SWODY1
SPC AC 271622
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1122 AM CDT SUN JUN 27 2010
VALID 271630Z - 281200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
FROM THE OH VALLEY INTO PA/NY...
...OH VALLEY TO PA/NY THROUGH TONIGHT...
A SERIES OF EMBEDDED SHORTWAVE TROUGHS OVER NRN PLAINS AND ADJACENT
PRAIRIE PROVINCES WILL ROTATE ESEWD AROUND THE SRN PERIPHERY OF A
DEEP CLOSED LOW NEAR JAMES BAY. THE MIDLEVEL WAVE WILL BE PRECEDED
BY A DEEPENING SURFACE CYCLONE THAT IS EXPECTED TO MOVE EWD FROM
WI/LOWER MI TODAY TO THE SAINT LAWRENCE VALLEY BY EARLY MONDAY. IN
ADVANCE OF THE SURFACE CYCLONE...THE UNSTABLE WARM SECTOR IS ALREADY
ESTABLISHED ACROSS THE OH VALLEY...AND WILL SPREAD NEWD ACROSS
PA/SRN NY THROUGH THIS EVENING.
A REMNANT MCV FROM OVERNIGHT CONVECTION WILL MOVE EWD FROM NRN
IL/SRN WI ACROSS NRN INDIANA/SRN LOWER MI AND NRN OH THROUGH THIS
AFTERNOON...ALONG THE NRN EDGE OF THE WARM SECTOR. A BELT OF
ENHANCED /30-40 KT/ LOW-MIDLEVEL WLY FLOW WITH THE MCV...AND A
STRONGLY UNSTABLE WARM SECTOR WITH MLCAPE VALUES UP TO 4000
J/KG...WILL CONTRIBUTE TO A FAVORABLE ENVIRONMENT FOR
INTENSIFICATION OF THE CONVECTION NOW OVER NW INDIANA. WIND
PROFILES WILL SUPPORT BOTH ORGANIZED MULTICELL CLUSTERS AND SOME
EMBEDDED SUPERCELL STRUCTURES...WITH DAMAGING WINDS THE PRIMARY
SEVERE THREAT. ISOLATED LARGE HAIL WILL ALSO BE POSSIBLE...ALONG
WITH A LOW-PROBABILITY THREAT FOR A TORNADO /PRIMARILY WITH STORMS
INTERACTING WITH THE WARM FRONT/OUTFLOW ACROSS SRN LOWER MI THIS
AFTERNOON/.
FARTHER S NEAR THE OH RIVER...A FEW SMALL THUNDERSTORM CLUSTERS WILL
LIKELY ACCOMPANY A DIFFUSE MIDLEVEL VORTICITY CENTER MOVING EWD OVER
SRN INDIANA/NRN KY. A FEW DAMAGING DOWNBURSTS WILL BE POSSIBLE WITH
THIS CONVECTION THROUGH THE AFTERNOON...GIVEN THE MAGNITUDE OF THE
INSTABILITY. MORE ISOLATED THUNDERSTORM DEVELOPMENT WILL BE
POSSIBLE THIS AFTERNOON ACROSS WRN PA/NY WHERE STRONG SURFACE
HEATING IS UNDERWAY. THIS CONVECTION COULD PRODUCE STRONG
GUSTS...BUT THE PRIMARY THREAT SHOULD BE LATER THIS EVENING AS MORE
WIDESPREAD/ORGANIZED STORMS APPROACH FROM THE W. MIDLEVEL LAPSE
RATES ARE RELATIVELY POOR FARTHER E OVER ERN PA/NY AND SRN NEW
ENGLAND...WHERE LINGERING CLOUDS REMAIN ALONG AND N OF THE WARM
FRONT. THE FOCUS FOR STORM DEVELOPMENT IS NOT CLEAR THIS FAR
E...THOUGH DEEP-LAYER VERTICAL SHEAR WILL BE AT LEAST MARGINALLY
FAVORABLE FOR ORGANIZED STORMS.
...MO TO OK/NW TX THIS AFTERNOON/EVENING...
THE SURFACE COLD FRONT /ASSOCIATED WITH THE AMPLIFYING NRN STREAM
TROUGH NEAR THE GREAT LAKES/ WILL MOVE SLOWLY SWD/SEWD ACROSS ERN
NM/W TX...NW OK...ERN KS...NW MO...AND IA DURING THE DAY. THE FRONT
/AND A PRE-FRONTAL WIND SHIFT/GRAVITY WAVE JUST SE OF THE I-44
CORRIDOR IN OK AND MO/ WILL FOCUS THUNDERSTORM DEVELOPMENT THIS
AFTERNOON...WITH COVERAGE ENHANCED DOWNSTREAM FROM REMNANT MIDLEVEL
VORTICITY CENTERS OVER NW TX AND NE KS. DEEP-LAYER VERTICAL SHEAR
WILL REMAIN WEAK TO THE S OF THE MAIN BELT OF WLYS /ESPECIALLY FROM
OK SWWD/. HOWEVER...DAYTIME HEATING WILL CONTRIBUTE TO AFTERNOON
MLCAPE VALUES OF 2000-3000 J/KG AND SOME POTENTIAL FOR SPORADIC
DOWNBURSTS AND MARGINALLY SEVERE HAIL WITH THE MORE INTENSE STORMS.
..THOMPSON/SMITH.. 06/27/2010
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