SPC AC 021946
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT WED JUN 02 2010
VALID 022000Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND EVENING FROM
THE S CNTRL PLAINS/OZARK PLATEAU THROUGH THE OHIO VALLEY AND THE LEE
OF THE LWR GREAT LAKES...
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND TONIGHT
ACROSS PARTS W CNTRL TX THROUGH THE RIO GRANDE VALLEY...
...20Z UPDATE...
THE PRIMARY FRONTAL WAVE IS NOW SLOWING MIGRATING EASTWARD INTO THE
LOWER GREAT LAKES REGION...ACCOMPANIED BY STRONGER LOWER/MID
TROPOSPHERIC FLOW FIELDS. A 30-50 KT WESTERLY MID-LEVEL JET STREAK
TRAILS TO THE WEST SOUTHWEST...ACROSS THE MIDDLE MISSISSIPPI
VALLEY...BUT A SIGNIFICANT CONGLOMERATE OUTFLOW BOUNDARY ASSOCIATED
WITH OVERNIGHT CONVECTION HAS GENERALLY ADVANCED TO THE SOUTH OF
THIS STRONGER FLOW.
...S CNTRL PLAINS INTO OH VALLEY...
THE SURFACE BOUNDARY SEEMS TO BE STALLING NEAR THE OHIO RIVER
WESTWARD INTO THE OZARK PLATEAU AND SOUTH CENTRAL PLAINS....AND HAS
BECOME THE FOCUS FOR INCREASING STORM DEVELOPMENT IN THE PRESENCE OF
STRONG INSTABILITY...AS CHARACTERIZED BY MIXED LAYER CAPE UP TO
3000-4000 J/KG. NEW STORMS ARE STILL EXPECTED IN CLOSER PROXIMITY
TO THE OUTFLOW BOUNDARY AND SURFACE FRONT INTERSECTION ACROSS
EASTERN OKLAHOMA/SOUTHEAST KANSAS AND SOUTHWEST MISSOURI INTO
NORTHWEST ARKANSAS...AS WEAK MID-LEVEL COOLING WEAKENS INHIBITION
LATE THIS AFTERNOON.
...LOWER GREAT LAKES...
LOW-LEVEL THERMAL/MOISTURE ADVECTION DEVELOPING NORTHEASTWARD TO THE
LEE OF LAKES MAY CONTRIBUTE TO SUFFICIENT DESTABILIZATION TO SUPPORT
A CONTINUING SEVERE THREAT LATE THIS AFTERNOON AND EVENING.
...TEXAS...
A WEAK MID-LEVEL THERMAL TROUGH TO THE WEST AND SOUTH OF AN
INCREASINGLY CUT-OFF CYCLONIC MID-LEVEL CIRCULATION HAS CONTRIBUTED
TO VERY STEEP MID-LEVEL LAPSE RATES AND STRONG CAPE OF 3000-4000+
J/KG ACROSS PARTS OF THE EDWARDS PLATEAU/HILL COUNTRY ...WESTWARD
INTO THE MEXICAN PLATEAU. LIGHT NORTHWEST FLOW TO THE WEST OF THE
UPPER TROUGH AXIS ACROSS THIS REGION MAY ALSO BE CONTRIBUTING TO
ENOUGH SHEAR TO ENHANCE STORM DEVELOPMENT...WHICH IS ALREADY
ONGOING. THE MOST SIGNIFICANT STORMS MAY BE THOSE DEVELOPING EAST
SOUTHEASTWARD OFF THE HIGHER TERRAIN OF THE MEXICAN PLATEAU THROUGH
THE RIO GRANDE RIVER AREA...BUT CONSOLIDATING OUTFLOWS ACROSS THE
EDWARDS PLATEAU COULD EVENTUALLY SURGE SOUTHWARD THROUGH THE RIO
GRANDE VALLEY WITH UPSCALE CONVECTIVE GROWTH LATE THIS AFTERNOON AND
TONIGHT. IN ADDITION TO THE RISK FOR STRONG DAMAGING WINDS...LARGE
HAIL IS ALSO POSSIBLE.
..KERR.. 06/02/2010
.PREV DISCUSSION... /ISSUED 1110 AM CDT WED JUN 02 2010/
...UPPER OH VALLEY...
REMNANTS OF OVERNIGHT MCS CONTINUES TO TRACK ENEWD 30-35KT AND
CURRENTLY EXTENDS FROM SWRN ONTARIO INTO NRN OH. SOUTHERLY LOW
LEVEL WINDS AND DAYTIME HEATING WILL POTENTIALLY LEAD TO STORMS
RE-INTENSIFYING BY EARLY THIS AFTERNOON OVER WESTERN NY/PA. GIVEN
THAT MLCAPES SHOULD REMAIN LESS THAN 500 J/KG AND MID LEVEL LAPSE
RATES ARE ONLY AROUND 6C/KM...PRIMARY THREAT WILL BE LOCALIZED
DAMAGING WINDS GIVEN DEEP LAYER SHEAR OF 40-50 KT.
...OK INTO LOWER OH VALLEY...
OVERNIGHT STORMS OVER THE MID MS VALLEY HAVE PUSHED THE EFFECTIVE
SURFACE BOUNDARY WELL S OF COLD FRONT. AT MID MORNING OUTFLOW
BOUNDARY EXTENDS WWD FROM SCENTRAL IL TO SWRN MO INTO NWRN OK.
AMPLE LOW LEVEL MOISTURE AND MODERATE CAPE VALUES WILL PROMOTE
CONSIDERABLE THUNDERSTORM ACTIVITY LATER THIS AFTERNOON ALONG THE
FRONT/BOUNDARIES...WITH HIGHEST CONFIDENCE ACROSS PARTS OF
MO/IL/IN/OH WHERE HIGHER SEVERE PROBABILITIES HAVE BEEN MAINTAINED.
ORGANIZED MULTICELL STORMS CAPABLE OF HAIL AND DAMAGING WINDS WILL
BE THE MAIN THREATS.
...NORTHERN NEW ENGLAND...
COLD FRONT EXPECTED TO APPROACH MAINE BY LATE AFTERNOON. WHILE THE
DEEP LAYER SHEAR WILL BE AROUND 40 KT...INSTABILITY AND LAPSE RATES
WILL ONLY BE MARGINALLY FAVORABLE FOR A FEW STRONG/SEVERE STORMS.
WITH MLCAPES AROUND 500 J/KG BY MID AFTERNOON SCATTERED
THUNDERSTORMS WILL DEVELOP. A FEW ORGANIZED MULTICELL STORMS WILL
BE POSSIBLE CAPABLE OF HAIL AND DAMAGING WINDS.
...NORTHEAST NM/TX PANHANDLE...
SHORTWAVE TROUGH OVER CO NOTED IN W/V IMAGERY WILL TRACK EASTWARD
AND PROMOTE SCATTERED THUNDERSTORMS THIS AFTERNOON OVER PARTS OF
SOUTHERN CO/NORTHERN NM. THESE STORMS WILL EMERGE INTO THE HIGH
PLAINS BY EARLY EVENING...WHERE STEEP LAPSE RATES AND INCREASING
MOISTURE WILL BE PRESENT. ISOLATED SUPERCELL STORMS ARE POSSIBLE
THROUGH THE EVENING WITH A RISK OF LARGE HAIL AND DAMAGING WINDS.
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