[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 032003
SWODY1
SPC AC 032001

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT SUN SEP 03 2006

VALID 032000Z - 041200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN NEB AND WRN IA...

...ERN NEB/WRN IA...
UPPER LOW...CURRENTLY MOVING INTO NWRN IA...WILL CONTINUE TO TRACK
SLOWLY TO THE ESE INTO IA THIS FORECAST PERIOD.  ATTENDANT SURFACE
LOW WITH THIS UPPER LOW WAS LOCATED OVER NERN NEB WITH A SURFACE
FRONT EXTENDING WSWWD THROUGH SRN NEB. COLD MID LEVEL TEMPERATURES
/-20 C AT 500 MB PER RUC GUIDANCE/ COMBINED WITH SURFACE HEATING
AHEAD OF SURFACE FRONT HAS RESULTED IN STEEP LOW AND MID LEVEL LAPSE
RATES. GIVEN FAVORABLE THERMODYNAMICS AND ASCENT WITHIN EXIT REGION
OF MID LEVEL JET...ADDITIONAL STORMS ARE EXPECTED TO DEVELOP ALONG
NEB/IA BORDER AND SPREAD INTO IA BEFORE DIMINISHING THIS EVENING
WITH LOSS OF DAYTIME HEATING.  STEEP LAPSE RATES AND COLD MID LEVEL
TEMPERATURES SUGGEST HAIL WILL BE THE PRIMARY THREAT.

...UPPER MS RIVER VALLEY...
TRENDS IN WATER VAPOR IMAGERY SUGGEST A SHORT WAVE TROUGH IS
ROTATING AROUND THE UPPER LOW AND CURRENTLY MOVING NWWD THROUGH SERN
AND CENTRAL MN.  ATTENDANT COLD FRONT ALONG LEADING EDGE OF UPPER
LOW WILL SPREAD INTO SWRN WI AND NWRN IL...WHILE A POST-FRONTAL
SURFACE TROUGH...EXTENDING SWD INTO ERN IA TO NERN MO...ACTS AS
ANOTHER FOCUS FOR THUNDERSTORM DEVELOPMENT.  EXTENSIVE CLOUDINESS IN
THE VICINITY OF BOTH SURFACE BOUNDARIES HAS LIMITED DIABATIC
HEATING...AND RESULTANT AVAILABLE INSTABILITY. ANY HEATING THAT CAN
OCCUR YET THIS AFTERNOON SHOULD ALLOW FOR AT LEAST MARGINAL
INSTABILITY.  THIS COMBINED WITH ASCENT AHEAD OF UPPER LOW AND WITH
SHORT WAVE TROUGH IS EXPECTED TO SUPPORT ADDITIONAL DIURNALLY DRIVEN
STORMS FROM CENTRAL MN/WRN WI INTO ERN IA AND NWRN IL. WEAK
INSTABILITY WILL LIMIT HAIL THREAT...WHILE THE POTENTIAL DOES EXIST
FOR ISOLATED NON-SUPERCELL TORNADO DEVELOPMENT ALONG THE FRONT THIS
AFTERNOON.  

...AZ/SERN CA...
STRONG SURFACE HEATING ACROSS SERN CA TO THE LOWER CO RIVER VALLEY
WITHIN A MOIST AIR MASS HAS RESULTED IN A MODERATELY UNSTABLE AIR
MASS.  ADDITIONAL SURFACE HEATING ACROSS WRN AZ SHOULD SUPPORT
SIMILAR TRENDS IN INSTABILITY. VISIBLE IMAGERY AND LIGHTNING DATA
INDICATED THUNDERSTORMS HAVE BEGUN TO DEVELOP ACROSS THE HIGHER
TERRAIN OF CENTRAL AND SERN AZ.  GIVEN ENELY LOW-MID LEVEL
WINDS...THERE WILL BE A GREATER POTENTIAL THIS FORECAST PERIOD FOR
ACTIVITY TO PROPAGATE SWWD INTO THE LOWER ELEVATIONS WHERE
INSTABILITY IS HIGHER AND SUPPORT WET MICROBURSTS.  MARGINALLY
SEVERE HAIL WILL ALSO BE A THREAT.

..PETERS.. 09/03/2006