Jun 18, 2014 1630 UTC Day 1 Convective Outlook
Updated: Wed Jun 18 16:27:39 UTC 2014 (20140618 1630Z Day 1 shapefile | 20140618 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140618 1630 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 668,486 71,701,119 Chicago, IL...Detroit, MI...Indianapolis, IN...Columbus, OH...Baltimore, MD...
Probabilistic Tornado Graphic
20140618 1630 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 % 18,622 131,396 Mitchell, SD...Huron, SD...Madison, SD...
5 % 78,986 1,402,232 Sioux Falls, SD...Sioux City, IA...Bismarck, ND...Mason City, IA...Fort Dodge, IA...
2 % 328,229 51,721,827 Chicago, IL...Detroit, MI...Indianapolis, IN...Columbus, OH...Milwaukee, WI...
Probabilistic Damaging Wind Graphic
20140618 1630 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
30 % 107,857 23,124,539 Chicago, IL...Columbus, OH...Cleveland, OH...Pittsburgh, PA...Toledo, OH...
15 % 559,150 49,479,674 Detroit, MI...Indianapolis, IN...Baltimore, MD...Milwaukee, WI...Washington, DC...
5 % 416,704 47,755,926 New York, NY...Philadelphia, PA...Charlotte, NC...Kansas City, KS...Kansas City, MO...
Probabilistic Large Hail Graphic
20140618 1630 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 49,682 912,408 Sioux Falls, SD...Sioux City, IA...Norfolk, NE...Aberdeen, SD...Watertown, SD...
30 % 50,537 622,138 Sioux Falls, SD...Bismarck, ND...Aberdeen, SD...Watertown, SD...Brookings, SD...
15 % 603,595 71,033,415 Chicago, IL...Detroit, MI...Indianapolis, IN...Columbus, OH...Baltimore, MD...
5 % 470,780 51,120,979 New York, NY...Philadelphia, PA...Charlotte, NC...Kansas City, KS...Kansas City, MO...
   SPC AC 181624

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1124 AM CDT WED JUN 18 2014

   VALID 181630Z - 191200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE GREAT PLAINS
   THROUGH THE GREAT LAKES AND OH VALLEY TO MID ATLANTIC...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED OVER MUCH OF THE NORTHERN AND
   CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY...AND FROM THE
   MID-MISSISSIPPI VALLEY AND SOUTHERN GREAT LAKES EASTWARD INTO THE
   MID-ATLANTIC STATES. MORE ISOLATED SEVERE STORMS MAY OCCUR FROM
   WESTERN AND CENTRAL KANSAS SOUTHWARD INTO WEST TEXAS. LARGE HAIL AND
   DAMAGING WINDS WILL BE THE MAIN THREATS...BUT TORNADOES ALSO MAY
   OCCUR...ESPECIALLY OVER PARTS OF SOUTH DAKOTA.

   ...SYNOPSIS...

   A MID TO UPPER-LEVEL LOW AND ASSOCIATED TROUGH FROM THE NRN
   INTER-MOUNTAIN REGION TO SWRN DESERTS WILL ASSUME AN INCREASING
   NEGATIVE TILT IN RESPONSE TO THE PROGRESSION OF A POTENT VORTICITY
   MAXIMUM FROM THE GREAT BASIN INTO NRN HIGH PLAINS. DOWNSTREAM FROM
   THESE DEVELOPMENTS...A SERIES OF VORTICITY MAXIMA WILL PROGRESS SEWD
   AROUND AN UPPER LOW CENTERED OVER FAR NERN CANADA...ENHANCING
   MIDLEVEL FLOW AND FORCING FOR ASCENT ACROSS THE NERN U.S. 

