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

[Jason A.C. Brock]

If that radar simulation is to be even half correct that Jim Posted the Wichita Falls area is going to be in some serious trouble after 8pm and continuing for severeal hours with multiple supercells coming into or very close to the city of Wichita Falls not to mention the several small towns in Western North Texas. The actual stormtracks at times look similiar to to the Terrible Tuesday scenario. I know its jsut a simulation and I also am not getting my hopes up for anything in February till I actually see it. I will be heading out tomorrow early afternoon towards the Altus Childress to Shamrock area. I am concerned storms may actually fire similiar to the model radar simulation and we get an Isolated Beast of a storm down near ABI towards sunset or jsut after. We may be sitting in Western Oklahoma droooling over the laptop looking at radar.
Ill just be hunting lightning and perhaps some illuminated storm structure type pics once sunset occurs. Even the lightning Illuminated tornado pics I have seen dont have be jsut drooling to try and get one. Then again I am a more of a structure and photographic chaser rather than an actual thrill seeker.
Everyone keep an open and clear mind tomorrow and have fun chasing and keep your head on a swivel....if it feels like something is wrong...more than likely it is...

 

[Donald Giuliano]

Nice WRF images, Jeff, I love the storm splitting in the model that you pointed out! Definitely awesome.

One thing to note, tomorrow will be cloudy in the warm sector, there is no question about it. This doesn't concern me, as the reason the cap is eroding and the instability skyrockets has little to do with daytime heating, but instead is almost entirely due to strong moisture advection in the morning combined with intense cold air advection aloft late in the day. I fully expect the temperature to be in the 65F range tomorrow afternoon in western OK, not much different from the 55-60 values we see right now (the models reflect this).

In my opinion the high RH values in the boundary layer are a huge plus, in fact probably a necessity, as they indicate cloudy skies during the day that will prevent the good boundary layer moisture from mixing out and becoming crappy. See the 00Z 23 Feb Del Rio sounding for what I fear would happen if tomorrow were sunny. 60-65/55-60 tomorrow night is perfectly sufficient, we don't need temperatures/dewpoints any higher than that. And the absolutely last thing we would need are clear skies around sunset, because the ground is still not all that warm, and we would be in danger of cooling off the boundary layer awfully fast.

 

[Daniel Christianson]

Well i hope this all works out, ive been sleeping with dreams of this chase lol , im going to head home and get some sleep but ill leave early am for Western OK, ill stop around Ponca City and go from there when i arrive good luck to all the chasers and lets hope this pans out to be a great chase...

 

[Dan Dawson]

Nice WRF images, Jeff, I love the storm splitting in the model that you pointed out! Definitely awesome.

One thing to note, tomorrow will be cloudy in the warm sector, there is no question about it. This doesn't concern me, as the reason the cap is eroding and the instability skyrockets has little to do with daytime heating, but instead is almost entirely due to strong moisture advection in the morning combined with intense cold air advection aloft late in the day. I fully expect the temperature to be in the 65F range tomorrow afternoon in western OK, not much different from the 55-60 values we see right now (the models reflect this).

In my opinion the high RH values in the boundary layer are a huge plus, in fact probably a necessity, as they indicate cloudy skies during the day that will prevent the good boundary layer moisture from mixing out and becoming crappy. See the 00Z 23 Feb Del Rio sounding for what I fear would happen if tomorrow were sunny. 60-65/55-60 tomorrow night is perfectly sufficient, we don't need temperatures/dewpoints any higher than that. And the absolutely last thing we would need are clear skies around sunset, because the ground is still not all that warm, and we would be in danger of cooling off the boundary layer awfully fast.

I mostly agree, Don, and furthermore, I would add that the rapid moisture transport on the LLJ will actually lead to mixing downward of higher dewpoints from aloft in the jet. Even if it is partly cloudy, we shouldn't be in much danger of actually mixing out dewpoints in this sort of scenario. It would be nice to have a bit of sun just to help with reaching convective temperature so that we don't have to entirely rely on forcing.

Otherwise, just about everything else about this event screams discrete tornadic supercell mode.

 

[Donald Giuliano]

I mostly agree, Don, and furthermore, I would add that the rapid moisture transport on the LLJ will actually lead to mixing downward of higher dewpoints from aloft in the jet. Even if it is partly cloudy, we shouldn't be in much danger of actually mixing out dewpoints in this sort of scenario. It would be nice to have a bit of sun just to help with reaching convective temperature so that we don't have to entirely rely on forcing.

Otherwise, just about everything else about this event screams discrete tornadic supercell mode.

