Texas Severe Weather Potential for 4/28 and 4/29

[Johnny]

Lots of severe thunderstorm warnings going up out west of Fort Worth. I tornado watch has been issued for this area.

http://www.stormdisplay.com/warnings.as ... s=&nmsgs=0

[Johnny]

A few cells are starting to pop out west of College Station now.


http://www.khou.com/images/weather/dop640.jpg

[southerngale]

The winds are already gusting in the low 30's here, and there's no storms around to speak of.

[Portastorm]

Yup. Getting busy. Tornado Watch flag just hoisted by SPC for the Hill Country just west of us in Austin. And that's east of the West Texas dryline so these storms won't even be -- technically -- a part of the squall line that is supposed to develop later tonight.

Atmosphere here is very Houston-like! At 1 p.m., we have an air temp of 76 and dew point of 69.

[Yankeegirl]

Very windy here as well...

[CrazyC83]

Could the watches be upgraded to PDS?

[CrazyC83]

Another area to watch could be on the northern end of the line - Dakotas and southern Manitoba...

[CrazyC83]

Is there a site that tells us what is going on in Mexico? After all, the weather watches extend all the way to the Rio Grande right now...

[Johnny]

It looks like the Dallas/Fort Worth areas is fixing to get in on some good solid rain/storms.

[Extremeweatherguy]

currently at IAH:

Temp: 78F
Dewpoint: 69F
Winds: Gusting to 29mph
Sky: Overcast (though looking outside...I see a few breaks with sun every now and then).

[jkt21787]

Could the watches be upgraded to PDS?

No, and why would they? SPC doesn't have any hatched tornado areas, and for good reason, the atmosphere does not support strong tornado formation. Just isolated tornadoes at best.

No PDS severe thunderstorm watch needed either. It shouldn't get any worse than an intense MCS, I don't think we're looking at a derecho here (going by the strict criteria needed for one).

[CrazyC83]

Could the watches be upgraded to PDS?

No, and why would they? SPC doesn't have any hatched tornado areas, and for good reason, the atmosphere does not support strong tornado formation. Just isolated tornadoes at best.

No PDS severe thunderstorm watch needed either. It shouldn't get any worse than an intense MCS, I don't think we're looking at a derecho here (going by the strict criteria needed for one).

PDS Severe Thunderstorm Watch? Why would they ever issue that?

[jkt21787]

Could the watches be upgraded to PDS?

No, and why would they? SPC doesn't have any hatched tornado areas, and for good reason, the atmosphere does not support strong tornado formation. Just isolated tornadoes at best.

No PDS severe thunderstorm watch needed either. It shouldn't get any worse than an intense MCS, I don't think we're looking at a derecho here (going by the strict criteria needed for one).

PDS Severe Thunderstorm Watch? Why would they ever issue that?

PDS severe thunderstorm watches can and are issued for expected derecho events.

Example...(THIS IS NOT CURRENT!!)
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 491
NWS STORM PREDICTION CENTER NORMAN OK
930 PM CDT THU JUN 16 2005

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

MUCH OF OKLAHOMA

EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 930 PM UNTIL
500 AM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

EXTREMELY DAMAGING THUNDERSTORM WIND GUSTS TO 90 MPH...LARGE HAIL
TO 2 INCHES IN DIAMETER...AND DANGEROUS LIGHTNING ARE POSSIBLE IN
THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES SOUTH
SOUTHWEST OF GAGE OKLAHOMA TO 40 MILES NORTH NORTHEAST OF
MCALESTER OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 487...WW 488...WW 489...WW
490...

DISCUSSION...INTENSE LINE OF THUNDERSTORMS OVER NORTHWEST OK WILL
TRACK SOUTHEASTWARD ACROSS THE STATE DURING THE NEXT SEVERAL HOURS.
STORMS HAVE ORGANIZED INTO MULTIPLE BOW ECHOES...AND WILL LIKELY
MAINTAIN INTENSITY THROUGH THE EARLY MORNING HOURS. GIVEN EXTREME
INSTABILITY AND MESOSCALE ORGANIZATION OF STORMS...POTENTIAL EXISTS
FOR A DERECHO WITH WIDESPREAD DAMAGING WINDS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 80
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 31040.

