SPC AC 090629
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 AM CST WED JAN 09 2008
VALID 101200Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN OH VALLEY
SWD TO THE CNTRL/ERN GULF COAST...
...SYNOPSIS...
LATEST MODEL GUIDANCE IS CONSISTENT IN THE EVOLUTION OF
STRONG...MIGRATORY TROUGH WHICH WILL BE IN THE PROCESS OF
INTENSIFYING OVER THE CNTRL/SRN PLAINS THURSDAY MORNING. THIS
SYSTEM IS FORECAST TO LIFT RAPIDLY NEWD THROUGH THE TN AND OH
VALLEYS /ASSUMING AN INCREASING NEGATIVE TILT/ AS ACCOMPANYING 85-95
KT MIDLEVEL JET STREAK PROPAGATES THROUGH THE TROUGH BASE INTO A
DOWNSTREAM POSITION.
IN THE LOW LEVELS...THE NAM...GFS AND ECMWF HAVE COME INTO BETTER
AGREEMENT WITH THE TRACK OF ASSOCIATED SURFACE LOW WITH THIS FEATURE
FORECAST TO DEEPEN WHILE DEVELOPING NEWD FROM ERN KS OR OK TO NEAR
THE IL/IND BORDER BY 11/00Z AND INTO SWRN ONTARIO BY 11/12Z. THE
ECMWF SOLUTION REMAINS THE MOST DYNAMIC...INDICATING NOTABLY
STRONGER DEEPENING OF SURFACE LOW THROUGH THE PERIOD. TRAILING COLD
FRONT IS ALSO EXPECTED TO STRENGTHEN CONSIDERABLY WHILE PUSHING
THROUGH THE MID SOUTH AND LOWER MS VALLEY EWD ACROSS THE OH AND TN
VALLEYS AND CNTRL GULF COAST STATES. THIS FRONT SHOULD REACH THE
APPALACHIANS BY 11/12Z.
...SRN OH VALLEY SWD TO CNTRL/ERN GULF COAST...
CURRENT SURFACE OBSERVATIONS AND MODEL GUIDANCE INDICATE THAT COLD
FRONT NOW MOVING THROUGH THE WRN AND CNTRL GULF COAST SHOULD WEAKEN
AND EVENTUALLY DISSIPATE OVER THE SHELF WATERS AS LEE CYCLOGENESIS
OCCURS OVER THE CNTRL/SRN HIGH PLAINS. BUOY OBSERVATIONS AND GOES
SOUNDER IPW IMAGERY SHOW A MOIST AIR MASS IMMEDIATELY TO THE S OF
THIS BOUNDARY /DEWPOINTS OF AROUND 70F/...WHICH WILL BE POISED TO
RETURN NWD BEGINNING DURING THE DAY ONE FORECAST PERIOD.
INDEED...STRENGTHENING SWLY LLJ WILL SUPPORT THE RAPID NWD/NEWD
ADVECTION OF AN INCREASINGLY MOIST BOUNDARY LAYER FROM THE CNTRL
GULF COAST THROUGH THE TN INTO SRN OH VALLEYS WITH DEWPOINTS
INCREASING TO AROUND 50F ALONG THE OH RIVER...TO MID/UPPER 60S ALONG
THE GULF COAST. THIS MOISTURE COUPLED WITH STEEPENING MIDLEVEL
LAPSE RATES ARE FORECAST TO CONTRIBUTE TO MODERATE INSTABILITY BY
AFTERNOON OVER SRN LA THROUGH SERN MS INTO CNTRL AL WITH ENVIRONMENT
ONLY BECOMING WEAKLY UNSTABLE ACROSS NRN PORTIONS OF SLIGHT RISK
AREA.
SURFACE-BASED TSTMS ARE EXPECTED TO INCREASE RAPIDLY IN BOTH
COVERAGE AND INTENSITY BY MID/LATE MORNING AHEAD OF COLD FRONT FROM
THE TN VALLEY TO THE CNTRL GULF COAST AS HEIGHT FALLS AHEAD OF UPPER
TROUGH BEGIN TO OVERSPREAD DESTABILIZING WARM SECTOR. TROPOSPHERIC
WIND FIELDS ARE FORECAST TO STRENGTHEN CONSIDERABLY THROUGH THE DAY
WITH BOTH DEEP LAYER AND LOW LEVEL SHEAR BECOMING MORE THAN
SUFFICIENT FOR SUPERCELLS AND BOWING STRUCTURES CAPABLE OF TORNADOES
AND DAMAGING WINDS.
THIS SEVERE THREAT MAY DEVELOP AS FAR N AS THE UPPER OH VALLEY INTO
AN ENVIRONMENT CHARACTERIZED BY SMALL INSTABILITY...BUT BOTH STRONG
ISALLOBARIC FORCING AND VERTICAL SHEAR. FARTHER S...SEVERE STORMS
WILL LIKELY CONTINUE AHEAD OF COLD FRONT ACROSS PORTIONS OF
GA...CNTRL/SRN AL AND THE FL PNHDL THURSDAY NIGHT WITH A THREAT OF
DAMAGING WINDS AND PERHAPS A FEW TORNADOES.
...CAROLINAS...
EROSION/NWD RETREAT OF WEDGE FRONT WILL ALLOW BOUNDARY LAYER
MOISTURE TO INCREASE OFF THE ATLANTIC WITH DEWPOINTS INCREASING
THROUGH THE 50S INTO LOWER 60S. VERTICAL SHEAR WILL CONCURRENTLY
INCREASE THROUGH THE PERIOD...ESPECIALLY THURSDAY NIGHT WITH
APPROACH OF UPPER TROUGH FROM THE W. POTENTIAL WILL EXIST FOR A FEW
SEVERE STORMS EITHER: 1) DEVELOPING MORE DISCRETELY THURSDAY
AFTERNOON AND NIGHT WITHIN DESTABILIZING AIR MASS...AND/OR 2) MOVING
INTO THE REGION FROM W LATE IN THE PERIOD ALONG AND AHEAD OF SURFACE
COLD FRONT.
..MEAD.. 01/09/2008
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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