Jul 27, 2015 2000 UTC Day 1 Convective Outlook
Updated: Mon Jul 27 19:36:19 UTC 2015 (20150727 2000Z Day 1 shapefile | 20150727 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150727 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 72,700 390,890 Bismarck, ND...Minot, ND...Mandan, ND...Dickinson, ND...Williston, ND...
SLIGHT 191,732 2,030,979 Sioux Falls, SD...Fargo, ND...Sioux City, IA...Rapid City, SD...Grand Forks, ND...
MARGINAL 217,456 6,447,132 Omaha, NE...Lincoln, NE...Des Moines, IA...Billings, MT...Bloomington, MN...
Probabilistic Tornado Graphic
20150727 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 23,124 137,622 Minot, ND...Williston, ND...Sidney, MT...
2 % 267,438 3,760,556 Omaha, NE...Lincoln, NE...Sioux Falls, SD...Billings, MT...Fargo, ND...
Probabilistic Damaging Wind Graphic
20150727 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 57,149 326,162 Bismarck, ND...Minot, ND...Mandan, ND...Dickinson, ND...Williston, ND...
30 % 72,405 390,617 Bismarck, ND...Minot, ND...Mandan, ND...Dickinson, ND...Williston, ND...
15 % 190,783 2,024,771 Sioux Falls, SD...Fargo, ND...Sioux City, IA...Rapid City, SD...Grand Forks, ND...
5 % 218,811 6,460,315 Omaha, NE...Lincoln, NE...Des Moines, IA...Billings, MT...Bloomington, MN...
Probabilistic Large Hail Graphic
20150727 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 56,618 321,817 Bismarck, ND...Minot, ND...Mandan, ND...Dickinson, ND...Williston, ND...
30 % 56,510 321,908 Bismarck, ND...Mandan, ND...Dickinson, ND...Williston, ND...Sidney, MT...
15 % 163,121 1,561,527 Sioux Falls, SD...Sioux City, IA...Rapid City, SD...Grand Island, NE...Minot, ND...
5 % 169,459 4,256,402 Omaha, NE...Lincoln, NE...Fargo, ND...Plymouth, MN...Eden Prairie, MN...
   SPC AC 271936

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0236 PM CDT MON JUL 27 2015

   VALID 272000Z - 281200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS FAR ERN MT AND INTO ND
   AND PARTS OF NWRN/N CENTRAL SD...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN PLAINS REGION...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE N CENTRAL U.S. AND
   SWD ACROSS THE CENTRAL HIGH PLAINS...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS WITH THE POTENTIAL FOR VERY LARGE
   HAIL...DAMAGING WIND GUSTS...AND A COUPLE OF TORNADOES ARE EXPECTED
   OVER PARTS OF THE WESTERN DAKOTAS AND FAR EASTERN MONTANA LATE THIS
   AFTERNOON INTO THE EVENING. THE RISK FOR SEVERE THUNDERSTORMS WILL
   BE LESS...BUT STILL PRESENT...ELSEWHERE ACROSS THE CENTRAL AND
   NORTHERN GREAT PLAINS EASTWARD TO THE UPPER MISSISSIPPI VALLEY
   THROUGH TONIGHT.

   ...20Z UPDATE...

   THE PREVIOUS OUTLOOK REMAINS ON TRACK AND NO CHANGES HAVE BEEN MADE
   THIS UPDATE CYCLE. CAPPING STILL REMAINS OVER THE SLIGHT AND
   ENHANCED RISK AREA AS IS EVIDENT IN THE 19Z GGW RAOB. AS UPPER
   FORCING AND HEIGHT FALLS CONTINUE TO SHIFT EASTWARD WITH THE UPPER
   TROUGH OVER THE NORTHERN ROCKIES...ADDITIONAL HEATING/MIXING SHOULD
   RESULT IN ISOLATED TO WIDELY SCATTERED THUNDERSTORM DEVELOPMENT BY
   00Z AND INCREASE IN COVERAGE/INTENSITY THEREAFTER. FOR FURTHER
   DETAILS...SEE PREVIOUS OUTLOOK DISCUSSION.

