Jun 30, 2014 2000 UTC Day 1 Convective Outlook
Updated: Mon Jun 30 19:52:30 UTC 2014 (20140630 2000Z Day 1 shapefile | 20140630 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...Severe thunderstorms expected over parts of the Midwest into the lower Great Lakes this afternoon and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20140630 2000 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 78,435 17,022,838 Chicago, IL...Milwaukee, WI...Madison, WI...Aurora, IL...Rockford, IL...
SLIGHT 292,920 27,000,735 Indianapolis, IN...Kansas City, KS...Kansas City, MO...Omaha, NE...Wichita, KS...
Probabilistic Tornado Graphic
20140630 2000 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
10 % 27,159 1,505,549 Davenport, IA...Iowa City, IA...Moline, IL...Quincy, IL...Rock Island, IL...
5 % 109,123 22,869,175 Chicago, IL...Milwaukee, WI...Kansas City, KS...Kansas City, MO...Madison, WI...
2 % 145,244 15,538,461 Indianapolis, IN...Wichita, KS...St. Louis, MO...Fort Wayne, IN...Des Moines, IA...
Probabilistic Damaging Wind Graphic
20140630 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 86,234 17,275,212 Chicago, IL...Milwaukee, WI...Madison, WI...Aurora, IL...Rockford, IL...
45 % 79,503 17,025,985 Chicago, IL...Milwaukee, WI...Madison, WI...Aurora, IL...Rockford, IL...
30 % 99,929 10,787,629 Kansas City, KS...Kansas City, MO...Wichita, KS...St. Louis, MO...Grand Rapids, MI...
15 % 155,703 14,159,308 Indianapolis, IN...Fort Wayne, IN...Des Moines, IA...Amarillo, TX...Lansing, MI...
5 % 236,544 27,053,186 Detroit, MI...Columbus, OH...Charlotte, NC...Cleveland, OH...Omaha, NE...
Probabilistic Large Hail Graphic
20140630 2000 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 54,802 4,638,331 Kansas City, KS...Kansas City, MO...Wichita, KS...Overland Park, KS...Topeka, KS...
45 % 25,772 1,418,132 Cedar Rapids, IA...Davenport, IA...Iowa City, IA...Moline, IL...Rock Island, IL...
30 % 70,501 6,335,917 Kansas City, KS...Kansas City, MO...Wichita, KS...Overland Park, KS...Rockford, IL...
15 % 273,491 36,201,011 Chicago, IL...Indianapolis, IN...Milwaukee, WI...Omaha, NE...St. Louis, MO...
5 % 152,117 8,336,739 Detroit, MI...Toledo, OH...Louisville, KY...Lincoln, NE...Lubbock, TX...
   SPC AC 301952

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0252 PM CDT MON JUN 30 2014

   VALID 302000Z - 011200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF THE MIDWEST
   FROM ERN IA INTO SWRN LOWER MI/NWRN INDIANA...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
   LOWER MI...SWWD INTO THE TX PANHANDLE...

   ...SUMMARY...
   DAMAGING SQUALL LINE WITH WIND GUSTS POSSIBLY EXCEEDING 60-70 MPH
   WILL SPREAD ACROSS EASTERN IOWA AND NORTHERN ILLINOIS/SOUTHERN
   WISCONSIN BY 7PM.  SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED
   ACROSS THE SURROUNDING MIDWEST INTO THE CENTRAL AND SOUTHERN HIGH
   PLAINS OF THE TEXAS PANHANDLE.

   ...EASTERN IA/NORTHERN IL/SOUTHERN WI...

   CLUSTERS OF CONVECTION THAT ORIGINATED OVER THE MID MO VALLEY HAVE
   RECENTLY EVOLVED INTO A MATURE SQUALL LINE OVER EASTERN IA.  WHILE
   MULTIPLE STORM MODES WERE NOTED EARLIER IN THE CONVECTIVE
   EVOLUTION...IT APPEARS A WELL-ORGANIZED DAMAGING MCS WILL RACE
   ACROSS ERN IA INTO NRN IL/SRN WI OVER THE NEXT 4-5 HOURS.  LEADING
   EDGE OF THIS ACTIVITY IS SURGING EAST AT 50KT+ AND NUMEROUS MEASURED
   WIND GUSTS OF 50-64KT HAVE BEEN REPORTED IN THE LAST HOUR OR SO
   ACROSS IA.  IF SQUALL LINE CONTINUES TO ACCELERATE WIND SPEEDS COULD
   EASILY EXCEED 65KT AT THE APEX OF THIS EVOLVING BOW AS IT SPREADS
   INTO NRN IL.  GIVEN THE CURRENT SPEED/MOVEMENT IT SHOULD SPREAD INTO
   WESTERN PORTIONS OF METRO CHICAGO BETWEEN 5-6 PM.  DAMAGING WINDS
   ARE HIGHLY LIKELY WITH THIS CONVECTION.

   ELSEWHERE...EARLIER THOUGHTS REGARDING CONVECTIVE POTENTIAL REMAIN.

   ..DARROW.. 06/30/2014

   .PREV DISCUSSION... /ISSUED 1133 AM CDT MON JUN 30 2014/

   ...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.

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