The SPC is forecasting ...Severe thunderstorms expected over parts of the middle Missouri Valley and upper Midwest later today and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

   SPC AC 161628

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CDT MON JUN 16 2014

   VALID 161630Z - 171200Z

   ...THERE IS A MDT RISK OF SVR TSTMS FROM SERN SD AND PARTS OF ERN
   NEB THROUGH SRN MN...NRN/CNTRL IA INTO SWRN WI...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE NRN AND CNTRL
   PLAINS INTO UPPER MIDWEST...

   ...SUMMARY...
   SEVERE THUNDERSTORMS CAPABLE OF POTENTIALLY WIDESPREAD DAMAGING
   WIND...VERY LARGE HAIL AND TORNADOES...A COUPLE OF WHICH COULD BE
   SIGNIFICANT...WILL OCCUR TODAY INTO TONIGHT FROM PARTS OF SOUTHEAST
   SOUTH DAKOTA AND CENTRAL AND EASTERN NEBRASKA EASTWARD ACROSS MUCH
   OF IOWA...SOUTHERN MINNESOTA...INTO WISCONSIN.

   ...SYNOPSIS...

   A TROUGH OVER THE WRN U.S. WILL INTENSIFY DURING THE DAY ONE PERIOD
   IN RESPONSE TO THE EQUATORWARD PROGRESSION OF MID AND UPPER-LEVEL
   JET STREAKS FROM THE FAR NERN PACIFIC INTO THE TROUGH BASE OVER THE
   GREAT BASIN. DOWNSTREAM FROM THESE DEVELOPMENTS...MORNING WATER
   VAPOR IMAGERY INDICATES A LOW-AMPLITUDE SHORT-WAVE TROUGH
   PROGRESSING INTO THE NRN AND CNTRL PLAINS WITH THIS FEATURE
   CONTINUING ENEWD INTO THE UPPER GREAT LAKES BY LATE TONIGHT/EARLY
   TUESDAY.

   AT THE SURFACE...A LEE CYCLONE OVER WRN SD WILL DEVELOP EWD ALONG A
   NWD-MOVING WARM FRONT INTO CNTRL MN BY 17/00Z BEFORE REACHING NRN WI
   BY 17/12Z. MEANWHILE...SECONDARY LOW PRESSURE OVER NERN CO WILL
   DEVELOP INTO SWRN NEB WHILE A DRYLINE SLOWLY MIXES EWD OVER THE
   CNTRL AND SRN HIGH PLAINS.

   ...NRN/CNTRL PLAINS INTO UPPER MIDWEST TODAY THROUGH TONIGHT...

   12Z OBSERVED SOUNDINGS FROM LBF...DDC...AND TOP SHOWED A VERY MOIST
   BOUNDARY LAYER WITH LOWEST-100-MB MEAN-MIXING RATIOS OF 14-15 G PER
   KG SURMOUNTED BY 700-500-MB LAPSE RATES OF 8-9 C/KM. DIFFERENTIAL
   ADVECTIONS ASSOCIATED WITH A NEWD-MIGRATING 40-50 KT LLJ AND
   STRENGTHENING SWLY FLOW IN THE 700-500-MB LAYER WILL RESULT IN THE
   DEVELOPMENT OF A SIMILAR THERMODYNAMIC STRATIFICATION INTO THE MID
   MO VALLEY TODAY WITH AFTERNOON MLCAPE VALUES OF 3000-4000+ J/KG TO
   THE S OF THE WARM FRONT.

   SEVERE TSTMS HAVE DEVELOPED THIS MORNING FROM THE VICINITY OF THE
   WARM FRONT OVER ERN SD SWD INTO THE WARM SECTOR OVER ERN NEB WITH
   THIS ACTIVITY LIKELY BEING FORCED BY WAA ALONG THE LLJ AND FORCING
   FOR ASCENT ATTENDANT TO THE ABOVE-MENTIONED SHORT-WAVE TROUGH MOVING
   INTO THE NRN AND CNTRL PLAINS. GIVEN THE CONTINUED INFLUX OF THE
   MODERATE TO STRONGLY UNSTABLE AIR MASS FROM THE S/SW...EXPECT A
   SUBSET OF THESE STORMS TO EVOLVE INTO A FORWARD PROPAGATING MCS
   /WITH EMBEDDED SUPERCELL AND BOWING STRUCTURES/ WITH THE RISK FOR
   VERY LARGE HAIL...TORNADOES...AND POTENTIALLY WIDESPREAD DAMAGING
   WINDS AFFECTING PORTIONS OF SRN MN AND IA THROUGH THIS
   AFTERNOON...AND EVENTUALLY INTO PARTS OF WI AND NRN IL THIS EVENING
   INTO TONIGHT.