Dan, you make a great point about the LLJ moisture transport scenario; in my experience moisture advecting north just off the surface and then mixing down is fairly common on good severe weather days, but often leads to extensive cloudiness/drizzle in the warm sector as this process is occurring (this happened on May 3rd, for instance, though on May 3rd the low-level clouds did burn off in the afternoon, and they are not forecast to do so tomorrow).

As far as clearing goes, I'd say 1 county's worth of clearing along/ahead of the dryline would be perfect, and may well happen...I believe this happened on May 4, 2003, if memory serves.

 

[BrandonWhittington]

Mid to upper 40 dewpoints are advancing north now at a decent clip, not fast nor slow. Dew point in ABI has risen 5 degrees in the last hour and now moisture will be knocking on the panhandles door in a few hours. Temperatures are remaining in the upper 40 and low 50s in the Eastern Texas Panhandle.

Also, dryline is already begining to take shape accross the central Texas and Oklahoma Panhandles, Dew points in the teens and lower 20s in the western TX Panhandles and around 40 in the eastern panhandles.

Cloud cover seems to be the greatest concern for chasing, as of 1:00 am CDT, clouds accross the Panhandles seem to have eroded away and gave way to perfect clear skies. Will the clouds hold off? Nope. Clouds should be on the increase on Friday. Temperatures in my opinion will be sitting around 70 degrees during the afternoon hours and I feel that Thunderstorms will fire around 5:30 pm, only giving us about an hour of chasing in the light. Something else, GFS and the NAM are showing a Dryline bulge in the Panhandles, adding to the severe threat, does anyone else see this happening? Well, my target should start here in my backyard of Booker, TX, and I will be covering from here to Woodward, down to Elk City. Well, good luck to all that chases on Friday.

 

[Bill Tabor]

Appears to me initiation will occur along dryline in western OK and northwest TX right around 0z from lack of cinh, mild convergence, a light mid level wave passage, and upper air jet support. At that time parameters are all strong for supercells and tornadoes through 6z including some significant.

I'm pondering whether the drive will be worth the likely night chase. All hell should break lose after dark . There is a small chance it could go at 23z or so. That little bit of time would make a huge impact on photography of course. I'd hate to be some ignorant traveller headed west down I-40 in western OK after dark. Reminds me of a night a few years back in the Tx panhandle where I40 got hit and I came upon a lot of the wreckage in the dark. I was following behind the tornadic squall line - lots of lightning.

Good luck all of you. Hope you have Threatnet in the dark. Remember to allow plenty of buffer to adjust for the latency of the radar images versus fast storm movement ~40 knots.

 

[Gerard Jebaily]

Given the way things are looking tomorrow i have decided to head west towards Elk City. I plan on leaving Norman around noon-1 pm to give me some extra time to eat and find a suitable source of wifi. My only two concerns about tomorrow are a slight lack of moisture and of course daylight. Im just going to go on good faith and beleive that Td's in the mid to upper 50's are sufficient due to my relative lack of experience in chasing early severe weather events. IMHO, I do think that even with cloud cover, there is more than adequate forcing for convective initiation. However I'm hoping storms remain isolated enough to manuver in front before they become a strong squall line. I anticipate storm motion to be about 40-45 mph. I will be monitoring 146.55 call KI4LJT. If you're near elk city, hit me up. Otherwise good luck and as always be safe out there. The night time events put me on edge and I just hope everyone gets home safely more than anything.

P.S. Im so glad winter is ending

 

[Chad Ringley]

Morning obs show that low 50 Tds have made it only to the DFW metroplex across the eastern half of the MDT risk area. A few low and mid 50 Tds are also showing up across the TX Panhandle..maybe a very narrow instability axis would develop?? Seems the moisture transport is taking a little bit longer than you guys would like.

I agree with Dan and Don's take on the cloud cover actually being a good thing. Right now, it seems the cloud cover is not necessairly so solid it would be a hindarance, but widespread enough to prevent too much of a increase in dewpoint depressions (Tds are still going to have to pick up the pace for this event to have any teeth).

Also, I still question exactly how long cells will be able to keep supercellular structure with such mammoth forcing. Last time I can remember an event with such strong dynamics in this time frame was..I think 2-3 March 2004...similar parameters where a squall line developed very early in the morning across the W TX Panhandle and puttered out as it moved across OK.

Good luck to all of those heading out today!

 

[BrandonWhittington]

Woke up this morning and looked outside and there is not a cloud in the sky. This has me excited as I was expecting some clouds to be thick over the panhandles. Daytime heating appears to be in great shape for the Panhandles and 50+ dew points are knocking on our door. My target in Shattuck, OK.

