3/30/08 FCST: OK/TX

[Darin Brunin]

Not optimistic about today at all. The veered flow at 850mb along with subsidence behind that lead shortwave that's going to move through an hour or two too early is really going to kill off any convective development until after dark when winds will start backing at low levels, which will increase convergence at the surface enough for initiation in around 1-2z. There may be a small opportunity after dark for a tornado or two but nothing that is making overly eager about being there.

 

[Bill Tabor]

Still at home. Generally my outlook on this has gone down for daylight activity, plus I am seeing very weak sfc winds throughout north Tx, Ok, southern Ks. This will limit the tornado potential during the daylight IMO, although I will note that 925mb winds are a bit stronger. With clear air over Tx Panhandle, western north Tx, and western Ok expect decent heating along dryline with current sfc low positioned in nw OK (last I looked). None of the models seem to indicate convective breakout GFS, NAM, or 4km WRF KF. The WRF KF indicates a small cell near the triple point at 0z or perhaps a hair later and maybe one just south of there on the dryline. On water vapor I also saw what I thought was a weak wave passing thru the TX panhandle an hour or so ago, but may be too weak. Still also, we have the weak sfc winds though. Plus for me that area in nw OK is a bit of a drive for me on a weak chance - although not bad for many of you in the Tx Panhandle, OK, and KS. Likely because of this I will pass.

Right now my current fav area would probably be close to CSM (adjust for dryline) from 0z to 6z. Lower level winds will increase particularly nearer the 3z timeframe to 6z and cinh will be greatly reduced. The parameters still look fairly strong to me for night time tornadoes in western to OK though not as strong as it did to me last night. For a chance at an end of daylight chase I might go slightly north or nw of CSM. (I partly picked CSM because I didn't have a lot of density of identifiers to choose in that area).

I'll be looking at tomorrow and may bite, but SPC mentions an angry squall but possible strong tornadic sups from Tulsa to Ft Smith to Springfield. I haven't actually looked at the day yet. That area has quite a few trees so I will think twice before doing it, but it may be an option.

Good luck to those of you out in the field. Perhaps I could leave late D seems to be my trademark) and catch a night tornadic storm, but I may wait for a better opportunity to burn all that high $ gas.

Note: Slight risk for north Tx, Ok, Ks today with 5% torn until at least 20z. By 01z I'd likely go moderate in western Ok, and possibly southern Ks, with a 20% chance of torns some strong to sig particularly in the sw quadrant of OK.

Let me add as far as RUC precip is concerned I don't always trust it. RUC was saying I might have a shot at a storm a day or so ago down toward Uvalde and it never materialized. It is often a bit too liberal in my opinion. Still, after just looking at mesoanalysis I see that much of the area of interest show little to know cinh sbcape wise although 100mb mlcape is still capped, Li's are open. This is a bit of a warning for me - but we'll see how it goes. If there is any chance of anything breaking closer to home I may go for it even if torn chances are lower.

 

[Bill Tabor]

What the heck is that n/s linear cloud boundary all the way through eastern OK and swiping through ne TX? It appears to be moving westward. Is that a large gravity wave? If so, that could make things...interesting.

Hmm, or perhaps large outflow boundary from large area of fairly strong eastern convection. Any thoughts on if this outflow boundary could be a kicker to initiate storms?

Latest Mesoanalysis now showing 100mb Mlcape now uncapped in parts of western OK and northern Tx with values from 1500 to 2000 and an axis of -8 and lower LI's extending from north Tx into this area. The sfc low appears to still be moving south into OK with area of circulation still in northwest OK per digital atmosphere. Lower dewpoints to the southwest of this feature.

Man, if the surface winds were forecast to be stronger and showing stronger I would have left long ago.

Also seeing a minor linear vis sat boundary oriented sw/ne forming near (west of) Anadarko toward El Reno, and possible micro cu beginning to show in extreme sw OK.

 

[Mikey Gribble]

I believe it is an outflow boundary. I can't find a radar loop that goes back four hours though so all I saw was visible satellite.
It also looks like there is a pretty good moisture convergence along the wind shift and differential heating boundary over central Oklahoma right now. That is the same area where the NAM wants to break out convection too. I just woke up from a nap so I haven't looked at this much BTW.

 

[Kenny Drake]

What the heck is that n/s linear cloud boundary all the way through eastern OK and swiping through ne TX? It appears to be moving westward. Is that a large gravity wave? If so, that could make things...interesting.

Hmm, or perhaps large outflow boundary from large area of fairly strong eastern convection. Any thoughts on if this outflow boundary could be a kicker to initiate storms?

I would agree that it is likely a gravity wave. Sfc features from the OK Mesonet do not show any signs of it being an OFB. We shall see what happens when this hits the unstable region west of I-35. I'm guessing all the convection in AK/LA is the source of it.

