2/23/07 FCST: OK / TX / KS

[Tim Marshall]

TARGET: WICHITA FALLS, TX TIME OF DEPARTURE: NOON. A stormy day ahead but there are problems with this system. Still figure it is worth the two hour drive to get into position to see some storms. PROS- Strato-cu finally arrived at 14z here, yeah. Sharp jet max progged to head into the area later today and I will play north of the main axis. Wind profiles look great for rotating storms. CONS- Lack of adequate surface moisture (40-50 dews yuck), lots of cirrus that will keep temps down, overpowering dynamics later that will end up making a squall line out of this mess. TM

 

[Chad Ringley]

Despite what the 4 km WRF reflectivity prog that Jeff pointed out shows, I am quite skeptical of legitimate supercell development before dark, and think this model may be way too aggressive with the apparent supercell development across SW KS by 0100z.

http://www.emc.ncep.noaa.gov/mmb/mmbpll/cent4km/v2/tcolc_f25.gif

In fact, the 4km NSSL WRF reflectivity prog paints an entirely different picture at the same time frame (0100z)
http://www.nssl.noaa.gov/wrf/rflslp25.png

Now I will be the first to admit that I do not know much of anything about the microphysics/parameterization schemes that these models use, but they definitely show very different scenarios before dark.

The first link from NCEP is the NMM core and the second link from NSSL is the ARW core (a newer version to be exact). The two cores are different and the first link actually has 4.5 km horizontal resolution. Both simulations have no cumulus parameterization scheme and the NSSL WRF-ARW core uses more advanced WSM6 microphysics scheme that is supposed to handle convective cells better (with graupel handled in a different way).

Something to keep in mind is that the field Jeff is showing is fundamentally different than the model-simulated reflectivity you are looking at. The total column condensate, as Jeff pointed out, is good for looking at total core depth which appears to show the development of discrete cells quite well. The reflectivity product in WRF is a tricky thing and though discrete cells aren't readily apparent, the simualtion could be producting something similar that doesn't show up all that well in the reflectivity product.

All that said, I'd have to side with the WRF-ARW core on this one. I'll be surprised if we have a sustained and chaseable period of isolated convection before we get a quasi-linear system.

 

[Eugene Thieszen]

I tend to agree that the parameters look best S of I-40 generally in the SW part of OK. That said, here in Cordell the present ambient conditions are a bit chilly (57) with cloud cover which causes some concern regarding heating. S wind around 15-20 is bringing in the moisture--a gradual rise in dewpoints over the past couple of hours.

The upside?? I can wait this one out here at home <grin> and see what develops.

GT

Gene

 

[Donald Giuliano]

A cursory glance this morning shows...

• Low-level cloudiness is absent north of Abilene/Lubbock. This is a big negative in my opinion, because it indicates that the good moisture hasn't come back yet, even above the surface. When the moisture returns (returns from when, last fall?), so will the clouds, and the sooner the better for storms. So far, I'm not impressed, and it should be pointed out that the 00z NAM showed dewpoints in the low-mid 50s over western OK by 18z, with upper 50s pushing the Red River. I have a hard time believing that given present obs, and the 12z NAM backed off a bit to having 55 pushing the Red River.
• The RUC is less bullish on moisture return than the NAM and more in line with sfc obs, not good. I think the truth lies somewhere in between, since the moisture is still advecting north a little faster than the RUC would have us believe.
• After dark, things still look like they could get crazy, even on the RUC, which does eventually get the moisture up here around the 00z timeframe. Not good for chasing, but then this was never really a daytime event anyway.

All in all, I'm still very impressed by the after dark scenario, assuming the NAM verifies (a big IF to be sure). Was hoping against hope for some daytime action, but it appears that was too much to ask.

 

[Andrea Griffa]

Mmmm I don't like so much the new run of Ruc..Too less moisture in my target zone(Dodge city/Buffalo). As to Ruc the major part of the moisture(with 60F dew) remains in Vernon/Wichita Falls territory.

That's in contrast with Eta 00Z..I wait for Eta 12Z.

