Jun 7, 2007 1300 UTC Day 1 Convective Outlook
Updated: Thu Jun 7 15:35:17 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Public Severe Weather Outlook

The SPC is forecasting ...high risk of severe thunderstorms expected over parts of the upper mississippi river valley and the western great lakes later today and tonight....   Please read the latest public statement about this event.

Categorical Graphic
20070607 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20070607 1300 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20070607 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20070607 1300 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 071235
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0735 AM CDT THU JUN 07 2007
   
   VALID 071300Z - 081200Z
   
   ...THERE IS A HIGH RISK OF SVR TSTMS OVER MUCH OF WI INTO ERN
   MN...NERN IA...NWRN IL...WRN UP OF MI...
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS A LARGER PORTION OF THE
   UPPER/MIDDLE MS RIVER VALLEY INTO THE GREAT LAKES...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES INTO THE
   SRN PLAINS...
   
   ...NRN MS RIVER VALLEY INTO THE WRN/CENTRAL GREAT LAKES...
   SEVERE THUNDERSTORM/TORNADO OUTBREAK STILL APPEARS LIKELY SPREADING
   ACROSS THE NRN MS RIVER VALLEY INTO THE WRN GREAT LAKES THIS
   AFTERNOON AND EVENING...WITH STORMS MOVING RAPIDLY ENEWD AND
   DEVELOPING SSWWD THROUGH THE EVENING AND OVERNIGHT.  NUMEROUS
   PARAMETERS CONTINUE TO SUPPORT LONG-LIVED SUPERCELLS AND RAPIDLY
   MOVING BOW ECHOES ACROSS THIS REGION.  HOWEVER...THERE IS STILL SOME
   CONCERN ABOUT LOW LEVEL MOISTURE EARLY THIS MORNING WITH MUCH OF THE
   AREA YET TO TAP INTO RICHER GULF MOISTURE RETURN NOW EXTENDING OUT
   OF THE SRN PLAINS INTO ERN KS/NWRN MO.  HOWEVER...EXTREME SSWLY LOW
   LEVEL FLOW AND DOWNWARD MIXING UNDER STRONG CAP SHOULD SUPPORT AT
   LEAST 5F SURFACE DEW POINT JUMP BY THE LATE MORNING INTO ERN MN/WRN
   WI /12Z MPX SOUNDINGS INDICATED H85 DEW POINT NEAR 15C/. 
   THUS...EXPECT AXIS OF LOWER TO MID 60F SURFACE DEW POINTS WILL BE IN
   PLACE AHEAD OF VERY STRONG LOW PRESSURE SYSTEM AND ASSOCIATED DRY
   LINE/SURFACE FRONT EXPECTED TO SURGE EWD ACROSS MN THIS MORNING. 
   HOWEVER...FORECAST SOUNDINGS CONTINUE TO INDICATE LOW LEVEL MOISTURE
   WILL BE SUFFICIENT FOR MODERATE MLCAPE /1000-2000 J PER KG/ THIS
   AFTERNOON. 
   
   HIGHLY ELEVATED CLUSTERS HAVE PERSISTED ALONG NOSE OF 90 KT LLJ
   EARLY THIS MORNING WITH SEVERAL REPORTS OF LARGE HAIL FROM THIS
   ACTIVITY OVERNIGHT WITHIN VERY LITTLE MUCAPE.  THIS IS INDICATIVE OF
   BOTH STRENGTH OF ASCENT AND STEEPNESS OF LAPSE RATES ALREADY
   OVERSPREADING THE REGION.  DEVELOPMENT OF SURFACE BASED SEVERE WILL
   MOST LIKELY OCCUR WITHIN STRONG ASCENT AND WEAKENING CAP OVER
   CENTRAL/NRN MN EARLY THIS AFTERNOON...POSSIBLY BY 18Z.  ACTIVITY
   WILL THEN CONTINUE TO INCREASE IN COVERAGE AND INTENSITY AS DRY
   LINE/SURFACE FRONT SURGES EWD ACROSS THE MS RIVER VALLEY...AND
   BUILDS SWWD INTO ERN/CENTRAL IA AND FAR NERN MO AS CAP BREAKS ALONG
   THIS PORTION OF FRONT BY 21Z.  FORECAST SOUNDINGS CONTINUE TO
   INDICATE EXTREME LOW AND DEEP LAYER SHEAR WITH EFFECTIVE SHEAR IN
   EXCESS OF 70 KT AND SFC-1 KM SRH GREATER THAN 100 M2/S2 IN MOST
   LOCATIONS.  IN ADDITION...STORM MOTIONS OF 50-60 KT WILL BE COMMON. 
   THEREFORE...TORNADOES AND WIND DAMAGE WILL LIKELY ACCOMPANY FAST
   MOVING LINES/SUPERCELLS.  VERY LARGE HAIL SHOULD ALSO OCCUR WITH THE
   MORE INTENSE CORES.  THREATS OF A FEW SIGNIFICANT TORNADOES...ALONG
   WITH WIDESPREAD WIND DAMAGE... WARRANT THE HIGH RISK.  ACTIVITY WILL
   LIKELY PERSIST WELL INTO THE NIGHT AS INTENSE LLJ AND UPPER SYSTEM
   SHIFT EWD.  SEVERE THREAT IS EXPECTED TO OVERSPREAD MUCH OF THE
   CENTRAL GREAT LAKES AFTER DARK.
   
   ...MID MS RIVER VALLEY SSWWD INTO SRN PLAINS...
   MODELS CONTINUE TO INDICATE RAPID THUNDERSTORM DEVELOPMENT ALONG
   THIS PORTION OF FRONT/DRY LINE INTO WRN MO/FAR ERN KS AND NERN OK
   ...POSSIBLY AS EARLY AS 00Z. STORMS ARE EXPECTED TO BECOME MORE
   WIDESPREAD AFTER DARK ACROSS THIS REGION. LOWER 70F SURFACE DEW
   POINTS ARE EXPECTED TO SPREAD NNEWD OUT OF SRN OK THROUGH THE DAY. 
   HEATING WILL BE RETARDED FOR MUCH OF THE DAY BY EXISTING CLOUDS. 
   HOWEVER...CLOUDS WILL LIKELY BREAK UP LATER TODAY AND ALLOW A VERY
   UNSTABLE AIR MASS TO DEVELOP DESPITE THE MODEST LAPSE RATES IN
   PLACE.  THOUGH DEVELOPMENT IS EXPECTED TO BE MORE ISOLATED/
   CONDITIONAL ACROSS THIS REGION BEFORE DARK...BROAD AREA OF STRONG
   MID LEVEL WSWLY FLOW AND SWLY H85 FLOW IN EXCESS OF 40 KT WILL
   SUPPORT IMPRESSIVE HODOGRAPHS.  THUS...SUPERCELLS AND ORGANIZED
   CLUSTERS ARE EXPECTED WITH THE POTENTIAL FOR SOME VERY LARGE HAIL. 
   SHOULD STORMS FULLY BREAK CAP INTO THE EARLY EVENING...TORNADOES AND
   WIND DAMAGE ARE CERTAINLY POSSIBLE WITH THIS ACTIVITY WHICH SHOULD
   RACE ENEWD AT AROUND 40 KT.
   
   ..EVANS/TAYLOR.. 06/07/2007
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z