Tuesday, September 25, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 260056
SWODY1
SPC AC 260054

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 PM CDT TUE SEP 25 2007

VALID 260100Z - 261200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN LOWER MI...

..LOWER MI/NE IND/NW OH...
AN UPPER-LEVEL TROUGH OVER THE UPPER MS VALLEY IS EVIDENT ON WATER
VAPOR IMAGERY WITH A PLUME OF MID-LEVEL MOISTURE EXTENDING NWD
ACROSS THE MS VALLEY INTO THE GREAT LAKES REGION. AT THE SFC...A
COLD FRONT IS LOCATED FROM LAKE MICHIGAN SWWD ACROSS NRN IL INTO ERN
MO. AHEAD OF THE BOUNDARY...OBJECTIVE ANALYSIS INDICATES MODERATE
INSTABILITY IS PRESENT ACROSS THE WARM SECTOR AND NUMEROUS
THUNDERSTORMS ARE ONGOING ATTM. THIS ACTIVITY WILL GRADUALLY MOVE
NEWD INTO NRN OH AND SOUTHWESTERN ONTARIO THIS EVENING.

CONCERNING THE STORM ENVIRONMENT...REGIONAL WSR-88D VWPS SHOW DEEP
SOUTHWEST FLOW WITH ENOUGH SPEED SHEAR FOR ORGANIZED THUNDERSTORMS.
ALTHOUGH LOW-LEVEL LAPSE RATES ARE BECOMING LESS STEEP WITH TIME...
UNIDIRECTIONAL BOUNDARY LAYER FLOW SHOULD BE SUFFICIENT FOR AN
ISOLATED WIND DAMAGE THREAT FOR A FEW MORE HOURS. THE GREATEST
THREAT FOR WIND DAMAGE SHOULD EXIST IN THE VICINITY OF DETROIT WHERE
VERTICAL SHEAR IS GREATER THAN AREAS FURTHER SOUTH AND THE AIRMASS
HAS REMAINED UNTOUCHED. AS STORMS CONTINUE TO BECOME WIDESPREAD THIS
EVENING...DECREASING INSTABILITY AND WEAK LOW-LEVEL CONVERGENCE WILL
RESULT AN INCREASINGLY MARGINAL WIND DAMAGE THREAT.

..WEST TX...
WATER VAPOR IMAGERY CURRENTLY SHOWS A PLUME OF MOISTURE FROM THE ERN
PACIFIC EXTENDING ENEWD ACROSS NRN MEXICO INTO WRN AND CNTRL TX. AT
THE SFC...A FRONTAL BOUNDARY IS LOCATED ACROSS WEST TX NEAR THE
PECOS RIVER ENEWD INTO NRN TX HILL COUNTRY. LOW-LEVEL CONVERGENCE
ALONG THE BOUNDARY AND DESTABILIZATION IS SUPPORTING SCATTERED
THUNDERSTORMS WEST AND SOUTHWEST OF SAN ANGELO. THE LATEST RUC MODEL
SUGGESTS THE CLUSTER MAY PERSIST FOR A FEW MORE HOURS. HOWEVER...ANY
WIND DAMAGE THREAT SHOULD BE MARGINAL DUE TO WEAKENING LOW-LEVEL
LAPSE RATES AND DECREASING INSTABILITY THIS EVENING.

.BROYLES.. 09/26/2007

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