Sep 4, 2015 0600 UTC Day 1 Convective Outlook
Updated: Fri Sep 4 05:54:47 UTC 2015 (20150904 1200Z Day 1 shapefile | 20150904 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150904 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 40,529 668,640 Fargo, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...West Fargo, MN...
MARGINAL 55,059 1,214,950 St. Cloud, MN...Aberdeen, SD...Elk River, MN...Ramsey, MN...Watertown, SD...
Probabilistic Tornado Graphic
20150904 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
20150904 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
15 % 38,335 653,722 Fargo, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...West Fargo, MN...
5 % 57,415 1,244,830 St. Cloud, MN...Aberdeen, SD...Elk River, MN...Ramsey, MN...Watertown, SD...
Probabilistic Large Hail Graphic
20150904 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
15 % 38,705 655,000 Fargo, ND...Grand Forks, ND...Moorhead, MN...West Fargo, ND...West Fargo, MN...
5 % 57,087 1,222,798 St. Cloud, MN...Aberdeen, SD...Elk River, MN...Ramsey, MN...Watertown, SD...
   SPC AC 040554

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1254 AM CDT FRI SEP 04 2015

   VALID 041200Z - 051200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF EASTERN NORTH
   DAKOTA/NORTHWEST MINNESOTA...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK
   OVER PORTIONS OF CENTRAL/EASTERN NORTH DAKOTA...NORTHEAST SOUTH
   DAKOTA AND WESTERN/CENTRAL MINNESOTA...

   ...SUMMARY...
   ISOLATED TO WIDELY SCATTERED SEVERE THUNDERSTORMS WILL BE POSSIBLE
   FRIDAY AFTERNOON AND EVENING ACROSS PORTIONS OF EASTERN NORTH
   DAKOTA...NORTHEAST SOUTH DAKOTA AND WESTERN MINNESOTA. LARGE HAIL
   AND DAMAGING WINDS WILL BE THE MAIN THREATS.

   ...SYNOPSIS...
   A SEASONABLY STRONG/SLIGHTLY AMPLIFYING UPPER-LEVEL TROUGH OVER THE
   PACIFIC NORTHWEST WILL MOVE LITTLE FRIDAY AS AN UPPER-LEVEL RIDGE
   EXTENDS FROM THE SOUTHERN PLAINS INTO THE GREAT LAKES. AN IMPULSE
   WITHIN THE SOUTHWESTERLY MID-LEVEL FLOW OVER THE CENTRAL/NORTHERN
   HIGH PLAINS FRIDAY MORNING WILL LIFT NORTHEAST ACROSS THE
   DAKOTAS/MINNESOTA DURING THE AFTERNOON/EVENING. A FRONTAL BOUNDARY
   WILL EXTEND FROM NORTH DAKOTA SOUTHWEST ACROSS NORTHERN WYOMING LATE
   FRIDAY AFTERNOON...WITH ANOTHER QUASI-STATIONARY FRONT FROM
   SOUTHERN/CENTRAL MINNESOTA EAST INTO THE OHIO VALLEY.  

   ...PORTIONS OF THE DAKOTAS/MINNESOTA...
   SURFACE DEW POINTS IN THE UPPER 60S/LOWER 70S WILL BE PRESENT ACROSS
   THE UPPER MIDWEST/NORTHERN PLAINS ON FRIDAY. DESPITE MORNING
   CLOUDS/SCATTERED STORMS...DIURNAL HEATING AND A PLUME OF STEEP
   MID-LEVEL LAPSE RATES WILL LEAD TO AREAS OF MODERATE-STRONG
   SURFACE-BASED INSTABILITY BY AFTERNOON ACROSS CENTRAL/EASTERN
   PORTIONS OF THE DAKOTAS EASTWARD INTO MINNESOTA. LOW-MID LEVEL WIND
   FIELDS WILL INCREASE SOMEWHAT WITH THE APPROACH OF THE UPPER-LEVEL
   IMPULSE DURING THE AFTERNOON/EVENING...RESULTING IN SUFFICIENT
   DEEP-LAYER SHEAR /35-40 KTS/ ACROSS THE SLIGHT RISK AREA FOR STORM
   ORGANIZATION. EXPECT ISOLATED TO WIDELY SCATTERED THUNDERSTORMS TO
   DEVELOP BY LATE AFTERNOON ACROSS EASTERN NORTH DAKOTA AND MOVE
   NORTHEAST DURING THE EVENING. WITH ADEQUATE DEEP SHEAR FOR UPDRAFT
   ROTATION...LARGE HAIL AND DAMAGING GUSTS WILL BE POSSIBLE WITH THE
   MORE DISCRETE STORMS. STORMS MAY TEND TO DEVELOP INTO CLUSTERS WITH
   TIME POSING A CONTINUED SEVERE RISK MAINLY IN THE FORM OF DAMAGING
   WINDS. 

   ...EASTERN MONTANA/NORTHWEST NORTH DAKOTA LATE FRIDAY NIGHT...
   SOME SIGNAL EXISTS IN LATEST GUIDANCE REGARDING THE POTENTIAL FOR
   STRONG STORMS IN THE 06Z-12Z SAT TIME FRAME OVER PORTIONS OF EASTERN
   MONTANA/NORTHWEST NORTH DAKOTA...WHERE DEVELOPING WARM ADVECTION AND
   AN APPROACHING IMPULSE WITHIN SOUTHWESTERLY MID-LEVEL FLOW COULD
   PROVIDE SUFFICIENT LARGE-SCALE FORCING FOR ASCENT TO AID IN
   THUNDERSTORM DEVELOPMENT. CONSIDERED A WESTWARD EXTENSION OF THE
   MARGINAL/5 PERCENT SEVERE PROBABILITIES...HOWEVER WITH QUESTIONS ON
   TIMING AND MAGNITUDE OF ELEVATED INSTABILITY/THUNDERSTORM
   INTENSITY...OPTED TO DEFER TO LATER OUTLOOKS IN THIS AREA.

   ..BUNTING/COOK.. 09/04/2015

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