SWODY1
SPC AC 031619
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CDT THU JUN 03 2010
VALID 031630Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN NEW ENGLAND SWWD INTO
THE LOWER OH/TN VALLEYS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN AND
CENTRAL PLAINS...
...SRN NEW ENGLAND SWWD INTO NJ...
AT MID MORNING...WEAK SURFACE LOW WAS LOCATED OVER NRN VT...WITH
TRAILING COLD FRONT EXTENDING SWD TO WEST OF NJ. THE COMBINATION OF
MOIST BOUNDARY LAYER AND MORNING SUNSHINE WAS ALREADY RESULTING IN
MODERATE INSTABILITY...WITH MLCAPES EXPECTED TO RANGE FROM 1500-2000
J/KG WITH ADDITIONAL HEATING. DESPITE NO REAL EVIDENCE OF AN
UPSTREAM UPPER IMPULSE...CONVERGENCE ALONG BOUNDARY IN WEAKLY CAPPED
ENVIRONMENT SHOULD AID THUNDERSTORMS FORMING ALONG/EAST OF FRONT
THIS AFTERNOON. THE COMBINATION OF EFFECTIVE SHEAR AT 35 KT AND
DEGREE OF INSTABILITY MAY SUPPORT ORGANIZED MULTICELL STORMS ALONG
WITH ISOLATED SUPERCELLS. UNIDIRECTIONAL WLY WINDS...ABOVE THE
BOUNDARY LAYER...AND MODERATELY STEEP LOW/MID LAPSE RATES WILL
SUPPORT STORMS CAPABLE OF DAMAGING WINDS AND HAIL.
...DELMARVA WWD ACROSS THE SRN LOWER OH AND TN VALLEYS...
SEVERAL FEATURES SHOULD AID IN SCATTERED TO NUMEROUS THUNDERSTORMS
DEVELOPING ACROSS THE REGION THROUGH THE AFTERNOON HOURS. FIRST
FEATURE IS REMNANT MCV...CURRENTLY APPROACHING WRN PA. CURRENT
MOTION/EXTRAPOLATION PLACES THIS FEATURE INTO S CENTRAL PA/MD
PANHANDLE BY MID AFTERNOON. WEAK CONVECTION HAS ALREADY DEVELOPED
AHEAD OF THIS SYSTEM OVER WV...AND SHOULD INTENSIFY AS MOVES INTO
VA/MD PANHANDLE/SRN PA THIS AFTERNOON... REFERENCE MESOSCALE
DISCUSSION 784.
FURTHER WEST...ANOTHER WEAK SURFACE LOW WAS LOCATED IN FAR NWRN
OH...WITH A SURFACE TROUGH EXTENDING WSWWD INTO CENTRAL MO. THIS
TROUGH WILL MOVE SLOWLY SWD AND CONVERGENCE WILL BE ENHANCED AHEAD
OF IT AS AN UPPER THERMAL TROUGH SHIFTS EWD ACROSS THE TN/OH
VALLEYS. DEEP LAYER SHEAR AT 20-30 KT WILL BE SUFFICIENT FOR
SUSTAINED MULTICELL STORMS...AND IN CONJUNCTION WITH MODERATE
INSTABILITY...SEVERE HAIL AND DAMAGING WINDS WILL BE POSSIBLE DURING
THE AFTERNOON/EARLY EVENING HOURS.
...NRN/CENTRAL PLAINS...
WATER VAPOR LOOPS AND MORNING ANALYSIS SHOWS A FAST MOVING UPPER
TROUGH MOVING INTO THE NRN ROCKIES...AND IS FORECAST TO BE LOCATED
IN ERN MT/WY BY 04/00Z. SURFACE LOW WAS ALREADY DEVELOPING NEAR THE
SD/WY BORDER AND IS EXPECTED TO ADVANCE EWD INTO CENTRAL SD BY
00Z...WITH SURFACE TROUGH EXTENDING SWWD INTO NERN CO. EVEN THOUGH
HIGH CLOUDS HAVE COVERED MUCH OF THE SLIGHT RISK REGION THIS
MORNING...THESE CLOUDS WILL THIN AND AID IN WARMING TEMPERATURES
INTO THE 80S. DEWPOINTS CURRENTLY IN THE LOWER TO MID 50S WILL RISE
TO NEAR 60F AS SLY WINDS STRENGTHEN THROUGH THE DAY. THUNDERSTORMS
ARE EXPECTED TO DEVELOP NEAR THE LOW/SURFACE TROUGH BETWEEN 21-00Z
AND THEN SHIFT EWD THROUGH THE EVENING HOURS. EFFECTIVE SHEAR VALUES
OF 35-45 KNOTS...ALONG WITH MODERATE INSTABILITY AND STEEP MID LEVEL
LAPSE RATES...FAVOR
SUPERCELL STORMS WITH LARGE HAIL AND DAMAGING WINDS. HOWEVER...
STRONG DIRECTIONAL AND SPEED SHEAR IN THE LOWER 1-2 KM INDICATES
TORNADOES ARE ALSO POSSIBLE...ESPECIALLY ACROSS PORTIONS OF
CENTRAL/ERN SD AND NEB.
..IMY/KERR.. 06/03/2010
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