Tuesday, June 22, 2010

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 221643
SWODY2
SPC AC 221643

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1143 AM CDT TUE JUN 22 2010

VALID 231200Z - 241200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SE WI...NE/NCNTRL
IL...EXTREME NRN IND...MUCH OF LOWER MI AND EXTREME NW OH...

...THERE IS A SLGT RISK OF SVR TSTMS FROM WRN NEW
ENGLAND/MID-ATLANTIC REGION SWWD INTO THE SRN PLAINS...

...SYNOPSIS...
PRIMARY FEATURE OF INTEREST WILL BE THE EJECTION AND AMPLIFICATION
OF THE UPPER TROUGH FROM THE NRN PLAINS/UPPER MS VALLEY INTO THE
LOWER GREAT LAKES REGION ON WEDNESDAY. ASSOCIATED SURFACE LOWS WILL
TRACK FROM PARTS OF IA EWD ALONG A NWD DEVELOPING WARM FRONT INTO
MI/SWRN ONTARIO THROUGH WEDNESDAY EVENING. A COLD FRONT WILL SURGE
SEWD ACROSS THE MIDWEST AND THE CNTRL/SRN PLAINS BY 12Z THURSDAY.

...UPPER MS VLY INTO THE MIDWEST/OH VALLEY/GREAT LAKES REGION...
ONE OR MORE ROUNDS OF ACTIVE SEVERE WEATHER WILL AFFECT A CORRIDOR
FROM THE UPPER MS VALLEY TO THE LOWER GREAT LAKES ON WEDNESDAY AND
WEDNESDAY NIGHT.

FIRST ORDER OF BUSINESS WILL BE THE NOCTURNAL MCS/POSSIBLE DERECHO
EXPECTED TO ONGOING AT 12Z WEDNESDAY OVER PORTIONS OF THE UPPER MS
VALLEY. THE FORWARD-PROPAGATING MCS IS LIKELY TO CONTINUE TRACKING
EWD ACROSS LAKE MI AND INTO AT LEAST THE SRN HALF OF LOWER MI DURING
THE MORNING THEN SWRN ONTARIO DURING THE AFTERNOON. AIR MASS
DOWNSTREAM WILL GRADUALLY RECOVER IN WAKE OF TODAY/S DEPARTING
IMPULSE...AT LEAST AS FAR N AS SRN LOWER MI. AS A RESULT...THERE IS
SUFFICIENT EVIDENCE TO EXPECT A CONTINUATION OF DAMAGING WIND RISKS
DURING THE MORNING INTO THE EARLY AFTERNOON...ALTHOUGH THERE MAY BE
AN INITIAL WEAKENING TREND OF THE ACTIVITY AS IT ENCOUNTERS SLIGHTLY
LESS UNSTABLE REGIME OVER THE CNTRL/LOWER GREAT LAKES.

AFTERNOON ATTENTION WILL FOCUS ON THE 30-60 METER HEIGHT FALLS
ASSOCIATED WITH THE APPROACHING MID-LEVEL WAVE. THERE IS MEDIUM TO
HIGH CONFIDENCE THAT THE AIR MASS WILL RECOVER OVER PARTS OF UPPER
MS VALLEY EWD INTO THE CENTRAL GREAT LAKES WITH AN EXTENSIVE ZONE OF
LOWER 70S SURFACE DEW POINTS ANTICIPATED ALONG/AHEAD OF THE SURFACE
LOW/COLD FRONT. STEEPENING LOW-LEVEL LAPSE RATES IN WAKE OF
DISSOLVING MORNING CLOUD COVER WILL BOOST MLCAPES 2000-3000 J/KG AND
NEW STORMS WILL DEVELOP FROM SRN WI/NRN IL BY MID-AFTERNOON.
VERTICAL WIND PROFILES WILL BE LARGELY UNIDIRECTIONAL...BUT STRONG
SPEED SHEAR WILL CONTRIBUTE TO SUPERCELL PROFILES WITH LARGE HAIL
AND A FEW TORNADOES LIKELY WITH INITIAL DEVELOPMENT. ACTIVITY WILL
LIKELY DEVELOP UPSCALE INTO ANOTHER MCS BY EVENING...TRACKING EWD
ACROSS SRN LOWER MI AND NRN IND WITH HIGH WINDS. ACTIVITY MAY
EVENTUALLY REACH THE LOWER GREAT LAKES/UPSTATE NY/WRN NEW ENGLAND BY
12Z THURSDAY WITH RISKS FOR DAMAGING WINDS AS THE LOW-LEVEL AIR MASS
RECOVERS RAPIDLY IN ADVANCE OF THE MID-LEVEL IMPULSE.

FARTHER S...A FEW THUNDERSTORMS ARE EXPECTED TO FORM ALONG THE
RETREATING WARM FRONT ACROSS PARTS OF THE MID/UPPER OH VALLEY DURING
PEAK HEATING WEDNESDAY. THESE STORMS WILL BE EMBEDDED ALONG THE
FRINGE OF 40 KT WLY MID-LEVEL FLOW AND A MODEST DEGREE OF LOW-LEVEL
TURNING. AS A RESULT...A COUPLE OF TORNADOES/ DAMAGING WIND GUSTS
WILL BE POSSIBLE WITH THE STORMS AS THEY MOVE TOWARD WRN PA DURING
THE EVENING.

...MID-MS VALLEY TO THE SRN PLAINS...
THUNDERSTORMS WILL LIKELY BACKBUILD SWWD ALONG THE SURGING COLD
FRONT FROM THE DEVELOPING GREAT LAKES MCS INTO PARTS OF NRN OK.
REGION WILL REMAIN REMOVED FROM HIGHER MOMENTUM ALOFT...BUT HOT
BOUNDARY LAYER AND FOCUS FOR STORMS WILL LEAD TO AT LEAST WIDELY
SCATTERED DAMAGING WIND/HAIL POSSIBILITIES.

...CENTRAL APPALACHIANS TO NC...
FORMIDABLE CONVECTIVELY-ENHANCED IMPULSE NOW OVER THE MID-MS VALLEY
WILL TRACK ESE INTO THE CENTRAL APPALACHIANS BY 12Z WEDNESDAY.
STORMS ASSOCIATED WITH THIS FEATURE WILL TURN MORE SELY ALONG THE
INSTABILITY AXIS INTO PARTS OF SRN VA/NC DURING THE DAY WEDNESDAY
WITH SPORADIC DAMAGING WIND GUSTS POSSIBLE.

..RACY.. 06/22/2010

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