Jul 21, 2014 1300 UTC Day 1 Convective Outlook
Updated: Mon Jul 21 12:56:48 UTC 2014 (20140721 1300Z Day 1 shapefile | 20140721 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...Severe thunderstorms expected over parts of the Northern Plains and Upper Mississippi Valley later today and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20140721 1300 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 63,509 1,451,420 Fargo, ND...St. Cloud, MN...Bismarck, ND...Grand Forks, ND...Moorhead, MN...
SLIGHT 126,619 5,570,386 Minneapolis, MN...St. Paul, MN...Rochester, MN...Duluth, MN...Bloomington, MN...
Probabilistic Tornado Graphic
20140721 1300 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
5 % 66,012 1,075,544 Fargo, ND...Bismarck, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...
2 % 79,374 4,330,013 Minneapolis, MN...St. Paul, MN...Duluth, MN...Bloomington, MN...Plymouth, MN...
Probabilistic Damaging Wind Graphic
20140721 1300 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 67,831 1,256,218 Fargo, ND...St. Cloud, MN...Bismarck, ND...Grand Forks, ND...Moorhead, MN...
45 % 62,597 1,368,698 Fargo, ND...St. Cloud, MN...Bismarck, ND...Grand Forks, ND...Moorhead, MN...
30 % 43,247 3,498,004 Minneapolis, MN...St. Paul, MN...Duluth, MN...Bloomington, MN...Plymouth, MN...
15 % 83,644 2,105,246 Rochester, MN...Eau Claire, WI...Lakeville, MN...Apple Valley, MN...Wausau, WI...
5 % 384,346 6,350,399 Madison, WI...Reno, NV...Amarillo, TX...Sioux Falls, SD...Green Bay, WI...
Probabilistic Large Hail Graphic
20140721 1300 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 37,646 557,486 Fargo, ND...Bismarck, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...
30 % 46,060 695,295 Fargo, ND...Bismarck, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...
15 % 137,023 6,063,131 Minneapolis, MN...St. Paul, MN...Rochester, MN...Duluth, MN...Bloomington, MN...
5 % 87,856 1,838,356 Sioux Falls, SD...Waterloo, IA...La Crosse, WI...Wausau, WI...Cedar Falls, IA...
   SPC AC 211256

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0756 AM CDT MON JUL 21 2014

   VALID 211300Z - 221200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF ND...SD...AND
   MN...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK
   AREA...FROM WRN ND ESEWD INTO WRN UPR MI AND CNTRL WI...

   ...SUMMARY...
   DAMAGING WINDS AND LARGE HAIL ARE LIKELY FROM NORTH DAKOTA INTO
   WESTERN AND NORTHERN MINNESOTA AND NORTHERN SOUTH DAKOTA THIS 
   AFTERNOON INTO TONIGHT. SOME WIND GUSTS COULD BE PARTICULARLY
   DAMAGING. OTHER STORMS WITH SEVERE WIND AND HAIL MAY OCCUR OVER
   REMAINDER OF MINNESOTA AND OVER PARTS OF WISCONSIN AND UPPER
   MICHIGAN. ISOLATED STORMS WITH STRONG WINDS WILL BE POSSIBLE ACROSS
   THE CENTRAL AND SOUTHERN HIGH PLAINS...AND OVER THE GREAT BASIN.

   ...SYNOPTIC SETUP...
   MODERATE WSW FLOW WILL PREVAIL ACROSS THE NRN RCKYS...THE NRN PLNS
   AND UPR MS VLY THIS PERIOD...ON NRN FLANK OF UPR RIDGE BUILDING NEWD
   FROM THE SRN RCKYS. WITHIN THIS FLOW...SATELLITE AND VWP DATA
   SUGGEST PRESENCE OF SEVERAL LOW-AMPLITUDE DISTURBANCES THAT WILL
   TRACK ACROSS THE REGION. ONE OF THESE...NOW OVER ERN WY...SHOULD
   CONTINUE ENE INTO THE ERN DAKOTAS BY EVE AND TO LK SUPERIOR BY 12Z
   TUE AS ANOTHER...STRONGER IMPULSE MOVES FROM SE BC TO SRN MB.

