5/7/08 FCST: TX / OK / KS / LA / AR / MO

[Brian McKibben]

It is still 156 hours out, but the GFS shows a nice little 500mb jet moving over OK and TX on 7 May.

At the surface Tds look to be in the mid 60s with some warm surface temps as well. This is yielding at least 3000 j/kg SBCAPE and the cinh decreases to around 10-20 j/kg from SW Okla. up the I-44 corridor by 00z.

The GFS breaks out precip near the surface low in SW Okla. and along the extending warm front.

I may be wishing but it looks nice the next good chance for storms in KS/OK/TX

 

[afischer]

A significant severe weather event may shaping up for the central/southern plains on Wednesday. 00Z European and 00Z GFS are in fairly ridiculous agreement that the complex troughiness currently over the Gulf of Alaska/Pac NW waters will evolve SSE into a closed low and then eject fairly quickly ENE into KS on Wednesday afternoon/evening. Rich boundary layer moisture stalling over deep south TX and western/central Gulf of Mexico this weekend should be drawn northward easily into the system. Won't get into trying to assess mesoscale details or timing, but this has the potential to be a particularly nasty event... not unheard of considering the calendar reads early May. The high-res European's surface low by 00Z Thursday is 985mb! GFS model soundings ahead of the dryline show classic, large, sickle-shaped hodographs.

 

[Ben Prusia]

This looks like a day that is worth watching. GFS out to 120 hours has moved the system further north, allowing for most of southern Kansas to remain in the warm sector. Both the Euro and the GFS are in agreement on the position of the system, with the surface low positioned in central Kansas, as what afischer said.

Just taking a glance at the 0Z GFS Saturday run, triple point sets up in central Kansas, with sharp dryline extending southward along I-35 at 0Z Thursday. GFS only indicates dews reaching the mid 60's, but the mid layers of the atmosphere will remain moist. The model also indicated widespread precipitation in the area of Kansas southward, so as again, this looks like a day that is worth watching...even as ICT mentioned in this morning's AFD:

MODELS CONTINUE TO ADVERTISE A STRONG SYNOPTIC SYSTEM PULLING OUT OF THE SOUTHWEST US INTO THE PLAINS FOR WED. INSTABILITY AND DEEP LAYER SHEAR AHEAD OF THIS SYSTEM SUGGESTS THIS COULD BE A FAIRLY VOLATILE DAY WHEN IT COMES TO SEVERE WEATHER ACROSS MUCH OF KS. LATEST GFS SHOWS WARM SECTOR NOW WELL INTO SOUTHERN KS FOR WED AFTERNOON...SO WILL INCREASE POPS SOME IN MOST LOCATIONS...AND KEEP A WATCHFUL EYE ON THIS TIME FRAME.

Quite a few WFOs (ICT/TOP/EAX) mentioning possible significant severe weather that day, and as I have the day off, should be interesting... maybe our first decent shot of some actual daytime storms.

 

[Kenny Drake]

Ensembles generally want to emphasize the strength of the northern jet stream and as such don't agree at all with this shortwave. I'll definitely be keeping an eye on this day as it's climatologically favorable for a svr outbreak if the shortwave ends up being where the GFS and ECMWF say it will be. Generally I don't like these sort of fast moving storm systems as large-scale forcing tends to lead to a huge svr squall line such as the one that moved through Kansas City a couple of days ago. However, its still 4 days out and given how well the NAM has been doing this spring I'll stick with GFS and ECMWF for now. I'll start taking this day seriously on Tuesday if it looks like it will pan out.

http://www.emc.ncep.noaa.gov/gmb/ens/fcsts/ensframe.html

 

[John Farley]

Well, this thread has certainly been quiet for a while. It looks like instability will be hard to come by and precipitation will be very widespread, making for a tough chase day. But I am wondering if there might be a potential target around the Hannibal-Quincy area somewhere along where it looks like the warm front will be in northeastern MO or west-central IL. I know this was not particularly an area of interest earlier, but this evening's model runs suggest some potential there - perhaps locally a little more instability, and certainly decent shear and divergent, if not the strongest, upper winds. Am I out to lunch on thinking this area might have some potential, or do others see some possibility here, too? If others do chime in on this, maybe the mods might want to add MO, IL, and possibly IA to the thread.

