SPC AC 090058
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0658 PM CST SAT JAN 08 2011
VALID 090100Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS FOR LATE TONIGHT/EARLY SUNDAY
MORNING ACROSS DEEP SOUTH TX...
...SOUTH TX...
A SLIGHT RISK HAS BEEN ADDED FOR DEEP S TX FOR LATER TONIGHT/EARLY
SUNDAY MORNING /06-12Z/...WITH THE GREATEST THREATS BEING A TORNADO
OR TWO AND DAMAGING WIND GUSTS.
PROGRESSIVE MID-UPPER LEVEL SHORTWAVE TROUGH...NOW LOCATED OVER NRN
CHIHUAHUA MEXICO INTO NM...WILL CONTINUE EWD THIS FORECAST PERIOD
AND SHOULD EXTEND SWD FROM W TX INTO THE LOWER RIO GRANDE VALLEY/S
TX REGION BY 12Z. STRONG /80-90 KT/ SWLY MIDLEVEL JET WITHIN THE
BASE OF THIS TROUGH IS EXPECTED TO MOVE THROUGH DEEP S TX BETWEEN
06-12Z.
IN THE LOW LEVELS...A WARM FRONT HAS MOVED VERY LITTLE SINCE EARLIER
TODAY...AND AT 09/00Z WAS ANALYZED FROM S OF LRD TO 35 S CRP. AIR
MASS S OF THIS BOUNDARY IS QUITE MOIST /REF 00Z BRO SOUNDING/ WITH A
FAIRLY DEEP BOUNDARY LAYER...SURFACE DEWPOINTS IN THE MID-UPPER 60S
AND PW VALUES JUST ABOVE 1 INCH. ALTHOUGH THE BRO SOUNDING ALSO
SHOWED A STRONG CAP BASED AROUND 800 MB...MODELS SUGGESTED THIS CAP
WILL BE ELIMINATED LATER TONIGHT ALLOWING FOR SURFACE BASED STORM
DEVELOPMENT. THIS WILL OCCUR AS FORCING FOR ASCENT WITHIN THE EXIT
REGION OF THE STRONG MIDLEVEL JET AND COOLING MIDLEVEL TEMPERATURES
SPREAD ACROSS S TX. THIS PROCESS SHOULD OCCUR INITIALLY ALONG THE
RIO GRANDE RIVER /AROUND LRD/ BY 06Z...AND THEN TO THE S TX COAST BY
09Z.
TSTMS...MAINLY ELEVATED...WILL CONTINUE TO DEVELOP THIS EVENING N OF
THE WARM FRONT INTO PARTS OF CENTRAL TX WITHIN INCREASING LOW LEVEL
WAA REGIME AS SLY LLJ STRENGTHENS TO 30-40 KT ACROSS S TO CENTRAL TX
AND BENEATH COOLING MIDLEVEL TEMPERATURES/STEEPER LAPSE RATES. AS
THE STRONGER FORCING FOR ASCENT ARRIVES IN DEEP S TX /BY
06Z/...TSTMS BECOMING SURFACE BASED WILL DEVELOP EWD ALONG THE WARM
FRONT WITH THIS BOUNDARY MOVING NWD SOME TO VICINITY OF COT BY 06Z
AND TO THE MID TX COAST BY 12Z. EFFECTIVE BULK SHEAR /50-70 KT/
WILL BE MORE THAN SUFFICIENT FOR ORGANIZED STORMS/SOME
SUPERCELLS...WHILE LOW LEVEL SHEAR /0-1 KM SRH 200-300 M2/S2/ ALONG
LLJ AXIS WILL SUPPORT A TORNADO THREAT. LOW LEVEL SHEAR MAY BE
ENHANCED ALONG THE WARM FRONT AND INVOF A SURFACE LOW EXPECTED TO
TRACK ALONG THIS BOUNDARY AND REACH THE COAST BY 12Z. ADDITIONAL
STORMS WILL BE POSSIBLE ALONG A COLD FRONT TRAILING SWD FROM THE
SURFACE LOW...WITH DAMAGING WINDS THE PRIMARY THREAT WITH THIS
FRONTAL ACTIVITY.
..PETERS.. 01/09/2011
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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