DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 130723
SWODY3
SPC AC 130721

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0221 AM CDT FRI APR 13 2007

VALID 151200Z - 161200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
HIGHLY-AMPLIFIED/PROGRESSIVE UPPER FLOW PATTERN FORECAST TO CONTINUE
OVER THE CONUS FOR DAY 3...WITH TWO CLOSED LOWS EXPECTED OVER THE
CONUS BY THE END OF THE PERIOD -- ONE INVOF THE FOUR CORNERS AND THE
OTHER OVER THE MID-ATLANTIC REGION.

THOUGH SCATTERED SHOWERS AND THUNDERSTORMS ARE FORECAST OVER THE
ROCKIES AS WRN TROUGH/LOW SHIFTS ACROSS THIS REGION...SEVERE
POTENTIAL SHOULD REMAIN CONFINED TO THE ERN SYSTEM AS IT MOVES
OFFSHORE DURING THE FIRST HALF OF THE PERIOD.

..CAROLINAS...
STORMS MAY BE ONGOING OVER COASTAL SC/ERN NC AND THE OUTER BANKS AT
THE START OF THE PERIOD...WITH BOTH THE GFS AND THE NAM PROGGING THE
FRONT TO CLEAR THE CAROLINA COAST BETWEEN 15/15Z AND 15/18Z. WITH
THE MAIN SEVERE THREAT POSSIBLY OFFSHORE WITHIN A PRE-FRONTAL BAND
OF STORMS PRIOR TO 12Z...WILL NOT INTRODUCE A SLIGHT RISK FOR THE
COASTAL CAROLINAS THIS FORECAST.

MODELS HINT THAT A SECONDARY AREA OF LOW-TOPPED/POST-FRONTAL STORMS
MAY DEVELOP DURING THE AFTERNOON OVER PORTIONS OF THE CAROLINAS...AS
DAYTIME HEATING WITHIN CLEAR SLOT OCCURS BENEATH -20C AIR AT H5
SPREADING ATOP THIS REGION. DEGREE OF INSTABILITY COULD SUPPORT A
FEW VIGOROUS UPDRAFTS CAPABLE OF PRODUCING MARGINAL HAIL. ANY
SEVERE THREAT LINGERING OVER THE CAROLINAS SHOULD END BY EARLY
EVENING.

..S FL...
COLD FRONT -- LYING NE-SW ACROSS NRN FL AT THE START OF THE PERIOD
PER LATEST NAM/GFS GUIDANCE -- SHOULD SWEEP RAPIDLY SEWD ACROSS THE
FL PENINSULA THROUGH THE DAY...CLEARING S FL/THE KEYS DURING THE
AFTERNOON. SWLY LOW-LEVEL FLOW ROUGHLY PARALLEL TO THE FRONT WOULD
YIELD LITTLE LOW-LEVEL CONVERGENCE...WHILE H5 TEMPERATURES GREATER
THAN -8C SUGGEST VERY WEAK LAPSE RATES/LITTLE POTENTIAL FOR
APPRECIABLE DESTABILIZATION. THEREFORE...WILL INTRODUCE ONLY 5%
SEVERE PROBABILITIES FOR THE FL PENINSULA THIS PERIOD.

.GOSS.. 04/13/2007

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