Jul 23, 2017 1630 UTC Day 1 Convective Outlook
Updated: Sun Jul 23 16:26:12 UTC 2017 (20170723 1630Z Day 1 shapefile | 20170723 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170723 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 106,680 33,162,242 Philadelphia, PA...Detroit, MI...Baltimore, MD...Washington, DC...Cleveland, OH...
MARGINAL 503,355 94,615,393 New York, NY...Chicago, IL...Indianapolis, IN...Columbus, OH...Memphis, TN...
Probabilistic Tornado Graphic
20170723 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20170723 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 % 106,736 33,183,162 Philadelphia, PA...Detroit, MI...Baltimore, MD...Washington, DC...Cleveland, OH...
5 % 502,482 94,829,326 New York, NY...Chicago, IL...Indianapolis, IN...Columbus, OH...Memphis, TN...
Probabilistic Large Hail Graphic
20170723 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 % 297,712 54,271,902 Chicago, IL...Detroit, MI...Indianapolis, IN...Columbus, OH...Memphis, TN...
   SPC AC 231626

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1126 AM CDT Sun Jul 23 2017

   Valid 231630Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MID-ATLANTIC TO
   GREAT LAKES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTHERN GREAT
   PLAINS TO THE CAROLINAS AND MIDWEST...

   ...SUMMARY...
   Widely scattered severe storms producing damaging winds and some
   hail are possible across parts of the Mid-Atlantic and Great Lakes
   regions late this afternoon and evening.

   ...Mid-Atlantic States to Great Lakes/Midwest...
   Overall setup appears rather nebulous, but have maintained Slight
   risk in an arc surrounding remnant outflows and ongoing convection
   over IN/OH to the southern Appalachians. Pockets of stronger heating
   to the north and east of this activity should yield weak to moderate
   buoyancy amid modest 700-500 mb lapse rates around 6 degree C/km as
   sampled by several 12Z RAOBs. A broad swath of moderate mid-level
   westerlies to the south of the Upper Great Lakes shortwave trough
   will support 30-35 kt effective shear. Ongoing convection will
   increase in coverage this afternoon as it spreads east, with
   multicell clusters and transient supercell structures possibly
   developing. Strong wind gusts and marginally severe hail should be
   the main hazards.

   In the wake of ongoing convection over the Midwest, isolated to
   scattered storms should redevelop late today into the evening,
   possibly producing localized damaging winds and hail. 

   ...OK to Carolinas...
   Hot temperatures and rich boundary-layer moisture will yield large
   buoyancy south of remnant outflow boundaries. While tropospheric
   winds will be light, scattered storms developing along these
   boundaries will pose a risk for sporadic downbursts into this
   evening. See MCD 1407 for further discussion of the threat in the
   southern Appalachians vicinity.

   ..Grams/Smith.. 07/23/2017

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