SWODY2
SPC AC 071717
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1217 PM CDT TUE OCT 07 2008
VALID 081200Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
ALTHOUGH MODELS ARE SUGGESTIVE THAT AMPLIFICATION WILL OCCUR WITHIN
THE MAIN BELT OF WESTERLIES ACROSS THE NORTHERN/EASTERN PACIFIC INTO
THE NORTHWESTERN STATES...UPPER FLOW ACROSS MUCH OF THE NATION
APPEARS LIKELY TO REMAIN LARGELY ZONAL THROUGH THIS FORECAST PERIOD.
WITHIN THIS REGIME...THE EXIT REGION OF A STRONG MID/UPPER JET
STREAK IS PROGGED TO NOSE EAST OF THE UPPER MISSISSIPPI VALLEY
THROUGH THE LOWER GREAT LAKES REGION BY 12Z THURSDAY. AS THIS
OCCURS...THE IMPACT ON DOWNSTREAM COUPLED NORTHERN AND SOUTHERN
BRANCH SHORT WAVE TROUGHS IS STILL A SOURCE OF CONSIDERABLE
UNCERTAINTY AMONG MODEL DATA. BUT...IT APPEARS PROBABLE THAT AN
INCREASINGLY SHEARED/DEFORMED NORTHERN BRANCH TROUGH WILL LIFT
THROUGH THE GREAT LAKES REGION...WHILE THE SOUTHERN BRANCH
TROUGH/CLOSED LOW BECOMES INCREASINGLY CUT-OFF...OR PROGRESSES MORE
SLOWLY...ACROSS THE SOUTHEASTERN STATES.
LOW-LEVEL MOISTENING IN THE WAKE OF A RETREATING SURFACE RIDGE...
AND AHEAD OF A WEAKENING SURFACE COLD FRONT /ASSOCIATED WITH THE
LEAD SHORT WAVE IMPULSES/...MAY STILL BE SUFFICIENT TO MAINTAIN
PROBABILITIES OF THUNDERSTORMS FROM THE EASTERN GULF STATES
NORTHWARD INTO THE GREAT LAKES REGION WEDNESDAY/WEDNESDAY NIGHT.
BUT...THESE PROBABILITIES...AND CONVECTIVE POTENTIAL IN GENERAL...
ARE EXPECTED TO REMAIN FAIRLY LOW DUE RATHER MODEST LARGE-SCALE
FORCING FOR UPWARD VERTICAL MOTION AND WEAK DESTABILIZATION.
...SOUTHEAST STATES...
BEYOND LATE MORNING INTO MIDDAY WEDNESDAY...THE FOCUS FOR THE
PRIMARY CONVECTIVE DEVELOPMENT MAY SHIFT FROM THE WEAKENING COLD
FRONT...SHIFTING EAST OF THE MISSISSIPPI/ALABAMA BORDER AREA...TO A
SURFACE WAVE ALONG A RESIDUAL SURFACE BOUNDARY ACROSS SOUTHERN
ALABAMA/GEORGIA INTO SOUTH ATLANTIC COASTAL AREAS. UNLESS THIS WAVE
DEVELOPMENT IS CONSIDERABLY STRONGER THAN CURRENT MODEL FORECASTS
INDICATE...BOUNDARY LAYER BASED INSTABILITY INLAND OF COASTAL AREAS
PROBABLY WILL BE WEAK AND FAIRLY CONFINED. COUPLED WITH THE
LIKELIHOOD THAT LOW/MID LEVEL FLOW FIELDS MAY ONLY BECOME MARGINALLY
SUPPORTIVE OF SUPERCELLS OR ORGANIZED CONVECTIVE ACTIVITY...THE
POTENTIAL FOR SEVERE STORMS APPEARS RELATIVELY LOW. IT MAY NOT BE
COMPLETELY NEGLIGIBLE...HOWEVER...AND AN ISOLATED SEVERE STORM OR
TWO IS NOT OUT OF THE QUESTION...MAINLY NEAR OR JUST EAST OF THE
WAVE AS IT TRACKS EASTWARD THROUGH THE PERIOD.
..KERR.. 10/07/2008
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