SWODY1
SPC AC 310503
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CDT MON AUG 31 2009
VALID 311200Z - 011200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODEST WESTERLIES WILL DOMINATE THE CONUS AMIDST A GRADUALLY
DEAMPLIFYING LONGWAVE PATTERN. REMNANT LONGWAVE TROUGH WILL PERSIST
OVER THE EASTERN CONUS...WITH SLOW MOVING SURFACE FRONTAL BOUNDARY
ALONG THE GULF COAST TO THE COASTAL CAROLINAS. IN THE WEST...UPPER
LOW OVER THE NORTHERN INTERMOUNTAIN WEST WILL LIKELY OPEN/SLOWLY
PROGRESS ENE TOWARD MT/NORTHERN WY ON THE NORTHERN PERIPHERY OF THE
SOUTHERN ROCKIES UPPER RIDGE.
...NORTHERN GREAT DIVIDE...
WITH A RELATIVELY MOIST AIRMASS IN PLACE...GENERAL EASTWARD
PROGRESSION OF OPENING UPPER LOW AND ASSOCIATED COLD POCKET ALOFT
/AROUND -12C AT 500 MB/ WILL RESULT IN STEEPENING MID LEVEL LAPSE
RATES DOWNSTREAM ACROSS MT/WY TODAY. TSTMS SHOULD DIURNALLY
INCREASE/DEVELOP EASTWARD OVER THE HIGHER TERRAIN THROUGH THE
DAY...WITH DEVELOPMENT POSSIBLE INTO THE EAST-CENTRAL/SOUTHEAST MT
PLAINS BY LATE THIS AFTERNOON/EARLY EVENING IN VICINITY OF LEE
TROUGH. STEEP LAPSE ENVIRONMENT WITH UP TO 500-1200 J/KG
MUCAPE...AND MODEST VERTICAL SHEAR /30 KT OR LESS/...MAY PROVE
SUFFICIENT FOR SOME STRONG/POTENTIALLY SEVERE TSTMS CAPABLE OF
HAIL/GUSTY WINDS ACROSS PORTIONS OF MT/NORTHERN WY THIS
AFTERNOON/EARLY EVENING.
...SOUTHEAST WY/CO/NM FRONT RANGE AND ADJACENT HIGH PLAINS...
OTHER ISOLATED TO SCATTERED TSTMS WILL BE POSSIBLE IN VICINITY OF
HIGHER TERRAIN/DEVELOPING LEE TROUGH FROM EASTERN WY TO EASTERN CO
AND NORTHEAST/EAST CENTRAL NM. SIMILAR TO THE PAST FEW DAYS...A FEW
OF THE STRONG STORMS DURING THE AFTERNOON/EARLY EVENING WILL BE
CAPABLE OF SEVERE HAIL/GUSTY WINDS...BUT OVERALL SEVERE POTENTIAL
WILL LIKELY REMAIN MARGINAL/ISOLATED IN NATURE. CAPPING ACROSS THE
PLAINS SHOULD AGAIN CONFINE THE SEVERE THREAT TO THE FRONT RANGE
AREAS/IMMEDIATELY ADJACENT HIGH PLAINS.
...FL/SOUTHEAST STATES...
LOW LATITUDE/SUBTROPICAL DISTURBANCE/S ALOFT...WITHIN THE BASE OF
THE WANING EASTERN STATES LONGWAVE TROUGH...SHOULD PROGRESS EASTWARD
ALONG THE EASTERN GULF COAST/NORTHERN FL THROUGH THE PERIOD.
SCATTERED TSTMS WILL LIKELY BE FOCUSED TODAY ALONG THE SOUTHWARD
SAGGING EFFECTIVE FRONTAL ZONE AND FL SEA BREEZE/S. ESPECIALLY ALONG
THE SURFACE FRONT...CLOUD COVER/MODEST LAPSE RATES WILL TEND TO
TEMPER OPPORTUNITIES FOR APPRECIABLE DESTABILIZATION AND OVERALL
STORM VIGOR...BUT A MOIST AIRMASS/MODERATE CYCLONIC WSW FLOW ALOFT
COULD YIELD A FEW MICROBURSTS MAINLY ACROSS FL/PERHAPS COASTAL GA
THIS AFTERNOON.
...SOUTHERN AZ...
WITH A SLIGHT EASTWARD SHIFT OF THE UPPER RIDGE AND GRADUAL
MOISTENING THROUGH THE PERIOD...TSTMS MAY CONTINUE TO BECOME A BIT
MORE COMMON OVER THE HIGHER TERRAIN OF AZ. SIMILAR TO THE 00Z/31
TUCSON OBSERVED RAOB...15-20 KT OF ESE STEERING FLOW ACROSS
SOUTHEAST AZ MAY SUPPORT SOME STRONGER WIND GUSTS DEVELOPING ONTO
THE DESERT FLOOR LATE THIS AFTERNOON/EARLY EVENING. HOWEVER...GIVEN
THE PROXIMITY OF THE UPPER RIDGE AND INITIALLY MODEST
MOISTURE...SEVERE PROBABILITIES DO NOT APPEAR TO BE WARRANTED AT
THIS TIME.
..GUYER/GARNER.. 08/31/2009
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