4/13/07 FCST: TX / OK / AR / MO / IL / TN

[SteveCarter]

Hate to copy and paste, but... MEMPHIS, TN........A STRONG LOW PRESSURE SYSTEM WILL DEVELOP ACROSS THE GREAT PLAINS
AND BEGIN PUSHING TOWARDS THE MIDSOUTH FRIDAY NIGHT. THIS SYSTEM
CONTINUES TO LOOK STRONG WITH THE INCREASING POSSIBILITY OF
BRINGING STRONG TO SEVERE THUNDERSTORMS TO THE AREA. THIS SYSTEM
WILL DEFINITELY BE SOMETHING TO KEEP AN EYE ON FOR FUTURE
FORECASTS. end paste.

Other forecasts from that area to Birmingham are saying about the same thing. Southern states may be in for more than previously thought. Thinking about going to the AL/MS/TN line Sat early. Still....a ways to go yet, and I'm sure a lot of fine-tuning will take place.

 

[Bill Tabor]

Wow, looks like big dynamics are coming to play. Could be some really fast storm motions judging by the 850mb and 500mb projected speeds. I much prefer the current NAM solution which is slower and further west and south by a bit. The GFS veered 850's aren't too impressive. I'll be looking for this system to slow and back up a bit more in the NAM solution - hopefully. Obviously a potential big tornado day if the sfc to 850mb can back. There will likely be some tornadoes regardless.

I'll not try and pin down a general area yet as it is still only Monday and not ready to play musical models quite yet.

 

[Simon Brewer]

WOW, this 'possible event' is still 3 days away, but it looks like a huge severe weather outbreak for Texas all the way up though Missouri and maybe southern Iowa or parts of Illinois! The forecast at all levels by the GFS and European are pointing for a very big tornado event!

 

[Ray Walker]

ya this event looks pretty conductive for a significant tornado outbreak. Tx, Ok, SE Ks, Mo, Ar, and Louisiana had better be on gaurd. If enough instability can develop then major tornadoes are likely in these areas Thursday through Friday night.

 

[Jim Bishop]

Holly crap, Friday still look huge from Eastern Texas up to Missouri. As of right now this setup screams tornadoes. It's just going to come down to location.

European is a bit slower and further south than GFS. Gabe already mention how the WRF was slower than the GFS yesterday. Maybe that trend is valid given the slower European solution? We shall see.

Another thing I wanted to point out is the SPC wording. In the relatively short period of time they've had the 4-8 day outlook available, I'm not sure I've ever seen 1)such a detailed discussion for an event, and 2) stated "the possibility of significant supercells with tornadoes". I couldn't agree more with that, just found it interesting.

 

[matt patterson]

Not to rehash on anything already noted above, but the 6z GFS is once again being progressive with the system sliding the low into sw mo by 00z.. However the NCEP model discussion still favors the EC due to consistancy and its "middle of the road" solution.... I still think that C/E OK, SE KS, and down into the lonestar state is the place to be on FRIDAY afternoon.... I bet we see the GFS slow down in the next 2 runs as the system will be coming on shore..

http://www.hpc.ncep.noaa.gov/discussions/pmdhmd.html

 

[V. Gensini]

Im not getting to excited until this system moves onshore. 00z gfs and 12z gfs have weakend the system considerably, not to mention bringing the system further south. I guess we will have to wait to see

 

[SteveCarter]

Don't think I would pay to much attention to Iowa/IL/IN areas. This really seems to be taking a more southern turn. AR/TN/LA/eOK/ into MS/AL/cTN by Saturday, and finally sGA/FL by sunday? Even Carolinas Sunday? This is definately going to be a good potent sysytem.. The worry about moisture seems none existent now. A LOT of fine tuning to follow tho. And with it on a weekend......glad it IS going to be over such a large area...lol

 

[Brian Stertz]

Looks like a OK/TX main stage for Friday

Further inspection OF THE 12Z ETA...

The 995mb surface low forecast position looks to be centered near Medford OK by 00z Friday night. The 0-3km helicity is maximized across NC Oklahoma in vicinity of the warm front which is forecasted to stretch west to east just south of the OK-KS stateline. The forecasted 00z dryline position is located along a line from Enid to the OKC Metro to the west side of Ft. Worth TX. Things look very interesting for tornadic supercells...a few of which will be strong/intense with "stinger tail" type structures.


Looks like the 12z ETA was in strong suggestion that Friday's big-top event would be focused along/east of the I-35 corridor from N.Oklahoma southward into NC/NE Texas. The 0-3km CAPE forecast is solid ahead of the dryline and the shear is looking good. The storm motions were pretty rapid given the strong mid-level wind field of 50+ kts. over a large area. This may change if the supercells can get a slight eastward movement. Looks like the best forecasted combo of shear & instability should favor from SC/SE Oklahoma and NC/NE Texas if the 12z ETA pans out.

