Monday, September 24, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 250102
SWODY1
SPC AC 250059

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT MON SEP 24 2007

VALID 250100Z - 251200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
PLAINS AND UPPER MIDWEST...

..CNTRL PLAINS/UPPER MIDWEST...
THE LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH OVER THE
ROCKIES WITH A SHORTWAVE TROUGH EVIDENT ON RUC ANALYSIS OVER THE
UPPER MS VALLEY. AT THE SFC...A COLD FRONT IS LOCATED FROM NEAR
MINNEAPOLIS MN EXTENDING SWWD TO NEAR LINCOLN NEB. LOW-LEVEL
CONVERGENCE HAS INCREASED ALONG THE BOUNDARY OVER THE LAST FEW HOURS
AND THUNDERSTORMS ARE EXPANDING IN COVERAGE. THE DEVELOPMENT OF
SEVERAL LINEAR MCS/S SHOULD CONTINUE THIS EVENING.

CONCERNING THE STORM ENVIRONMENT...REGIONAL WSR-88D VWPS SHOW
MODERATE TO STRONG VERTICAL SHEAR ALONG THE ENTIRE LENGTH OF THE
BOUNDARY. TWO POCKETS OF MODERATE INSTABILITY EXIST ACCORDING TO
OBJECTIVE ANALYSIS. THE FIRST IS LOCATED ACROSS IA AND WRN WI WHERE
A NEARLY CONTINUOUS LINE IS ONGOING. THIS LINE MAY HAVE A FEW
DAMAGING WIND GUSTS FOR A COUPLE MORE HOURS ACROSS WRN AND NRN WI
AND POSSIBLY FAR WRN UPPER MI...REF MCD 2015. ISOLATED LARGE HAIL
WILL ALSO BE POSSIBLE ESPECIALLY ACROSS WRN IA WHERE STORMS ARE A
BIT MORE CELLULAR. HOWEVER...THE SEVERE THREAT SHOULD BECOME
INCREASINGLY MARGINAL AS INSTABILITY DECREASES AND LOW-LEVEL LAPSE
RATES BECOME LESS STEEP WITH TIME.

THE SECOND AREA OF MODERATE INSTABILITY IS LOCATED ACROSS CNTRL KS
AND FAR SRN NEB WHERE A FEW CLUSTERS OF STRONG THUNDERSTORMS ARE
ONGOING. A FOCUSED LOW-LEVEL JET IS LOCATED ACROSS THE CNTRL PLAINS
AND LIFT ASSOCIATED WITH THE JET SHOULD ALLOW FOR A GRADUAL INCREASE
IN STORM COVERAGE THIS EVENING. IT ALSO APPEARS A LINEAR MCS WILL
DEVELOP IN THIS REGION. OBJECTIVE ANALYSIS SHOWS AN EWD EXTENSION OF
THE ELEVATED MIXED LAYER ACROSS WCNTRL KS INTO SE NEB AND THIS WILL
BE MORE FAVORABLE FOR LARGE HAIL THAN AREAS TO THE NORTHEAST.
ISOLATED WIND DAMAGE WILL ALSO BE POSSIBLE ESPECIALLY WITH THE MORE
PERSISTENT ROTATING STORMS. THE WIND DAMAGE POTENTIAL MAY
TEMPORARILY INCREASE THIS EVENING ESPECIALLY IF A WELL-ORGANIZED
LINEAR MCS CAN FORM ACROSS THE REGION.

.BROYLES.. 09/25/2007

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