SPC AC 121239
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0739 AM CDT WED JUL 12 2006
VALID 121300Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS PARTS OF NERN U.S....
...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF MT AND ADJACENT HIGH
PLAINS...
...SYNOPSIS...
MID-SUMMER LARGE SCALE PATTERN OVER CONUS WITH STRONGER WLYS
CONFINED TO NEAR CANADIAN BORDER. GREATER SEVERE THUNDERSTORM
THREAT TODAY WILL BE ASSOCIATED WITH THE RATHER BROAD TROUGH AND
ASSOCIATED WIND MAX MOVING ACROSS THE NERN U.S. AND A DEAMPLIFYING
S/WV MOVING ACROSS NRN ROCKIES THIS AFTERNOON.
...NERN U.S...
A VERY MOIST/TROPICAL-LIKE AIR MASS WILL SPREAD ACROSS NERN U.S.
TODAY. SURFACE LOW LOCATED N OF DTW WAS ASSOCIATED WITH A TROUGH
MOVING THRU GREAT LAKES AND FORECAST TO TRACK EWD ACROSS NY AND WRN
NEW ENGLAND THIS AFTERNOON AND EVENING. SOUTH OF THE SURFACE LOW A
BAND OF 30-40KT LOW THROUGH MID LEVEL FLOW WILL SPREAD EWD FROM
UPPER OH VALLEY TO SRN NEW ENGLAND.
EXTENSIVE CLOUDINESS WILL SLOW HEATING MUCH OF NERN U.S...HOWEVER
SHEAR PROFILES WILL BECOME FAVORABLE FOR BOTH DEVELOPMENT OF
CONVECTIVE LINE SEGMENTS AND LOW TOPPED SUPERCELLS NEAR AND SOUTH OF
THE SURFACE LOW TRACK. GIVEN HIGH MOISTURE...EXPECT POCKETS OF
SURFACE HEATING OCCURRING IN WAKE OF CURRENT LARGE AREA OF PCPN NOW
MOVING EWD NY/PA TO ALLOW AN INCREASE IN MLCAPE TO 1500
J/KG...PARTICULARLY PA SWD.
MODEL FORECAST SOUNDINGS INDICATE 20-30KT OF SFC-1KM SHEAR AND LCLS
LESS THAN 1KM WILL SUPPORT TORNADOES LATER THIS AFTERNOON ACROSS PA
AND INTO SERN NY IF SUFFICIENT INSTABILITY DEVELOPS.
ADDITIONALLY...30-40KT STEERING FLOW SHOULD PROMOTE FORMATION OF
SHORT LINE SEGMENTS WITH AN ENHANCED POTENTIAL FOR WIND DAMAGE FROM
CENTRAL PA EWD INTO PARTS OF SRN NEW ENGLAND BY THIS EVENING.
SRN LIMIT OF ANY ORGANIZED SEVERE THREAT WILL BE ALONG SRN FRINGE OF
STRONGER MID LEVEL FLOW. LEE TROUGH CURRENTLY DELMARVA ALONG WITH
HIGH THETA-E AIR MASS WILL PROVIDE SOME ENHANCEMENT OF SURFACE
CONVERGENCE THIS AREA WHERE MLCAPES WITH SFC TEMPS AOA 90F COULD
REACH TO AOA 2000 J/KG. THIS WILL INCREASE POTENTIAL FOR WET
MICRO-BURSTS.
...MT AND WRN ND...
AS STRONGER MID LEVEL FLOW SPREADS EWD WITH PASSAGE OF THE S/WV
TROUGH HEADING EWD FROM OR/WA...POTENTIAL FOR SEVERE THUNDERSTORMS
WILL INCREASE THIS AFTERNOON HIGHER TERRAIN CENTRAL MT. WHILE
INSTABILITY/MOISTURE WILL BE SOMEWHAT LIMITED...THE STEEP LAPSE
RATES COUPLED WITH SFC-6KM SHEAR OF 35-40KT WILL SUPPORT HIGH BASED
MULTICELLULAR STORM DEVELOPMENT. PREDOMINANT THREAT WILL BE
DAMAGING WINDS...HOWEVER MARGINALLY SEVERE HAIL IS ALSO LIKELY WITH
STRONGER UPDRAFTS. ACTIVITY WILL SPREAD ACROSS NRN HIGH PLAINS INTO
TONIGHT...WITH CONTINUING SEVERE POTENTIAL AFTER DARK.
..HALES/CARBIN.. 07/12/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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