Aug 30, 2015 0600 UTC Day 1 Convective Outlook
Updated: Sun Aug 30 05:34:17 UTC 2015 (20150830 1200Z Day 1 shapefile | 20150830 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150830 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 56,225 247,585 Great Falls, MT...Helena, MT...Havre, MT...Lewistown, MT...
Probabilistic Tornado Graphic
20150830 1200 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20150830 1200 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
5 % 55,312 246,154 Great Falls, MT...Helena, MT...Havre, MT...Lewistown, MT...
Probabilistic Large Hail Graphic
20150830 1200 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
5 % 41,173 230,210 Great Falls, MT...Helena, MT...Havre, MT...Lewistown, MT...
   SPC AC 300534

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1234 AM CDT SUN AUG 30 2015

   VALID 301200Z - 311200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS PARTS OF MT...

   ...SUMMARY...
   ISOLATED SEVERE STORMS WITH WIND AND HAIL MAY DEVELOP ACROSS PARTS
   OF MONTANA THIS AFTERNOON INTO MID-EVENING.

   ...MT...
   A PROGRESSIVE SHORTWAVE TROUGH NEAR THE WA COAST SHOULD DAMPEN AS IT
   REACHES THE NRN GREAT PLAINS INTERNATIONAL BORDER AREA EARLY MON.
   EVEN WITH DAMPENING...A BROAD BELT OF 500-MB SWLYS AOA 50 KT IS
   EXPECTED TO BE CENTERED ACROSS THE NRN ROCKIES AND ADJACENT HIGH
   PLAINS THIS AFTERNOON. WITH VERY STRONG UPPER-LEVEL
   FLOW...HODOGRAPHS WILL BECOME RATHER ELONGATED FAVORING A
   CONDITIONAL RISK FOR SPLITTING SUPERCELL STRUCTURES.

   WITH AN INITIAL FRONTAL SURGE THIS MORNING OVER THE NRN HIGH
   PLAINS...AFTERNOON TEMPERATURES ARE EXPECTED TO BE AROUND 10-15 DEG
   F COOLER COMPARED TO SAT ACROSS CNTRL MT. NEVERTHELESS...INVERTED-V
   THERMODYNAMIC PROFILES SHOULD REMAIN COMMON BUT BUOYANCY WILL LIKELY
   BE MEAGER WITH MLCAPE ONLY AROUND 250-500 J/KG. FAVORABLE TIMING OF
   MID-LEVEL DCVA WITH RESPECT TO THE DIURNAL HEATING CYCLE SHOULD
   FOSTER ISOLATED TSTMS FORMING OVER THE W-CNTRL MT MTNS IN THE EARLY
   AFTERNOON. THIS ACTIVITY SHOULD DEVELOP/SPREAD E THROUGH THE
   AFTERNOON WITH A RISK FOR ISOLATED SEVERE WIND GUSTS AND MARGINALLY
   SEVERE HAIL...BEFORE LIKELY DIMINISHING ACROSS PARTS OF ERN MT JUST
   AFTER SUNSET.

   ...SOUTHEAST STATES...
   SCATTERED TSTMS SHOULD BE ONGOING ALONG THE S ATLANTIC COAST AT 12Z
   DOWNSTREAM OF A PERSISTENT UPPER-LEVEL CIRCULATION CENTERED NEAR
   MOBILE BAY. CONVECTION SHOULD DEVELOP INLAND AND BECOME WIDESPREAD
   THROUGH THE DAY AS THE CIRCULATION GRADUALLY SHIFTS NE TOWARDS NRN
   GA. THE BEST POTENTIAL FOR WEAKLY ORGANIZED CONVECTION APPEARS TO BE
   OVER PARTS OF CNTRL/SRN GA WITHIN A BELT OF ENHANCED MID/UPPER-LEVEL
   SLYS. BUT GIVEN LARGE UNCERTAINTY OVER WHETHER SUFFICIENT DIABATIC
   HEATING CAN OCCUR TO SUPPORT A RISK FOR LOCALLY DAMAGING
   WINDS...WILL DEFER TO LATER OUTLOOKS FOR POSSIBLE MARGINAL RISK
   DELINEATION.

   ..GRAMS/PICCA.. 08/30/2015

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z