SWOD48
SPC AC 180914
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0314 AM CST MON JAN 18 2010
VALID 211200Z - 261200Z
...DISCUSSION...
DAY 4...MODEL CONSENSUS IS THAT SRN STREAM SHORTWAVE TROUGH WILL
EJECT ENEWD THROUGH THE TN VALLEY AND SERN U.S. THURSDAY...BUT ECMWF
AND GFS SOLUTIONS HAVE TRENDED FARTHER NORTH COMPARED TO 24 HOURS
AGO. DESPITE THIS TREND...WILL MAINTAIN SEVERE PROBABILITIES ACROSS
NRN FL INTO SRN GA. PARTIALLY MODIFIED GULF AIR WILL ADVECT NEWD
INTO THIS REGION AND CONTRIBUTE TO AT LEAST MODEST INSTABILITY. THE
MOIST AXIS WILL BE CO-LOCATED WITH STRONG DEEP LAYER WINDS AND
VERTICAL SHEAR ATTENDING THE EJECTING UPPER TROUGH. STORMS
DEVELOPING EWD THROUGH THIS AREA MAY BE ROOTED CLOSE ENOUGH TO THE
SURFACE TO POSE A SEVERE RISK.
DAY 6 AND 7...ECMWF ENSEMBLE MEANS...GFS AND MREF MEMBERS HAVE
CONVERGED ON A SIMILAR SOLUTION AND MOVE THE LARGE UPPER TROUGH OVER
THE ERN PACIFIC EWD INTO THE PLAINS BY SATURDAY. SEVERAL IMPULSES
WILL ROTATE THROUGH THE UPPER LOW AS IT MOVES EAST. A LARGE CYCLONE
WILL DEVELOP OVER THE PLAINS IN ASSOCIATION WITH THIS FEATURE
SATURDAY BEFORE SHIFTING EWD INTO THE MS VALLEY SUNDAY. INTRUSION OF
CP AIR IN WAKE OF EJECTING IMPULSE THURSDAY WILL NOT EXTEND FAR INTO
THE GULF. AS A RESULT...RICHER LOW LEVEL MOISTURE WILL BE POISED TO
ADVECT NWD AS CYCLONE DEEPENS...THOUGH DURATION OF THE MOIST
ADVECTION WILL NOT BE OPTIMAL. A FORCED BAND OF STORMS WILL LIKELY
DEVELOP INITIALLY OVER THE SRN AND CNTRL PLAINS INTO THE LOWER-MID
MS VALLEY SATURDAY. ACTIVITY WILL SUBSEQUENTLY SHIFT EWD THROUGH THE
TN VALLEY AND SERN STATES SUNDAY. UNCERTAINTY REMAINS REGARDING
EVOLUTION OF THERMODYNAMIC ENVIRONMENT. HOWEVER...STORMS WILL BE
EMBEDDED WITHIN STRONG VERTICAL SHEAR AND SUFFICIENT MOISTURE MAY
ADVECT NWD TO SUPPORT SURFACE BASED STORMS AND A SEVERE THREAT
DURING THIS TIME.
..DIAL.. 01/18/2010
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