SPC AC 221630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1030 AM CST THU FEB 22 2007
VALID 221630Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...MID ATLANTIC REGION THIS AFTERNOON...
AN INTENSE MID LEVEL SHORTWAVE TROUGH NOW OVER WRN PA...AND AN
ASSOCIATED 120+ KT MID LEVEL JET OVER INDIANA/OH/WV...WILL TRANSLATE
ESEWD OVER THE MID ATLANTIC REGION BY LATE AFTERNOON WHILE
CONTINUING TO AMPLIFY. A BAND OF STRONG ASCENT ACCOMPANIES THIS
WAVE ALONG THE SURFACE COLD FRONT MOVING THROUGH CENTRAL PA AS OF
16Z...AND THIS BOUNDARY WILL PROVIDE A FOCUS FOR ADDITIONAL
CONVECTIVE DEVELOPMENT. SURFACE TEMPERATURES WARMING INTO THE 50S
OVER NRN VA AND LOW-MID 40S INTO SE PA...ALONG WITH DEWPOINTS NEAR
40 F...WILL CONTRIBUTE TO STEEP LOW-LEVEL LAPSE RATES AND THE
POTENTIAL FOR SBCAPE VALUES OF 75-150 J/KG BY EARLY AFTERNOON. THE
CONVECTIVE CLOUDS MAY ALSO BECOME SUFFICIENTLY DEEP/COLD TO SUPPORT
A THREAT FOR AT LEAST ISOLATED LIGHTNING STRIKES.
THERE WILL BE A NARROW WINDOW OF OPPORTUNITY FOR CONVECTIVELY
ENHANCED WIND GUSTS WITH SHALLOW CONVECTION ALONG THE FRONT. THE
STEEP LAPSE RATES AND 35-45 KT FLOW IN THE LOWEST 1-2 KM AGL COULD
SUPPORT A FEW GUSTS APPROACHING SEVERE LEVELS FOR A COUPLE OF HOURS
AROUND EARLY AFTERNOON.
...PACIFIC COAST AND GREAT BASIN...
A DEEP/COLD TROUGH IS BEGINNING TO MOVE INLAND OVER THE PACIFIC
COAST AND SHOULD PROGRESS EWD TO THE GREAT BASIN BY EARLY FRIDAY.
STEEP LAPSE RATES WILL ACCOMPANY THE MID LEVEL THERMAL TROUGH /WITH
500 MB TEMPERATURES OF -30 TO -34 C/. WEAK INSTABILITY MAY SUPPORT
A FEW LOW-TOPPED/POST-FRONTAL THUNDERSTORMS LATE TODAY...WHILE OTHER
ISOLATED THUNDERSTORMS MAY DEVELOP OVER PARTS OF THE GREAT BASIN
ALONG THE PRIMARY BAROCLINIC ZONE LATE TODAY INTO EARLY TONIGHT.
...OK LATE TONIGHT...
PRESSURE FALLS IN THE LEE OF THE ROCKIES WILL INDUCE STRENGTHENING
SLY LOW-LEVEL FLOW AND ASSOCIATED WAA/MOISTURE ADVECTION OVER THE
SRN PLAINS. A WEAK LEAD SHORTWAVE TROUGH /NOW OVER THE NRN GULF OF
CA/ WILL EJECT NEWD TOWARD OK BY LATE TONIGHT. WEAK ASCENT AND
INCREASINGLY MOIST PROFILES...ALONG WITH MODEST MID LEVEL LAPSE
RATES...MAY RESULT IN SUFFICIENT MID LEVEL CAPE FOR A FEW ELEVATED
THUNDERSTORMS BEFORE 12Z.
..THOMPSON.. 02/22/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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