   ..LEITMAN.. 07/27/2015

   .PREV DISCUSSION... /ISSUED 1130 AM CDT MON JUL 27 2015/

   ...SYNOPSIS...
   AS WEAK MID-LEVEL TROUGHING SHIFTS SLOWLY ACROSS THE ERN U.S.
   TODAY...A MORE SUBSTANTIAL/ENERGETIC TROUGH IS FORECAST TO ADVANCE
   NEWD ACROSS THE INTERMOUNTAIN W TOWARD THE NRN PLAINS THIS
   PERIOD...IMPINGING AS IT DOES ON BACKGROUND CENTRAL U.S. RIDGING.

   AT THE SURFACE...WEAK LOW PRESSURE OVER ERN MT ATTM IS FORECAST TO
   DEEPEN/SHIFT NNEWD TOWARD THE CANADIAN BORDER WITH TIME...WHILE A
   TRAILING COLD FRONT SURGES EWD AND INTO THE NRN -- AND EVENTUALLY
   CENTRAL -- PLAINS STATES THROUGH THE SECOND HALF OF THE PERIOD.

   ...N CENTRAL CONUS AND SWD INTO THE CENTRAL HIGH PLAINS...
   BACKGROUND RIDGING/SUBSIDENCE PERSISTS ACROSS THE PLAINS ATTM...AND
   SHOULD PREVAIL INTO THE AFTERNOON ALLOWING THE AIRMASS TO REMAIN
   LARGELY CAPPED OVER THE NEXT SEVERAL HOURS.  WITH TIME
   HOWEVER...DIURNAL HEATING/MIXING/DESTABILIZATION COMBINED WITH THE
   ADVANCE OF THE WRN TROUGH AND ASSOCIATED MID-LEVEL HEIGHT FALLS WILL
   EVENTUALLY YIELD INITIATION OF CONVECTION.  INITIAL STORM
   DEVELOPMENT IS EXPECTED ACROSS THE HIGH PLAINS -- LIKELY WITHIN
   SEVERAL SEPARATE CLUSTERS FROM ERN MT SWD TO ERN CO.  FARTHER
   SE...STORM REDEVELOPMENT MAY ALSO OCCUR INVOF OUTFLOW ASSOCIATED
   WITH ONGOING IA CONVECTION AS A WEAK VORT MAX SHIFTS ACROSS THE
   CENTRAL PLAINS THIS AFTERNOON.

   WHILE INITIAL CONVECTION WILL LIKELY INITIATE IN A KINEMATIC
   ENVIRONMENT SUPPORTIVE OF MARGINAL/MULTICELL ORGANIZATION...THE
   CONTINUED ADVANCE OF THE WRN TROUGH WILL BE ACCOMPANIED BY
   INCREASINGLY STRONG SWLYS AT MID LEVELS.  AS THIS STRONGER FLOW
   ALOFT OVERSPREADS A LOW-LEVEL JET INCREASING THROUGH THE
   EVENING...SHEAR PROFILES WILL BECOME INCREASINGLY SUPPORTIVE OF
   WELL-ORGANIZED/SUPERCELL STORMS.  INITIAL CELLULAR STORM MODES
   SHOULD GRADUALLY GROW UPSCALE INTO LINES/BOWS IN SOME AREAS --
   PARTICULARLY ACROSS ND WHERE A BOWING MCS IS EXPECTED TO EVOLVE. 
   ALONG WITH ATTENDANT WIND POTENTIAL ACROSS ND...VERY LARGE HAIL AND
   A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE WITH ANY CELLULAR
   CONVECTION.  FARTHER S...MAIN RISKS WILL BE DAMAGING WINDS AND LARGE
   HAIL -- WITH THE ENTIRE ZONE OF GREATEST RISK TO SHIFT GRADUALLY EWD
   THROUGH THE OVERNIGHT HOURS.

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z