Potential for Severe thunderstorm or tornado watches.

Potential for Severe thunderstorm or tornado watches that could spread east with the storm.

MESOSCALE DISCUSSION 0367

   NWS STORM PREDICTION CENTER NORMAN OK
   0358 PM CDT TUE MAR 27 2012
   
   AREAS AFFECTED...EASTERN IA/SOUTHERN WI/NORTHWEST IL/NORTHEAST MO
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 272058Z - 272300Z
   
   MONITORING FOR AN INCREASING SEVERE THREAT...WHICH COULD INITIALLY
   OCCUR ACROSS PORTIONS OF THE REGION INTO THE 23Z-02Z TIME FRAME. A
   WATCH MAY BE NEEDED THIS EVENING.
   
   A WEAK COLD FRONT CONTINUES TO MAKE A GRADUAL EASTWARD PROGRESSION
   TOWARD THE UPPER MS RIVER VALLEY AT MID AFTERNOON WITHIN A
   NORTHEAST-SOUTHWEST ORIENTED CORRIDOR FROM WESTERN WI TO
   SOUTH-CENTRAL IA/NORTHWEST MO. MODEST LOW-LEVEL MOISTURE...WITH
   SURFACE DEWPOINTS GENERALLY IN THE 50S F...OTHERWISE CONTINUES TO
   STEADILY INCREASE WITH NORTH-NORTHEASTWARD EXTENT IMMEDIATELY AHEAD
   OF THE FRONT. NEAR/AHEAD OF THIS FRONT...LOW-LEVEL CONVERGENCE
   REMAINS MODEST AS WINDS AT/JUST ABOVE THE SURFACE HAVE CONTINUED TO
   VEER PER SURFACE OBSERVATIONS/REGIONAL DERIVED WIND DATA.
   HOWEVER...A LOW-AMPLITUDE EASTWARD-MOVING SHORTWAVE TROUGH/SPEED MAX
   CURRENTLY OVER SD/SOUTHWEST MN PER WATER VAPOR IMAGERY MAY PROVIDE
   AN IMPETUS FOR AT LEAST ISOLATED DEEP CONVECTIVE DEVELOPMENT OVER
   THE NEXT FEW HOURS...AS INHIBITION OTHERWISE CONTINUES TO ERODE
   WITHIN THE MODESTLY MOIST NEAR-FRONTAL WARM SECTOR.
   
   WHILE CONFIDENCE IN CONVECTIVE DETAILS ARE NOT PARTICULARLY
   HIGH...AN ASSORTMENT OF NUMERICAL GUIDANCE INCLUDING A NUMBER OF 15Z
   SREF MEMBERS IMPLY THAT SUCH DEVELOPMENT WILL BE MORE PROBABLE INTO
   THE 23Z-02Z TIME FRAME ESPECIALLY ACROSS FAR EASTERN IA/FAR
   NORTHWEST IL AND ADJACENT PARTS OF NORTHERN MO...ALTHOUGH A GRADUAL
   DEEPENING OF THE CUMULUS FIELD HAS BEEN NOTED AS FAR NORTHEAST AS
   SOUTHWEST WI AT MID-AFTERNOON. IF/WHERE DEEP CONVECTIVE DEVELOPMENT
   DOES OCCUR INTO THIS EVENING...STRONG EFFECTIVE SHEAR /45-50 KT OR
   GREATER/ WILL SUPPORT ORGANIZED/SUSTAINED STORMS INCLUDING INITIAL
   MODE SUPERCELLS CAPABLE OF SEVERE HAIL/PERHAPS A TORNADO...WITH
   DAMAGING WINDS A POSSIBILITY AS WELL. CONVECTIVE TRENDS WILL
   CONTINUE TO BE MONITORED FOR A POSSIBLE WATCH.