Sep 24, 2018 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Mon Sep 24 07:24:32 UTC 2018 (20180924 0730Z Day 3 shapefile | 20180924 0730Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180924 0730 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 165,290 59,401,287 New York, NY...Philadelphia, PA...Baltimore, MD...Boston, MA...Washington, DC...
MARGINAL 103,060 17,814,930 Columbus, OH...Cleveland, OH...Cincinnati, OH...Buffalo, NY...Lexington-Fayette, KY...
Probabilistic Graphic
20180924 0730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 3 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 165,146 59,517,595 New York, NY...Philadelphia, PA...Baltimore, MD...Boston, MA...Washington, DC...
5 % 103,016 17,696,660 Columbus, OH...Cleveland, OH...Cincinnati, OH...Buffalo, NY...Lexington-Fayette, KY...
   SPC AC 240724

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0224 AM CDT Mon Sep 24 2018

   Valid 261200Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   APPALACHIANS ACROSS THE NORTHEAST...

   ...SUMMARY...
   Strong/isolated severe storms will be possible Wednesday across the
   Northeast.

   ...Synopsis...
   Long-wave troughing is forecast to remain established over the
   central U.S. this period, flanked by ridging across the eastern
   Pacific/West Coast states, and over the western Atlantic/Southeast
   states.  Within the broader/long-wave cyclonic flow, a
   shorter-wavelength trough is forecast to advance quickly
   east-northeastward from the Upper Great Lakes/western Ontario, to
   the Lower Great Lakes and western Quebec through the daylight hours,
   and then across New England and into the Canadian Maritimes by the
   end of the period.

   Meanwhile, a second short-wave trough is progged to dig quickly
   southeastward across the Canadian Prairies, reaching the
   north-central U.S. after dark.

   At the surface, a seasonably strong cold front is forecast to
   continue advancing quickly eastward/southeastward across the
   southern and eastern portions of the country.  By the end of the
   period, the front will likely have moved off the New England coast,
   trailing southwestward from the Mid-Atlantic region to the western
   Gulf Coast vicinity by 27/12z.  Progression of this front will be
   accompanied by a zone of showers and thunderstorms, which will
   likewise traverse the southern and eastern U.S. through the period.

   Meanwhile farther north, a second cold front is forecast to advance
   southeastward out of Canada and across the northern Intermountain
   Region/northern Plains.  However, with a drier pre-frontal airmass
   ahead of this front, only isolated shower activity is expected.

   ...The Northeast...
   Modest pre-frontal heating/destabilization is expected Wednesday
   across the Northeast, which should support continuation -- and some
   intensification -- of the ongoing frontal convective band as it
   moves across the upper Ohio Valley and lower Great Lakes region into
   the central Appalachians through the day.  With the front serving as
   a linear-organizing mechanism and with shear sufficient for
   long-lived updrafts, evolution into semi-continuous squall line is
   expected.  While flow aloft is not progged to be excessively strong
   -- and with a limited across-boundary component to the shear vector,
   combined with only modest CAPE, the overall setup is not ideal, with
   respect to widespread/significant wind risk.  Still, locally
   gusty/damaging winds can be expected along more intense/possibly
   bowing line segments -- primarily from early afternoon through early
   evening.

   ..Goss.. 09/24/2018

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z