Apr 30, 2017 1630 UTC Day 1 Convective Outlook
Updated: Sun Apr 30 16:29:41 UTC 2017 (20170430 1630Z Day 1 shapefile | 20170430 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170430 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 126,105 17,805,644 Detroit, MI...Indianapolis, IN...Nashville, TN...New Orleans, LA...Toledo, OH...
MARGINAL 216,832 46,387,409 Chicago, IL...Columbus, OH...Washington, DC...Cleveland, OH...St. Louis, MO...
Probabilistic Tornado Graphic
20170430 1630 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
5 % 101,648 12,363,955 Indianapolis, IN...Nashville, TN...Toledo, OH...Birmingham, AL...Fort Wayne, IN...
2 % 118,955 17,772,350 Detroit, MI...New Orleans, LA...St. Louis, MO...Louisville, KY...Huntsville, AL...
Probabilistic Damaging Wind Graphic
20170430 1630 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 % 110,260 15,876,695 Detroit, MI...Indianapolis, IN...Nashville, TN...New Orleans, LA...Toledo, OH...
5 % 231,601 47,998,081 Chicago, IL...Columbus, OH...Washington, DC...Cleveland, OH...St. Louis, MO...
Probabilistic Large Hail Graphic
20170430 1630 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 % 216,529 44,216,964 Detroit, MI...Indianapolis, IN...Columbus, OH...New Orleans, LA...Cleveland, OH...
   SPC AC 301629

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1129 AM CDT Sun Apr 30 2017

   Valid 301630Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS DEEP SOUTH TO
   MIDWEST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL GULF
   COAST TO LOWER GREAT LAKES...

   ...SUMMARY...
   Scattered damaging winds and a few tornadoes are possible across
   parts of the Deep South into the Midwest, mainly this afternoon into
   early evening.

   ...Deep South...
   A QLCS is ongoing across MS into southeast LA, with a decaying
   comma-head MCV over north-central MS. This line should be the
   primary focus for a continuing severe threat this afternoon.
   Although high-level winds are weak per regional 12Z soundings,
   strong low-level shear will continue to support embedded
   mesovortices capable of a few tornadoes and damaging winds. The
   instability axis will occlude as the eastward surge of the QLCS
   outpaces Gulf boundary-layer moisture return, limiting a more
   substantial risk farther north in the TN Valley.

   ...Midwest...
   Low confidence persists regarding the likelihood of appreciable
   destabilization in a scenario that appears otherwise favorable for
   severe storms given ample deep-layer/low-level shear. This low
   confidence is related to extensive convection ongoing from the
   Mid-MS Valley into the Mid/Deep South. A couple clusters of severe
   storms may develop downstream of this midday activity across parts
   of IN/KY/OH where diabatic heating should be more pronounced amid
   middle 60s surface dew points. Farther west over the Mid-MS Valley
   in the wake of the midday convection, widely scattered storms should
   attempt to form late afternoon along/near the cold front/surface
   cyclone track. Instability will probably remain rather weak and
   deep-layer winds meridional, suggesting overall severe coverage
   should be isolated.

   ..Grams/Mosier.. 04/30/2017

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z