May 3, 2015 0600 UTC Day 1 Convective Outlook
Updated: Sun May 3 05:58:29 UTC 2015 (20150503 1200Z Day 1 shapefile | 20150503 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150503 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 47,855 1,963,009 Rochester, MN...Eau Claire, WI...La Crosse, WI...Wausau, WI...Mason City, IA...
MARGINAL 155,393 9,446,646 Omaha, NE...Minneapolis, MN...St. Paul, MN...Lincoln, NE...Madison, WI...
Probabilistic Tornado Graphic
20150503 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
2 % 75,935 4,125,459 St. Paul, MN...Rochester, MN...Sioux City, IA...Eagan, MN...Eau Claire, WI...
Probabilistic Damaging Wind Graphic
20150503 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 % 47,761 1,960,779 Rochester, MN...Eau Claire, WI...La Crosse, WI...Wausau, WI...Mason City, IA...
5 % 153,105 9,373,978 Omaha, NE...Minneapolis, MN...St. Paul, MN...Lincoln, NE...Madison, WI...
Probabilistic Large Hail Graphic
20150503 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 % 47,935 1,963,905 Rochester, MN...Eau Claire, WI...La Crosse, WI...Wausau, WI...Mason City, IA...
5 % 154,447 9,427,301 Omaha, NE...Minneapolis, MN...St. Paul, MN...Lincoln, NE...Madison, WI...
   SPC AC 030558

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT SUN MAY 03 2015

   VALID 031200Z - 041200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM A WRN PORTION OF UPPER
   MI...WI...SOUTHEAST MN AND NORTHEAST IA...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK
   AREA AND EXTENDING SOUTHWEST THROUGH PORTIONS OF THE MID MO VALLEY
   TO WRN NEB...

   ...SUMMARY...
   SCATTERED STRONG TO SEVERE STORMS WITH HAIL AND DAMAGING WINDS ARE
   EXPECTED THIS AFTERNOON AND EVENING FROM WESTERN UPPER MICHIGAN
   THROUGH WISCONSIN...SOUTHEAST MINNESOTA TO NORTHEASTERN IOWA.  A
   MARGINAL RISK OF SEVERE STORMS SURROUNDS THE SLIGHT RISK AREA AND
   EXTENDS SOUTHWEST THROUGH WESTERN IOWA...EASTERN NEBRASKA TO WESTERN
   KANSAS.

   ...SYNOPSIS...
   A PROGRESSIVE BROAD UPPER TROUGH WITH AN EMBEDDED SHORTWAVE TROUGH
   WILL SKIRT THE U.S./CANADIAN BORDER FROM THE NRN PLAINS TO THE UPPER
   GREAT LAKES WITH WLY 700-500-MB WINDS STRENGTHENING ACROSS MN/WI AND
   UPPER MI.

   IN THE LOWER LEVELS...RIDGING EXTENDING W/SWWD FROM A SURFACE HIGH
   SHIFTING EAST OF THE SRN MID-ATLANTIC COAST IS EXPECTED TO REMAIN
   PROMINENT INLAND OF THE WRN AND CENTRAL GULF COAST TODAY.  THIS
   LIKELY WILL PRECLUDE A SUBSTANTIVE RETURN FLOW OF GULF MOISTURE TO
   THE VICINITY OF A COLD FRONT ADVANCING SOUTHEAST OF THE NORTHERN
   PLAINS.  BY MID-LATE AFTERNOON...THIS FRONT SHOULD EXTEND FROM
   WESTERN UPPER MI THROUGH SOUTHEAST MN...NORTHWEST IA...AND NORTHEAST
   TO SOUTH-CENTRAL NEB...WHERE IT WILL INTERSECT THE NORTHERN EXTENT
   OF A DRY LINE /EXTENDING SWD THROUGH WRN KS TO WRN TX/. 
   MEANWHILE...A STRENGTHENING S/SWLY LLJ THROUGH THE AFTERNOON AND
   EVENING FROM OK/W TX INTO KS AND ARCING NEWD THROUGH IA TO WI/UPPER
   GREAT LAKES REGION WILL AID IN A RELATIVELY NARROW CORRIDOR OF
   MOISTURE RETURN ALONG AND AHEAD OF THE COLD FRONT.  

   ...UPPER MI/WI/SOUTHEAST MN/NORTHEAST IA...
   SURFACE DEW POINTS IN THE 50S F EXPECTED INTO THIS REGION DURING THE
   AFTERNOON COMBINED WITH STRONG SURFACE HEATING AHEAD OF THE COLD
   FRONT BENEATH STEEPENING MIDLEVEL LAPSE RATES /7.5-8 C PER KM/
   SHOULD RESULT IN MLCAPE OF 1000-1500 J/KG.  DESPITE THE LACK OF
   STRONGER FORCING ALOFT...ASCENT ALONG THE COLD FRONT AND SURFACE
   HEATING SHOULD SUFFICIENTLY WEAKEN INHIBITION FOR TSTM DEVELOPMENT
   BY MID-LATE AFTERNOON.  EFFECTIVE BULK SHEAR UP TO 35 KT /ATTENDANT
   TO STRENGTHENING WIND PROFILES/ SUGGESTS THE LIKELIHOOD FOR
   ORGANIZED STORMS...WITH LARGE HAIL AND DAMAGING WINDS BEING THE
   PRIMARY THREATS.  MIXED STORM MODES ARE EXPECTED WITH HIGH-RES
   MODELS INDICATING INITIAL STORMS SHOULD BE DISCRETE...WHILE LINEAR
   FORCING FOR ASCENT WITH THE FRONT FAVORS UPSCALE GROWTH INTO A
   QUASI-LINEAR CONVECTIVE SYSTEM ADVANCING EWD THROUGH UPPER
   MI...WI...SERN MN AND NRN IA THROUGH THE EVENING.  SINCE LINEAR
   FORCING MAY BE GREATER FOR THIS OUTLOOK...THE TORNADO THREAT IS LOW
   /2 PERCENT/.

   ...ERN NEB TO WRN KS...
   STRONG HEATING BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES /8-8.5
   C PER KM/ SHOULD WEAKEN SURFACE-BASED INHIBITION BY AFTERNOON WITH
   STORMS DEVELOPING ALONG THE WRN EXTENT OF THE COLD FRONT AS IT
   ADVANCES SE/SWD.  ALTHOUGH INSTABILITY SHOULD BE COMPARABLE TO
   LOCATIONS FARTHER NORTHEAST ACROSS THE SLIGHT RISK AREA...WEAKER
   EFFECTIVE BULK SHEAR /20-30 KT/ IS EXPECTED TO LIMIT THE OVERALL
   SEVERE RISK.  A DEEP MIXED BOUNDARY LAYER WILL SUPPORT ISOLATED
   STRONG TO SEVERE WIND GUSTS...WHILE STEEP LAPSE RATES ALSO AID IN A
   MARGINALLY SEVERE HAIL THREAT.  MODELS CONTINUE TO SUGGEST UPSCALE
   GROWTH OF STORM CLUSTERS WILL BE POSSIBLE ACROSS NRN KS INTO NEB
   RESULTING IN A CONTINUED MARGINAL SEVERE RISK WITHIN THE NOSE OF A
   STRENGTHENING SLY LLJ.

   ..PETERS/CARBIN.. 05/03/2015

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