STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 3 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWK48 KWNS.
VALID 301200-011200
A SLIGHT RISK OF SEVERE THUNDERSTORMS IF FORECAST OVER PORTIONS OF
THE MID ATLANTIC MONDAY AFTERNOON AND EVENING.
MID/UPPER LEVEL PATTERN WILL NOT UNDERGO ANY DRASTIC CHANGES
MONDAY...AS COMPARED TO THE PRIOR FEW DAYS. PROGRESSIVE TROUGH NOW
OVER THE NRN PLAINS WILL HAVE EJECTED ACROSS ERN CANADA AND LEFT A
BROADER TROUGH AXIS OVER THE NORTHEAST INTO THE OH RIVER VALLEY.
ANOTHER TROUGH WILL CONTINUE EWD ACROSS THE PAC NW...WITH MID/UPPER
LEVEL RIDGE BUILDING OVER THE ROCKIES AND NRN HIGH PLAINS.
...MID ATLANTIC...
SURFACE TROUGH ASSOCIATED WITH BROADER TROUGH ALOFT WILL MOVE INTO
THE MID ATLANTIC REGION NEAR PEAK HEATING MONDAY AFTERNOON...WHERE
SUFFICIENT MOISTURE WILL BE IN PLACE FOR MODERATE INSTABILITY.
THOUGH DEEP WLY FLOW IS FORECAST ACROSS THE REGION...DEEP LAYER
SHEAR IS EXPECTED TO BE SUFFICIENT /I.E. SFC-6 KM SHEAR AROUND 40
KT/ FOR A FEW SEVERE THUNDERSTORMS...MAINLY IN THE FORM OF
ORGANIZED LINES AND/OR SPLITTING SUPERCELLS. ACTIVITY WILL LIKELY
DEVELOP JUST EAST OF THE MOUNTAINS AND MOVE EWD TOWARDS THE COAST
THROUGH THE EARLY EVENING.
...OH RIVER VALLEY INTO THE SRN PLAINS...
SURFACE FRONT WILL SLOW/STALL ACROSS THIS REGION DURING THE
AFTERNOON...WITH MODERATE TO STRONG INSTABILITY DEVELOPING WITHIN
THE WARM SECTOR. DESPITE THE DEGREE OF INSTABILITY...CONVERGENCE
ALONG THIS FRONT WILL REMAIN WEAK AS WILL THE DEEP LAYER SHEAR.
THUS...WILL OPT TO FORECAST ONLY LOW PROBABILITIES OF SEVERE
THUNDERSTORMS ALONG THE LENGTH OF THIS BOUNDARY ATTM.
...ERN MT...
LARGE SCALE ASCENT WILL INCREASE ACROSS MT DURING THE DAY AHEAD OF
APPROACHING MID/UPPER LEVEL SHORTWAVE TROUGH. ETA AND GFS FORECAST
A WELL DEFINED SURFACE TROUGH SHIFTING EWD INTO ERN MT MONDAY
AFTERNOON...ENHANCING THE CONVECTIVE POTENTIAL ACROSS THIS REGION.
HOWEVER...LOW LEVEL MOISTURE REMAINS QUESTIONABLE FOR MORE THAN
ISOLATED SEVERE THUNDERSTORMS ATTM AND WILL THEREFORE FORECAST ONLY
LOW PROBABILITIES FOR NOW.
...WRN GULF COAST REGION...
ETA AND GFS ARE VERY DIFFERENT IN THEIR HANDLING OF ELY/TROPICAL
WAVE EXPECTED TO EJECT NNWWD OUT OF THE GULF OF MEXICO MONDAY.
HOWEVER...HPC/TPC ARE FORECASTING LOW CENTER TO MOVE INTO THE WRN
GULF COAST LATE MONDAY...MORE IN LINE WITH 00Z ETA WHICH ALSO
BRINGS A 40 KT SLY LLJ ALONG THE SABINE RIVER VALLEY MONDAY
EVENING. THUS...LOW PROBABILITIES OF WIND DAMAGE/TORNADOES IS
WARRANTED ACROSS ERN TX AND MUCH OF LA.
..EVANS.. 06/28/03
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED FOR 1200Z
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