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

[Chris Wilburn]

Just like most of the people that have replied to this thread I too have doubts about initiation before dark. However, it is certainly possible. Looking at tonights 00z runs I like an area from Just west of Woodward to down around Elk City and points just west and possibly even extreme sw Oklahoma near Altus. Closer to the low you may get better forcing and surface winds, but the further south you go looks to be better for forecasted dewpoints and CAPE. I like the area from Woodward and points south for the higher dewpoints and forecasted CAPE of near 1,500 J/kg. I think the threat could last well after dark as the low-level jet kicks in. The further east the storms move they will encounter less instability and begin to fade as they move toward the I-35 corridor. Helicity is progged to be as high as 400-500 at 06z Saturday. Overall, speed shear and vertical shear looks really good, esp. after 00z. Helicity increases after or around 00z. If there can be enough convergance on the dryline I think there will be enough moisture and CAPE form storms to fire before sunset. But if they will is anbodys guess at this time. I will for sure go out if I can get Friday night at work off. I would target anywhere from just north of Woodward to down near Elk City and take it from there.

Chris Wilburn

 

[Craig Maire II]

2/23/07 FCST: OK / TX / KS Reply to Thread

Since I have a BAD case of SDS, some extra money and no class on Friday I changed my mind earlier and here I am sitting in Wichita Kansas at the Days Inn Hotel I plan on waking up at around 11am and heading out towards Dodge City Kansas to see what the dryline does tomorrow and tomorrow night. After a 7 hour drive this hotel bed and the McDonalds I just ate are and were a great treat!!

 

[Chris C Sanner]

I'm initially targeting Altus or Elk City for tommorow with no definite plans of going. Right now, I'm waiting for the soundings tommorow morning as well as another word from the experts at the SPC and NWS before really making a decision. If daytime initiation doesn't look too likely, I'll probably just sit it out because the season is yet still very young and chasing tornadic supercells moving at 50mph through western Oklahoma at night just doesn't appeal to me at the moment

One thing I'm looking for to make the decision is some sign of a subtle wave kicking out ahead of the main system, a bit more moisture and full sunshine, or any kind of sign from the models which I don't know if I'd trust fully anyways

Either way, it is sure nice to have these kinds of talks again eh?

 

[Lance Maxwell]

Geez guys, looking at these forecast hodos for the Clinton area from 00z and 03z (2/24) I just am amazed. Should these storms stay supercellular for a couple of hours after dark, there could be serious problems for the western half of Oklahoma tomorrow night.

 

[Mike Hollingshead]

I may be pulling the plug on my Friday chase. The difference between the nam and gfs is driving me nuts. It has done this for several runs now. The gfs is a good bit slower than the nam. If the nam is right, maybe get something by dark, if the gfs is, probably be a good bit later, when one should be sleeping to wake up and position early enough Sat. Anymore I prefer the gfs.

Edit: Ah hell maybe it's not that much different. This is what one gets after looking at it from 240hr.

 

[Bill Schintler]

Chase target for February 23

9:55 PM CST, 02/22/07

Chase target:
Beeler, KS (35 miles NE of Garden City).

Timing:
Storm initiation 5:30 PM CST.

Storm mode:
Isolated supercells with large hail along with a brief tornado risk. Storm motion will be northeast at 35 mph.

Discussion:
Evening analysis indicated long-wave trough axis coming on shore while a LLJ had already developed in western KS and the TX panhandle. SFC dewpoints were only in the low-30’s although strong moisture advection will commence over the next several hours. An extensive ST deck will be in place in the moist axis east of the DL Friday which will limit much in the way of insolation however strong forcing in the left-exit region of the 80kt H5 streak should overcome inhibition.

