SPC AC 231627
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1027 AM CST WED DEC 23 2009
VALID 231630Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS THE ERN HALF OF TX...LA AND THE
OZARKS REGION...
..SYNOPSIS...
MID MORNING WV IMAGERY AND 12Z HAND ANALYSIS SHOWS COMPLEX AREA OF
LOW PRESSURE ALOFT OVER AZ/NM. A 100 KT WIND MAX AT 500 MB OVER SAN
DIEGO INDICATES UPPER LOW SHOULD CONTINUE SEWD TODAY INTO FAR WRN
TX/SRN NM...BEFORE TURNING EAST TONIGHT AS JET MAX MOVES TO THE BASE
OF THE UPPER TROUGH. WV IMAGERY ALSO SHOWS ONE WEAK WAVE MOVING NEWD
THROUGH SERN KS...AND ANOTHER MID/HIGH LEVEL TROUGH SHIFTING EWD
INTO WRN AR AND LA. SATELLITE SHOW MID/HIGH LEVEL DRYING/POSSIBLE
SUBSIDENCE OVER A LARGE PORTION OF TX AND THIS WAS SUPPORTED WITH
500 MB ANALYSIS OF THERMAL RIDGE OVER WRN/CENTRAL TX.
AT THE SURFACE...A WEAK SURFACE WAVE WAS LOCATED IN SERN KS...IN
ASSOCIATION WITH WAVE ALOFT. COLD FRONT TRAILED SWWD FROM THE LOW
THROUGH CENTRAL OK...AND THEN WSWWD INTO EAST CENTRAL NM. THE KS LOW
WILL WEAKEN...AS SECONDARY AREA OF LOW PRESSURE DEVELOPS ALONG FRONT
IN E CENTRAL NM...AND DEEPENS AS IT SHIFTS EWD ACROSS TX THROUGH THE
PERIOD...WITHIN PRIMARY AREA OF LARGE SCALE FORCING.
...OZARKS REGION...
CONVECTION ASSOCIATED WITH KS WAVE...ERN KS INTO NERN OK...WILL
SHIFT EWD THROUGH THE AFTERNOON. ALTHOUGH THE BOUNDARY LAYER IS
EXPECTED TO REMAIN STABLE...STEEP MID LEVEL LAPSE RATES AND MUCAPES
AOB 500 J/KG MAY MARGINALLY SEVERE HAIL WITH SCATTERED STORMS THIS
AFTERNOON AND TONIGHT.
...SRN OK/SWRN AR SWD INTO THE ERN HALF OF TX...
WEAK BAND OF CONVECTION CONTINUES FROM VCT TO SHV IN ZONE OF LOW
LEVEL WARM ADVECTION. LIGHTNING HAS DECREASED WITH THIS ACTIVITY
THROUGH THE MORNING HOURS...LIKELY DUE TO SOME WARMING AND
STRENGTHENING CAP ALOFT. WITH BOUNDARY LAYER WARMING...A FEW OF
THESE STORMS MAY BREECH THE CAP LATE THIS AFTERNOON. SUFFICIENT
SHEAR AND INSTABILITY WOULD SUPPORT SUPERCELLS.
HOWEVER...AS LARGE SCALE FORCING SPREADS INTO THE WRN PORTIONS OF
NRN/CENTRAL TX THIS AFTERNOON...MORE INTENSE CONVECTION APPEARS
LIKELY IN THIS REGION. STEEP MID LEVEL LAPSE RATES COMBINED WITH
DEWPOINTS IN THE MID 60S WILL RESULT IN MLCAPES NEAR 1500
J/KG...AHEAD OF SURFACE LOW/SEWD MOVING COLD FRONT. DEEP LAYER SHEAR
WILL INCREASE AS STRONGER WINDS ALOFT STRENGTHEN...AND SUPPORT
SUPERCELLS. A FEW TORNADOES...LARGE HAIL...AND DAMAGING WINDS ARE
EXPECTED WITH THESE STORMS AS THEY SHIFT EWD THROUGH TX LATE THIS
AFTERNOON AND INTO TONIGHT.
AS THE STORMS PROGRESS EWD INTO DEEP ERN TX AND EVENTUALLY INTO SWRN
AR/LA TONIGHT...BACKING DEEP LAYER FLOW/SHEAR VECTORS AND STRONG
FORCING FOR ASCENT SHOULD FAVOR A SQUALL LINE EVOLVING. WHILE THE
PRIMARY THREAT WILL BECOME WIND DAMAGE...THE THREAT FOR A TORNADO OR
TWO WILL EXIST WITH EMBEDDED BOWS/SUPERCELLS.
..IMY.. 12/23/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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