DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 061627
SWODY1
SPC AC 061624

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CDT THU SEP 06 2007

VALID 061630Z - 071200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL
PLAINS AND MIDWEST STATES...

..CENTRAL PLAINS AND MIDWEST STATES...
MORNING WATER VAPOR LOOPS SHOWS STRONG UPPER TROUGH MOVING EASTWARD
ACROSS UT/WY/CO. THIS FEATURE IS FORECAST TO EJECT INTO THE CENTRAL
PLAINS THIS EVENING. AHEAD OF THE SYSTEM...SOUTHWESTERLY LOW LEVEL
WINDS ARE FORECAST TO INCREASE OVER THE CENTRAL PLAINS HELPING TO
TRANSPORT RICH MOISTURE NORTHWARD AND DESTABILIZE AIR MASS. SURFACE
DEWPOINTS WELL INTO THE UPPER 60S AND LOWER 70S ARE EXPECTED ACROSS
PARTS OF SRN NEB/SRN MN AND MUCH OF IA BY 00Z. POCKETS OF HEATING
AND LOW LEVEL WARM ADVECTION WILL YIELD AFTERNOON MLCAPE VALUES OF
900-1500 J/KG.

PRESENT INDICATIONS ARE THAT INITIAL THUNDERSTORMS WILL BE
POST-FRONTAL OVER WESTERN NEB AS STRONGER FORCING APPROACHES.
STRONG WESTERLY FLOW ALOFT AND STEEP LOW LEVEL LAPSE RATES WILL
PROMOTE A RISK OF DAMAGING WINDS IN THESE AREAS. STORMS WILL SPREAD
EASTWARD INTO MORE MOIST/UNSTABLE AIR MASS OVER CENTRAL NEB AND
INTENSIFY FURTHER DURING THE EVENING. STRENGTH OF FORCING AND
DEGREE OF INSTABILITY SUGGEST THE LIKELIHOOD OF ORGANIZATION INTO A
LINEAR MCS EXTENDING FROM SOUTHEAST SD INTO NORTHERN KS...MOVING
INTO PARTS OF MN/IA/MO DURING THE NIGHT. THIS LINE OF STORMS WILL
LIKELY MAINTAIN A RISK OF DAMAGING WINDS AND HAIL THROUGH AT LEAST
06Z.

..MO/IL...
REMNANT UPPER LOW IS TRACKING NORTHEASTWARD THIS MORNING ACROSS MO.
ISOLATED STORMS IN THIS REGIME HAVE SHOWN LOW/MID LEVEL ROTATION AND
BRIEF TORNADOES FOR THE PAST COUPLE OF DAYS...AND THAT SCENARIO MAY
CONTINUE TODAY. AXIS WHERE A BRIEF TORNADO OR TWO ARE MOST LIKELY
TODAY EXTENDS FROM SOUTHWEST MO IN WEST-CENTRAL IL ALONG AND WEST OF
THE STRONGER LOW LEVEL WINDS.

.HART/GUYER.. 09/06/2007

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