Severe weather Tuesday may 13th...30% hatched area already :

[CrazyC83]

the new day 1 outlook actually took away the 10% hatched tornado

Yep, shear has decreased. Main threat is hail up to softball size.

[MGC]

Lots of cloud cover here in Norman OK at noon. DP was 72 last time I checked so there is plenty of low level moisture. I expect to the storms to start forming later this afternoon possibly near or just to my east. I should get off work today around 3pm so I might give chase if conditions are good for a tornado or two......MGC

[Ed Mahmoud]

Purcell profiler not showing great low level wind energy...




Edited to remove hot link to latest Purcell profiler, from profiler.noaa.gov which was loading v--e--r--y slowly.


Maybe it'll speed up later...

http://www.profiler.noaa.gov/npn/profiler.jsp

[Ed Mahmoud]

The 12Z GFS, which seems to be doing a little better on predicting current rainfall pattern than the WRF, sees storms starting between Abilene and San Angelo between 4 pm and 7 pm, with heaviest storms South of the Red River after dark. The current Northeast Texas activity, which appears somewhat elevated, really seems to get going when it reaches Western Arkansas.



Checking various forecast soundings in Arkansas, CAPE near 1000 J/Kg, higher in Southern Arkansas, and helicity at 200 J/Kg increasing South to over 300 J/Kg near Hot Springs would mean a definite tornado threat.


The West Central Texas activity has much stronger instability, but much weaker low level winds. Probably more a hail threat.

[Ed Mahmoud]

Yugo sized hail near Abilene late afternoon/evening?


Satellite loop shows most of the morning shower/t-shower activity moving out just in time for peak heating!


Latest 15Z RUC shows storms initiating near Abilene on the dry line between 4 pm and 7 pm, with forecast CAPE near 4000 Joules/Kg.


Using the old formula, half the square root of double the CAPE, we're talking 40 m/s updrafts. Faster than the speed limit outside of Germany. That'll hold up the hailstones for a while in any cell that has a circulation.


Profiler.noaa.gov is really creeping, but Jayton profiler wasn't showing a whole lot of low level wind earlier, so tornado threat isn't high, but there was sufficient mid level winds for supercells.

[Ed Mahmoud]

Tornado watch along I-35 corridor near Waco to Tulsa

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 311
NWS STORM PREDICTION CENTER NORMAN OK
205 PM CDT TUE MAY 13 2008

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

MUCH OF CENTRAL AND EASTERN OKLAHOMA
A LARGE PART OF NORTHERN TEXAS

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 205 PM UNTIL
900 PM CDT.

TORNADOES... HAIL TO 3.5 INCHES IN DIAMETER ...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 50 MILES WEST OF TEMPLE TEXAS
TO 30 MILES NORTH NORTHWEST OF MUSKOGEE OKLAHOMA. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU1).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...VERY UNSTABLE AIR MASS WITH MLCAPES AOA 3000 J/KG AND
LITTLE REMAINING INHIBITION ARE IN PLACE AHEAD OF COLD FRONT ACROSS
NRN TX/SRN OK. THUNDERSTORMS EXPECTED TO DEVELOP RAPIDLY DURING THE
AFTERNOON ALONG/AHEAD OF COLD FRONT AND THE DRY LINE EXTENDING SWD
IN NRN TX. MDT/STG DEEP LAYER SHEAR WILL SUPPORT SUPERCELLS
INCLUDING THREAT OF VERY LARGE HAIL AND TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 24030.

[6SpeedTA95]

Whats up guys, its pretty warm here in OKC and humid to boot. But it appears the tornado threat has diminished, we'll see what the 3pm update shows.

[Ed Mahmoud]

Cool new product from NWS Fort Worth-Dallas



Local convective parameters.

The National Weather Service in Fort Worth is now offering Experimental Convective Parameters on this website!
The analysis is heavily weighted to the latest surface observation. Thus, you will likely see some small "bulls-eye" type areas where the analysis is reflecting an outlying or possibly incorrect surface observation.

The parameters are generated hourly, with the generation process starting around 22 minutes past the hour. The images should be available by 30 past each hour. It takes some time for hourly surface data to arrive and get processed prior to being able to calculate the various parameters we are offering.

We are currently producing the following images:

CAPE
CIN
EHI
Helicity (0-1km)
Helicity (0-3 km)
Shear
Shear (0-1 km)
SigTor
Convective Interest

[MGC]

TV weather in OKC just reported that the cap is weakening rapidly in central OK and things should start getting interesting very soon. Sun has been peeking through the clouds, I'd estimate there is 50% cloud cover.........MGC

[Bunkertor]

Haha, a Yugo.

[snoopj]

That's a cool thing DFW is doing. I wish other tornado alley locations would do that.

--snoopj

[zaqxsw75050]

sun is out here at my house(couple miles south of DFW airport). humidity is high and very uncomfortable outside. should get interesting pretty soon.

[Ed Mahmoud]

That's a cool thing DFW is doing. I wish other tornado alley locations would do that.

--snoopj

Not sure why, but compared to other local SRH office web sites I visit, OUN and FWD have lots of useful stuff. Visit some other sites in areas that can be affected by significant severe weather, like SJT, not so much good stuff.

[MGC]

Just looked outside....hardly any vertical development. Cap must be holding.....MGC

[wx247]

Hopefully the cloud cover we have now sticks around and limits instability here.

[Ed Mahmoud]

Just looked outside....hardly any vertical development. Cap must be holding.....MGC

Shouldn't hold for long based on 19Z OUN special sounding...




OKC is now 3ºF warmer than it was at 19Z, really, it should go any minute.


Of course, sure things bust sometimes...

[Ed Mahmoud]

Winds at OKC are now from the West, and radar shows a boundary, probably the dry line, just East of there, so the storms may go just East of there.

[Bunkertor]

True i wondered why they released a special baloon one hour after 18z, but i didn´t take a look at it..

[wx247]

Cell trying to build south of Cushing, OK and north of I-44.

[Ed Mahmoud]

As mentioned during 12:29 post, 12Z GFS showed activity then in Northeast Texas heading into Arkansas while intensifying, and new activity developing in the general region between San Angelo and Abilene.


Storms firing on I-10 between FST and SOA, SW of SJT as seen on SJT radar loop.


Storms in far NE Texas into Louisiana look like they are picking up a bit in intensity.