 

[John Peters]

It looks to me like Wednesday would have massive potential for NE TX, AR, LA if there were slightly more instability. 60 hr forecast sounding for SHV depicts very modest mid to upper level lapse rates (EL of just under 300 mb, which is pretty low considering the location climatology and ~65 deg tds). It doesn't seem like cap is going to be an issue based on latest eta, and any discrete storms will have just awesome sheer profiles (approaching 80kts at 500 mb, 40-50 LLJ). Eta is also depicting a pocket of >500 m2/s2 SRH over north central AR. Looks like we may not see any giant hail, but i think there will certainly be a tornado potential.

 

[Bill Tabor]

With (TX) weak sfc winds currently showing on latest NAM run (0z) and veered 850mb flow, mostly southerly 700mb and 500mb flow and sfc low and mid level low transitioning quickly to the east near the Red I wouldn't be surprised to see a squall line / possibly MCS in Tx. Good opportunity for wind and hail I think tornado chances are currently on the low side except for the occasionally stray tornado which there will probably be a few.

 

[Chris C Sanner]

Taking a break from studying for finals, I have been carefully watching the potential for a cold core tornado type of situation occuring near the surface low tomorrow for a couple of days and just saw the SPC highlighted this in their discussion. It looks like the instability in the lower levels will be rather strong given some daytime heating and winds will have a nice directional component near the surface low and an associated E-W boundary which shows up on the model charts. It's not a for sure situation, but if some sunshine heats up the atmosphere it could get rather interesting. Given the fact I don't want to chase E. Texas, I think I'm preliminary targeting somewhere in southern Oklahoma for this tomorrow if we can get some sunshine. If not, I'm targeting my couch and more studying....

 

[Bill Schintler]

Chase target for Wednesday, May 7

Chase target:
Gainesville, TX (just north of Fort Worth)

Timing and storm mode:
Discrete storms should form along a dry line by 3 PM CDT.

Synopsis:
UA analysis indicates ridging over the central CONUS with a 130 kt jet max approaching SERN NM. BL moisture has been slow to recover in the TX panhandle following last nights widespread convection and veering LLVL flow, which has effected the evolution of todays convection. MDLs have a good handle on ongoing convective trends in the TX panhandle as well as SFC moisture in NRN TX and OK.

Discussion:
The most likely location for severe WX appears to be near the leading edge of a dry slot and associated DL as the cold-core low tracks through CNTRL OK. By 20Z, a narrow axis of instability should develop along and just N of the Red River, and along I-35 in NRN TX. 2000 J/kg of CAPE is likely as cold mid- and upper-level temperatures overspread the area, with the majority of the CAPE concentrated below 23kft. Elevated convection will be ongoing over much of WRN OK early in the period due to large scale assent there, and CIN will rapidly erode along the leading edge of clearing near the Red River and I-35 by 19-20Z. A sharp gradient in the H9-H5 flow speed will exist S of the Red River between 20Z and 23Z and S of the ULVL low, with unidirectional shear increasing rapidly from N to S along the NRN periphery of the trough and strongest cyclonic flow. In addition, SFC-3km SRH will increase to 300m2/s2 over a limited area within a region of backing SFC flow E of the DL.

- bill
11:15 PM CDT, 05/06/08

 

[David Wolfson]

Currently (05Z) experiencing tonight's meso-convective mess in Vernon, TX. Some method to my madness post-chase as the target tomorrow is... Vernon, TX for possible long-track tors. Thence following the late afternoon quasi-cold core action as it propels me back toward Amarillo at night and home Thursday . It looks like a pretty wild setup all-in-all as low pressure at all levels closes off and stacks over sw OK through the afternoon.

The SPC convective outlook reads like a dim sum for severe over the forecast area. Take your pick, put on your track shoes, and keep your head down.

The storm knocked out cable and motel wifi, so am running off "local battery" with my mobile VZW card.

