SWODY1
SPC AC 241614
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1114 AM CDT THU JUN 24 2010
VALID 241630Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN KY/WV NEWD INTO PARTS
OF NY AND NEW ENGLAND...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS AND
UPR MS VLY...
...SYNOPSIS...
FAST W TO WNW FLOW WILL PREVAIL FROM THE NRN PLNS TO THE NRN/MID
ATLANTIC CSTS TODAY...N OF ELONGATED RIDGE OVER THE SOUTH...AND
DOWNSTREAM FROM POSITIVE TILT TROUGH IN THE WEST. STRONG SHORTWAVE
IMPULSE NOW CROSSING THE LWR GRT LKS SHOULD REACH NEW ENGLAND BY EVE
AND THE CANADIAN MARITIMES EARLY FRI. AT THE SAME TIME...A SERIES
OF WEAK DISTURBANCES EXPECTED TO EJECT ENE FROM WRN TROUGH ACROSS MT
AND SRN AB/SK LATER IN THE PERIOD.
DIFFUSE COLD FRONT TRAILING SW INTO THE LWR OH VLY FROM ST LAWRENCE
VLY/NRN ME SFC LOW...AND DEVELOPING LEE TROUGH E OF THE CNTRL/NRN
APPALACHIANS...SHOULD BE THE MAIN FOCI FOR DIURNAL STORM
DEVELOPMENT/SVR THREAT TODAY.
...ERN KY/SRN OH/WV INTO NEW ENGLAND THIS AFTN/EARLY EVE...
PASSAGE OF DEBRIS FROM UPSTREAM STORMS...AND SFC HEATING...ARE
DESTABILIZING REGION ALONG AND AHEAD OF COLD FRONT ATTM FROM ERN
KY/WV NEWD INTO THE HUDSON VLY. AREA SOUNDINGS DO NOT SHOW PRESENCE
OF A WELL-DEFINED EML. BUT COMBINATION OF CONTINUED SFC HEATING
/ENHANCED BY WLY DOWNSLOPE E OF THE MOUNTAINS/ AND EXISTING LOW LVL
MOISTURE /SFC DEWPOINTS IN THE UPR 60S F AND PW AOA 1.50 IN/ SHOULD
BOOST AFTN SBCAPE TO AROUND 2500 J/KG IN ERN KY AND TO AROUND 1500
J/KG FROM ERN MD/VA NEWD INTO THE LWR HUDSON VLY/SRN NEW ENGLAND.
TSTMS SHOULD FIRST FORM/INTENSIFY ALONG COLD FRONT IN NRN/WRN PA
INTO SE OH...WITH OTHER DEVELOPMENT EXPECTED AHEAD OF FRONT BY EARLY
AFTN FROM SE NY/ERN PA SWD INTO MD/VA...AND OVER ERN KY/WV. LARGELY
UNIDIRECTIONAL 40-50 KT MEAN WLY FLOW /WITH 500 MB SPEEDS OF 50-60
KTS/ SHOULD SUPPORT SUSTAINED STORMS/SUPERCELLS FROM MD/NRN VA NWD.
THESE MAY ORGANIZE INTO SHORT BANDS/SMALL CLUSTERS. COUPLED WITH
STEEPENING LOW LVL LAPSE RATES /ESPECIALLY E OF THE MOUNTAINS/...A
THREAT WILL EXIST FOR NARROW SWATHS OF DMGG WIND AND PERHAPS
MARGINALLY SVR HAIL THROUGH EARLY EVE. GIVEN PRESENCE OF A FEW
SUSTAINED SUPERCELLS AND STRENGTH OF SHEAR...ONE OR TWO TORNADOES
CANNOT BE RULED OUT. THIS THREAT APPEARS GREATEST FROM THE CT RVR
VLY INTO ME...WHERE SLIGHTLY BACKED LOW LVL FLOW WILL EXIST CLOSER
TO UPR VORT/SFC LOW. WEAKER SHEAR WILL EXIST FARTHER SW INTO ERN
KY/WV. BUT COMBINATION OF MODERATE WNW SHEAR WITH SUBSTANTIAL
SBCAPE LIKELY WILL YIELD A FEW BANDS/CLUSTERS OF MULTICELLS WITH
LOCALLY DMGG WIND.
...ND/NW MN THIS AFTN/EVE...
MODIFIED POLAR AIR /WITH SFC DEWPOINTS IN THE 50S F/ WILL PREVAIL AT
LWR LVLS OVER THE NRN PLNS THIS PERIOD...N OF WEAK FRONT MARKING SRN
EDGE OF THE WLYS. LOW LVL WAA ALSO WILL PERSIST...AHEAD OF
AFOREMENTIONED DISTURBANCES IN WLY FLOW ALOFT. THIS SETUP MAY
SUPPORT AN INCREASING POTENTIAL FOR SLIGHTLY ELEVATED STORMS TO
MOVE/DEVELOP SE ACROSS ND AND INTO THE UPR MS VLY LATER
TODAY/TONIGHT. THESE STORMS MAY INTENSIFY/BECOME MORE NEARLY
SFC-BASED AS THE BOUNDARY LAYER DESTABILIZES. SELY LOW LVL WINDS
VEERING TO 30-40 KT WLY FLOW AT MID LVLS MAY SUPPORT A FEW
SUPERCELLS WITH LARGE HAIL AND LOCALLY DMGG WIND...MAINLY THIS AFTN
THROUGH MID EVE.
..CORFIDI/STOPPKOTTE.. 06/24/2010
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