 

[Chris C Sanner]

With the pressure gradient tightening, I don't see any reason to believe we won't get the moisture in place in time. What is going to be interesting is seeing where the clouds might hold off this afternoon, if anywhere. The Tornado threat is going to be highly conditional of the instability that is present. SPC seems to think we'll possibly have a supercell or two before everything congeals into a squall line and then we'll possibly have an isolated supercell out ahead of the line tonight. With all that said, I'll be in Altus almost certainly and possibly Childress, but I want to give myself a bit of a buffer in case we have to play catch-up. I really like that the GFS in particular develops isolated precip in that area and you'll have the best moisture there for sure.

Should be a "fun" ride home regardless of if we see something in the day

 

[Donald Giuliano]

Investigating the 12z NAM a little more shows that the dryline is really hanging back now, with it still being along/just west of I-35 as late as 12z Sat, and 1000-1500 SBCAPE still ahead of it in a narrow corridor. Just makes me wonder how interesting things might get tonight. Perhaps we could see a situation where storms occasionally fire along the dryline, move east and go crazy for awhile before dying in the stabler air farther east? I have a hard time believing there won't be any storms at all in an uncapped environment with weak lift around the 850mb layer (at least according to the NAM), and squallishness seems unlikely until the main vort kicks out over the dryline around sunrise tomorrow.

 

[Bill Tabor]

Latest NAM/WRF run is considerably less bullish on the situation particularly during daytime. Previously it was showing some cells at 0z but not so much now. Also dryline appears further west.

Will note appears to me that moisture is getting up there at least in the mid 50's (north Tx). Ruc believes a cell will break out at 0z. Not sure how much you can really trust the NAM / RUC precipitation forecast, in my experience not alot particularly on the iffy situations; however I tend to usually trust RUC more.

Various parameters such as EHI, LI, etc appear to be lessened from last nights run. We do have cloud cover now. Seems I am a bit concerned for enough heating to make the dryline enough of a convergent boundary to fire storms even with overhead.

Summary: I think the overall risk has diminished from what we were seeing last night, which was looking very strong at the time. Storms firing near dark in north Tx/Ok are even somewhat more questionable now. This may not break out until the big wave hits later.

At this point you just have to roll the dice and take your chance. Risk the drive and possible bust, or not. For night chasers certainly something will happen during the overnight hours, but it isn't really the best type of situation for night chasing. That's typically better in the summer with slower moving storms, good lightning and ability to see the base.

 

[Kenny Drake]

Investigating the 12z NAM a little more shows that the dryline is really hanging back now, with it still being along/just west of I-35 as late as 12z Sat, and 1000-1500 SBCAPE still ahead of it in a narrow corridor. Just makes me wonder how interesting things might get tonight. Perhaps we could see a situation where storms occasionally fire along the dryline, move east and go crazy for awhile before dying in the stabler air farther east? I have a hard time believing there won't be any storms at all in an uncapped environment with weak lift around the 850mb layer (at least according to the NAM), and squallishness seems unlikely until the main vort kicks out over the dryline around sunrise tomorrow.

Yes I have noticed this with each new RUC model run. For those hoping to catch a cell before sunset you might want to think about heading slightly farther west, but definitely still stay ahead of the "firing line" because they will be clipping along at a faster rate. However, the vort max is still being progged to enter the area at roughly the same time so the dryline holding back may be bad depending on the amount of daytime heating the area receives. As for dewpoints, low 50s now showing up in SW Oklahoma. Moisture advection appears to be arriving on cue. Analyzed RUC Forecast sounding for Altus at 10AM progging insane amounts of heating by 1pm (which I do not believe, they are in excess of 20C and currently there is a steady stratus deck overhead). 850mb appears to be saturated at present and is progged to mix down to the surface yielding upper 50F Td's by 3pm. 850mb analysis shows ongoing moisture advection from NE Mexico through Texas and into west central OK.

Visible Sattelite imagery at 11:02PM CST shows clearing immediately ahead of the dryline with a stratus deck from the TX/OK border to western portions of central OK. I can make out some possible small Cu going up WNW of Childress.