   AT THE SURFACE...AN AREA OF LOW PRESSURE OVER CNTRL NEB WILL DEVELOP
   NEWD INTO NERN SD/SERN ND BY 19/12Z...WHILE AN ASSOCIATED COLD FRONT
   ADVANCES EWD THROUGH THE DAKOTAS...AND SEWD THROUGH THE CNTRL HIGH
   PLAINS. A DRYLINE WILL SHARPEN TODAY FROM THE VICINITY OF THIS LOW
   PRESSURE SSWWD THROUGH WRN OR CNTRL KS INTO WRN TX. MEANWHILE...A
   WARM FRONT WHICH HAS BEEN REINFORCED BY CONVECTIVE OUTFLOW WILL
   ATTEMPT TO MOVE NWD THROUGH PARTS OF THE MID MO VALLEY AND MIDWEST.
   THE LOCATION OF THIS BOUNDARY WILL LIKELY FLUCTUATE LATITUDINALLY
   ACROSS THE SRN GREAT LAKES/NRN OH VALLEY OWING TO THE EFFECTS OF
   CONVECTIVE OUTFLOW. FARTHER E...THIS BOUNDARY WILL SLOWLY SETTLE SWD
   INTO THE MID ATLANTIC STATES AS A COLD FRONT. 

   ...DAKOTAS/MID MO VALLEY THIS AFTERNOON INTO TONIGHT...

   THE CO-LOCATION OF A VERY MOIST BOUNDARY LAYER WITH A PRONOUNCED EML
   WILL ONCE AGAIN YIELD STRONG TO EXTREME INSTABILITY TODAY FROM PARTS
   OF ERN NEB/WRN IA INTO SERN SD WITH MLCAPE APPROACHING 3000-4500
   J/KG. WHERE STRONGER HEATING CAN OCCUR FROM CNTRL SD INTO ND ALONG
   THE EWD-MOVING COLD FRONT OR INVERTED TROUGH...AFTERNOON MLCAPE MAY
   RISE INTO THE 1000-2000 J/KG RANGE.

   THE ERN EDGE OF HEIGHT FALLS/FORCING FOR ASCENT ATTENDANT TO THE
   UPPER TROUGH EDGING EWD INTO THE NRN HIGH PLAINS WILL ENHANCE
   DEEP-LAYER ASCENT ALONG THE INVERTED TROUGH/COLD FRONT TO FOSTER
   WIDELY SCATTERED SURFACE-BASED TSTMS THIS AFTERNOON FROM CNTRL SD
   INTO PARTS OF WRN/CNTRL ND. OTHER MORE ISOLATED STORMS WILL BE
   POSSIBLE THIS AFTERNOON INTO EVENING AHEAD OF THE SURFACE LOW AND
   ALONG THE WARM FRONT OVER SERN SD INTO SWRN MN/NWRN IA. THE MOST
   FAVORABLE OVERLAP OF VERTICAL SHEAR AND INSTABILITY WILL RESIDE FROM
   S-CNTRL ND INTO CNTRL SD WHERE SUPERCELLS CAPABLE OF LARGE
   HAIL...DAMAGING WINDS A FEW TORNADOES ARE POSSIBLE. 

   FARTHER E ALONG THE WARM FRONT...STRONGER VERTICAL SHEAR WILL
   LARGELY BE CONFINED TO THE LOWEST 3-4 KM WITH GENERALLY WEAK FLOW IN
   THE UPPER TROPOSPHERE. NONETHELESS...THE PRESENCE OF EXTREME
   INSTABILITY AND AMPLE LOW-LEVEL SHEAR INVOF OF THE SURFACE LOW AND
   WARM FRONT SUGGEST A VERY LARGE HAIL AND TORNADO THREAT GIVEN STORM
   DEVELOPMENT AND SUSTENANCE.

   ...CNTRL/SRN PLAINS THIS AFTERNOON/EVENING...

