SPC AC 260558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT WED SEP 26 2007
VALID 261200Z - 271200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER OH
VALLEY AND NEW ENGLAND...
...UPPER OH VALLEY/NEW ENGLAND...
A SHORTWAVE TROUGH EVIDENT ON WATER VAPOR IMAGERY OVER THE GREAT
LAKES REGION IS FORECAST TO LIFT QUICKLY NEWD ACROSS QUEBEC TODAY.
SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE NERN STATES WITH A COLD
FRONT APPROACHING FROM THE WEST. MODEL FORECASTS DEVELOP MODERATE
INSTABILITY AHEAD OF THE FRONT FROM SRN NEW ENGLAND SWWD ACROSS SE
NY INTO PA. WIDESPREAD THUNDERSTORM ACTIVITY SHOULD INITIATE AROUND
MIDDAY ALONG THE FRONT WITH SCATTERED CONVECTION ALSO DEVELOPING
ALONG A PREFRONTAL TROUGH EXTENDING SWD INTO THE MID-ATLANTIC.
SEVERAL LINEAR MCS/S MAY DEVELOP AS THE FRONT MOVES INTO THE REGION
LATE THIS AFTERNOON.
A MID-LEVEL JET ASSOCIATED WITH THE SHORTWAVE TROUGH WILL MOVE NEWD
ACROSS NRN NEW ENGLAND TODAY. THIS WILL CREATE MODERATE VERTICAL
SHEAR PROFILES ACROSS NEW ENGLAND AND NEW YORK SUGGESTING SHEAR WILL
BE ADEQUATE FOR SEVERE STORMS. THE AMOUNT OF INSTABILITY SHOWN ON
FORECAST SOUNDINGS COMBINED WITH UNIDIRECTIONAL LOW-LEVEL WIND
PROFILES SHOULD BE ENOUGH FOR A WIND DAMAGE THREAT. A MORE
PERSISTENT THREAT FOR WIND DAMAGE MAY EXIST WITH ANY LINEAR MCS THAT
ORGANIZES ACROSS THE REGION.
FURTHER SOUTHWEST ACROSS THE UPPER OH VALLEY...FORECAST SOUNDINGS
SHOW SLIGHTLY WEAKER VERTICAL SHEAR PROFILES. HOWEVER...THE NAM AND
GFS ARE BOTH IN AGREEMENT DEVELOPING A POCKET OF GREATER INSTABILITY
ACROSS PA. IN ADDITION...LOW-LEVEL LAPSE RATES WILL BE STEEPER THAN
AREAS FURTHER NORTHEAST AND A WIND DAMAGE THREAT SHOULD ALSO EXIST
WITH THE STRONGER MULTICELL STORM CLUSTERS THIS AFTERNOON.
...SE NM/WEST TX...
A PLUME OF MID-LEVEL MOISTURE IS EVIDENT ON WATER VAPOR IMAGERY
ACROSS NRN MEXICO EXTENDING EWD INTO MUCH OF CNTRL AND NORTH TX. A
DISTURBANCE IS EMBEDDED IN THE BAND OF MOISTURE OVER SRN NM AND THIS
FEATURE WILL COME INTO THE SRN PLAINS TODAY. AT THE SFC...A
STATIONARY FRONT IS FORECAST TO BE IN PLACE IN THE VICINITY OF
LUBBOCK. A CLUSTER OF THUNDERSTORMS SHOULD DEVELOP ALONG THIS
BOUNDARY THIS AFTERNOON WITH AN MCS DEVELOPING ACROSS WEST TX BY
THIS EVENING.
CONCERNING THE STORM ENVIRONMENT...MID-LEVEL WINDS ARE FORECAST TO
INCREASE TODAY ACROSS WEST TX AS THE DISTURBANCE MOVES OUT INTO THE
PLAINS. MODERATE TO STRONG VERTICAL SHEAR PROFILES ACROSS THE REGION
SHOULD BE SUFFICIENT FOR ORGANIZED THUNDERSTORMS. IF ENOUGH
INSTABILITY CAN DEVELOP...A FEW SUPERCELLS WITH LARGE HAIL MAY
DEVELOP IN THE LATE AFTERNOON. WIND DAMAGE WOULD ALSO BE POSSIBLE
DUE TO STEEP LOW-LEVEL LAPSE RATES AS AN MCS ORGANIZES EARLY THIS
EVENING. HOWEVER...THE AMOUNT OF THE INSTABILITY AND THE EXACT
PLACEMENT OF THE MCS REMAINS QUESTIONABLE. THE MOST LIKELY AREA
WOULD BE FROM HOBBS NM TO LUBBOCK AS SUGGESTED BY THE GFS. IF MORE
INSTABILITY DEVELOPS THAN IS CURRENTLY FORECAST...AN UPGRADE TO
SLIGHT RISK MAY BECOME NECESSARY LATER TODAY.
..BROYLES/JEWELL.. 09/26/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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