Sunday, July 10, 2011

July 10 Severe Weather Discussion

There is a slight risk of severe thunderstorms over the following areas:
-Wisconsin
-North IL
-Much of Nebraska
-Iowa
-Much of Minnesota
-East South Dakota
-Southeast North Dakota

SYNOPSIS... Low pressure system with attached warm front and trough will move east and initiate showers and thunderstorms in the Dakotas. That warm front will then turn into a warm front in Wisconsin, where that will also initiate storms.

Conditions will be favorable for supercells in the same areas as yesterday as a moderate mid level flow off the higher elevations out west will provide forcing into a very moist environment to initiate thunderstorms.

Following excerpts from the SPC


...CNTRL HI PLNS INTO NEB THIS AFTN THROUGH EARLY SUN...
   SIMILAR TO YESTERDAY...SETUP WILL ONCE AGAIN BE FAVORABLE FOR THE
   DEVELOPMENT OF STRONG AFTN/EVE STORMS OVER THE RCKYS OF CO AND SRN
   WY.  THIS REGION WILL AGAIN LIE BENEATH BRANCH OF MODERATE /30+ KT/
   WSWLY MID LVL FLOW IMMEDIATELY TOPPING S CNTRL U.S. UPR RIDGE. 
   SETUP SHOULD FOSTER ENE PROPAGATION OF CONVECTION OFF THE HIGHER
   TERRAIN AND INTO DEEPLY MIXED/FAIRLY MOIST ENVIRONMENT OVER THE
   CNTRL HI PLNS.  SOME OF THE STORMS COULD YIELD SVR HAIL AND LOCALLY
   DMGG WIND.  NOCTURNAL STRENGTHENING OF SLY LLJ AND PRESENCE OF
   DISTURBANCES IN THE SRN STREAM FLOW /PER WATER VAPOR IMAGERY/
   SUGGEST THAT THE STORMS WILL EVOLVE INTO A LARGE CLUSTER THAT COULD
   EXTEND THE RISK FOR DMGG WIND AND MARGINALLY SVR HAIL AS FAR E AS
   CNTRL/ERN NEB BY EARLY SUN.
AMPLE MOISTURE /PW AOA 1.25 INCHES AND SFC DEWPOINTS IN THE MID TO
   UPR 60S F/ BENEATH DEEP EML WILL LEAD TO VERY STRONG INSTABILITY
   /SBCAPE AOA 4000 J PER KG/.  COUPLED WITH 40+ KT WLY DEEP
   SHEAR...SETUP LOOKS FAVORABLE FOR SUPERCELLS WITH VERY LARGE HAIL
   AND DMGG WIND.  WHILE DEEP WIND PROFILES LARGELY WILL BE
   UNIDIRECTIONAL...GIVEN DEGREE OF INSTABILITY...SUFFICIENT LOW LVL
   DIRECTIONAL SHEAR WILL EXIST TO POSE A THREAT FOR
   TORNADOES...ESPECIALLY NEAR OUTFLOW BOUNDARY/STNRY FRONT REMNANTS
   FROM CNTRL SD/S CNTRL ND ESE INTO WRN MN AND PERHAPS NE NEB/NRN IA. 
   THE STORMS SHOULD MOVE/DEVELOP ESE ACROSS THE REMAINDER OF THE ERN
   DAKOTAS/MN...WI/IA...AND POSSIBLY NRN IL THIS EVE THROUGH EARLY SUN
   IN THE FORM OF ONE OR TWO SMALL MCSS.
Hail outlook
Tornado outlook
today's wind outlook

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