DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 041234
SWODY1
SPC AC 041232

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0732 AM CDT THU SEP 04 2008

VALID 041300Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN MS INTO THE OH RIVER
VALLEY...

...NRN MS ACROSS THE LOWER OH RIVER VALLEY INTO SRN GREAT LAKES...
THE REMNANTS OF GUSTAV WILL ACCELERATE NEWD AS AN UPPER-LEVEL TROUGH
FROM THE WEST BEGINS TO ABSORB THE SYSTEM...WITH WIDESPREAD
PRECIPITATION SHIELD SPREADING NEWD ACROSS THE MID MS RIVER VALLEY
INTO THE SRN GREAT LAKES TODAY. MORNING WV IMAGERY INDICATES VERY
DRY AIR ALOFT SPREADING INTO THE MID SOUTH...TO THE SOUTH OF MAIN
CIRCULATION...WHICH SHOULD AID DESTABILIZATION AHEAD OF SFC COLD
FRONT/TROUGH SHIFTING EWD INTO THE LOWER/MID MS RIVER VALLEY THIS
AFTERNOON. AS DESTABILIZATION OCCURS...THUNDERSTORMS SHOULD
REDEVELOP/INCREASE AHEAD OF THIS FEATURE AND SPREAD QUICKLY NNEWD
UNDER 40 TO 50 KT LOW-LEVEL JET. THE STRONGEST COLLOCATION OF
LOW-LEVEL SHEAR AND MARGINAL MLCAPE WILL EXIST FROM SERN IL/SRN IND
SWD INTO THE LOWER MS RIVER VALLEY...WHERE LOW/MID 70F SURFACE DEW
WILL BE IN PLACE. THIS SHOULD BE SUPPORTIVE OF EMBEDDED ROTATING
STORMS AND A FEW TORNADOES. ALTHOUGH LESS OF A THREAT...MARGINALLY
SEVERE WIND GUSTS WILL ALSO BE POSSIBLE DUE TO THE FLOW ASSOCIATED
WITH THE LOW-LEVEL JET.

FARTHER NORTHEAST INTO THE SRN GREAT LAKES REGION...MODEL FORECASTS
DEVELOP A CLUSTER OF THUNDERSTORMS ON THE NOSE OF THE LOW-LEVEL JET.
THE STRONG LOW-LEVEL FLOW ALONG WITH A 45 TO 55 KT MID-LEVEL JET
OVER THE GREAT LAKES REGION SHOULD CREATE MODERATE VERTICAL SHEAR
PROFILES. THIS ALONG WITH STEEPENING LOW-LEVEL LAPSE RATES IN THE
AFTERNOON SHOULD BE FAVORABLE FOR AT LEAST MARGINALLY SEVERE WIND
GUSTS. A MARGINAL TORNADO THREAT MAY ALSO DEVELOP DURING THE LATE
AFTERNOON/OVERNIGHT AS REMNANTS OF GUSTAV AND ASSOCIATED MAXIMUM LOW
LEVEL SHEAR SPREADS NEWD INTO THIS REGION.

...ERN CO/WRN KS/SWRN NEB...
NORTHWEST FLOW WILL BE ESTABLISHED EARLY IN THE PERIOD ACROSS THE
PACIFIC NORTHWEST AND CNTRL ROCKIES AS AN UPPER-LEVEL TROUGH MOVES
INTO THE MS VALLEY REGION. A SECONDARY MORE SUBTLE UPPER-LEVEL
TROUGH IS FORECAST TO MOVE INTO THE CNTRL ROCKIES TONIGHT. AHEAD OF
THIS FEATURE...THE MODELS FORECAST THE DEVELOPMENT OF A CONVECTIVE
COMPLEX IN ERN CO AND WRN KS AFTER 03Z ON THE NOSE OF A 30 TO 40 KT
LOW-LEVEL JET. THIS ACTIVITY SHOULD BE ELEVATED WITH FORECAST
SOUNDINGS SHOWING INSTABILITY PRIMARILY ABOVE 700 MB.
HOWEVER...EFFECTIVE SHEAR SHOULD BE STRONG ENOUGH COMBINED WITH
STEEP MID-LEVEL LAPSE RATES TO SUPPORT A MARGINAL HAIL THREAT LATE
TONIGHT AS THIS ACTIVITY SPREADS ESEWD.

..EVANS/SMITH.. 09/04/2008

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