SWODY1
SPC AC 010545
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1245 AM CDT TUE SEP 01 2009
VALID 011200Z - 021200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
WEAK WESTERLIES WILL CONTINUE TO PREVAIL WITHIN A RELATIVELY
AMPLIFIED LARGE SCALE FLOW REGIME. SOUTHEAST STATES FRONTAL ZONE
WILL CONTINUE TO SHIFT SOUTHWARD ACROSS NORTHERN FL/NORTHERN GULF OF
MEXICO...WITH COOL/STABLE CONDITIONS DOMINATING MUCH OF THE EAST
WITH BROAD SURFACE HIGH PRESSURE CENTERED ACROSS THE GREAT LAKES
REGION. DETACHED FROM APPRECIABLE WESTERLIES...REMNANT UPPER LOW
WILL CONTINUE TO MIGRATE EASTWARD OVER THE NORTHERN HIGH PLAINS...AS
A BROAD UPPER RIDGE OTHERWISE REMAINS CENTERED OVER THE SOUTHERN
ROCKIES.
...HIGH PLAINS...
AS UPPER LOW SHIFTS EASTWARD OVER EASTERN MT TOWARD THE WESTERN
DAKOTAS...RESIDUAL COOL POCKET ALOFT WILL CONTRIBUTE TO STEEPENING
MID LEVEL LAPSE RATES ACROSS THE NORTHERN HIGH PLAINS...WHILE
HEIGHTS MODESTLY RISE OVER THE SOUTH CENTRAL HIGH PLAINS. ACROSS THE
NORTHERN HIGH PLAINS...TSTMS SHOULD INCREASE THROUGH THE AFTERNOON
IN VICINITY OF LEE SIDE SURFACE FRONT/TROUGH AND MOISTURE AXIS
ACROSS EASTERN MT/NORTHEAST WY AND THE ADJACENT WESTERN DAKOTAS. A
STEEP LAPSE RATE ENVIRONMENT WITH MODEST BUOYANCY /500-1000 J PER KG
MUCAPE/ MAY BE SUFFICIENT FOR SOME TSTMS TO PRODUCE HAIL TO SEVERE
LEVELS AMIDST A WEAKLY SHEARED REGIME AHEAD OF THE UPPER LOW.
FARTHER SOUTH...OTHER POTENTIALLY STRONG/SEVERE TSTMS WILL LIKELY
AGAIN DEVELOP ACROSS THE FRONT RANGE/ADJACENT HIGH PLAINS OF
SOUTHEAST CO/NORTHEAST NM BY LATE AFTERNOON/EARLY EVENING. MODEST
MOISTURE/BUOYANCY AND STRONGLY VEERED LOW TO MID TROPOSPHERIC WINDS
/30-35 KT EFFECTIVE BULK SHEAR/ WILL SUPPORT MULTICELLULAR STORMS
CAPABLE OF SEVERE HAIL/GUSTY WINDS THROUGH EARLY EVENING.
...CENTRAL/SOUTHERN FL PENINSULA...
A MODESTLY AMPLIFYING UPPER TROUGH AXIS AND PERHAPS ONE OR MORE
EMBEDDED SUBTROPICAL DISTURBANCES WILL CONTINUE TO DEVELOP EASTWARD
OVER THE EASTERN GULF TODAY...WITH A CONTINUED GULF MOISTURE INFLUX
ACROSS THE FL PENINSULA. SHOWERS/TSTMS WILL CONTINUE TO BE COMMON
ALONG THE FAR NORTHERN FL FRONTAL ZONE...WITH OTHER TSTMS LIKELY
FARTHER SOUTH IN VICINITY OF SEA BREEZE/S WITH PROSPECTS FOR
SOMEWHAT GREATER DESTABILIZATION ACROSS THE SOUTHERN FL PENINSULA.
WHILE CLOUD COVER MAY TEND TO TEMPER HEATING...AND MID LEVEL LAPSE
RATES/MODEST VERTICAL SHEAR ARE LIMITING FACTORS...A FEW OF THE
STRONGER STORMS MAY BE CAPABLE OF DOWNBURSTS/PERHAPS PULSE HAIL ON
AN ISOLATED BASIS THIS AFTERNOON.
...SOUTHERN AZ...
WHILE DETAILS ARE A BIT UNCLEAR...IT SEEMS THAT MOISTURE MAY
GRADUALLY INCREASE INTO SOUTHERN AZ THROUGH THE PERIOD...ESPECIALLY
SOUTHWEST AZ/LOWER CO RIVER VALLEY...OWING TO CONVECTION OVER
NORTHWEST MEXICO AND THE GRADUAL APPROACH OF HURRICANE JIMENA TOWARD
BAJA /PER LATEST NHC GUIDANCE/. AS THE PERSISTENT UPPER RIDGE
REMAINS CENTERED NEAR THE FOUR CORNERS AREA...15-20 KT ESE STEERING
FLOW SAMPLED BY 00Z/SEP 1 OBSERVED RAOBS FROM TUCSON/PHOENIX SEEMS
LIKELY TO PERSIST THROUGH THE DAY. AS SUCH...IT SEEMS PROBABLE THAT
SOME OF THE STRONGER STORMS WILL BE CAPABLE OF GUSTY OUTFLOW
WINDS/BLOWING DUST AS THEY DEVELOP ACROSS/ONTO THE DESERT FLOOR LATE
THIS AFTERNOON/EVENING.
..GUYER/GARNER.. 09/01/2009
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