SWODY3
SPC AC 270728
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT FRI AUG 27 2010
VALID 291200Z - 301200Z
...SYNOPSIS...
MODELS INDICATE THAT SUBTROPICAL RIDGING WILL REMAIN STRONG ACROSS
MUCH OF THE CENTRAL PACIFIC...AND EAST OF THE ROCKIES...WITH A
STRENGTHENING HIGH CENTER OVER THE CENTRAL APPALACHIANS AND MID
ATLANTIC COAST REGION DURING THIS PERIOD. IN BETWEEN...UPPER
TROUGHING APPEARS LIKELY TO REMAIN AMPLIFIED THROUGH AT LEAST EARLY
MONDAY. AFTER BOTTOMING OUT OVER THE GREAT BASIN/COLORADO
VALLEY...A SIGNIFICANT EMBEDDED SHORT WAVE IMPULSE MAY BEGIN LIFTING
NORTHEASTWARD VERY LATE IN THE PERIOD...AS A SERIES OF UPSTREAM
SHORT WAVE IMPULSES/MID AND UPPER SPEED MAXIMA PROGRESS AROUND THE
NORTHERN PERIPHERY OF THE PACIFIC RIDGE INTO THE BRITISH
COLUMBIA/PACIFIC NORTHWEST COAST.
IN RESPONSE TO THE EVOLVING PATTERN...NCEP SREF GUIDANCE SUGGESTS
THAT VERY MOIST BOUNDARY LAYER AIR LINGERING OVER THE GULF COAST
REGION MAY CONTINUE SLOWLY RETURNING NORTHWARD THROUGH PARTS OF THE
SOUTHERN PLAINS AND OZARK PLATEAU. BUT MOISTENING IS LIKELY TO
REMAIN MORE MODEST NORTHWARD ALONG AND EAST OF THE PLAINS SURFACE
TROUGH...AND NEAR A LINGERING STALLED FRONTAL ZONE ACROSS THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY. MEANWHILE... GRADUAL
DRYING WILL CONTINUE BENEATH WEST SOUTHWESTERLY MID/UPPER FLOW
ACROSS THE EASTERN GREAT BASIN AND SOUTHERN PLATEAU INTO THE CENTRAL
AND SOUTHERN ROCKIES.
...GREAT BASIN/ROCKIES...
RESIDUAL LOW-LEVEL MOISTURE IN THE PRESENCE OF STEEP LAPSE RATES
SHOULD REMAIN SUFFICIENT FOR AT LEAST WEAK...TO PERHAPS POCKETS OF
MODERATE...DESTABILIZATION WITH DAYTIME HEATING. COUPLED WITH
MOMENTUM AND SHEAR NEAR A BELT OF 40-50+ KT CYCLONIC 500 MB FLOW
...THE ENVIRONMENT IS EXPECTED TO BE FAVORABLE FOR THE DEVELOPMENT
OF SEVERE STORMS. IT NOT YET CLEAR THAT COVERAGE WILL BE SUPPORTIVE
OF SLIGHT RISK PROBABILITIES...BUT STRONG MID-LEVEL FORCING FOR
UPWARD VERTICAL MOTION EXPECTED TO SPREAD ACROSS EASTERN UTAH COULD
AID DEVELOPMENT LATE SUNDAY AFTERNOON AND EVENING.
...NORTHERN HIGH PLAINS...
MOISTENING NORTHEASTERLY UPSLOPE FLOW COUPLED WITH FORCING
DOWNSTREAM OF THE GREAT BASIN TROUGH COULD CONTRIBUTE TO SUFFICIENT
DESTABILIZATION FOR A COUPLE OF STRONG/SEVERE STORMS SUNDAY
AFTERNOON AND EVENING. BENEATH MODERATE TO STRONG SOUTHWESTERLY
MID/UPPER FLOW...AN ISOLATED SUPERCELL OR TWO MAY NOT BE OUT OF THE
QUESTION IN THE PRESENCE OF STRONG VERTICAL SHEAR.
..KERR.. 08/27/2010
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