Certainly a solid MDT risk on tap for Friday if forecast holds true. Now comes the time to fine tune the target zone for the chase as the model updates warrant. All I have to say is that Oklahoma has been due for some significant severe wx, and this looks quite likely with this storm.

 

[matt patterson]

WOW!!!!!! the 00z nam really pushed the sfc low farther to the south... The 00z solution tonight would create a very difficult chase in terms of terrain... We will have to see if the future solutions bring back the futher north track...

 

[Dal Archer]

Aaaggghhhh! I agree Matt. Things are looking less favorable if the NAM pans out. The current solution could force things into SE OK/NE TX which certainly screws things up as far as chasing is concerned. I do not look forward to trying to navigate in the mountains of SE OK.

I am really hoping that things stay closer to the GFS solution. I will be interested to get a look at the next run of the GFS and also take another look at the next update on the NAM. This setup looks so good and I would hate to see things get messed up by pushing things too far to the south into unfavorable terrain.

Oh well, we still have some time and hopefully further runs will look much better.

 

[Fred Gossage]

00Z NAM shows the potential for a significant nocturnal tornado event across Arkansas and Lousiana, spreading across Mississippi and into Alabama Friday night and Saturday morning. Forecast soundings from the 00Z NAM show over 1000 j/kg CAPE with over 450 SRH, coupled with 67-69 F dewpoints and near 70 F temps over the Tuscaloosa/Centreville/Birmingham, Alabama area at 7:00 am CDT Saturday.

 

[Chris Wilburn]

I just noticed the same thing Matt. Also, nice dewpoints barely even make it into the extreme southcentral/southeastern Oklahoma area. The 00z NAM also weakens the surface low to 1000mb and is forecasted to be on the OK/TX border along the I-35 corridor at 00z. Still looks like a very nice system, esp. as mid 60 td's are now forecasted for northcentral Texas and central Texas. I should point out that parts of very extreme southcentral and southeastern Oklahoma td's are forecasted from low 60's to even a narrow band of mid 60's possible. Maybe things will change but for me personally I don't like the southern forecast of the surface low and hope it changes over the next couple days. However, for chasers in northcentral Texas and central Texas they may be in for a real treat. Like Matt pointed out above storms will not be in very favorable chasing terrain if things remain the way they are. I like many others am not a big fan of chasing the jungle of southeast Oklahoma. I have never chase northeast Texas, but I haven't heard too many good things in regards to chase terrain down there. If I had to pick an area now it would be just along the I-35 corridor in northcentral Texas where td's should be low to mid 60's and CAPE is forecasted near 2,000 J/kg. Maybe a westward shift of the low/dryline will occur in the next couple days and we can get away from areas of poor chase terrain. Still a few days out, but those are my thoughts at this time.

 

[Mikey Gribble]

NORTHERN HALF OF TEXAS
I'm not impressed with the 00Z run of the NAM. I think you would have the possibility of maybe a couple tornadoes, but I don't think about tornadoes when I see this kind of setup. Deep layer shear and instability are more than adequate for supercells, but the tornado potential just isn't there IMO if the 00Z NAM is to be believed.
You have overnight convection and cloud cover over the northern part of the warm sector. It does show temperatures rebounding a bit, but not as much as you would like to see. LCL's would be plenty low. Directional shear sucks and helicity continues to decrease throughout the afternoon as the stronger low level flow moves off to the East. The better low level shear is too far out over the warm sector. Storm motions are fast, but doable, so I wouldn't be too concerned about that (I always think the cutoff for being chaseable is around 35kts). Unless I lived close by, I wouldn't chase the northern half of Texas target. It definitely isn't worth the drive from ICT considering it's only the begining of April.

SOUTHERN HALF OF TEXAS
I do think you have a shot at a couple tornadoes down in the Houston to Lufkin area and directly East of there. CAPE is better, but deep layer shear is weaker (still good enough for supercells), but it becomes quite strong by 00Z as the mid-level jet moves into Texas. Low level shear is sufficient for tornadoes at 18Z, but helicity weakens to <200m2/s2 in Texas by 00Z as the stronger low level flow shifts East. So long as storms fire early and work there way out into the warm sector (into the better low level shear) I think there will be a window for tornadoes before storms outrun the instability axis.
DISCLAIMER - I looked at the 00Z run for less than 20 minutes and I haven't been following previous runs closely, so I could definitely be overlooking some things. This was just my first impression.

 

[mark plate]

I certainly expect the south solution to be correct. The ECMWF/UKMET have been consistent with this for several runs and now the NAM/WRF has jumped aboard. When the ECMWF and UKMET agree on something far different than the GFS, they are almost always the way to go. Assuming these southern models are correct, significant surface based storms will not be too far north into Oklahoma. In fact, the new NAM/WRF suggests snow is more likely in Oklahoma than tornadoes, with heavy snow just to the north in southern Kansas. I expect temps Friday to be very similar to today here in northeast Oklahoma...struggling to warm above the low-mid 50s. This looks like an ARKLATEX chase and mainly after dark.