Aug 22, 2015 0600 UTC Day 1 Convective Outlook
Updated: Sat Aug 22 06:04:50 UTC 2015 (20150822 1200Z Day 1 shapefile | 20150822 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150822 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 66,271 6,370,531 Omaha, NE...Minneapolis, MN...St. Paul, MN...Lincoln, NE...Sioux City, IA...
SLIGHT 156,232 6,979,819 Kansas City, MO...Wichita, KS...Des Moines, IA...Overland Park, KS...Kansas City, KS...
MARGINAL 168,480 7,632,288 Oklahoma City, OK...Tulsa, OK...Springfield, MO...Cedar Rapids, IA...Norman, OK...
Probabilistic Tornado Graphic
20150822 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
10 % 41,993 3,217,071 Omaha, NE...Lincoln, NE...Sioux City, IA...Plymouth, MN...Eden Prairie, MN...
5 % 144,230 8,634,209 Kansas City, MO...Minneapolis, MN...St. Paul, MN...Des Moines, IA...Overland Park, KS...
2 % 88,444 3,197,822 Wichita, KS...Cedar Rapids, IA...Fargo, ND...Eau Claire, WI...Grand Forks, ND...
Probabilistic Damaging Wind Graphic
20150822 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
30 % 64,641 6,241,305 Omaha, NE...Minneapolis, MN...St. Paul, MN...Lincoln, NE...Bloomington, MN...
15 % 157,820 7,121,414 Kansas City, MO...Wichita, KS...Des Moines, IA...Overland Park, KS...Kansas City, KS...
5 % 167,404 7,609,831 Oklahoma City, OK...Tulsa, OK...Springfield, MO...Cedar Rapids, IA...Norman, OK...
Probabilistic Large Hail Graphic
20150822 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
SIG SEVERE 68,210 4,089,217 Omaha, NE...Lincoln, NE...Topeka, KS...Sioux City, IA...Plymouth, MN...
30 % 49,568 3,217,923 Omaha, NE...Lincoln, NE...Sioux City, IA...Plymouth, MN...Maple Grove, MN...
15 % 171,470 10,109,947 Kansas City, MO...Minneapolis, MN...Wichita, KS...St. Paul, MN...Des Moines, IA...
5 % 168,985 7,640,962 Oklahoma City, OK...Tulsa, OK...Springfield, MO...Cedar Rapids, IA...Norman, OK...
   SPC AC 220604

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0104 AM CDT SAT AUG 22 2015

   VALID 221200Z - 231200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS FROM CENTRAL AND SOUTHERN MN
   THROUGH WESTERN IA...EXTREME EASTERN NEB...AND EXTREME NORTHWEST
   MO...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENH RISK AND
   SOUTH THROUGH WESTERN MO AND EASTERN/CENTRAL KS...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AND
   SOUTH INTO CENTRAL MO...NORTHWEST AR...NORTHERN AND CENTRAL OK...TO
   WESTERN KS...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND
   EVENING ACROSS THE UPPER MIDWEST...PORTIONS OF THE MIDDLE AND LOWER
   MISSOURI VALLEY INTO CENTRAL AND EASTERN KANSAS.  DAMAGING
   WINDS...LARGE HAIL...AND A FEW TORNADOES WILL BE THE SEVERE-WEATHER
   THREATS.

   ...SYNOPSIS...
   AN UNSEASONABLY STRONG MID- TO UPPER-LEVEL TROUGH IS EXPECTED TO
   EVOLVE ACROSS THE NORTHERN PLAINS INTO THE UPPER MS VALLEY THIS
   FORECAST PERIOD...WITH STRENGTHENING DEEP-LAYER WIND FIELDS AND AN
   EXPECTED PRE-FRONTAL ENVIRONMENT BECOMING MOIST WITH MODERATE TO
   VERY STRONG INSTABILITY.  OPERATIONAL DETERMINISTIC MODELS ARE QUITE
   SIMILAR WITH THE TRACK AND TIMING OF THIS TROUGH WITH DEEPENING AND
   CLOSED LOW FORMATION OVER NORTHERN MN AND ADJACENT SOUTHERN
   CANADA...AND THE TROUGH BECOMING NEGATIVELY TILTED BY 12Z SUNDAY
   ACROSS THE UPPER MS VALLEY.  60-120-METER 500-MB HEIGHT FALLS PER 12
   HOURS ARE EXPECTED ACROSS ND/SD THROUGH THIS AFTERNOON...WITH
   STRONGER 500-MB HEIGHT FALLS /120-180-METERS IN 12 HOURS/ ACROSS THE
   UPPER MS VALLEY AFTER 22/00Z.  THE EVOLUTION OF THE MID- TO
   UPPER-LEVEL TROUGH WILL SUPPORT A DEEPENING SURFACE LOW TRACKING
   FROM CENTRAL SD INTO NORTHWEST ONTARIO.  A TRAILING COLD FRONT WILL
   MOVE STEADILY EAST/SOUTHEAST INTO THE UPPER MIDWEST AND MID-MISSOURI
   VALLEY THIS AFTERNOON...EXTENDING FROM WRN MN THROUGH NORTHWEST
   IA...SOUTHEAST NEB TO NORTHWEST KS BY MID-LATE AFTERNOON...AND THEN
   FROM NORTHEAST MN/NORTHWEST WI TO EASTERN IA...CENTRAL MO AND
   CENTRAL OK BY 12Z SUNDAY. 

