[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 041247
SWODY1
SPC AC 041245

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT MON SEP 04 2006

VALID 041300Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NRN/CENTRAL IL...SRN WI
AND FAR ERN IA...

...SYNOPSIS...
CLOSED LOW OVER CENTRAL IA AND ASSOCIATED TROUGH OVER THE MID/UPPER
MS VALLEY REGION WILL MOVE ESEWD AND AMPLIFY...AS UPPER RIDGE BUILDS
NWD FROM THE NRN ROCKIES INTO THE CANADIAN ROCKIES. IN ASSOCIATION
WITH THE UPPER LOW...A WEAK SURFACE LOW IN NWRN IL WILL MOVE EWD
INTO NRN IND BY LATE AFTERNOON WITH A TRAILING FRONTAL BOUNDARY
EXTENDING SWWD INTO SRN OK/WRN TX. FURTHER TO THE EAST...A
STATIONARY FRONT STRETCHES FROM AL NEWD INTO WRN NC...AND THEN EWD
INTO EXTREME SERN VA.

...FAR ERN IA/NRN IL/SRN WI...
EARLY THIS MORNING...ONE BAND OF CONVECTION WAS LOCATED IN THE ZONE
OF STRONG DIFFLUENCE ALOFT FROM ERN IL INTO SRN WI...WHILE ANOTHER
CLUSTER OF STORMS WAS LOCATED JUST SOUTHEAST OF THE UPPER LOW. THE
STORMS IN IA ARE EXPECTED TO MOVE/DEVELOP EWD WITH THE UPPER LOW
INTO NRN/CENTRAL IL THIS AFTERNOON. DESPITE MEAGER BOUNDARY LAYER
MOISTURE...MID LEVEL LAPSE RATES NEAR 7C/KM AND -16 TO -18C 500 MB
TEMPERATURES WILL RESULT IN SBCAPES OF 500-1000 J/KG. ALTHOUGH THE
PRIMARY BELT OF STRONGER MID AND UPPER LEVEL WINDS WILL BE ON THE
SOUTHERN PERIPHERY OF THE LOW FROM CENTRAL MO EWD INTO SRN
INDIANA...DEEP LAYER SHEAR AT 20-30 KT WILL SUPPORT MULTICELL
CLUSTERS ACROSS THE OUTLOOK AREA. THE STEEP LAPSE RATES AND COLD
TEMPERATURES ALOFT WILL SUPPORT MARGINALLY SEVERE HAIL IN THE
STRONGEST STORMS. THE STORMS SHOULD WEAKEN QUICKLY AFTER 00Z AS THE
BOUNDARY LAYER COOLS AND STABILIZES.

...SRN/CNTRL APPALACHIANS...
MODELS ARE CONSISTENT IN DEVELOPING CONVECTION OVER THE AREA LATE
THIS AFTERNOON...THOUGH SOME DIFFERENCES EXIST IN EXACT LOCATION. A
FEW SHOWERS HAD ALREADY FORMED FROM ERN TN NEWD INTO SWRN VA... IN
ZONE OF WEAK ISENTROPIC LIFT NORTH OF STATIONARY FRONT. ALTHOUGH
LIFT IS FORECAST TO WEAKEN THIS MORNING...MODELS DEPICT A HIGH LEVEL
SHORTWAVE TROUGH...CURRENTLY OVER ERN OK...MOVING INTO TN/NRN MS BY
LATE AFTERNOON. THIS FEATURE PLUS STRENGTHENING DIFFLUENCE
ALOFT...AHEAD OF A 90-100 KT HIGH LEVEL JET MAX...WILL RESULT IN
LARGE SCALE FORCING. ALTHOUGH TEMPERATURES NEAR 90 AND DEWPOINTS
AROUND 70 SHOULD RESULT IN MLCAPES FROM 1500-2500 J/KG SOUTH OF THE
FRONT...IT APPEARS THE MAIN FORCING WILL BE NORTH OF THE
FRONT...WHERE INSTABILITY WILL BE WEAKER. HOWEVER...MUCAPES FROM 500
TO 1000 J/KG AND DEEP LAYER SHEAR NEAR 30 KT MAY SUPPORT ISOLATED
STRONG/MARGINALLY SEVERE STORMS ACROSS PORTIONS OF ERN TN...NRN
AL...WRN CAROLINAS AND WRN VA THIS AFTERNOON AND EVENING.

...CO AND NERN NM FRONT RANGE...
DEEP ELY UPSLOPE WINDS WITH MID LEVEL WINDS VEERING TO NWLY WILL
RESULT IN FAVORABLE VERTICAL SHEAR PROFILES FOR ORGANIZED/ROTATING
STORMS THIS AFTERNOON. WATER VAPOR IMAGERY INDICATES A SHORT WAVE
TROUGH WAS ROTATING SWD ACROSS ERN WY...AND LATEST MODEL GUIDANCE
MAINTAINS THIS FEATURE IN ERN CO THROUGH THE AFTERNOON. THE BOUNDARY
LAYER WILL NOT BE PARTICULARLY MOIST...THOUGH STEEP LOW/MID LEVEL
LAPSE RATES SHOULD RESULT IN SBCAPES FROM 500-1000 J/KG. WEAK
FORCING WITH SHORTWAVE TROUGH AND UPSLOPE FLOW MAY INITIATE A FEW
STORMS WITH SEVERE HAIL/GUSTY WINDS OVER THE ERN  FOOTHILLS MID/LATE
AFTERNOON. A MORE STABLE ENVIRONMENT OVER THE PLAINS SHOULD LIMIT
THE STORMS EWD EXTENT. SINCE STORM COVERAGE IS EXPECTED TO BE
LIMITED...ONLY 5% HAIL/WIND PROBABILITIES ARE FORECAST.

..IMY/GRAMS.. 09/04/2006