[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 031607
SWODY1
SPC AC 031605

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1105 AM CDT SUN SEP 03 2006

VALID 031630Z - 041200Z

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

...ERN NEB/WRN IA...
WELL-DEFINED COLD UPPER LOW OVER SERN SD IS FORECAST TO CONTINUE
MOVING SEWD INTO NWRN IA THIS AFTERNOON AND CENTRAL IA TONIGHT.  500
MB TEMPERATURES OF -18 TO -20C ASSOCIATED WITH THE LOW WILL ENHANCE
LOW-MID LEVEL LAPSE RATES...ESPECIALLY WHERE BREAKS IN CLOUD COVER
ALLOW STRONGER DIURNAL HEATING TO OCCUR.  ALTHOUGH SURFACE DEWPOINTS
WILL LIKELY REMAIN IN THE LOW 50S...TEMPERATURES WARMING INTO THE
LOW 70S WILL RESULT IN MODEST INSTABILITY WITH MLCAPE OF 500-1000
J/KG.  DYNAMIC FORCING FOR ASCENT WILL BE AIDED BY LEFT EXIT REGION
OF STRONG WESTERLY MID/UPPER LEVEL JET STREAK ON THE SRN PERIPHERY
OF THE UPPER LOW.  THIS WILL CONTRIBUTE TO SUFFICIENT DEEP LAYER
SHEAR OF 35-45 KT TO AID STORM ORGANIZATION AND INTENSITY.  CELLS
ARE FORECAST TO INCREASE IN COVERAGE OVER EXTREME ERN NEB AND WRN IA
BY EARLY AFTERNOON SPREADING EWD TOWARD CENTRAL IA BEFORE
DIMINISHING IN INTENSITY DURING THE EVENING.  ISOLATED LARGE HAIL
WILL BE THE PRIMARY SEVERE THREAT.

...UPPER MS VALLEY...
COLD FRONT WILL MOVE SLOWLY EWD ACROSS SERN MN/ERN IA TOWARD SWRN
WI/NWRN IL THIS AFTERNOON.  EXTENSIVE BAND OF CLOUDS AND WIDELY
SCATTERED PRECIPITATION WITHIN THE FRONTAL ZONE WILL INHIBIT
WIDESPREAD DIABATIC HEATING...ALTHOUGH ANY BREAKS IN THE CLOUD COVER
THAT CAN DEVELOP WILL CONTRIBUTE TO DESTABILIZATION WITH MLCAPE
AROUND 500 J/KG.  THE POSSIBILITY OF ISOLATED NON-SUPERCELL TORNADO
DEVELOPMENT /SIMILAR TO YESTERDAY ACROSS IA/ WILL BE MAINTAINED
ALONG THE FRONT THIS AFTERNOON.

...AZ/SERN CA...
DEEP LAYER MOISTURE CONTINUES TO SPREAD NWD FROM TROPICAL STORM JOHN
INTO SOUTH CENTRAL/ERN AZ...AS MODERATE SWLY UPPER FLOW ACROSS THE
LOWER CO RIVER VALLEY INTO WRN/NRN AZ RESULTS IN A SSW/NNE MID AND
UPPER LEVEL MOISTURE DISCONTINUITY IN THE WATER VAPOR IMAGERY ACROSS
CENTRAL AZ.  12Z SOUNDINGS INDICATE AMPLE PRECIPITABLE WATER VALUES
OF 1.0-1.5 INCHES ACROSS CENTRAL/SRN AZ INTO SERN CA...AND CLEARING
SKIES OVER WRN AZ/SERN CA WILL PERMIT STRONG DIURNAL HEATING TO
OCCUR. THIS WILL CONTRIBUTE TO MODERATE INSTABILITY WITH MLCAPE OF
1000-1500 J/KG.

VERTICAL WIND PROFILES SHOW STRONGER ENELY MID LEVEL WINDS COMPARED
TO YESTERDAY...WHICH MAY RESULT IN A STRONGER PROPAGATIONAL
COMPONENT TO STORM MOTION DEVELOPING THIS AFTERNOON AND EVENING.  A
FEW STRONGER STORMS ARE EXPECTED ACROSS THIS REGION WITH POTENTIAL
TO PRODUCE MARGINALLY SEVERE HAIL AND WET MICROBURSTS.

..WEISS/GUYER.. 09/03/2006