   ...UPPER MIDWEST TO LOWER MO VALLEY AND KS...
   LOW-LEVEL MOISTURE WILL RETURN POLEWARD IN ADVANCE OF THE COLD FRONT
   TODAY WITH MIDDLE 60S TO NEAR 70 F SURFACE DEW POINTS IN PLACE BY
   LATE AFTERNOON.  THIS COMBINED WITH AN EXPANDING EML PLUME WITH
   700-500-MB LAPSE RATES OF 8-9 C/KM ACROSS THE CENTRAL PLAINS...MID
   MISSOURI VALLEY INTO MN WILL RESULT IN MUCAPE 2000-3000 J/KG NORTH
   TO SOUTH ACROSS THE UPPER MIDWEST TO EASTERN NEB/WESTERN IA...WHILE
   VALUES AT OR ABOVE 3000 J/KG WILL BE POSSIBLE ACROSS KS BY LATE
   AFTERNOON.

   DESTABILIZATION ACROSS EASTERN ND THIS MORNING MAY ALLOW FOR A FEW
   STRONG TO SEVERE STORMS.  ALTHOUGH THE EASTWARD EXTENT OF THE EML
   SHOULD INITIALLY CAP THE WARM SECTOR...NEW STORM DEVELOPMENT COULD
   OCCUR BY MID-AFTERNOON ACROSS WESTERN/CENTRAL MN INTO NORTHWEST IA
   AND NORTHEAST NEB AS DPVA ATTENDANT TO A LEAD IMPULSE SPREADS ACROSS
   THESE AREAS.  INITIAL STORM MODE THIS AFTERNOON IS EXPECTED TO BE
   DISCRETE SUPERCELLS GIVEN ORTHOGONAL DEEP-LAYER SHEAR VECTORS OF
   35-50 KT ACROSS THE COLD FRONT...WITH AN INCREASE IN STORM
   COVERAGE/INTENSITY AS STRONGER FORCING FOR ASCENT ARRIVES BY 22/00Z
   WITH THE APPROACHING STRONG TROUGH.  ALL SEVERE HAZARDS ARE EXPECTED
   WITH THE INITIAL DISCRETE STORMS INCLUDING VERY LARGE HAIL AND A FEW
   TORNADOES FROM CENTRAL MN TO EASTERN NEB AND WESTERN IA...GIVEN THE
   STEEP MIDLEVEL LAPSE RATES...STRONG EFFECTIVE BULK SHEAR AND
   ENHANCED LOW-LEVEL SHEAR ALONG A 35-45 KT SOUTHERLY LLJ ACROSS THE
   CATEGORY 3 SEVERE RISK AREA.  AS THE STRONGER HEIGHT FALLS/FORCING
   FOR ASCENT ARRIVE THIS EVENING...STORMS WILL LIKELY GROW UPSCALE
   INTO A SQUALL LINE ACROSS CENTRAL/EASTERN MN...INTO WESTERN WI AND
   CENTRAL IA WITH A CONTINUED THREAT FOR DAMAGING WINDS AND SOME HAIL.

   STORM DEVELOPMENT IS EXPECTED TO INCREASE ALONG THE TRAILING PORTION
   OF THE COLD FRONT BY EARLY EVENING FROM SOUTHEAST NEB/NORTHWEST MO
   INTO NORTHERN KS...AS THE SOUTHERN EXTENT OF HEIGHT FALLS AND UPLIFT
   ALONG THE FRONT ENCOUNTER POTENTIALLY VERY STRONG INSTABILITY. 
   GIVEN DIFFLUENT FLOW ALOFT...ORTHOGONAL DEEP-LAYER SHEAR VECTORS
   WILL BE COMMON ACROSS THIS PORTION OF THE COLD FRONT AS WELL...
   SUGGESTING DISCRETE STORMS WILL BE POSSIBLE FOR THE INITIAL STORM
   MODE...ESPECIALLY INTO NORTHEAST KS WHERE STORMS SHOULD FORM PRIOR
   TO THE ONSET OF BOUNDARY-LAYER COOLING.  VERY LARGE HAIL AND
   DAMAGING WINDS WILL BE POSSIBLE WITH THESE INITIAL STORMS. 
   OTHERWISE...STRONG/DAMAGING WINDS SHOULD BECOME THE PRIMARY
   SEVERE-WEATHER THREAT INTO THE EVENING AS THE COLD FRONT ADVANCES
   SOUTH.  MODELS DIFFER WITH THE SOUTHWARD EXTENT OF THIS SEVERE
   WEATHER THREAT...THOUGH MUCH OF CENTRAL AND EASTERN KS AND WESTERN
   MO WILL HAVE A CONDITIONAL SEVERE THREAT...GIVEN THE DEGREE OF
   INSTABILITY.

   ..PETERS/GLEASON.. 08/22/2015

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