SPC AC 290700
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0200 AM CDT FRI AUG 29 2008
VALID 311200Z - 011200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
HIGHLY AMPLIFIED/MERIDIONAL LONGWAVE PATTERN WILL DOMINATE THE CONUS
ON SUNDAY. THIS WILL BE HIGHLIGHTED BY A DEEP TROUGH OVER THE
WESTERN STATES. SURFACE LOW WILL SHIFT EASTWARD OVER THE
DAKOTAS...WITH A COLD FRONT FROM THE NORTHERN PLAINS TO THE GREAT
BASIN SERVING AS A FOCUS FOR TSTM DEVELOPMENT. IN THE EAST...A
LONGWAVE RIDGE WILL DOMINATE THE EASTERN HALF OF THE CONUS/CANADA.
EXPANSIVE SURFACE HIGH PRESSURE WILL ENCOMPASS THE GREAT LAKES
REGION AS A RESIDUAL FRONTAL BOUNDARY SHIFTS SLOWLY SOUTHWARD ACROSS
THE GULF COAST/SOUTHEAST STATES.
...NORTHERN PLAINS...
LARGELY PARALLEL TO DEEP LAYER SOUTHWESTERLY FLOW...SURFACE LOW AND
ATTENDANT COLD FRONT WILL SLOWLY SHIFT EASTWARD ACROSS THE DAKOTAS
ON SUNDAY. AIDED BY A SHORTWAVE TROUGH SPREADING NORTHEASTWARD OVER
PORTIONS OF WY/MT...IT WOULD SEEM LIKELY THAT SCATTERED TSTMS WILL
DEVELOP/INCREASE SUNDAY AFTERNOON/EVENING ALONG AND NORTHWEST OF THE
SURFACE FRONT ACROSS THE DAKOTAS. WITH BOUNDARY LAYER MOISTURE
HAVING INCREASED DURING THE DAY-2 PERIOD...POTENTIAL FOR MODERATE
INSTABILITY JUXTAPOSED WITH MODERATELY STRONG FLOW ALOFT WILL
SUPPORT SOME WELL-ORGANIZED TSTMS /INCLUDING SUPERCELLS/ WITH A RISK
OF SEVERE HAIL/WIND. PORTIONS OF THE REGION MAY WARRANT A
CATEGORICAL SLIGHT RISK IN SUBSEQUENT OUTLOOKS.
...EASTERN GREAT BASIN/UT VICINITY...
DEEPENING WESTERN STATES UPPER TROUGH/INCREASING LARGE SCALE FORCING
FOR ASCENT WILL LEAD TO A NUMBER OF POTENTIALLY STRONG/RELATIVELY
LOW-TOPPED TSTMS ON SUNDAY ALONG/AHEAD OF AN EAST-ADVANCING COLD
FRONT. INCREASING WIND FIELDS ALOFT AND STEEPENING LAPSE RATES WILL
RESULT IN A RISK OF SEVERE HAIL/WIND WITH THE STRONGEST
TSTMS...ESPECIALLY SUNDAY AFTERNOON/EVENING ACROSS FAR EASTERN NV
AND UT.
...CENTRAL GULF COAST STATES...
LATEST NHC FORECASTS SUGGEST GUSTAV WILL STRENGTHEN AND MOVE INTO
THE CENTRAL GULF OF MEXICO AS A HURRICANE ON SUNDAY -- REFERENCE
LATEST NHC GUIDANCE FOR DETAILS. ON THE NORTHERN PERIPHERY OF
GUSTAV...THERE IS AT LEAST SOME POSSIBILITY THAT LOW LEVEL FLOW
FIELDS COULD STRENGTHEN SUFFICIENTLY LATE SUNDAY NIGHT FOR AN
ISOLATED TORNADO RISK ACROSS THE CENTRAL GULF COAST REGION. BUT
GIVEN THE EXPECTED LATE DAY-3 TIMING AND INHERENT TRACK
UNCERTAINTIES...WILL NOT INCLUDE ANY TORNADO PROBABILITIES AT THIS
TIME.
..GUYER.. 08/29/2008
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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