SPC AC 040650
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0150 AM CDT MON SEP 04 2006
VALID 061200Z - 071200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE-SCALE PATTERN WILL DEAMPLIFY THIS PERIOD AS ERN U.S. TROUGH
LIFTS NEWD ACROSS THE NORTHEASTERN CONUS. WEAKER CYCLONIC FLOW
ACROSS THE CENTRAL AND ERN CONUS IN THE WAKE OF THIS TROUGH COMBINED
WITH A WEAKENING WRN RIDGE SHOULD RESULT IN A FLATTER TROUGH
EXTENDING WWD ACROSS MUCH OF THE CONUS THROUGH THE LATTER HALF OF
THE PERIOD.
AT THE SURFACE...THE MAIN FEATURE OF INTEREST WILL BE THE FRONT OVER
THE ATLANTIC COAST STATES. THIS BOUNDARY SHOULD MOVE OFFSHORE
DURING THE PERIOD...THOUGH MODELS DIFFER WITH RESPECT TO TIMING OF
THIS FEATURE.
...CENTRAL AND SRN HIGH PLAINS...
MODELS SUGGEST THAT WIDESPREAD CONVECTION SHOULD DEVELOP ACROSS THE
HIGH PLAINS FROM THE NEB PANHANDLE SWD INTO ERN NM/TX PANHANDLE...AS
SHORT-WAVE TROUGH CROSSING THE ROCKIES MOVES SEWD IN NWLY FLOW
ALOFT.
DESPITE LIMITED LOW-LEVEL MOISTURE...STEEP LAPSE RATES ALOFT
COMBINED WITH DAYTIME HEATING SHOULD YIELD 500 TO 1000 J/KG
MEAN-LAYER CAPE...SUFFICIENT FOR A FEW STRONGER CONVECTIVE CELLS.
STORM INTENSITY MAY BE ASSISTED BY FAVORABLE SHEAR...RESULTING FROM
30 KT NWLY FLOW ALOFT BENEATH LOW-LEVEL SELYS. GIVEN ASSOCIATED
THREAT FOR HAIL AND LOCALLY STRONG WIND GUSTS...WILL INTRODUCE 5%
SEVERE THREAT ACROSS THIS REGION...WITH POTENTIAL UPGRADE TO SLIGHT
RISK POSSIBLE IN LATER FORECASTS.
...COASTAL CAROLINAS/SERN VA...
GFS AND NAM DIFFER CONSIDERABLY WITH REGARDS TO TIMING OF UPPER
TROUGH MOVING ACROSS THE OH VALLEY TOWARD NEW ENGLAND...AND
ASSOCIATED SURFACE BAROCLINIC ZONE OVER THE ATLANTIC COAST STATES.
THE FASTER GFS SHOWS THE SURFACE FRONT MOVING OFF THE ATLANTIC COAST
BY 06/12Z -- I.E. THE START OF THIS FORECAST PERIOD...WHILE THE NAM
SHOWS THIS FRONT LINGERING INLAND ACROSS THE CAROLINAS/VA THROUGH
07/06Z -- APPROXIMATELY 18 HOURS SLOWER.
NCEP SREF INDICATES A SURFACE FRONTAL PROGRESSION SIMILAR TO THAT OF
THE NAM. THEREFORE...WILL INCLUDE 5% SEVERE PROBABILITY ACROSS ERN
PORTIONS OF THE CAROLINAS INTO SERN VA...AS MOIST/MODESTLY-UNSTABLE
AIRMASS SHOULD EXIST AHEAD OF BOUNDARY WITH SHEAR SUFFICIENT FOR
ORGANIZED STORMS.
..GOSS.. 09/04/2006
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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