Friday afternoon, very strong forcing from a compact lead wave ejecting ahead of the main trough should enhance convergence near a developing triple point at the northern end of an advancing dryline. Cold temperatures aloft (-20C at 500mb) on top a moist airmass (SFC/H85 dewpoints of 11C/8C) will contributes to MLCAPE’s of 1000J/kG despite forecasted weak insolation. Examining model soundings, the NAM is most bullish with moisture return as well as with steeper lapse rates, while the NGM develops very little CAPE and the GFS is between the two and is probably best representative of the forecasted moisture/temperature structure. This model produces a long “skinnyâ€￾ CAPE area in the H75 to H3 layer on top of a 100mb deep moist layer. Shear parameters will be quit impressive while not being so strong so as to completely shear the relatively weak updrafts indicated by the CAPE distribution. An axis of deep-layer shear (0-6km) of 35-40 kts will spread into the area while an H85 flow of 45 kts on top of slightly backed SFC flow will result in SRH’s (0-3km) of 250 m2/s2. A significant concern will be a dry layer advancing in from the SW in the H6/H5 layer which may serve to choke the weak updrafts.

- bill

 

[Mickey Ptak]

Well, regardless of the negs I am out there for sure. I just can't pass up a W OK chase, be it day or night. 2005 and 2006 made me a believer in expecting the unbelievable. I'd seen tornadoes come out of crap I would have never thought could be possible. Not saying tomorrow is prime but if there is a chance, I am there.

On a forecasting note, I find it interesting that the NAM or WRF (whatever the name is now) has forecasted CINH to be gone on both of today’s 12Z and 00Z runs before 0Z Saturday. I am no expert on model outputs, so it could be hog wash, but I do find it intriguing that it had not changed with both runs. This same model has precip braking out on or before 00Z as well. Hmmmm. On the other hand this morning’s GFS run, it still had a stout CAP to brake. I am not waiting up to look at the next GFS so I will just make it due until morning when I can dig in to the morning analysis with a fresh head.

For those who do chance it tomorrow be safe and have fun.

Mick

 

[Joey Ketcham]

As Tyler said, we will be out as well.. we are gonna head out at 6:30AM and start heading towards SW Oklahoma.. hope to see some of you guys out there.

 

[Kenny Drake]

I have been paying attention to this setup since last Sunday and for one, have been surprised at the consistency the GFS has had since last weekend, and the NAM too has been consistent. Given this, I feel pretty confident using the progs given by both models, which really are not that much different. I am not going to write-up a full forecast because what others have said I agree with. However, I should mention that the NWS FO in Norman is not set on seeing much tomorrow in the way of tornadoes, given their latest forecast discussion (9:55PM CST):

NAM STILL HAS THE UPPER TROUGH OVERTAKING THE DRYLINE AFTER
MIDNIGHT FRIDAY NIGHT WHICH WOULD GENERALLY WORK AGAINST A MAJOR
SEVERE WEATHER OUTBREAK THIS TIME OF YEAR WHEN DEWPOINTS ARE ONLY
FORECAST IN THE MID/UPPER 50S (NEAR 60 LATE SE OKLAHOMA) AND MUCAPES
OF 500-750 J/KG. SHEAR IN THIS CASE COULD ACTUALLY BE TOO STRONG BY
RIPPING APART UPDRAFTS IF MOISTURE IS NOT DEEP ENOUGH. WE EXPECT TO
ISSUE QUITE A FEW WARNINGS FRIDAY NIGHT BUT THINK WE`LL HAVE
MAINLY STRAIGHT LINE WINDS AND MARGINALLY SEVERE HAIL.

Not to mention, if the CAP can be broke close to sunset these storms will be chugging along faster than my liking, especially for a night chase.

Personally, IF I go out tomorrow I will be targeting Elk City. This would give easy access to points north and south of I-40 along with a fairly simple drive back home (to Norman). However, given the circumstances (possible bust, if no fast moving night-time supercells) I will probably sit this one out. Regardless, this spring-like pattern is very welcoming and it will only help future chase opportunities (such as, giving the gulf water time to heat up.)
There will be plenty more chase opportunities this spring, in fact I noticed another 500mb open wave is supposed to eject out into the plains during the middle of next week.

 

[Rodney Harper]

It looks like moisture recovery is under way NW of Ft. Worth as dewpoints are getting close to 40 now as compared to being in the 20's all day. I still like my bet at Wichita Falls hope to see some of all out there and be safe.

 

[Donald Giuliano]

Though I was initially considering this "event" to be a yawner in OK (since it is February, after all), and I am taking a wait-and-see approach to chasing tomorrow due to the lack of daylight...

