Slight Risk 17th April - Tx, Ok

[Nick F]

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1128 AM CDT FRI APR 17 2009

VALID 171630Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF TEXAS...WRN

OK...SW KS AND SE CO...

...EAST TEXAS...

THE LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL LOW OVER THE SRN

ROCKIES WITH A BROAD DRY SLOT EXTENDING EWD TO AN MCS LOCATED IN

ECNTRL TX. THE MCS WILL MOVE ENEWD ACROSS EAST TX THIS AFTERNOON.

THE SRN PART OF THE MCS SHOULD STRENGTHEN MOVING EWD ALONG A WARM

FRONT AND GRADIENT OF MODERATE INSTABILITY INTO THE

HOUSTON/GALVESTON AREAS. ALTHOUGH MUCH OF THE MCS MAY BE SLIGHTLY

ELEVATED ATTM...FORECAST SOUNDINGS QUICKLY WEAKEN THE CAP OVER SE TX

OVER THE 1-2 HOURS WHICH WILL ALLOW THE STORMS TO BECOME SFC-BASED.

STRONG VERTICAL SHEAR PROFILES ALREADY IN PLACE WILL SUPPORT

ISOLATED SUPERCELLS. IN ADDITION...THE RUC ANALYZES A 45 TO 55 KT

LOW-LEVEL JET OVER SOUTHEAST TEXAS AND THE HOUSTON WSR-88D VWP

CONFIRMS THIS WITH A 55 KT SLY WIND AT 1 KM. THIS IS PRODUCING A

LOW-LEVEL SHEAR ENVIRONMENT FAVORABLE FOR AT LEAST AN ISOLATED

TORNADO THREAT. THIS THREAT SHOULD EXPAND EWD WITH TIME AND MAY

AFFECT AREAS OF FAR SE TX LATER THIS AFTERNOON.

NORTH OF THE WARM FRONT IN THE LUFKIN AND TYLER AREAS...INSTABILITY

DROPS OFF DRAMATICALLY AND VERTICAL SHEAR IS WEAKER. THESE TWO

FACTORS SHOULD KEEP THE SEVERE THREAT MORE ISOLATED AS THE

SQUALL-LINE OVER ECNTRL TX AFFECTS NERN TX THIS AFTERNOON.

...WCNTRL TX/TX PANHANDLE/WRN OK/SE CO/SW KS...

A 65 TO 75 KT MID-LEVEL JET IS CURRENTLY ROUNDING THE BASE OF AN

WELL-DEVELOPED UPPER-LEVEL LOW OVER THE SRN ROCKIES. AT THE SFC...A

WELL-DEFINED DRYLINE IS PRESENT EXTENDING SEWD ACROSS THE TX

PANHANDLE INTO WCNTRL TX. THUNDERSTORMS WITH HAIL POTENTIAL ARE

ONGOING ON THE NERN SIDE OF THE UPPER-LEVEL LOW OVER SE CO AND THE

OK PANHANDLE. MID-LEVEL LAPSE RATES ARE STEEP AND TEMPS ALOFT ARE

COLD ASSOCIATED WITH THE UPPER-LEVEL LOW. THIS SHOULD CONTINUE TO BE

FAVORABLE FOR HAIL ESPECIALLY AS SFC TEMPS WARM THIS AFTERNOON. THE

HAIL THREAT SHOULD EXPAND SEWD WITH TIME ACROSS THE ERN TX PANHANDLE

WHICH IS SUPPORTED BY THE SHORT-RANGE MODELS.

FURTHER SOUTH ALONG THE DRYLINE IN WCNTRL TX...SFC DEWPOINTS ARE

CURRENTLY IN THE UPPER 50S F. THE AIRMASS IS NOT YET UNSTABLE DUE TO

LOW CLOUD COVER IN THE WAKE OF AN MCS WHICH WILL CONTINUE TO HAMPER

DESTABILIZATION THIS AFTERNOON...DELAYING CONVECTIVE INITIATION

UNTIL THIS EVENING ALONG THE DRYLINE. BY THAT TIME...03Z MODEL

FORECASTS DEVELOP SUFFICIENT INSTABILITY IN A STRONGLY SHEARED

ENVIRONMENT FOR SUPERCELLS. FORECAST SOUNDINGS THIS EVENING ACROSS

WCNTRL TX SHOW 55 TO 65 KT OF VERTICAL SHEAR WITH 500 MB TEMPS IN

THE -17 TO -19 C RANGE. THIS SHOULD SUPPORT A THREAT OF LARGE HAIL

AND AN ISOLATED THREAT FOR VERY LARGE HAIL SHOULD EXIST WITH ANY

SUPERCELLS THAT BECOME DOMINANT DURING THE MID TO LATE EVENING.

ALTHOUGH MORE CONDITIONAL...A TORNADO WILL BE POSSIBLE AS WELL.

..BROYLES/GARNER.. 04/17/2009

First tornado watch of the morning there:

http://www.spc.noaa.gov/products/watch/ww0159.html

Once this MCS stuff moves on we should see storms firing further to the west and NW as the dry line moves in from the west later, think I'll target somewhere like Throckmorton, TX - Abilene, TX area in west-central Texas.

[Tony Gilbert]

Hi Nick. Yep I'm going to try and get back on this one later this evening. Though a quick look seems to be rather restrictive on tornado development ATM. Though given the likely development of surface boundaries some weak CZ tornadoes could get reported.

PS. Last nights risk for tornadoes was definitely underestimated by the SPC IMO

[MAF]

cheers nick, thats my evening and night sorted if its quiet here in work

Current watch status

Probability of 2 or more tornadoes Mod (30%)

Probability of 1 or more strong (F2-F5) tornadoes Low (10%)

courtesy NOAA

[MAF]

Watch 162 issued

SEL2

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 162

NWS STORM PREDICTION CENTER NORMAN OK

345 PM CDT FRI APR 17 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

TEXAS COASTAL PLAINS

COASTAL WATERS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 345 PM UNTIL

1000 PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

courtesy NOAA

full text here > http://www.spc.noaa.gov/products/watch/ww0162.html

[dogs32]

Two reported at

2149 17 W FORDER LINCOLN CO 3868 10403 (BOU)

0124 12 NE BRISTOL PROWERS CO 3824 10216 (PUB)

and 34 hail reports

Edited April 18, 2009 by dogs32