I have class until 3:20pm CST so I want to be quite sure that I will not be completely dissapointed after hauling butt to get to my destination (which will either be Altus or Elk City). The destination will be determined based on the moisture content Elk City will be at near the time of expected initiation (5-6pm CST). Altus is a sure bet, Elk City is more conveniant road-wise.

 

[Donald Giuliano]

After looking even further into the NAM, it appears that everything is just pushed a little farther west on the 12z with the dryline being farther west as opposed to the 00z, but every bit as promising for nighttime tornadic activity. CAPE 1500-2000 at 03z in the eastern TX panhandle with phenomenal shear, WOW! This is looking to be a very interesting evening post-sunset.

Normally I'm very concerned about dewpoint depressions being above 10-15 in these low-moisture scenarios (hence I'm not fond of excessive sunshine, not to mention the mixing out of moisture), because of how nighttime cooling tends to make for a massive cap when the moisture is marginal (below about 65 F as a rule of thumb). In this scenario, however, any cap that appears will rapidly be destroyed by CAA aloft, so 70/50-55 around 21-22z is probably not an indicator that the nighttime event will junk out, because the strong moisture advection near the surface combined with the strong CAA aloft will give us the ingredients to look for after dark regardless.

 

[Ryan Pfannkuch]

Well, I'm already commited to sitting this one out considering my lack of confidence in daytime initiation issues...but after closely examining the 15z RUC and looking at moisture trends, I 'll go ahead and throw out what would be my 4-county target area at this point, pretty much straddling the OK-TX Panhandle border along I-40: Collingsworth (TX), Wheeler (TX), Roger Mills (OK) and Beckham (OK)....pretty reasonable agreement with some of the recent posts.

This is right at the NW edge of the main surge of mid 50s dewpoints, and is also right in the crosshairs of the initial 500 mb vort max and associated cooling moving out of NM between 0-3z.
http://wxcaster2.com/CENTRAL_RUC_500_GPHTMPWNDVORT_12HR.gif

As others have likely noticed, the 3z RUC fcst sounding for Childress is pretty darn interesting with 0-3km SRH of 417, MLCAPE of 1221 and LI of -6.3. http://68.226.77.253/skewts/RUC-test/012/SKT_RUC__KCDS.png

However, estimated storm motion is 49 kts by this time...anybody heading that way, please play it safe in the dark.

 

[Justin Bailey]

current conditions
childress: fair, temp-69, td-53, winds gusting from the south at 26mph.
altus: overcast, temp-63, td-54, south winds gusting to 25mph.

IDK how deep the moisture field is but mid-50's have arrived!!! i say we still have a shot at initiation before dark.

EDIT: surprised to see alva reporting in with a td of 54! didn't think mid-50's would be streaking that far north this fast. also, Norman has mentioned in thier short term forcast that initiation late this afternoon is still possible.

 

[Joey Ketcham]

Tyler and I are sitting right off I40 in Yukon Oklahoma, skies are mostly sunny with temps of about 72 degree's, getting some good warmning out here. I think we are going to head to Elk City and see what's going on from there and decide if we want to go west more into Texas or stay in SW Oklahoma.

 

[Kenny Drake]

TARGET: Elk City

Discussion:

Low 50 Td's now entering the area. GFS and NAM forecast soundings both show an uncapped environment at KCLK (Clinton) by 00Z (which is just east of Elk City) with Td's in the mid 50's and temps near 70F. The vertical profile yields CAPE ~600 J/kg and an adiabatic temp profile up to LCL (hence no CIN). However, with the 500mb vortmax approaching the area, CAPE should only go up, possibily even after dark with cooling mid to upper levels. With the dryline progged to be slightly farther west than earlier model runs, am anticipating ongoing convection that will rapidly approach the area with an ENE storm motion 40-50kts. I am expecting the cells to conglomerate into a linear MCS between 10pm and 12am CST with embedded supes and possibly a nader or two given the wind shear. Should be a fun drive back to Norman, will have to pay very close attention.

Due to class restraints I cannot leave until 3:30PM CST so I should be in Elk City by 6PM, under an anvil if I'm lucky enough.

 

[Glenn Dixon]

lessee........leave Denton at 5:00pm............hmmmm....................

nah, can't make that work. Crap.