SWODY2
SPC AC 061731
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT THU MAY 06 2010
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE OH RIVER
VALLEY TO LOWER GREAT LAKES...
...SYNOPSIS...
PROGRESSIVE/MODERATELY STRONG AND RELATIVELY LOW AMPLITUDE
WESTERLIES WILL PREVAIL OVER THE CONUS INTO FRIDAY. A SHORTWAVE
TROUGH CURRENTLY OVER THE NORTHERN HIGH PLAINS WILL ADVANCE EASTWARD
FROM THE NORTH-CENTRAL PLAINS/UPPER MIDWEST EARLY FRIDAY TO THE
GREAT LAKES VICINITY FRIDAY NIGHT. ASSOCIATED SURFACE CYCLONE IS
EXPECTED TO GRADUALLY DEEPEN EAST-NORTHEASTWARD ACROSS THE MIDDLE MS
RIVER VALLEY/MIDWEST ON FRIDAY...TO THE LOWER GREAT LAKES VICINITY
FRIDAY NIGHT. MEANWHILE...A WARM FRONT WILL RETREAT NORTHWARD ACROSS
THE MID ATLANTIC STATES/UPPER OH VALLEY AHEAD OF A COLD FRONT
STEADILY ADVANCING EAST-SOUTHEASTWARD ACROSS THE OH/TN RIVER VALLEYS
AND MID-SOUTH/ARKLATEX.
...OH VALLEY/LOWER GREAT LAKES TO APPALACHIANS...
TSTM CLUSTERS PERHAPS WITH SOME SEVERE POTENTIAL SHOULD BE ONGOING
FRIDAY MORNING ACROSS THE MIDDLE MS RIVER VALLEY VICINITY/ADJACENT
MIDWEST. ON THE SOUTHERN FRINGE OF THIS ACTIVITY...A MORE
APPRECIABLE SEVERE RISK SHOULD EVOLVE DURING THE AFTERNOON ACROSS
MUCH OF THE OH VALLEY VICINITY. STRONG EARLY DAY SOUTHWESTERLY
MOISTURE TRANSPORT WILL AID IN A QUICK INFLUX OF UPPER 50S/LOWER 60S
F SURFACE DEWPOINTS INTO A PRE-COLD FRONTAL WARM SECTOR ACROSS THE
OHIO VALLEY. STRONG BOUNDARY LAYER HEATING WITH 70S/SOME 80S F
SURFACE TEMPERATURES BY EARLY/MID AFTERNOON WILL CONTRIBUTE TO A
MODERATELY UNSTABLE/WEAKLY CAPPED WARM SECTOR AIRMASS...WITH
INCREASING TSTM COVERAGE DURING THE AFTERNOON GIVEN THE APPROACH OF
THE UPSTREAM POTENT/COMPACT SHORTWAVE TROUGH AND AN INTENSIFYING
MID/UPPER JET.
COUPLED WITH THE POSSIBILITY OF MLCAPE OF 1000-2000 J/KG ACROSS THE
WARM SECTOR...VERY STRONG/MODESTLY VEERING WIND FIELDS WILL FAVOR
BOTH SUPERCELLS AND BOWING STRUCTURES...WITH LIKELY A TREND TOWARD
UPSCALE GROWTH AND ONE OR MORE FAST-MOVING LINEAR CONVECTIVE SYSTEMS
BY LATE AFTERNOON/EARLY EVENING. WITH 40-50 KT SOUTHWESTERLY FLOW
EXPECTED AROUND 1 KM...THE RELATIVELY GREATEST TORNADO THREAT MAY BE
NEAR/JUST SOUTHEAST OF THE GRADUALLY DEEPENING SURFACE LOW TRACK
ACROSS INDIANA INTO OH...WHERE ISALLOBARICALLY BACKED WINDS WILL
ENHANCE LOW LEVEL SHEAR/HODOGRAPH CURVATURE. OTHERWISE...CORRIDORS
OF WIND DAMAGE/HAIL ARE EXPECTED. AN ISOLATED SEVERE RISK MAY EXIST
AS FAR EAST AS PORTIONS OF NY/EASTERN PA TO SOUTHERN NEW ENGLAND
FRIDAY NIGHT.
...MID-SOUTH/ARKLATEX...
HAVE SPATIALLY EXTENDED TSTM POTENTIAL/CONDITIONAL SEVERE RISK
SOUTHWESTWARD ACROSS THE MID-SOUTH/ARKLATEX ALONG EXPECTED COLD
FRONTAL POSITION NEAR/JUST AFTER PEAK HEATING. IN SPITE OF POTENTIAL
FOR STRONG CAPPING/WARM LAYER NEAR 700 MB AS REFLECTED BY 12Z
NAM/GFS FORECAST SOUNDINGS...AND LITTLE IN THE WAY OF LARGE SCALE
FORCING FOR ASCENT...ASSORTMENT OF NUMERICAL GUIDANCE...INCLUDING
MULTI-FACETED SREF MEMBERS AND 12Z NAM/GFS...IMPLY POTENTIAL FOR AT
LEAST ISOLATED TSTM DEVELOPMENT BY LATE AFTERNOON/EARLY EVENING.
PROVIDED TSTM DEVELOPMENT...AMPLE MOISTURE/STRONG INSTABILITY
COUPLED WITH 30-40 KT WEST-SOUTHWEST MID LEVEL FLOW WOULD SUPPORT
SOME SUSTAINED STORMS CAPABLE OF SEVERE HAIL/WIND.
...FL PENINSULA...
EASTWARD SHIFTING UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE A
BIT MORE PREVALENT ON FRIDAY AS COMPARED TO TODAY. HOWEVER...A
RESIDUAL MOIST AIRMASS /LOWER 70S F SURFACE DEWPOINTS/ AND
SUFFICIENTLY COOL TEMPERATURES ALOFT/STEEP LAPSE RATES MAY YIELD A
FEW STRONG-SEVERE DOWNBURSTS AND SOME HAIL FRIDAY AFTERNOON IN
VICINITY OF THE EAST COAST SEA BREEZE.
..GUYER.. 05/06/2010
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