[ed. 15Z] The morning alas reveals that the hoped-for stacked vorticity and <988 surface low by 18Z near Childress isn't coming together very well at all. If some clearing materializes there's some chance for an isolated storm with cold-core attitude in this general area and north IMO. Although there may be some chances later east of I-35, poor chase country, flooding issues, and my budget won't send me there today.

 

[Shane Adams]

Visible satellite loops and profilers show the speed trough nosing out into west Texas attm. Although ongoing convection will no doubt limit overall instability potential in the main target area of S/SE OK/N/NE TX, today is all about shear. This area has some of the worst chase terrain in the country, but there is enough "room" between the initiation point and the bad terrain to get a shot at some viewable storms, between the I-35 & US75 corridors. It will be a mess with all the muck out there, but the southern edge of the precip is beginning to move out of the target area. OK mesonet analysis shows that the surface setup in this area is largely un-affected by this morning's convection, and this coupled with the advertised windfields is enough to get my attention. Today will be a very tough chase, but I cannot ignore the helicity potential later today along the RR.

Plan is to go south to Ardmore, then probably play it east from there, depending on exactly where convection fires initially. I'm going to stay north of the river in anticipation of rocket storm speeds, and hope like crazy I can get something timed right to produce as it races by. It's an exercise in futility on paper, but there's a sweet potential reward swimming in all that mess today. I'm gonna bite.

 

[Chris C Sanner]

Right now it looks like there is going to be a very narrow window for tornadoes today in the mid to late afternoon near the surface low. I'm planning on heading out the door shortly as the southern surface low has formed in NW Texas. Plan will be to stick E or NE of the low in the best cape and clear air and hope the colder 500mb temps, big low level lapse rates, and degree of cape in the lowest 3km gives us a tornado or two. Not sure if the chances are all that high, but it's worth a play today with finals almost over. Maybe I'm just used to the SC Oklahoma area, but I don't think the terrain is all that bad. Targeting Duncan to Davis and following the Surface low east from there. Probably will have to track further south but I'm going to aim for the area with the greatest backed surface flow. Everyone crazy enough like me to go out have fun and good luck!

 

[John Peters]

SPC has upgraded the tornado potential to 15% hatched for NE TX with mdt risk, and i must say I agree with that move. Tds in the 70s, patches of clearing, MLCAPE as high as 3000 j/kg-1, 80-100kts at 500 mb!, helicity between 400 and 700 m2/s2, and a pretty strong LLJ, i could see a few discrete storms producing long tracked families of tornadoes in this concentrated area.

 

[Tim Marshall]

TARGET: FTW-PARIS, TX TIME OF DEPARTURE: I'll hold up here north of FTW until the dryline arrives. It's about time storms come to me. PROS- Strong dynamic system approaching with cold pool west and strong jets overhead. Dryline is mixing eastward and has already passed Abilene and Brownwood. I'll stay north of DFW in the backed surface flow and better directional shear. CONS - Lots of low clouds, worked over air, and poor directional shear south of the target area. It will be difficult to keep up with a storm as it will be racing north-northeast. Add to that traffic, and poor visibility due to lots of trees east of here and that will make for a frustrating chase. But, it's close to home so I'll take a chance at rolling the dice one more time. Expect storms to fire near the DFW area and race north-northeastward as the dryline pushes east. I'll probably end up near Paris, TX tonight. TM

 

[Jeff Snyder]

We're about to head south towards N TX... My half-effort sfc analysis shows three boundaries of interest -- a warm front that stretches from SW Oklahoma to NE OK (not too far from I44), a wind shift line (or very weak eastern dryline) that stretches from W of SPS to SEP to TPL, and a "primary" dryline that runs from S of LBB to Snyder to E of JCT. The dewpoints behind the eastern 'wind shift' are largely in the 50-60F range, while the Tds drop rapidly into the 20s and 30s behind the primary dryline. Destabilization is occurring W of I35, though it would be nice to get rid of the elevated trash near I35. Some Tcu and Cu are noted developing between this wind shift line and the primary dryline to the W, so it'll be interesting to see how the surface pattern evolves through late afternoon.