I have been increasingly impressed by each of the NAM runs for the last 24hr, and am *extremely* impressed by the 00Z. If this verifies, look out Oklahoma/Kansas west of I-35! There's plenty to grouse about in terms of chasing, but in terms of pure meteorology I can't find anything wrong with this event, as if it verifies it's easily the most impressive synoptic setup I've seen since 2003. 1000-2000 CAPE in February with essentially 0 CINH and insane shear due to time of year, and after dark with isolated storms no less?!? And it actually looks realistic, since 55-60F Tds seem easily attainable given the moisture present along the Gulf Coast right now, and the 500mb vort is hanging back a bit to avoid an explosion as the extremely cold air moves over the boundary layer, so a 12 hr period of isolated cells appears feasible as little ripples in the flow touch off a cell here and there?!?!??! Pinch me, I must be dreaming! Oh wait, I hate chasing at night...never mind, of course something had to go wrong!

 

[Jeff Snyder]

Model consistency has been quite impressive. In fact, I don't think the forecasts from the GFS have changed much since last weekend (Day 6). Sure, the exact position of the 500mb low has shifted 100-200 miles at times, but the overall pattern and timing (+/- 6 hrs) has remained relatively consistent. Props to the model, and props to the atmosphere for being in a pattern of relatively low uncertaintly and relatively high predictability...

Not much is new in the 00z runs, and I'm just waiting for the 4km WRF run to post (with explicit convection -- I've found this model to be very good at forecasting storm mode, though I don't think there's much uncertainty in that with this cyclone). I really do hope the NAM verifies better than the GFS, since there are significant differences in the lowest 200mb of the models. The NAM is quite a bit warmer in the boundary layer ahead of the dryline, which creates a low-CINH (or no CINH) environment. In contrast, the GFS keeps the boundary layer much more stable (much higher CINH) owing to considerably lower low-level theta-e. For example, compare the GFS and NAM forecast soundings for Gage, OK, HERE. The GFS seems to be 10-13F cooler near the surface ahead of the warm front than the NAM. The GFS seems to be wanting to keep a thick stratus deck in the warm sector tomorrow (looking at 850mb RH)...

Decent moisture is currently taking the scenic route by advecting through northeastern Mexico before heading northward into western Texas. For example, notice the much deeper moisture on the 00z BRO and MMAN (in far northeastern Mexico) compared to the pitiful CRP soundings. SPC / RUC Mesonalysis at 850mb shows the good moisture taking the scenic route as well...

Speaking of moisture... I'm terribly concerned about moisture and instability north of Oklahoma. Personally, I'm not giving Kansas much thought. That's not to say that I don't think anything will happen there, but I'm more confident staying in OKlahoma and Texas.

 

[Jeff Miller]

The Scenic Route..

Did a dewpoint analysis...

This is 0443zz. Has some work to do for sure. Im anxious to see what will happen with this the next 12 hours for moisture return.

 

[Jeff Snyder]

For those who are interested, I suggest checking out the 00z 4km explicit convection WRF at http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/cent4km/v2/ ... To find storm cores, I like to view the "Total column condensate" product. Check out the splitting supercell in TX from 24h-27h (00z-3z)! No signs of MCS/squall line development until after midnight.

 

[Mark Oerther]

The biggest concern tomorrow is the presence of moisture in the lower/mid levels(850, 700) before convective initiation. Jeff Snyder talked about the GFS having high 850mb RH values and the OOz WRF does as well. At 18z on the 23rd there is greater than 90% RH values throughout the warm-sector. Also at 12z at 700mb there is also a strong presence of moisture. While I believe the surface moisture will make into western OK with values at or slightly above 55, I am however concerned with sufficient surface heating. This seems to be a common mode of failure for early chases.

With that being said, if the skies remain clear or even mostly clear everything else will be in place. Even if there is a stratus deck I still believe it is a well worth chase set up for those in the OKC-OUN area. Storms may initiate near OK/TX panhandle border but will not be well developed until they move into west/central OK and with 255/37kt storm motion it will be good to set up well east of the initiation and wait for the storm as it develops and comes to you.

All in all it will rain....more rain means more soil moisture...more soil moisture leads to later evapotransporation....which leads to more and better chase events for the spring.