SWODY2
SPC AC 190600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CST TUE JAN 19 2010
VALID 201200Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN TX THROUGH THE LOWER
MS VALLEY AND SRN PORTIONS OF THE GULF COASTAL STATES...
...SYNOPSIS...
SERIES OF VORTICITY MAXIMA EMANATING FROM ACTIVE ERN PACIFIC
SUBTROPICAL JET WILL AFFECT THE PLAINS AND LOWER MS VALLEY THIS
PERIOD. ONLY SLIGHT TIMING AND AMPLITUDE DIFFERENCES ARE EVIDENT
AMONG THE GFS...ECMWF AND NAM MODELS. LEAD IMPULSE WILL DEAMPLIFY AS
IT EJECTS INTO THE MID MS VALLEY EARLY WEDNESDAY. FEATURE OF PRIMARY
INTEREST WILL BE SECONDARY SHORTWAVE TROUGH THAT WILL MOVE EWD
THROUGH THE SRN PLAINS DURING THE AFTERNOON AND EVENING...REACHING
THE LOWER MS VALLEY LATER WEDNESDAY NIGHT. INITIAL SURFACE LOW
SHOULD WEAKEN OVER THE MID MS VALLEY...WHILE SECONDARY CYCLOGENESIS
OCCURS FARTHER SOUTH ACROSS OK...REACHING THE LOWER-MID MS VALLEY
LATER WEDNESDAY. SYNOPTIC WARM FRONT WILL LIKELY DEVELOP NWD INTO
THE TN VALLEY...WITH THE MARINE/COASTAL FRONT ADVANCING TO NEAR THE
GULF COAST.
...SE TX INTO THE LOWER MS VALLEY AND CNTRL GULF COASTAL AREA...
SWLY LOW-LEVEL JET WILL STRENGTHEN OVER ERN TX EWD INTO THE GULF
COASTAL STATES WEDNESDAY AFTERNOON AND OVERNIGHT WITHIN UPPER
DIVERGENCE ZONE DOWNSTREAM OF ADVANCING SHORTWAVE TROUGH. RECENT
OBSERVATIONS ALREADY INDICATE LOW 60S DEWPOINTS OVER S TX. THE
LOW-LEVEL JET SHOULD ADVECT LOW-MID 60F DEWPOINTS INTO SERN TX AND
SRN PARTS OF THE GULF COASTAL STATES AND UPPER 50F TO NEAR 60F
DEWPOINTS FARTHER NORTH. RICHER GULF MOISTURE WILL PROBABLY REMAIN
JUST OFFSHORE SOUTH OF COASTAL FRONT. NWD ADVECTION OF PARTIALLY
MODIFIED GULF AIR SHOULD BE SUFFICIENT FOR AT LEAST MODEST
DESTABILIZATION GIVEN COLD TEMPERATURES ALOFT WITH -14C TO -15C AT
500 MB. DEVELOPMENT OF CLOUDS AND CONVECTION WITHIN WARM ADVECTION
REGIME WILL PROBABLY LIMIT MUCAPE TO AOB 1000 J/KG.
THUNDERSTORMS WILL LIKELY DEVELOP DURING THE DAY WITHIN ZONE OF
ISENTROPIC LIFT FROM ERN TX INTO THE LOWER MS VALLEY. ACTIVITY WILL
SHIFT EWD INTO THE SERN STATES WEDNESDAY NIGHT WITH POSSIBLE UPSCALE
GROWTH TO AN MCS. MUCH OF THE CONVECTION WILL PROBABLY REMAIN AT
LEAST SLIGHTLY ELEVATED GIVEN LIMITED INSOLATION POTENTIAL AND EARLY
ONSET OF PRECIPITATION WITHIN AN INITIALLY STABLE BOUNDARY LAYER.
HOWEVER...STORMS DEVELOPING FROM SERN TX THROUGH THE SRN PORTIONS OF
THE GULF COASTAL STATES MAY BECOME ROOTED NEAR THE SURFACE GIVEN A
CONTINUED INFLUX OF GULF MOISTURE. HODOGRAPH SIZE WILL INCREASE
SIGNIFICANTLY FROM LATE AFTERNOON INTO THE EVENING AS THE LOW-LEVEL
JET STRENGTHENS. VERTICAL SHEAR PROFILES WILL SUPPORT POTENTIAL FOR
SUPERCELLS AND BOWING SEGMENTS WITH DAMAGING WIND AND ISOLATED
TORNADOES POSSIBLE.
...NERN TX...ERN OK THROUGH AR AND SRN MO...
PRIMARY LOW-LEVEL JET IS FORECAST TO REMAIN SOUTH OF THIS REGION
RESULTING IN WEAKER 0-1 KM SHEAR. STORMS DEVELOPING IN THIS AREA
WILL PROBABLY REMAIN AT LEAST SLIGHTLY ELEVATED GIVEN LESS BOUNDARY
LAYER MOISTURE AND LOW CHANCES FOR INSOLATION. HOWEVER...COLD AIR
ALOFT WITH -16C TO -18C AT 500 MB WOULD SUPPORT SURFACE BASED STORMS
IF MORE INSOLATION OCCURS THAN CURRENTLY FORECAST. IN EITHER
CASE...PRIMARY THREAT IN THIS REGION WILL PROBABLY BE ISOLATED HAIL
SUPPORTED BY MODERATELY STEEP MID-LEVEL LAPSE RATES AND SUFFICIENT
BULK SHEAR FOR UPDRAFT ROTATION.
...NRN AND CNTRL CA...
ANOTHER IN A SERIES OF IMPULSES WILL MOVE EWD INTO CA ACCOMPANIED BY
STEEP LAPSE RATES. SUFFICIENT INSTABILITY MIGHT DEVELOP TO SUPPORT A
THREAT OF GUSTY WINDS AND SMALL HAIL GIVEN FAVORABLE VERTICAL SHEAR
FOR ORGANIZED STORMS. ANY THREAT APPEARS GREATEST ALONG COASTAL
REGIONS WHERE ONSHORE FLOW AND MORE FAVORABLE TIMING OF THERMAL
TROUGH SHOULD RESULT IN GREATER INSTABILITY THAN FARTHER INLAND.
..DIAL.. 01/19/2010
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