 

[Joey Ketcham]

Sun's poking through here in SE KS. Tyler and I are on our way to pick up Chris Wilburn, we will be heading towards the TX/OK border.

 

[Jason Boggs]

I'm thinking about sitting in Shamrock, TX this evening because there is WIFI there at the McDonalds and there is a good N-S road there. Storms will not be chaseable (in a literal sense) today and tonight. A chaser will just have to try to get in position and hope the storm produces something as it passes by at 40-45 kts. EVERYONE, PLEASE BE CAREFUL AND STAY SAFE!!!

 

[Amos Magliocco]

I pulled the plug on my chase trip. Today looks dry and late to me; I have very low confidence in rapid moisture return of any depth in February. Add cloud cover to that and I don't see how instabilities will be sufficient for updrafts to survive the shear. Latest RUC shows a diffuse dryline which hampers lift. I can imagine severe storms well after dark.

Saturday I still like for late morning/early afternoon cold core near the low but it's farther than I want to travel in February for stormchasing. I never have luck in February, so I'm sure there will be a tornado or two Saturday, but I probably would have missed them anyway.

I've been awake since six o'clock trying to decide, and about two hours ago my central heat kicked on. I had to laugh. I'm pretty sure I've never heard the heater start on the morning of a potential chase. I'll take it as a sign. (that way I can blame it when I miss all the cool storms)

Good luck to all.

 

[Jeff Snyder]

At least the biggest question marks with this system have been known since early in the week... I'm a little disappointed with the moisture return so far, as the 60F isodrosotherm is STILL down near I10. RUC / SPC Mesoanalysis shows higher 850mb Tds sneaking up from Mexico near and just west of DRT, and a few soundings in the area (OUN, FWD, etc) show areas of higher Tds just off the surface. The 12z MAF sounding has ankle-deep moisture (~40-50mb), but the DRT sounding is much better (~200mb deep). The 9z RUC showed southwesterly 850mb flow across the southern plains, which would be quite bad since 850mb is not too far off the surface in the TX panhandle, and such a scenario would likely eat the moisture in top-down fasion (like we saw a couple of times last year). Fortunately, the 12z RUC isn't quite as bad. One of the things that all models have been very consistent on is the forecast of 54-60F Tds across most of the target area, so I'm trying to stay optimistic. FWIW, the latest 12z RUC shows <55F Tds N of I40. Looking at sfc obs, I don't think this is unreasonable. So, that is making me favor the area S of I40 (CDS to start?). One a more positive note, the 12z RUC does show convective inititiation 23-00z just ahead of the dryline along the OK/TX panhandle border.

Current profiler data from Jayton TX is interesting as well. It shows ~25kts at 850mb, but very light (<10kts) from about 725-825mb. Again, the elevation is relatively out there, so the lower part of that calm layer is less than 1km off the ground. Now, this may not entirely accurate, but the temporal evolution seems consistent. Weak winds ~1km off the surface does not spell rapid advection of anything. This is an extremely anamolous situation for late February, and the number of tornadoes that have occurred in western OK and adjacent portions of KS and TX since 1950 for this time of year may well be able to be counted on only two hands.

I'm likely aiming towards the CDS area owing to moisture issues.

 

[Ryan Pfannkuch]

I don't know if it's because these early setups in the High Plains have burned me before or what, but I can honestly say I just haven't been able to get too hyped up for this event to this point.

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.

In addition, a glance at the operational RUC and some of its lesser known counterparts don't seem too optimistic either for a daylight show. This 20km developmental QPF prog suggests that very little will happen before midnight (see comparison of 3-hr precip at 6z and 9z)
http://maps.fsl.noaa.gov/plots_20km_dev2///sa5_ppt_am_18.png
http://maps.fsl.noaa.gov/plots_20km_dev2///sa5_ppt_am_21.png

Now this is likely a few hours TOO late with initiation of strong convection, but at least seems more realistic to me than the first image above. I also noticed the 9z SREF only outputs a 30-50% probability of SBCAPE of 1000j/kg or higher by 3z (NWS Dodge City mentions this in their AFD).
http://www.spc.noaa.gov/exper/sref/gifs/2007022309/SREF_prob_sfccape_1000__f018.gif

Now that I have become the most unpopular guy on here with my skepticism of seeing much before dark especially north of I-40, I do fully believe that decent potential exists for plenty of hail and a few TORs, just more of a bona-fide late show. Now, along with the rest of you, I will hope I am wrong and earlier stuff does develop!