Apr 15, 2018 1300 UTC Day 1 Convective Outlook
Updated: Sun Apr 15 12:51:55 UTC 2018 (20180415 1300Z Day 1 shapefile | 20180415 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180415 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 57,432 10,888,643 Charlotte, NC...Raleigh, NC...Greensboro, NC...Durham, NC...Winston-Salem, NC...
SLIGHT 79,766 12,426,570 Jacksonville, FL...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...Richmond, VA...
MARGINAL 94,871 18,318,016 Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...Orlando, FL...
Probabilistic Tornado Graphic
20180415 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
10 % 44,970 8,049,064 Charlotte, NC...Greensboro, NC...Winston-Salem, NC...Savannah, GA...Columbia, SC...
5 % 51,314 9,211,396 Jacksonville, FL...Raleigh, NC...Durham, NC...Richmond, VA...Fayetteville, NC...
2 % 95,439 14,930,338 Virginia Beach, VA...Tampa, FL...St. Petersburg, FL...Norfolk, VA...Chesapeake, VA...
Probabilistic Damaging Wind Graphic
20180415 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
30 % 57,365 10,875,939 Charlotte, NC...Raleigh, NC...Greensboro, NC...Durham, NC...Winston-Salem, NC...
15 % 79,776 12,437,452 Jacksonville, FL...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...Richmond, VA...
5 % 94,712 18,296,547 Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...Orlando, FL...
Probabilistic Large Hail Graphic
20180415 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
5 % 86,705 24,341,062 Jacksonville, FL...Charlotte, NC...Miami, FL...Tampa, FL...St. Petersburg, FL...
   SPC AC 151251

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0751 AM CDT Sun Apr 15 2018

   Valid 151300Z - 161200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SAVANNAH VALLEY
   TO SOUTHERN VA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTH FL TO VA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTH FL TO THE
   UPPER OH VALLEY...

   ...SUMMARY...
   A line of strong to severe thunderstorms will move northeast across
   the Southeast and Lower Mid-Atlantic States today into tonight.
   Damaging winds and tornadoes are most likely from the Savannah
   Valley into southern Virginia this afternoon and early evening.

   ...North FL to VA...
   A generally decaying line of thunderstorms is ongoing from southwest
   GA to the eastern FL Panhandle. With a nadir in instability inland
   ahead of this line, severe risk with this activity should remain
   localized through most of the morning. But as the large-scale
   outflow impinges on the Atlantic coastal plume of mean mixing ratios
   near 14 g/kg per 12Z Jacksonville and Charleston soundings,
   convection will intensify towards midday amid MLCAPE of 500-1000
   J/kg. The line will also expand northward given robust mid-level
   height falls downstream of a 100-kt 500-mb southerly jet. In spite
   of highly meridional deep-layer wind fields, 50-60 kt low-level
   southerlies atop backed southeasterly surface winds (in response to
   cyclogenesis) will result in enlarged hodographs. A few supercells
   embedded within or just ahead of the line seem probable, with the
   tornado risk appearing maximized from the Savannah Valley into parts
   of southern VA during the afternoon. Otherwise, swaths of scattered
   damaging winds and brief QLCS tornadoes are expected through early
   evening. The severe threat will nocturnally wane tonight but at
   least an isolated wind/brief tornado risk may persist towards the
   Mid-Atlantic Coast within a low CAPE/high shear environment.

   ...South FL...
   The severe threat should decrease with southern extent given minimal
   mid-level height falls and weaker deep-layer shear. While multiple
   rounds of convection should affect the peninsula, focusing on the
   east-coast sea breeze this afternoon and along the impinging cold
   front in the afternoon and evening, overall severe potential should
   remain marginal, favoring locally strong winds and marginal hail.

   ..Grams/Goss.. 04/15/2018

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