SWODY2
SPC AC 041731
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT FRI JUN 04 2010
VALID 051200Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
PLAINS...UPPER-MIDWEST AND OH VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
MID-ATLANTIC AND NEW ENGLAND...
...OH VALLEY/MID-MO VALLEY/CNTRL PLAINS...
A ZONAL FLOW PATTERN WILL BE IN PLACE ACROSS THE NRN STATES SATURDAY
WITH SEVERAL EMBEDDED IMPULSES. MODEL FORECASTS MOVE A SUBTLE
SHORTWAVE TROUGH AND ASSOCIATED LOW-LEVEL JET EWD ACROSS MID-MO
VALLEY SATURDAY MORNING AND INTO THE OH VALLEY BY AFTERNOON.
THUNDERSTORMS SHOULD BE ONGOING AT 12Z SATURDAY ON THE NOSE OF THE
LOW-LEVEL JET ACROSS IA WITH SCATTERED CONVECTION POSSIBLE NEAR A
SLOW MOVING FRONT ACROSS NRN IL...NRN IND AND NRN OH. ALONG AND
SOUTH OF THE FRONT...SFC DEWPOINTS AROUND 70 F AND SFC HEATING
SHOULD RESULT IN A BROAD CORRIDOR OF MODERATE TO STRONG INSTABILITY
BY MIDDAY. IN ADDITION...ETA-KF FORECAST SOUNDINGS SHOW 0-6 KM SHEAR
IN THE 40 TO 55 KT RANGE ALONG THIS CORRIDOR SUGGESTING THE SEVERE
THREAT WILL INCREASE AS SFC TEMPS WARM DURING THE DAY. INITIALLY...A
POTENTIAL FOR SUPERCELLS WITH LARGE HAIL SHOULD EXIST IN SRN IA AND
NW IL WHERE MLCAPE VALUES ARE FORECAST TO BE IN THE 3000 TO 4000 /KG
RANGE WITH STRONG DEEP LAYER SHEAR ENHANCED BY AN APPROACHING 65 TO
80 KT MID-LEVEL JET. THE SUPERCELL THREAT SHOULD DEVELOP EWD AND
CONTINUE THROUGH THE AFTERNOON INTO THE EARLY EVENING AS THE
SHORTWAVE TROUGH MOVES EWD ACROSS THE OH VALLEY. TORNADOES WILL BE
POSSIBLE WITH THE MORE DOMINANT SUPERCELLS ESPECIALLY IN NRN
IL...NCNTRL IND AND WRN OH AS THE LOW-LEVEL JET MOVES ACROSS THE
REGION LATE SATURDAY AFTERNOON. AN ENHANCED WIND DAMAGE THREAT MAY
ALSO DEVELOP IF A COLD POOL CAN ORGANIZE ALONG THE INSTABILITY
GRADIENT. AN ISOLATED STRONG TORNADO AND VERY STRONG WIND GUSTS WILL
BE POSSIBLE.
ALTHOUGH THUNDERSTORM DEVELOPMENT SHOULD BE MORE ISOLATED ACROSS SRN
MO AND NE KS...ETA-KF FORECAST SOUNDINGS DO SHOW STRONG
INSTABILITY...STEEP MID-LEVEL LAPSE RATES AND MODERATE DEEP LAYER
SHEAR. THIS SUGGESTS A POTENTIAL FOR LARGE HAIL AND ISOLATED WIND
DAMAGE WILL EXIST WITH ANY STORMS THAT CAN INITIATE DURING THE LATE
AFTERNOON AND EARLY EVENING.
...MID-ATLANTIC/NEW ENGLAND...
A SUBTLE UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE NERN
STATES SATURDAY. ON THE SRN END OF THE TROUGH...AN AXIS OF MODERATE
INSTABILITY SHOULD BE IN PLACE BY MIDDAY FROM THE MID-ATLANTIC NEWD
INTO SRN NEW ENGLAND WHERE SFC DEWPOINTS ARE FORECAST TO BE IN THE
UPPER 60S F. AS SFC TEMPS WARM DURING THE DAY...THUNDERSTORMS SHOULD
INITIATE IN THE HIGHER TERRAIN OF THE NRN APPALACHIAN MTNS AND MOVE
EWD INTO THE COASTAL PLAINS. ETA-KF FORECAST SOUNDINGS IN THE
COASTAL PLAINS AT 21Z SHOW 0-6 KM SHEAR VALUES IN THE 40 TO 50 KT
RANGE SUGGESTING A SUPERCELL THREAT WILL EXIST. ALTHOUGH SUPERCELLS
MAY PRODUCE HAIL...THE WIND DAMAGE THREAT MAY BE THE GREATER THREAT
ESPECIALLY IF THE STORMS CAN CONGEAL INTO A BOWING LINE-SEGMENT
DURING THE LATE AFTERNOON.
...NRN PLAINS...
A SHORTWAVE TROUGH IS FORECAST TO MOVE ESEWD INTO THE NRN PLAINS
SATURDAY. MODEL FORECASTS DEVELOP A POCKET OF MODERATE INSTABILITY
AHEAD OF THE TROUGH WITH CONVECTION INITIATING ON THE WRN GRADIENT
OF INSTABILITY BY EARLY AFTERNOON. THE STORMS SHOULD MOVE ESEWD
ACROSS ERN ND DURING THE AFTERNOON. ETA-KF FORECAST SOUNDINGS IN ERN
ND SHOW COLD AIR ALOFT AND STEEP MID-LEVEL LAPSE RATES WHICH SHOULD
BE ADEQUATE FOR HAIL WITH THE MORE INTENSE CORES. UNIDIRECTIONAL
WIND PROFILES MAY ALSO HELP THE STORMS PRODUCE STRONG GUSTY WINDS.
...FRONT RANGE...
A SUBTLE UPPER-LEVEL RIDGE IS FORECAST ACROSS THE ROCKIES SATURDAY
AS A 65 TO 80 KT MID-LEVEL JET MOVES AWAY FROM THE CNTRL HIGH PLAINS
WITH THE RIGHT ENTRANCE REGION OF THE JET LOCATED ACROSS NE CO. THIS
ALONG WITH SFC HEATING SHOULD HELP THUNDERSTORMS INITIATE IN THE
FOOTHILLS OF THE FRONT RANGE WITH THE CONVECTION MOVING EWD INTO THE
PLAINS SATURDAY AFTERNOON. ALTHOUGH INSTABILITY SHOULD BE
WEAK...STRONG DEEP LAYER SHEAR AND STEEP MID-LEVEL LAPSE RATES
EVIDENT ON FORECAST SOUNDINGS SHOULD BE ADEQUATE FOR A MARGINAL HAIL
THREAT.
..BROYLES.. 06/04/2010
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