[Extremeweatherguy]

If a derecho does form, however, a PDS will be issued. According to Jeff, there is a chance this may happen.

[Extremeweatherguy]

000
FXUS64 KHGX 282023
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
320 PM CDT FRI APR 28 2006

.DISCUSSION...
KHGX VAD PROFILE SHOWS DEEP SOUTHERLY FLOW IN PLACE ACROSS SE TX THIS
AFTN WITH 45 KNOT LOW LEVEL JET TRANSPORTING PWS OF 1.6-1.7 INCHES
INTO THE AREA. A WEAK SURFACE FRONT WAS LOCATED ACROSS CENTRAL/EAST
TX WITH WIDESPREAD ELEVATED CONVECTION OCCURRING NORTH OF THIS
BOUNDARY. MEANWHILE...STORMS WERE BEGINNING TO DEVELOP ALONG THE
DRYLINE IN SOUTHWEST TEXAS FROM THE MIDLAND AREA SOUTH TO THE
TEXAS/MEXICO BORDER. 12Z RUNS OF THE GFS/NAM ARE A BIT SLOWER WITH
THE EVOLUTION OF THE MOVEMENT OF THE DRYLINE AND UPPER LOW OVER NEW
MEXICO. THE MODELS SHOW CONVECTION OVER WEST TEXAS ORGANIZING INTO
AN MCS OVER THE HILL COUNTRY/EDWARDS PLATEAU THIS EVENING AS
IMPRESSIVE 130 KNOT JET STREAK LIFTS NORTHEASTWARD INTO WEST TX.
STRONG UPPER DIFFLUENCE AND 50-60 KNOT LOW LEVEL JET SHOULD HELP TO
SUSTAIN THE CONVECTION AS IT PUSHES EASTWARD TOWARD OUR CWA LATER
TONIGHT DESPITE THE CAPPING IN PLACE AND THE LACK OF INSTABILITY
THAT WILL BE PRESENT. RIGHT NOW THINK SQUALL LINE WILL REACH SE TX
VERY LATE TONIGHT (AFTER 08Z) AND EXIT AREA MID-LATE MORNING
SATURDAY. MODELS CONTINUE TO DEPICT IMPRESSIVE SHEAR PROFILES OVER SE
TX LATER TONIGHT WITH HELICITIES IN EXCESS OF 400 M2/S2 IN SOME
CASES.PRIMARY SEVERE THREAT WILL BE DAMAGING WINDS...WITH A MUCH LOWER
RISK OF LARGE HAIL OR ISOLATED TORNADOES ALSO PRESENT. STORMS WILL
PRODUCE BRIEF HEAVY RAINFALL...BUT NOT OVERLY CONCERNED ABOUT THE
RAINFALL THREAT SINCE REGION HAS BEEN DRY LATELY AND STORMS SHOULD
MOVE THROUGH FAIRLY QUICKLY.

WHILE FEEL THE NAM IS TOO SLOW DRYING THE AREA OUT SATURDAY
AFTN/EVENING...DO THINK THERE IS A POSSIBILITY OF THE DRYLINE
HANGING UP OVER OUR EASTERN/COASTAL ZONES SATURDAY AFTN. MOST OF THE
ENERGY WITH THE UPPER TROUGH WILL STILL BE WELL TO THE WEST...SO IF
THE ATMOSPHERE CAN RECOVER FROM MORNING CONVECTION THERE WILL BE A
POSSIBILITY OF ISOLATED TSRA RE-FIRING OVER OUR FAR ERN ZONES SAT
AFTN. WILL MAINTAIN 30 POPS THIS AREA AS A RESULT. DRYLINE SHOULD EXIT
AREA EARLY SAT EVENING WITH PRECIP ENDING. DRY CONDITIONS WILL FOLLOW
FOR SAT NIGHT THROUGH MONDAY.

