Sunday, August 30, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 300558
SWODY1
SPC AC 300557

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT SUN AUG 30 2009

VALID 301200Z - 311200Z

...NO SVR TSTM AREAS FORECAST...

...PORTIONS OF ID/MT/WY...
CLOSED UPPER LOW WILL CONTINUE TO SLOWLY MIGRATE EAST-SOUTHEASTWARD
OVER ORE TO SOUTHERN ID TODAY AND TONIGHT. EVEN WITH MODEST HEATING
DOWNSTREAM OF THIS UPPER LOW...AMPLE LARGE SCALE FORCING FOR
ASCENT/UPPER JET EXIT REGION AMIDST STRONG DIFFLUENCE SHOULD FAVOR A
DIURNAL UPSWING IN TSTMS ESPECIALLY OVER THE HIGHER TERRAIN THIS
AFTERNOON. RELATIVELY HIGH PW ENVIRONMENT AND COOL THERMAL PROFILES
ALOFT /AROUND -14C AT 500 MB/ WILL CONTRIBUTE TO SUFFICIENT
DESTABILIZATION /500-1000 J PER KG MUCAPE/ BY AFTERNOON FOR SOME
STRONG/SEVERE TSTMS ACROSS PORTIONS OF CENTRAL/SOUTHERN ID AND
ADJACENT SOUTHWEST MT/NORTHWEST WY. MODERATELY STRONG/BUT LARGELY
UNIDIRECTIONAL DEEP LAYER FLOW ON THE EASTERN PERIPHERY OF THE UPPER
LOW WILL FAVOR SOME RELATIVELY WELL-ORGANIZED STORMS /PERHAPS SOME
WITH BOUTS OF MID LEVEL ROTATION/ CAPABLE OF SEVERE HAIL AND GUSTY
WINDS THIS AFTERNOON/EARLY EVENING.

...EASTERN CO/NORTHEAST NM...
BENEATH A RESIDUAL BELT OF MODERATE /25 KT/ NORTHWESTERLY FLOW
ALOFT...SLOW EASTWARD SHIFT OF THE PLAINS SURFACE RIDGE WILL
MAINTAIN RELATIVELY MOIST SOUTHEASTERLY LOW LEVEL TRAJECTORIES
ACROSS THE FRONT RANGE/ADJACENT HIGH PLAINS. WITH TSTMS EXPECTED TO
INITIALLY DEVELOP OVER THE HIGHER TERRAIN THIS AFTERNOON...STRONGLY
VEERED WIND PROFILES WITH AROUND 35 KT OF EFFECTIVE BULK
SHEAR...BENEATH RELATIVELY COOL MID LEVEL TEMPERATURES /-10C AT 500
MB/...WILL FAVOR A SOME MULTICELL/BRIEF SUPERCELLULAR STORMS CAPABLE
OF SEVERE HAIL THIS AFTERNOON/EARLY EVENING. TENDENCY FOR CAPPING
ACROSS THE PLAINS AND GENERAL SOUTHERLY STORM MOTIONS SHOULD CONFINE
THE PRIMARY SEVERE THREAT TO THE CO/NM FRONT RANGE AND IMMEDIATE LEE
/50-100 NM/ OF THE HIGHER TERRAIN.

...CENTRAL/EASTERN GULF COAST STATES TO CAROLINAS...
AS LONGWAVE TROUGH/BROAD CYCLONIC FLOW PERSISTS OVER THE EASTERN
CONUS...SOUTHWEST-NORTHEAST ORIENTED FRONTAL ZONE FROM THE
EAST-CENTRAL GULF COAST STATES TO THE CAROLINAS WILL BE THE PRIMARY
FOCUS FOR SHOWER/TSTM DEVELOPMENT THROUGH THE PERIOD...AIDED BY
LARGE SCALE LIFT VIA UPPER JET ENTRANCE REGION AND/OR A MID LEVEL
DISTURBANCE CROSSING THE GULF COAST STATES. WHILE AN
ORGANIZED/APPRECIABLE SEVERE RISK IS NOT EXPECTED OWING TO LIMITED
LAPSE RATES/BUOYANCY AND/OR MODEST SHEAR...SOME OF THE STRONGER
STORMS WILL BE CAPABLE OF DOWNBURSTS MAINLY THIS AFTERNOON/EARLY
EVENING.

..GUYER/GARNER.. 08/30/2009

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