SPC AC 270544
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1144 PM CST TUE JAN 26 2010
VALID 281200Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE TX HILL
COUNTRY...
...TX HILL COUNTRY...
AN UPPER-LEVEL TROUGH WILL MOVE ACROSS NRN MEXICO THURSDAY AS A
MID-LEVEL JET ROUNDS THE BASE OF THE TROUGH. THE EXIT REGION OF THIS
JET WILL AFFECT SOUTHWEST AND CNTRL TX CREATING STRONG DEEP LAYER
SHEAR PROFILES THURSDAY AFTERNOON AS A LOW-LEVEL JET TRANSPORTS
MOISTURE NWD. THUNDERSTORMS WITH A MARGINAL SEVERE THREAT SHOULD BE
ONGOING THURSDAY MORNING ACROSS WEST TX WITH THE STORMS SPREADING
EWD INTO THE TX HILL COUNTRY THURSDAY AFTERNOON. A BAND OF VERY
STRONG LARGE-SCALE ASCENT ASSOCIATED WITH THE APPROACHING
UPPER-LEVEL TROUGH WILL HELP CONVECTIVE COVERAGE AND INTENSITY TO
INCREASE DURING THE DAY. THUNDERSTORMS APPEAR LIKELY TO ORGANIZE
INTO A LINE ALONG A COLD FRONT MOVING SEWD INTO INCREASING LOW-LEVEL
MOISTURE.
ETA-KF FORECAST SOUNDINGS IN THE TX HILL COUNTRY BY 21Z THURSDAY
SHOW SFC DEWPOINTS IN THE LOWER 60S F WITH 40 KT OF FLOW AT 1 KM AND
0-6 KM SHEAR IN THE 65 TO 75 KT RANGE. THE MOISTURE AND SHEAR COULD
SUPPORT A WIND DAMAGE THREAT WITH SHORT-LINE SEGMENTS. THE WINDOW
FOR SEVERE COULD BE NARROW AND CONCENTRATED NEAR AND JUST AFTER PEAK
HEATING. FOR THIS REASON...THE SLIGHT RISK HAS BEEN NARROWED FOR
THIS OUTLOOK. THE 21Z FORECAST SOUNDING AT AUSTIN DID SHOW A 500 MB
TEMPERATURE OF -15C AND A 700 TO 500 MB LAPSE RATE OF 7.0 C/KM WHICH
WOULD BE SUFFICIENT FOR HAIL GIVEN THE STRONG DEEP LAYER SHEAR. A
MARGINAL SEVERE THREAT MAY CONTINUE SEWD ONTO THE TX COASTAL PLAIN
DURING THE OVERNIGHT PERIOD WHERE SFC DEWPOINTS ARE FORECAST TO BE
IN THE MID 60S F.
..BROYLES.. 01/27/2010
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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