The SPC is forecasting ...Severe thunderstorms expected over parts of the Middle-upper Mississippi Valley region today and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

   SPC AC 301633

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1133 AM CDT MON JUN 30 2014

   VALID 301630Z - 011200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF MO...IA...IL...NW
   IND...SW MI...AND SRN WI...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
   FROM THE SRN HIGH PLNS NEWD INTO THE GRT LKS/OH VLY...

   ...SUMMARY...
   NUMEROUS SEVERE THUNDERSTORMS CAPABLE OF LARGE
   HAIL...TORNADOES...AND SWATHS OF DAMAGING WIND ARE EXPECTED TODAY
   INTO TONIGHT OVER MUCH OF THE CORN BELT AND MIDWEST. MORE WIDELY
   SCATTERED SEVERE STORMS WILL BE POSSIBLE OVER THE SOUTH-CENTRAL
   PLAINS.

   ...SYNOPTIC SETUP...
   SEASONABLY STRONG...CYCLONIC MID/UPR-LVL FLOW WILL PREVAIL OVER THE
   N CNTRL STATES THROUGH TUE...ON SRN SIDE OF SLOWLY-PROGRESSIVE
   MB/ONT UPR LOW. A FAIRLY SUBSTANTIAL SHORTWAVE IMPULSE IN THIS
   FLOW...NOW OVER THE NRN HIGH PLNS...WILL SWEEP E INTO THE UPR MS VLY
   BY THIS EVE...BEFORE TURNING NE ACROSS THE UPR GRT LKS EARLY TUE.
   AHEAD OF THIS TROUGH...EXPECT LOW-AMPLITUDE DISTURBANCE NOW OVER
   CNTRL NEB TO TRACK RAPIDLY ENE INTO LWR MI EARLY TUE.

   AT THE SFC...COLD FRONT ASSOCIATED WITH MB/ONT LOW WILL PROGRESS
   STEADILY E ACROSS THE UPR MS VLY...AND SE ACROSS THE CNTRL PLNS.
   AHEAD OF THE FRONT...A SERIES OF LOOSELY-CONNECTED OUTFLOW
   BOUNDARIES EXTENDING ROUGHLY WNW-ESE FROM ERN NEB TO CNTRL IL/IND
   LIKELY WILL PERSIST THROUGH TNGT. THE BOUNDARIES MAY DRIFT A BIT
   NEWD ACROSS ERN IA AND IL TODAY...BUT NEWD ADVANCE MAY BE OFFSET IN
   PLACES BY POTENTIAL STORM DEVELOPMENT IN THE REGION THIS AFTN.
   FARTHER SW...LEE TROUGH/DRY LINE WILL PERSIST OVER THE SRN HIGH
   PLNS.  

   ...CNTRL PLNS TO MID/UPR MS VLY AND LWR MI TODAY/TNGT...
   SETUP APPEARS FAVORABLE FOR SIGNIFICANT SVR WEATHER OVER THE LWR MO
   AND MID MS VLYS TODAY INTO TNGT. A BAND OF MODERATE TO STRONG WLY
   DEEP SHEAR WILL OVERLIE A SIMILARLY-ORIENTED CORRIDOR OF SUBSTANTIAL
   INSTABILITY IN THE PRESENCE OF AT LEAST MODEST LARGE-SCALE FORCING
   FOR ASCENT. THIS SETUP COULD YIELD FAIRLY NUMEROUS SUPERCELLS THAT
   WILL HAVE THE POTENTIAL FOR UPSCALE GROWTH INTO A DERECHO-PRODUCING
   MCS.
     
   TSTMS NOW OVER ERN NEB AND WRN IA /REF WWS 372 AND 373/ ARE FORMING
   IN ZONE OF STRONGEST WAA/MOISTURE TRANSPORT AHEAD OF NEB/KS UPR
   IMPULSE. THIS ACTIVITY SHOULD INCREASE IN COVERAGE/STRENGTH AND
   MOVE/DEVELOP GENERALLY ESE TOWARD THE MS RVR TODAY AS SFC HEATING
   FURTHER DESTABILIZES AREA ALONG AND N OF DIFFUSE OUTFLOW BOUNDARIES
   /SBCAPE INCREASING TO AROUND 4000 J PER KG/. AREA VWP DATA SHOW DEEP
   WIND PROFILES BACKING ATTM...BUT REMAINING STRONG...AHEAD OF THE
   NEB/KS DISTURBANCE. PROFILES SHOULD REMAIN FAVORABLE FOR SUPERCELLS
   AND OTHER SUSTAINED STRUCTURES THROUGH THE AFTN. THESE WILL BE
   CAPABLE OF VERY LARGE HAIL...HIGH WIND...AND TORNADOES. DEPTH OF
   STRONG...LARGELY UNIDIRECTIONAL CLOUD-LAYER FLOW AND DEGREE OF
   LOW-LVL BUOYANCY ALSO SUGGEST THAT SETUP WILL REMAIN FAVORABLE FOR
   BOW-ECHOES AND MORE CONTINUOUS SWATHS OF DMGG WIND. THIS ACTIVITY
   MAY FURTHER AMALGAMATE INTO A DERECHO-PRODUCING MCS THAT CONTINUES
   E/ESE INTO IL BY EVE.  

   FARTHER DOWNSTREAM FROM THESE STORMS...BUOYANCY WILL REMAIN SOMEWHAT
   MORE LIMITED THIS AFTN E/SEWD INTO THE LWR OH VLY.
   NEVERTHELESS...SOME POTENTIAL WILL EXIST FOR DIURNAL STORM
   DEVELOPMENT OVER IL/IND THROUGH THE AFTN IN RESPONSE TO SFC HEATING
   AND STRENGTHENING/MOIST SW LOW LVL FLOW AHEAD OF NEB/KS IMPULSE.
   THESE STORMS COULD PRODUCE LOCALLY DMGG WIND/SVR HAIL.

   ...S CNTRL PLNS THIS AFTN/TNGT...
   STRONG HEATING OF MOIST...VERY UNSTABLE /SBCAPE AOA 4000 J PER KG/
   AIR AHEAD OF COLD FRONT AND SWD ALONG LEE TROUGH/DRY LINE WILL
   LIKELY RESULT IN RAPID DEVELOPMENT OF INTENSE STORMS SWWD ALONG
   THESE BOUNDARIES BY MID TO LATE AFTN AS EML CAP IS BREACHED BY
   LOW-LVL UPLIFT. AMPLE /40+ KT/ WSWLY DEEP SHEAR WILL EXIST IN KS FOR
   SUPERCELLS WITH LARGE HAIL/SVR WIND AND TORNADOES. DEVELOPMENT ALSO
   WILL BE FOSTERED BY ASCENT WITH NEB/KS UPR IMPULSE. FARTHER
   S...SOMEWHAT WEAKER SHEAR AMIDST VERY STRONG INSTABILITY SUGGESTS A
   MORE MULTICELLULAR/TRANSIENT SUPERCELL MODES WITH SWD EXTENT...BUT
   WITH A CONTINUED THREAT FOR SVR HAIL/WIND/ISOLD TORNADOES. THESE
   STORMS MAY EVOLVE INTO ONE OR TWO SE-MOVING CLUSTERS WITH EMBEDDED
   BOWING STRUCTURES BY LATE EVE.

   ..CORFIDI/MOSIER.. 06/30/2014

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