DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 130546
SWODY1
SPC AC 130544

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT MON MAY 13 2013

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE PACIFIC
NORTHWEST AND NRN ROCKIES...

...PACIFIC NORTHWEST/NRN ROCKIES...
AN UPPER-LEVEL TROUGH WILL QUICKLY APPROACH THE PACIFIC NORTHWEST
THIS MORNING AND MOVE INLAND THIS AFTERNOON. AT THE SFC...A COLD
FRONT IS FORECAST TO MOVE SEWD ACROSS NE ORE...NRN ID AND WRN MT
THIS AFTERNOON. LOW-LEVEL CONVERGENCE ALONG THE WIND SHIFT WILL
PROVIDE A FOCUS FOR THUNDERSTORM DEVELOPMENT AS SFC TEMPS WARM
DURING THE DAY. MODEL FORECASTS FIRST GENERATE CONVECTION IN NE ORE
EARLY THIS AFTERNOON AND EXPAND CONVECTIVE COVERAGE NEWD ACROSS NRN
ID AND NCNTRL MT BY LATE AFTERNOON.

FORECAST SOUNDINGS ALONG THE WIND SHIFT AT 21Z FROM NE ORE NEWD INTO
WCNTRL MT GENERALLY SHOW SBCAPE VALUES IN THE 500 TO 1000 J/KG
RANGE. THIS COMBINED WITH STRONG DEEP LAYER SHEAR OF 65 TO 75 KT
SHOULD BE SUFFICIENT FOR SUPERCELL DEVELOPMENT ESPECIALLY IN AREAS
THAT DESTABILIZE THE MOST. STEEP MID-LEVEL LAPSE RATES AND COLD
TEMPS ALOFT ASSOCIATED WITH THE APPROACHING SHORTWAVE TROUGH SHOULD
BE FAVORABLE FOR LARGE HAIL PRODUCTION. IN ADDITION...TEMP-DEWPOINT
SPREADS OF 25 TO 30 DEGREES F MAY HELP ENHANCE DOWNDRAFT SPEEDS
RESULTING IN DAMAGING WIND GUSTS.

...SRN FL...
A COLD FRONT WILL MOVE SWD ACROSS SRN FL TODAY AS AN UPPER-LEVEL
TROUGH MOVES EWD ACROSS THE ATLANTIC SEABOARD. THE SRN EXTENSION OF
THE UPPER-LEVEL TROUGH WILL PROVIDE SUPPORT FOR THUNDERSTORM
DEVELOPMENT ACROSS SE FL EARLY THIS AFTERNOON. FORECAST SOUNDINGS IN
THE MIAMI AREA AT 21Z SHOW MLCAPE VALUES AROUND 1500 J/KG WITH
UNIDIRECTIONAL WIND PROFILES AND STEEP LOW-LEVEL LAPSE RATES. THIS
COULD BE ENOUGH FOR A MARGINAL WIND DAMAGE THREAT.

..BROYLES.. 05/13/2013

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