SWODY2
SPC AC 041728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT SAT JUN 04 2011
VALID 051200Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MS
VALLEY...OH VALLEY...CNTRL APPALACHIAN MTNS...CAROLINAS AND VA...
...MID-MS VALLEY AND OH VALLEY...
NORTHWEST FLOW WILL GRADUALLY BECOME ESTABLISHED ACROSS THE OH
VALLEY AND CNTRL APPALACHIAN MTNS STATES SUNDAY AS A COLD FRONT
MOVES SWD ACROSS THE REGION. IN SPITE OF NLY FLOW ACROSS MUCH OF THE
OH VALLEY SUNDAY AFTERNOON...RESIDUAL MOISTURE WILL REMAIN IN PLACE
WITH MODEL FORECASTS DEVELOPING MODERATE INSTABILITY ACROSS A LARGE
AREA FROM THE MID-MS VALLEY EWD ACROSS THE OH AND TN VALLEYS.
SCATTERED THUNDERSTORMS SHOULD INITIATE AS SFC TEMPS WARM ON THE NRN
EDGE OF THE INSTABILITY AXIS FROM SRN IA SEWD ACROSS IL...IND AND KY
WITH THE CONVECTION SPREADING SEWD DURING THE AFTERNOON. FORECAST
SOUNDINGS AT 21Z SUNDAY ALONG THIS CORRIDOR SHOW MODERATE DEEP LAYER
SHEAR PROFILES WITH SUBSTANTIAL DIRECTIONAL SHEAR BELOW 700 MB WHICH
WILL BE FAVORABLE FOR SEVERE STORM DEVELOPMENT. A SUPERCELL AND
LARGE HAIL THREAT MAY DEVELOP ACROSS SRN IA...NE MO AND IL WHERE THE
COMBINATION OF DEEP LAYER SHEAR AND INSTABILITY IS FORECAST TO BE
THE GREATEST. FURTHER EAST ACROSS THE OH VALLEY...CONVECTION MAY
TEND TO LINE OUT WHERE SFC WINDS WILL BE MORE VEERED AND LOW-LEVEL
LAPSE RATES WILL BE QUITE STEEP. WIND DAMAGE WILL BE FAVORED WITH
ANY LINE-SEGMENTS THAT CAN REMAIN INTENSE SUNDAY AFTERNOON.
...CAROLINAS/MID-ATLANTIC/NRN APPALACHIAN MTNS...
A SHORTWAVE TROUGH IS FORECAST TO MOVE SEWD ACROSS THE NERN STATES
SUNDAY AFTERNOON IN NORTHWEST FLOW ALOFT. AT THE SFC...A MOIST AXIS
SHOULD BE IN PLACE FROM THE CAROLINAS EXTENDING NWD INTO THE
MID-ATLANTIC AND NRN APPALACHIAN MTNS. MODEL FORECASTS INITIATE
SCATTERED THUNDERSTORMS ALONG THE MOIST AXIS SUNDAY AFTERNOON WHERE
SEVERAL CONVECTIVE CLUSTERS MAY PERSIST INTO THE EARLY EVENING.
FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 21Z SUNDAY SHOW MLCAPE
VALUES IN THE 2000 TO 3000 J/KG RANGE. IN ADDITION TO THE
INSTABILITY...0-6 KM SHEAR VALUES ARE FORECAST TO BE IN THE 25 TO 35
KT RANGE SUGGESTING A SEVERE THREAT SHOULD EXIST DURING THE LATE
AFTERNOON. UNIDIRECTIONAL WIND PROFILES AND STEEP LOW-LEVEL LAPSE
RATES SHOULD RESULT IN A WIND DAMAGE THREAT WITH THE MORE INTENSE
CELLS. FURTHER NORTH ACROSS THE NRN APPALACHIAN MTNS...INSTABILITY
IS FORECAST TO BE MUCH WEAKER SUGGESTING ANY SEVERE THREAT WILL
LIKELY REMAIN MARGINAL.
...NRN PLAINS/UPPER MS-VALLEY...
WLY FLOW ALOFT WILL BE IN PLACE SUNDAY ACROSS THE NCNTRL STATES WITH
AN AXIS OF INSTABILITY LOCATED FROM ERN NEB NWD INTO THE ERN DAKOTAS
AND NRN MN. ALTHOUGH MUCH OF THE INSTABILITY AXIS MAY REMAINED
CAPPED SUNDAY AFTERNOON...MODEL FORECAST DO INITIATE SOME CONVECTION
MAINLY IN ERN ND AND NRN MN. FORECAST SOUNDINGS IN THIS AREA AT 00Z
MONDAY SHOW RELATIVELY WEAK INSTABILITY BUT STRONGER DEEP LAYER
SHEAR DUE TO A BROAD MID-LEVEL JET IN SRN CANADA. THIS MAY PROVIDE
ENOUGH SUPPORT FOR A MARGINAL SEVERE THREAT. HAIL AND ISOLATED WIND
DAMAGE WILL BE POSSIBLE IF SFC-BASED THUNDERSTORMS DEVELOP LATE
SUNDAY AFTERNOON.
..BROYLES.. 06/04/2011
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