   AT THE SFC...WEAK FRONTAL SURGES INTO THE NRN PLNS IN RECENT DAYS
   HAVE BECOME NEARLY STNRY THIS MORNING OVER THE DAKOTAS/MN. THE
   WSW-ENE ORIENTED BOUNDARIES SHOULD REMAIN MORE OR LESS STNRY THROUGH
   THE DAY AS WEAK CYCLOGENESIS OCCURS IN NRN SD...LARGELY IN RESPONSE
   TO PASSING UPR IMPULSE. THIS WAVE SHOULD TRACK NE TO NEAR DULUTH BY
   12Z TUE...POSSIBLY AUGMENTED BY AN MCS-RELATED CIRCULATION OR MCV.

   ...NRN PLNS/UPR MS VLY TODAY/TNGT...
   A POOL OF VERY UNSTABLE AIR /MLCAPE AOA 5000 J PER KG/ WILL EMERGE
   WITH STRONG SFC HEATING AND CONTINUED EVAPOTRANSPIRATION EXPECTED
   TODAY INVOF WEAK FRONTS STALLED WSW-ENE OVER ND AND CNTRL/NRN MN.
   CURRENT SFC AND SATELLITE DATA SUGGEST THAT COMBINATION OF HEATING
   AND ASCENT WITH WY IMPULSE COULD INITIATE STORMS BY MID TO LATE AFTN
   IN PARTS OF WRN AND CNTRL ND...WHERE LOW-LVL CONVERGENCE SHOULD BE
   MAXIMIZED ALONG AND N OF THE BOUNDARIES.

   GIVEN DEGREE OF BUOYANCY...THE STORMS LIKELY WILL QUICKLY BECOME SVR
   AS STORM OUTFLOW PREFERENTIALLY SPREADS E OR ENEWD. VERY LARGE
   HAIL...LOCALLY DMGG WIND...AND A COUPLE TORNADOES MAY OCCUR AS
   SUSTAINED STORMS...INCLUDING INTENSE MULTICELLS AND A FEW
   SUPERCELLS...ORGANIZE INTO CLUSTERS. A MORE ORGANIZED DAMAGING
   WIND/POTENTIAL DERECHO THREAT MAY DEVELOP BY EVE AS STORMS CONTINUE
   TO MERGE/DEVELOP EWD INTO ERN ND AND NRN/WRN MN. VERY STEEP MID-LVL
   LAPSE RATES ASSOCIATED WITH STOUT EML INITIALLY MAY LIMIT ANY SEWD
   PROPAGATIONAL COMPONENT TO THE CONVECTIVE SYSTEM...ALTHOUGH WITH
   TIME AND EWD EXTENT...THE MCS AND ITS ASSOCIATED WIND THREAT
   ULTIMATELY COULD EXPAND A BIT SEWD...PERHAPS AS FAR AS NRN/WRN WI
   EARLY TUE.

   FARTHER S...A MORE CONDITIONAL/SPORADIC SVR THREAT MAY DEVELOP FOR
   ISOLD SVR STORMS ALONG MIDDLE AND ERN PORTIONS OF THE LOW-LVL
   MOISTURE AXIS FROM NE SD SEWD INTO S CNTRL MN/NE IA LATER TODAY INTO
   TNGT. STRONG EML CAP SHOULD LIMIT COVERAGE. BUT GIVEN VERY  STRONG
   INSTABILITY...A CONDITIONAL RISK FOR SVR HAIL...WIND...AND PERHAPS A
   TORNADO WILL EXIST.

   ...CNTRL/SRN HIGH PLNS THIS AFTN/EVE...
   VERY STRONG HEATING ALONG LEE TROUGH/DRY LINES SEGMENTS BENEATH THE
   UPR RIDGE WILL YIELD INVERTED-V SOUNDINGS WITH 500-1000 J/KG MUCAPE
   FROM WRN NEB SSW INTO ERN NM/W TX. SHEAR WILL BE WEAK.  BUT ISOLD TO
   PERHAPS WDLY SCTD STORMS APPEAR LIKELY LATE THIS AFTN/EVE...AND
   THOSE THAT DO FORM WILL BE CAPABLE OF LOCALLY STRONG TO SVR WIND
   GUSTS.

   ..CORFIDI/MOSIER.. 07/21/2014

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z