SWODY2
SPC AC 071730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SUN JUN 07 2009
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE MIDWEST TO
PORTIONS OF OK/AR...
...SYNOPSIS...
A BROAD UPPER TROUGH WILL REMAIN CENTERED OVER THE WESTERN CANADIAN
PROVINCES AND NORTHERN ROCKIES ON MONDAY...WHILE A LEAD SHORTWAVE
TROUGH...AMIDST A BROAD CYCLONIC UPPER FLOW REGIME...PIVOTS
NORTHEASTWARD OVER THE UPPER MIDWEST/WESTERN GREAT LAKES REGION.
PRIMARY COLD FRONT WILL DEVELOP EAST-SOUTHEASTWARD ACROSS THE
MIDWEST/MIDDLE MISSISSIPPI VALLEY...WHILE THE PLAINS PORTION OF THE
FRONT SLOWLY SLIPS SOUTHWARD AND STALLS ACROSS OK.
...MIDWEST TO THE SOUTHERN PLAINS...
SHOWERS AND TSTMS WILL LIKELY BE ONGOING ACROSS PORTIONS OF THE
MIDWEST/WESTERN GREAT LAKES VICINITY. MUCH OF MONDAYS DETAILS DEPEND
ON EARLY DAY CONVECTION/CLOUD COVER...BUT IT SEEMS PROBABLE THAT A
DIURNAL UPSWING IN DEEP CONVECTIVE COVERAGE/INTENSITY WILL OCCUR
MONDAY AFTERNOON ALONG/AHEAD OF THE EASTWARD ADVANCING COLD FRONT
AND/OR PREFRONTAL TROUGH.
THE PARENT UPPER SYSTEM WILL BEGIN TO SHIFT NORTHEASTWARD AWAY FROM
THE REGION MONDAY AFTERNOON...BUT MODERATELY STRONG WESTERLY FLOW
ALOFT AND A BROAD MOIST/POTENTIALLY UNSTABLE WARM SECTOR WILL
SUPPORT A SEVERE RISK ESPECIALLY ACROSS PORTIONS OF IL/MO/INDIANA
MONDAY AFTERNOON/EVENING. A MIXED MODE OF SOME INITIAL SUPERCELLS
WILL BE POSSIBLE...BUT OTHERWISE AN EVOLUTION TO MULTICELLULAR
CLUSTERS/SMALL BOWING COMPLEXES SEEMS LIKELY. SEVERE HAIL AND
DAMAGING WINDS WILL LIKELY THE PRIMARY HAZARDS. EVEN WITH A TENDENCY
FOR VEERING/WEAKENING LOW LEVEL FLOW...A FEW TORNADOES MAY BE
POSSIBLE MAINLY ACROSS PORTIONS OF IL/INDIANA...AND POTENTIALLY INTO
LOWER MI IN VICINITY OF NORTHWARD RETREATING WARM FRONT AND
APPROACHING SURFACE LOW. IN ADDITION TO LOWER MI...THE SEVERE THREAT
MAY REACH PORTIONS OF WESTERN/NORTHERN KY AND WESTERN OH MONDAY
NIGHT.
FARTHER SOUTHWEST IN VICINITY OF THE FRONT...THE COVERAGE OF TSTMS
IS EXPECTED TO BE MORE ISOLATED TO WIDELY SCATTERED MONDAY
AFTERNOON/EVENING WITH SOUTHWESTWARD EXTENT FROM THE OZARKS INTO
OK/NORTHERN AR. SUPPORT ON THE LARGE SCALE WILL BE MORE MARGINAL
ACROSS THE REGION VIA NEUTRAL TO SLIGHTLY RISING HEIGHTS.
NEVERTHELESS...FRONTAL FORCING AND STRONG HEATING /ESPECIALLY IN
VICINITY OF DRYLINE INTO OK/ SHOULD BE SUFFICIENT TO AT LEAST
LOCALLY ERODE THE CAP BY AROUND SUNSET. RELATIVELY STRONG MID/HIGHER
LEVEL FLOW...STEEP MID LEVEL LAPSE RATES AND 2000-3500 J/KG
MLCAPE...WOULD SUPPORT SOME SUPERCELLS WITH HAIL AS THE PRIMARY
RISK. A STRENGTHENING LOW LEVEL JET /AROUND 35-40 KT/ ACROSS
NORTHWEST TX/WESTERN OK MAY SUPPORT A CONTINUED HAIL THREAT ACROSS
OK/NORTHERN AR MONDAY NIGHT.
...UPPER OH VALLEY/PA VICINITY TO THE MID ATLANTIC REGION...
AS A WARM FRONT RETREATS NORTHWARD ACROSS THE REGION AND LOW LEVEL
MOISTURE INCREASES...ISOLATED TO SCATTERED TSTMS SHOULD
DEVELOP/DIURNALLY INCREASE MONDAY AFTERNOON...INITIALLY OVER PA AND
THE HIGHER TERRAIN OF ADJACENT WV/VA. ISOLATED DAMAGING WIND GUSTS
AND HAIL WILL BE POSSIBLE WITH THE STRONGER TSTMS.
...CENTRAL HIGH PLAINS...
BENEATH MODERATELY STRONG CYCLONIC UPPER LOW...MID/UPPER 40S F
SURFACE DEWPOINTS COMBINED WITH WEAK LOW LEVEL UPSLOPE AND
DIFFERENTIAL HEATING ALONG THE SOUTHEAST WY/NORTHEAST CO FRONT RANGE
WILL LIKELY RESULT IN ISOLATED TO SCATTERED TSTM DEVELOPMENT MONDAY
AFTERNOON. WITH MODEST BUOYANCY AND 40+ KT MID LEVEL FLOW...SOME
SUPERCELLS WITH LARGE HAIL WILL BE POSSIBLE. ONE OR MORE WEAKLY
ORGANIZED TSTM CLUSTERS SHOULD DEVELOP EASTWARD ACROSS THE REMAINDER
OF NORTHEAST CO AND WESTERN NEB/NORTHWEST KS MONDAY
EVENING/NIGHT...WITH THE SEVERE THREAT EXPECTED TO GRADUALLY
DIMINISH AFTER DARK.
..GUYER.. 06/07/2009
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