   MORNING WATER VAPOR IMAGERY INDICATES THE PRESENCE OF A WEAK
   PERTURBATION OVER NM WHICH WILL PRECEDE THE STRONGER GREAT BASIN
   IMPULSE INTO THE CNTRL/SRN HIGH PLAINS TODAY. FORCING FOR ASCENT
   ASSOCIATED WITH THIS FEATURE WILL LIKELY PROMOTE WIDELY SCATTERED
   TSTM DEVELOPMENT ALONG THE DRYLINE THIS AFTERNOON FROM PORTIONS OF
   S-CNTRL NEB/N-CNTRL KS INTO WRN TX. THE 12Z ABQ SOUNDING SAMPLED 40
   KT SWLY FLOW IN THE 4-5 KM AGL LAYER WHICH SHOULD ENHANCE VERTICAL
   SHEAR AMIDST A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY MLCAPE OF
   2000-3000+ J/KG. AS SUCH...THE POTENTIAL WILL EXIST FOR SUPERCELL
   AND ORGANIZED MULTICELL MORPHOLOGIES WITH A RISK FOR DAMAGING WINDS
   AND LARGE HAIL.

   A SEPARATE AREA OF TSTMS MAY EVOLVE THIS AFTERNOON WITHIN AN
   INCREASING LOW-LEVEL UPSLOPE REGIME DEVELOPING WITHIN THE
   POST-FRONTAL ENVIRONMENT FROM THE CHEYENNE RIDGE TO PALMER DIVIDE.
   AMPLE VERTICAL SHEAR AND SUFFICIENT BUOYANCY WILL EXIST FOR
   ORGANIZED STORMS INCLUDING SUPERCELLS WITH A LARGE HAIL AND DAMAGING
   WIND THREAT DEVELOPING FROM SERN WY/NERN CO INTO PARTS OF WRN NEB BY
   LATE THIS EVENING.

   ...GREAT LAKES/MIDWEST INTO MID ATLANTIC THIS AFTERNOON INTO
   TONIGHT...

   REGIONAL RADAR IMAGERY SHOWS A WELL-DEFINED BOW ECHO AND ASSOCIATED
   MCV OVER WI AND ADJACENT LAKE MI WITH THE TRAILING EXTENSION OF THIS
   SYSTEM STRETCHING INTO NRN IL. EXPECT THIS MCS TO CONTINUE ESEWD
   TODAY...LIKELY INCREASING IN INTENSITY ALONG ITS SRN FLANK INVOF THE
   SURFACE FRONT WHERE DAYTIME HEATING AND BOUNDARY-LAYER DEWPOINTS IN
   THE UPPER 60S TO LOWER 70S WILL BOOST MLCAPE TO 2000-3000+ J/KG.
   WHEN COUPLED WITH A UNIDIRECTIONAL WIND PROFILE WITH MODEST
   DEEP-LAYER SPEED SHEAR...THE SETUP WILL BE SUPPORTIVE OF DAMAGING
   WINDS AND SOME HAIL.

   PERSISTENT LOW-LEVEL WAA IN THE WAKE OF THIS MCS MAY SUPPORT RENEWED
   TSTM DEVELOPMENT LATER TODAY INTO TONIGHT ALONG AND TO THE N OF THE
   OUTFLOW-WARM FRONT COMPOSITE BOUNDARY OVER PORTIONS OF
   IA...IL...SERN MN...WI WHERE SOME LARGE HAIL AND/OR DAMAGING WINDS
   ARE POSSIBLE. 

   FARTHER TO THE E FROM THE LOWER GREAT LAKES INTO MID
   ATLANTIC...CONVECTIVE EVOLUTION IS A BIT MORE UNCLEAR. HOWEVER...THE
   PRESENCE OF THE SYNOPTIC FRONT...CONVECTIVE OUTFLOW BOUNDARY
   ASSOCIATED WITH A RECENTLY DECAYED MCS OVER CNTRL PA AND GRADUAL
   HEIGHT FALLS ON THE SRN PERIPHERY OF THE ERN CANADA TROUGH MAY
   FOSTER WIDELY SCATTERED TSTMS THIS AFTERNOON INTO EVENING. MLCAPE OF
   1500-2500 J/KG COUPLED WITH STRENGTHENING MIDLEVEL FLOW AND
   RESULTANT VERTICAL SHEAR WILL BE SUPPORTIVE OF ORGANIZED STORM MODES
   CAPABLE OF DAMAGING WINDS AND LARGE HAIL.

   ..MEAD/MOSIER.. 06/18/2014

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