SWODY1
SPC AC 181548
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1048 AM CDT WED APR 18 2007
VALID 181630Z - 191200Z
..NO SVR TSTM AREAS FORECAST...
VERY STRONG UPPER TROUGH CURRENTLY OVER NV IS FORECAST TO ROTATE
EASTWARD ACROSS THE CENTRAL/NORTHERN ROCKIES TODAY.
MEANWHILE...RAPID SURFACE CYCLOGENESIS IS EXPECTED ACROSS PARTS OF
MT/WY...WITH LEE TROUGH EXTENDING SOUTHWARD INTO EASTERN CO. LARGE
SCALE FORCING THROUGHOUT THIS REGION...COMBINED WITH FAVORABLE
/ALBEIT RELATIVELY DRY/ THERMODYNAMIC PROFILES WILL FAVOR SCATTERED
THUNDERSTORMS CAPABLE OF GUSTY WINDS AND HAIL OVER MUCH OF WY/MT/CO
AND PARTS OF EASTERN UT.
..WESTERN WY/CO AND EASTERN UT...
MORNING SURFACE ANALYSIS SHOWS LOW NORTH OF SLC...WITH STRONG COLD
FRONT SURGING EASTWARD ACROSS WESTERN UT. THIS FRONT WILL PROGRESS
EASTWARD TODAY INTO WESTERN WY/CO. FORECAST SOUNDINGS OVER THIS
REGION SHOW STEEP LOW/MID LEVEL LAPSE RATES AND STRONG SOUTHWEST
FLOW THROUGH A DEEP LAYER. DEEP MIXING WILL YIELD STRONG GRADIENT
WINDS...WHICH WILL ONLY BE ENHANCED THIS AFTERNOON AS SCATTERED
THUNDERSTORMS DEVELOP NEAR THE FRONT. COLD TEMPERATURES ALOFT COULD
ALSO RESULT IN HAIL IN STRONGER STORMS.
..EASTERN CO/WY AND MUCH OF MT...
BY LATE THIS AFTERNOON...LEE TROUGH IS FORECAST TO EXTEND FROM MAIN
SYNOPTIC LOW OVER EASTERN MT INTO EASTERN WY/CO. STRONG
SOUTHEASTERLY LOW LEVEL WINDS OVER THE HIGH PLAINS OF MT/WY/CO WILL
MAINTAIN SURFACE DEWPOINTS GENERALLY IN THE 30S TO LOWER 40S...AS
WELL AS RESULT IN FAVORABLE CONVERGENCE AND SHEAR PROFILES FOR
ISOLATED THUNDERSTORM DEVELOPMENT. CONVECTION WILL LIKELY INITIATE
FIRST NEAR LOW OVER SOUTH CENTRAL MT...SPREADING NORTHWARD ACROSS MT
THROUGH THE EVENING. THESE STORMS WILL HAVE A RISK OF GUSTY WINDS
AND HAIL. OTHER MORE ISOLATED ACTIVITY IS ANTICIPATED ALONG THE LEE
TROUGH AS FAR SOUTH AS EAST-CENTRAL CO. THESE STORMS WILL BE WIDELY
SPACED...BUT COULD BE HIGH-BASED SUPERCELLS CAPABLE OF LOCALLY
DAMAGING WINDS AND HAIL AS WELL. OVERALL COVERAGE OF SEVERE STORMS
DOES NOT APPEAR TO WARRANT A SLIGHT RISK AT THIS TIME. HOWEVER...WE
WILL CONTINUE TO MONITOR FOR GREATER DESTABILIZATION THAN CURRENTLY
EXPECTED.
..OH VALLEY...
WEAK SURFACE LOW IS CURRENTLY NEAR SDF...WITH COLD FRONT EXTENDING
WESTWARD INTO SOUTHERN IL/SOUTHEAST MO. LOW CLOUDS ALONG/AHEAD OF
FRONT ACROSS THE LOWER OH AND TN VALLEYS ARE SLOWLY ERODING...WHICH
SHOULD ALLOW POCKETS OF DAYTIME HEATING AND DESTABILIZATION.
DEWPOINTS IN THE 40S TO NEAR 50F WILL YIELD AFTERNOON MLCAPE VALUES
UP TO 500 J/KG. MODEL GUIDANCE IS CONSISTENT IN THE DEVELOPMENT OF
SCATTERED THUNDERSTORMS OVER PARTS OF IND/KY THIS AFTERNOON...WHERE
THE STRONGEST STORMS COULD PRODUCE HAIL. ORGANIZED SEVERE STORMS
ARE NOT ANTICIPATED AT THIS TIME.
.HART/GUYER.. 04/18/2007
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