Saturday, August 28, 2010

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 280514
SWODY2
SPC AC 280513

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1213 AM CDT SAT AUG 28 2010

VALID 291200Z - 301200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
MODELS CONTINUE TO INDICATE THAT UPPER TROUGHING WILL REMAIN
AMPLIFIED ACROSS THE WESTERN U.S. THROUGH MUCH OF THIS FORECAST
PERIOD...BETWEEN STRONG SUBTROPICAL RIDGING ACROSS THE CENTRAL
PACIFIC AND EAST OF THE ROCKIES.

WITHIN THE EASTERN RIDGE...A HIGH CENTER IS STILL EXPECTED TO
STRENGTHEN ACROSS PARTS OF THE CENTRAL APPALACHIANS AND MID ATLANTIC
COAST STATES...BUT GUIDANCE SUGGESTS THAT AN UPPER IMPULSE EMERGING
FROM THE GULF OF MEXICO REGION WILL CONTINUE TO MIGRATE NORTHWARD
AROUND ITS SOUTHWESTERN/WESTERN PERIPHERY. THIS APPEARS LIKELY TO
BE ACCOMPANIED BY A RETURN OF VERY MOIST AIR THROUGH THE LOWER AND
MIDDLE MISSISSIPPI VALLEY...AND PORTIONS OF THE TENNESSEE AND LOWER
OHIO VALLEYS... ALONG WITH CONSIDERABLE...THOUGH MOSTLY
DIURNAL...THUNDERSTORM ACTIVITY.

ACROSS THE WEST...SUBSTANTIAL SPREAD EXISTS AMONG THE MODEL DATA
CONCERNING SHORT WAVE DEVELOPMENTS WITHIN THE BROADER SCALE
TROUGH...INCLUDING THE TIMING AND MANNER IN WHICH ONE IMPULSE BEGINS
TO PROGRESS THROUGH ITS BASE...ACROSS THE GREAT BASIN AND SOUTHERN
PLATEAU LATE SUNDAY AND SUNDAY NIGHT. HOWEVER...LATEST
GUIDANCE...THE SREF IN PARTICULAR...APPEARS A BIT FASTER WITH
LOW-LEVEL DRYING ACROSS EASTERN PORTIONS OF THE GREAT BASIN.
COUPLED WITH WEAK LOW-LEVEL MOISTURE RETURN AND SUBSTANTIAL
MID-LEVEL INHIBITION NEAR THE PLAINS SURFACE TROUGH AND STALLED
NORTHERN PLAINS FRONT...THUNDERSTORM PROBABILITIES MAY BE MOSTLY
NEAR MINIMUM THRESHOLD WITHIN SIZABLE GENERAL THUNDERSTORM RISK AREA
CURRENTLY OUTLOOKED.

...EASTERN GREAT BASIN/SOUTHERN PLATEAU...
IT STILL DOES NOT APPEAR OUT OF THE QUESTION THAT RESIDUAL
MOISTURE...IN CONJUNCTION WITH STRONG SURFACE HEATING AND FAVORABLE
OROGRAPHIC AND LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION WILL
CONTRIBUTE TO SUFFICIENT DESTABILIZATION FOR AT LEAST WIDELY
SCATTERED THUNDERSTORMS SUNDAY AFTERNOON. IF THIS OCCURS...STRONG
VERTICAL SHEAR AND MOMENTUM ASSOCIATED WITH 30-50+ KT SOUTHWESTERLY
LOWER/MID TROPOSPHERIC FLOW WILL CONTRIBUTE TO POTENTIAL FOR SEVERE
STORMS...WITH AT LEAST THE THREAT FOR LOCALLY DAMAGING WIND GUSTS.

..KERR.. 08/28/2010

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