12Z GFS SIMILAR TO PREVIOUS RUNS DEPICTING A WEAK FROPA TUESDAY WITH
FRONT STALLING ACROSS OUR SRN ZONES INTO WEDNESDAY. PWS INCREASE TO
1.5 INCHES AND ATMOSPHERE REMAINS UNCAPPED SO WILL GO WITH 20/30
POPS THESE PERIODS. A STRONGER FRONT IS EXPECTED TO MOVE ACROSS SE TX
THU/FRI. WILL KEEP LOW POPS GOING FOR THIS PERIOD AS WELL.

35

[jkt21787]

If a derecho does form, however, a PDS will be issued. According to Jeff, there is a chance this may happen.

I don't see a very high chance personally, though Jeff is the pro of course. With that said, I can't find any NWS office in the area nor SPC that came even close to mentioning such a scenario tonight. Bascially your typical severe MCS. SPC just has 15-30% wind areas, unhatched.

[tidesong]

TORNADO WARNING
TXC465-282100-
/O.NEW.KEWX.TO.W.0021.060428T2037Z-060428T2100Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
337 PM CDT FRI APR 28 2006

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* TORNADO WARNING FOR THE FOLLOWING COUNTIES...
VAL VERDE

* UNTIL 400 PM CDT

* AT 334 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO OVER VAL VERDE
COUNTY...BETWEEN LANGTRY AND PANDALE...MOVING NORTHEAST AT 25 MPH.

* THE TORNADO WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS OF VAL
VERDE COUNTY AND MOVE TOWARD JUNO.

A VEHICLE IS EASILY ROLLED AND CRUSHED BY A TORNADO. DO NOT TRY TO
OUTRUN ONE. IF NO STRONG BUILDING IS CLOSE...LEAVE YOUR VEHICLE AND
TAKE SHELTER IN A DITCH OR LOW SPOT. COVER YOUR HEAD.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM CDT FRIDAY EVENING FOR
SOUTH CENTRAL TEXAS.

[Extremeweatherguy]

If a derecho does form, however, a PDS will be issued. According to Jeff, there is a chance this may happen.

I don't see a very high chance personally, though Jeff is the pro of course. With that said, I can't find any NWS office in the area nor SPC that came even close to mentioning such a scenario tonight. Bascially your typical severe MCS. SPC just has 15-30% wind areas, unhatched.

good points, but this SPC comment (in their latest discussion) leaves me thinking that they may upgrade their risk potential later on:

STORMS MAY
ORGANIZE LINEARLY INTO A SQUALL LINE THIS EVENING...AND THEN MOVE
ACROSS ERN OK/ERN TX THROUGH THE END OF THE PERIOD. THUS...MORE
WIDESPREAD DAMAGING WIND THREAT COULD EVOLVE WITH TIME

[jkt21787]

If a derecho does form, however, a PDS will be issued. According to Jeff, there is a chance this may happen.

I don't see a very high chance personally, though Jeff is the pro of course. With that said, I can't find any NWS office in the area nor SPC that came even close to mentioning such a scenario tonight. Bascially your typical severe MCS. SPC just has 15-30% wind areas, unhatched.

good points, but this SPC comment (in their latest discussion) leaves me thinking that they may upgrade their risk potential later on:

STORMS MAY
ORGANIZE LINEARLY INTO A SQUALL LINE THIS EVENING...AND THEN MOVE
ACROSS ERN OK/ERN TX THROUGH THE END OF THE PERIOD. THUS...MORE
WIDESPREAD DAMAGING WIND THREAT COULD EVOLVE WITH TIME

True, but they are concerned with the instability as I am. Shear/dynamics will compensate, but question is how much. Typically its not enough to produce widespread significant wind events but the trends will have to be watched through the 01z outlook.

First tornadic cell has developed in Val Verde County Texas. Strong couplet there but in very rural areas.

[Extremeweatherguy]

impressive looking cell. Good thing it is in rural areas though.