   OTHER MORE ISOLATED STORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON
   FROM WRN SD TO N-CNTRL KS AS LOW-LEVEL CONVERGENCE IS ENHANCED BY
   THE DEEPENING SURFACE LOW OVER SWRN NEB. THE CO-LOCATION OF MODERATE
   TO STRONG INSTABILITY WITH VERTICALLY VEERING WIND PROFILES WITH
   35-50 KT OF EFFECTIVE BULK SHEAR WILL BE QUITE FAVORABLE FOR
   SUPERCELLS CAPABLE OF VERY LARGE HAIL...AND TORNADOES...A COUPLE OF
   WHICH COULD BE SIGNIFICANT. THE GREATEST TORNADO RISK MAY
   MATERIALIZE WITH ANY MATURE SUPERCELLS THAT CAN FAVORABLY INTERACT
   WITH THE OUTFLOW BOUNDARY GENERATED BY THE EARLY-DAY STORMS OVER ERN
   PARTS OF SD/NEB.

   ...OH VALLEY TO MID ATLANTIC THIS AFTERNOON/EVENING...

   TSTMS HAVE FORMED THIS MORNING ACROSS SRN PARTS OF IL/IND INTO CNTRL
   OH...PERHAPS IN RESPONSE TO THE GLANCING INFLUENCE OF A SHORT-WAVE
   TROUGH MOVING THROUGH THE UPPER GREAT LAKES. ABUNDANT SUNSHINE
   COUPLED WITH BOUNDARY LAYER DEWPOINTS IN THE 60S AND A MODESTLY
   STRONG UNIDIRECTIONAL WIND PROFILE MAY SUPPORT A GRADUAL
   INTENSIFICATION OF STORMS BY AFTERNOON FARTHER DOWNSTREAM WITH A
   RISK FOR LOCALLY STRONG WIND GUSTS.

   ADDITIONAL STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE THIS
   AFTERNOON OVER THE MID ATLANTIC AS FORCING FOR ASCENT IS ENHANCED BY
   A WEAK VORTICITY MAXIMUM CURRENTLY OVER THE UPPER OH VALLEY WHICH
   SHOULD TURN SE. VERTICAL SHEAR WILL REMAIN RATHER WEAK...BUT THE
   PRESENCE OF A MOIST...MODERATELY UNSTABLE AIR MASS MAY PROMOTE A FEW
   SEVERE STORMS CAPABLE OF STRONG WINDS.

   ...CNTRL MT THIS AFTERNOON/EVENING...

   A SERIES OF WEAK PERTURBATIONS WILL ROTATE AROUND THE PARENT UPPER
   LOW OVER THE PACIFIC NW...ENHANCING VERTICAL SHEAR AND FORCING FOR
   ASCENT ACROSS THE REGION. COOL MIDLEVEL TEMPERATURES COUPLED WITH
   SOME DAYTIME HEATING ALONG AN INVERTED TROUGH MAY PROMOTE POCKETS OF
   WEAK INSTABILITY AND THE POTENTIAL FOR ISOLATED SEVERE STORMS LATER
   TODAY.

   ...FL THIS AFTERNOON...

   SEASONABLY COOL MIDLEVEL TEMPERATURES IN CONCERT WITH A VERY MOIST
   AIR MASS WILL YIELD MODERATE AFTERNOON INSTABILITY WITH MLCAPE OF
   1500-2500+ J/KG. CONVERGENCE/UPLIFT ALONG DEVELOPING SEA BREEZE
   FRONTS WILL BE AUGMENTED BY THE PRESENCE OF A SWWD-MOVING VORTICITY
   MAXIMUM TO FOSTER SCATTERED TO NUMEROUS AFTERNOON STORMS CAPABLE OF
   ISOLATED DAMAGING WIND GUSTS.

   ...WRN TX THIS AFTERNOON/EVENING...

   STRONG HEATING ALONG THE DRYLINE MAY SUPPORT ISOLATED TSTM
   DEVELOPMENT LATER TODAY AMIDST A STEEP-LAPSE-RATE ENVIRONMENT WITH
   MLCAPE OF 2000-3000 J/KG. WHILE VERTICAL SHEAR WILL REMAIN
   WEAK...THE DEGREE OF INSTABILITY WILL PROMOTE STRONG UP/DOWNDRAFTS
   CAPABLE OF DAMAGING WINDS AND LARGE HAIL.

   ..MEAD/GUYER.. 06/16/2014

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z