 

[Scott Lincoln]

At first I wasn't super optimistic for you guys down in the Oklahoma area today, but if that is a gravity wave heading for the dryline, that could be interesting for sure. I think it has been argued that it was a gravity wave that initiated convection for the Jarrell, TX tornado day, and there may not have been initiation along the boundary like that without the gravity wave. I know there is some debate regarding tornadogenesis and whether or not it can be hampered or started with the help of the waves.

I'd definitely be a bit more interested in chasing the dry line knowing that there might be some interaction with an outflow boundary or gravity wave.

I should also add that there seems to be another boundary just NW of Oklahoma City area, oriented SW to NE. Seems to be on the 1km satellite loop as well. I wondered if it might be an outflow, but it seems to be fairly close to the small low in that part of the state. Maybe its the dryline, or some small warm front associated with that area of low pressure? Either way, the oklahoma mesonet data seems to be showing a nice hint of some backed winds between Enid and OKC. I would hope for some boundary interactions in that region right now. I think that would yield the best shot at seeing some late afternoon/evening tornadoes.

 

[Scott Lincoln]

Is it just me, or is the almost the entire area of tornado risk depicted by the latest SPC outlook BEHIND the dry line? I guess I'm confused. Is the dryline supposed to retreat before initiation? If anything it looks to have moved slightly eastward in the OK Mesonet loops...

 

[Rocky Rascovich]

Here at the farm near Piedmont.. getting heaping cumulus/congestus, winds are veering more southwesterly which I'm not enthused about, however, as soon as Charles Edwards gets here, Mark McGowen and myself with Charles will be heading toward Enid to Blackwell where we can hopefully get just east of the meso low, we'll keep an eye out on this gravity wave feature too.

cell: 405.226.2996

Rocky&family

 

[Mikey Gribble]

I was in the same boat Scott. I guess they expect the dryline to sharpen up farther West of there. I don't understand either.
Mesoscale discussion just issued for the NW Oklahoma area. They mentioned the possibility of day time convection, which I guess you can read for yourself. I don't see much in the way of a tornado threat until after dark though. I thought this was kind of funny though. Kerr said, "ALTHOUGH LOW-LEVEL HODOGRAPHS ARE PROGGED TO REMAIN SMALLISH THROUGH SUNSET"

I've never heard them refer to a hodograph as "smallish" before. Maybe small, short, not large, etc, but never smallish. I thought it was kind of funny. Maybe they can add that to the NWS dictionary.

 

[Bill Tabor]

PS: Let me add as a forecast thought for tonight nearer 3z to 6z appears 300mb to 250mb upper winds may be divergent over most of OK contributing to the severe threat.

 

[Tom Tackett]

The boundry observed on satellite and now radar, first mentioned by Bill Tabor, continues to move west at 2300Z and has evidently touched off some convection just north of Dallas. The boundry is beginning to slow down with its westward movement and even develop some curvature going from northwest to southeast across Collin, Dallas, Rockwall, and Kaufman Counties.

What will be interesting is where this boundry will be established across the Red River Valley of Texas/Olkahoma (if it is not washed out overnight and early in the day Monday), and what, if any role it could play in storm development or enhancement on Monday.

Great observation and perception Bill Tabor!!!

 

[Bill Tabor]

Thanks Tom. Cells developed near and southwest of CSM close to 0Z- my picked target. VAD wind profiles seem to indicate 25 knots inflow near the sfc if I am reading correctly - certainly enough for torns if this is true. That would be annoying as none of the models indicated that possibility. I also see that one of the cells is also a TVS. I suppose if any of you are near there you can take a picture of what I would have seen had I bothered leaving.

 

[Bill Tabor]

Environment in sw OK starting to show more cinh on mesoanalysis. Also it seems as though LCL's are appearing a little high. This could curtail storm growth soon, and limit tornado potential unless that lower level WAA can get started and a little more upper air support and cooling.

 

[Bill Tabor]

Appears to me after glancing at RUC and latest 0z NAM run that a sfc low will begin to transition from sw to ne across OK into KS by 12z. Along the way low level advection should increase. Already the sfc is showing stronger backed winds, and at 925mb they are forecast to be really stout. Currently at 0z analysis NAM showing a small bit of NVA in OK but by 6z that is gone. Winds at 500 are a little weak likely weakening overall deep layer shear, but as I mentioned previously the upper 300mb to 250mb should begin to put much of OK into divergence which should help vertical velocities. Storms ongoing and continuing east toward the OKC metro. I wouldn't be surprised if they continue and wonder what any gravity wave (if that's what it was) interaction may do. Cinh does remain and at times will become a bit stout it appears overnight so hard to say if it will completely kill off all these storms of if some continue. With still high capes forecast I believe they will continue to march along. This could eventually be a bit rough for OKC metro if these supercells maintain their strength or strengthen. Forecast composite parameters for tornadoes are still somewhat strong in parts of central and sw OK but not as strong as I was seeing on previous runs. This is a good thing because before they looked like 'dooms day'.

I would still estimate strongest potential between 3z and 6z unless cinh can shut things down and boundary can decouple.