Sep 3, 2015 1300 UTC Day 1 Convective Outlook
Updated: Thu Sep 3 12:40:31 UTC 2015 (20150903 1300Z Day 1 shapefile | 20150903 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150903 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20150903 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20150903 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20150903 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 031240

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0740 AM CDT THU SEP 03 2015

   VALID 031300Z - 041200Z

   ...NO SVR TSTM AREAS FORECAST...

   ...SUMMARY...
   A FEW STRONG STORMS CAPABLE OF GUSTY WINDS ARE POSSIBLE TODAY OVER
   THE GREAT LAKES AND ADJACENT OHIO VALLEY...AS WELL AS FROM PARTS OF
   ARIZONA AND NEW MEXICO THROUGH THE CENTRAL ROCKIES INTO THE CENTRAL
   HIGH PLAINS.

   ...SYNOPSIS...

   A LONG-WAVE TROUGH PRESENT OVER WRN NORTH AMERICA WILL AMPLIFY
   THROUGH THE DAY ONE PERIOD...RESULTING IN A BUILDING DOWNSTREAM
   RIDGE FROM THE MID/LOWER MO VALLEY TO HUDSON BAY.  THIS PATTERN
   EVOLUTION WILL YIELD A CORRIDOR OF HEIGHT FALLS/FORCING FOR ASCENT
   FROM THE GREAT BASIN INTO NRN HIGH PLAINS AND INCREASED CAPPING ATOP
   A MOIST AND POTENTIALLY MODERATELY UNSTABLE AIR MASS OVER THE ERN
   DAKOTAS THROUGH UPPER MS VALLEY.  

   MORNING WATER VAPOR IMAGERY INDICATES A NUMBER OF VORTICITY MAXIMA
   PRESENT WITHIN THIS SYNOPTIC-SCALE REGIME.  ONE SUCH FEATURE WILL
   SLOWLY DRIFT SEWD THROUGH THE GREAT LAKES WHILE A MORE PROGRESSIVE
   SHORT-WAVE TROUGH NEAR THE FOUR CORNERS WILL TRANSLATE NEWD INTO THE
   NRN PLAINS BY 04/12Z.

   AT THE SURFACE...A BAROCLINIC ZONE WILL REMAIN QUASI-STATIONARY FROM
   THE DAKOTAS TO GREAT BASIN...ANCHORED BY A LEE CYCLONE OVER THE NRN
   HIGH PLAINS.

   ...GREAT LAKES/OH VALLEY THIS AFTERNOON/EVENING...

   A SMALL MCS IS ONGOING AS OF 12Z OVER NRN LOWER MI...COINCIDENT WITH
   THE MID-LEVEL IMPULSE MENTIONED ABOVE.  A SUBSET OF THIS ACTIVITY
   WILL LIKELY PERSIST THROUGH THE MORNING WITH ADDITIONAL STORMS
   DEVELOPING BY AFTERNOON...MOST LIKELY FROM SRN LOWER MI INTO NRN
   PARTS OF IND/OH.  THE STRONGEST STORMS WILL BE CAPABLE OF GUSTY
   WINDS AND PERHAPS SOME SMALL HAIL.

   TO THE IMMEDIATE WEST OF THIS AREA...MODEL GUIDANCE INDICATES THAT A
   FAVORABLE OVERLAP OF LOW-LEVEL MOISTURE AND STEEP LAPSE RATES WILL
   PROMOTE MODERATE AFTERNOON INSTABILITY.  HOWEVER...CAPPING
   ASSOCIATED WITH THE BUILDING MID-LEVEL RIDGE CASTS CONSIDERABLE
   UNCERTAINTY AS TO WHETHER STORMS CAN DEVELOP AND BECOME SUSTAINED. 
   THEREFORE...NO SEVERE WEATHER PROBABILITIES WILL BE INCLUDED.  

   ...AZ/NM THIS AFTERNOON/EVENING...

   DAYTIME HEATING ALONG THE HIGH TERRAIN AND THE POSSIBLE EMERGENCE OF
   A WEAK MID-LEVEL PERTURBATION FROM NWRN MEXICO WILL PROMOTE
   SCATTERED TSTMS THIS AFTERNOON AMIDST A MOIST /I.E. PW OF AROUND 1.5
   INCHES/ AND MODESTLY UNSTABLE ENVIRONMENT.  AS SUCH...WATER-LOADING
   EFFECTS MAY ENHANCE CONVECTIVE DOWNDRAFT VIGOR WITH THE POTENTIAL
   FOR A FEW LOCALLY STRONG SURFACE WIND GUSTS. 

   ...CNTRL ROCKIES INTO CNTRL HIGH PLAINS THIS AFTERNOON/EVENING...

   FORCING FOR ASCENT/DCVA RELATED TO THE FOUR CORNERS MID-LEVEL
   DISTURBANCE WILL INTERACT WITH A STEEP-LAPSE-RATE ENVIRONMENT TO
   FOSTER HIGH-BASED STORMS LATER TODAY...A FEW OR WHICH COULD PRODUCE
   GUSTY WINDS.

   ..MEAD/GLEASON.. 09/03/2015

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