SWODY3
SPC AC 190807
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0207 AM CST TUE JAN 19 2010
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN AL...SRN GA...NRN FL
AND A SMALL PORTION OF SRN SC...
...SYNOPSIS...
MODEL CONSENSUS IS THAT SHORTWAVE TROUGH THAT WILL MOVE THROUGH THE
SRN PLAINS AND LOWER MS VALLEY WEDNESDAY WILL CONTINUE INTO THE TN
VALLEY AND SERN STATES THURSDAY. ATTENDANT SURFACE LOW WILL OCCLUDE
AS IT MOVES EWD THROUGH TN OR KY. TRAILING FRONT WILL MOVE THROUGH
MS...AL AND GA. MODELS INDICATE SECONDARY CYCLOGENESIS NEAR THE NC
COAST THURSDAY NIGHT AS UPPER JET EXIT REGION INTERACTS WITH
BAROCLINIC ZONE OFFSHORE.
...SERN AL...SRN GA AND NRN FL...
PARTIALLY MODIFIED GULF AIR WITH LOW 60S DEWPOINTS WILL LIKELY
ADVECT NEWD THROUGH SRN AL...SRN GA...NRN FL AND POSSIBLY SRN SC
ALONG A STRONG SWLY LOW LEVEL JET ATTENDING THE SHORTWAVE TROUGH. AN
MCS WILL PROBABLY BE ONGOING WITHIN ZONE OF ASCENT ALONG THE WARM
CONVEYOR BELT. WIDESPREAD CLOUDS AND PRECIPITATION SHOULD LIMIT
MLCAPE TO WELL BELOW 1000 J/KG EAST OF ONGOING STORMS. PARTIAL
CLEARING WILL BE POSSIBLE FARTHER DOWNSTREAM ACROSS FL AND SRN GA.
STORMS DEVELOPING NEAR THE SRN END OF THIS MCS WILL EXPERIENCE AN
INFLUX OF RICHER LOW-LEVEL MOISTURE AND THEREFORE ARE MORE LIKELY TO
BECOME ROOTED NEAR THE SURFACE. STRONG LOW-LEVEL AND DEEP LAYER
SHEAR ACCOMPANYING THIS IMPULSE WILL CONTRIBUTE TO A THREAT OF
SUPERCELLS AND BOWING STRUCTURES WITH DAMAGING WIND AND ISOLATED
TORNADOES POSSIBLE AS ACTIVITY DEVELOPS EWD.
...NRN AL THROUGH NRN GA...
BOTH THE NAM AND GFS INDICATE THE ATMOSPHERE WILL DESTABILIZE OVER
PARTS OF AL AND GA IN WAKE OF THE MCS...THOUGH THE CAPE VALUES ON
THE OPERATIONAL NAM FORECAST SOUNDINGS APPEAR OVERDONE DUE TO WHAT
APPEARS TO BE ACTIVATION OF THE SHALLOW CONVECTIVE SCHEME.
NEVERTHELESS...A DRYSLOT WILL LIKELY ADVECT NEWD THROUGH THIS REGION
ALONG UPPER JET AXIS...AND IF LOW CLOUDS CAN MIX OUT AHEAD OF THE
FRONT...MLCAPE FROM 500 TO 1000 J/KG WILL BE POSSIBLE. THE FRONTAL
CIRCULATION COUPLED WITH DEEPER ASCENT WITHIN THE UPPER JET EXIT
REGION COULD PROMOTE DEVELOPMENT OF ADDITIONAL STORMS ACROSS
CNTRL/NRN AL INTO NRN GA DURING THE AFTERNOON. LOW LEVEL WINDS ARE
FORECAST TO VEER BEHIND THE MCS...BUT STRAIGHT LINE HODOGRAPHS WITH
STRONG DEEP SHEAR WILL BE SUPPORTIVE OF SPLITTING SUPERCELLS. LARGE
HAIL AND ISOLATED STRONG WIND GUSTS WILL BE THE MAIN THREATS...BUT
AN ISOLATED TORNADO OR TWO CANNOT BE RULED OUT. WILL INTRODUCE 5%
SEVERE PROBABILITIES FOR NOW. HOWEVER...IF MODELS REMAIN CONSISTENT
WITH THIS SCENARIO NEXT FEW RUNS...THIS AREA WILL LIKELY BE INCLUDED
IN A CATEGORICAL RISK ON THE NEXT DAY 2 UPDATE.
...CA...
ANOTHER IN A SERIES OF UPPER TROUGHS WILL MOVE INTO CA THURSDAY
AFTERNOON. STEEP LAPSE RATES AND COLD AIR ALOFT WILL CONTRIBUTE TO
DESTABILIZATION...PARTICULARLY ALONG COASTAL AREAS. A FEW STORMS
MIGHT BECOME CAPABLE OF PRODUCING ISOLATED SMALL HAIL AND GUSTY
WINDS. WEAK INSTABILITY WILL CONTINUE TO SERVE AS A LIMITING FACTOR.
..DIAL.. 01/19/2010
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