watch tommorow while conducting mesoanaylsis during the early afternoon

I shouldnt have to make any descisons untill 19-20z tommorow due to my geographical proximity so i have no real target at this point

 

[Mikey Gribble]

I am just getting ready to run home and work on my forecasting, but everything seems to be coming together alright. My initial target will be Pratt and then I will move north or south of there a bit depending on where I want to target. Good luck if you are heading out. It is going to be a zoo.
here is the last post from my blog...

A localized tornado outbreak is looking somewhat likely this afternoon. SPC upgraded the tornado potential to 10% hatched, wich I agree with. I also very much agree with where they placed the highest tornado threat. I’ve gone over the forecast plenty so no need to do that again. A dryline will serve as a focus for convection this afternoon, with storms developing roughly along a Larned, KS to Woodward, Oklahoma line. My best guess on when storms will fire is 4-6pm. As SPC reminded us of yesterday though, it is very difficult to anticipate when the cap will break.
Discrete supercells should be the favored mode of convection. With low level shear strengthening through the afternoon tornadic supercells will become increasingly in the later afternoon/early evening.
My initial target is going to be Pratt. I am torn between going north from there to play the warm front, or dropping south from there to the KS/OK border where storms may be more discrete and longer lived. Strong low level shear should be more focused along the warm front though. Moisture pooling along the frontal boundary may lead to a locailized spike in instability also. I expect a cluster of several tornado reports in the vicinity of the warm front, which I will draw on a map when I get home.
The other area I am focusing on would the border area, with a starting target of Medicine Lodge. I think there will be at least one or two discrete supercells along this portion of the dryline. Shear profiles become more favorable for tornadoes later in the day down here. Low level shear will not be as strong as it is along the warm front though, but the more discrete nature of storms will help offset that.
So basically its a trade off, more discrete storms along the border or play the better shear along the warm front. Honestly I think both will produce tornadoes today. Pratt is right between the two targets, so that is the perfect starting point today IMO. Either target is an hour drive from there.
I am getting ready to go home. When I get there I will get a detailed map posted showing the surface boundaries and most likely area for tornadoes today.

 

[Jason Persoff]

Can't argue with Mikey's post above.

Currently in Lamar heading east.

12z data combined with 09z RUC shows concordance of Ts and Tds, so I'm hoping the RUC is on-call for the day. 500mb closed low over the Rockies will continue to provide an optimal envrionment over KS/OK/TX, and even back toward CO. SW winds will be maximized in a thick, elongated zone from SE CO to TX/OK PH to NE with speeds AOA 50-55kts. The midlevels have cooled a lot over the region, but look very solid over SC OK and into TX, though the PH region and all of KS will have very cool midlevels.

Potent, well delineated dry punch should form over the OK PH and spread NE around DDC to Quinter serving as a potent focusing mechanism. The 990mb sfc cyclone in SE CO should once again intensify allowing backing along the dry punch with easterly winds as it moves up close to the I-70 corridor in KS. CIN will hold things in check, but most of KS and some of C OK should become uncapped with CAPE >2000 J/kg. A potent southerly LLJ of nearly 40kt will nose into OK into the S KS region between 21z-00z.

At this point, I'm going for the triple point and probably will head over to DDC for reassessment as the day goes on suspecting I'll probably need to move slightly NE to be in range.

 

[Andrew Stoller]

Looking at satellite imagery, the stratus deck is really clearing and getting blown off to the north as the dry slot moves into the western OK/southwestern KS area, and unlike last weeks big bust in the same area, there's no MCS to the south that will produce high level cloud cover and inhibit full insolation. The 4KM WRF, the RUC, and the NAM all seem to break out convection in the 22z time frame near the OK/KS border area from Fairview to Pratt. This seems likely with the more southern trajectory of the surface low as progged by the NAM, RUC, and ECMWF.

 

[Jeff Duda]

According to 12Z analyses, there is quite a bit of isentropic lift occurring over a 200 mb deep layer (generally from 900 mb - 700 mb in C KS) early this morning. Clouds are clearing in SW KS and portions of W OK, but the lift may keep some of the clouds around for a few more hours before full heating and rapid destabilization commence. Looks like the surface low is currently centered between Garden City and Dodge City and has been moving very slowly north, along with the warm front, which currently sits anywhere from along the KS-OK border east of I-35 arcing towards the low in SC KS. I'm assuming the clouds will delineate the northward progression of the warm front through the day. Both the RUC and RR suggest the warm front will lift steadily north towards I-70 by 00Z with some higher theta-e air seeping farther NW into NW KS very near the sfc low. They also both suggest the dryline will not progress east at all, hanging back in far W OK/C KS or as far west as the far eastern TX PH.

 

[Greg McLaughlin]

I am not liking the cu field developing in northwest Texas into western Oklahoma. This is the type of cu field you would expect to see around 3-4pm. This could be the precip developing that the models have been hinting at during the early afternoon hours across Oklahoma. I hope this doesn't happen as it could waste yet another potential day.

 

[Andrew Ryan]

I am not liking the cu field developing in northwest Texas into western Oklahoma. This is the type of cu field you would expect to see around 3-4pm. This could be the precip developing that the models have been hinting at during the early afternoon hours across Oklahoma. I hope this doesn't happen as it could waste yet another potential day.

I'm not too worried about that, Greg. The environment still pretty well capped and there is no meaningful lift in the area. I think it's a good sign that we have a cu field now. Instability is building quickly even though we have some high and mid level clouds.

 

[Tim Marshall]

Heading to the zone of backed winds west of Wichita.

 

[Greg McLaughlin]

We were just talking about that Ryan. There is no evidence of any impulse near the warm sector attm and the 12z OUN sounding had a nice nose on it. I am curious why the RUC and NAM develop precip so early in the day across Oklahoma. I am hoping it is erroneous. Otherwise everything looks pretty good.

 

[Bill Hark]

Sitting in Pratt checking data. Nice clearing and southeasterly winds but I don't like the cirrus. I am concerned it will be an early show with many storms. Interestingly, there is already a sig tor bullseye for my area and just to the south.

Bill Hark

 

[Michael Riedl]

Headed out from EL Do along 254, the HRR looks nice for Kingman-Pratt-Greensburg area.

Meteorological discussion- the HRR looks nice with bountiful CAPE across the area and actually drags some Supercells north of Wichita.

SRH along the dryline looks good and along/near the triple point.

Clouds seem like they should start breaking up here soon, if they haven't already out west.

I feel really rushed today because something that I planned on taking an hour took 2.