May 28, 2017 1630 UTC Day 1 Convective Outlook
Updated: Sun May 28 15:58:58 UTC 2017 (20170528 1630Z Day 1 shapefile | 20170528 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170528 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 231,377 41,243,502 Houston, TX...San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...
MARGINAL 471,812 63,729,770 Chicago, IL...Indianapolis, IN...Charlotte, NC...Milwaukee, WI...Washington, DC...
Probabilistic Tornado Graphic
20170528 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
2 % 176,525 32,524,051 Detroit, MI...Columbus, OH...Cleveland, OH...Raleigh, NC...Pittsburgh, PA...
Probabilistic Damaging Wind Graphic
20170528 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 % 222,005 38,169,023 Houston, TX...San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...
5 % 392,326 56,631,028 Indianapolis, IN...Charlotte, NC...Washington, DC...Virginia Beach, VA...Atlanta, GA...
Probabilistic Large Hail Graphic
20170528 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
15 % 199,218 37,904,376 Houston, TX...San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...
5 % 487,988 64,698,557 Chicago, IL...Indianapolis, IN...Charlotte, NC...Milwaukee, WI...Washington, DC...
   SPC AC 281558

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1058 AM CDT Sun May 28 2017

   Valid 281630Z - 291200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   TX/LA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   LOWER MI/IN/OH INTO THE CAROLINAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   SOUTHERN PLAINS INTO THE GREAT LAKES...OHIO VALLEY...AND
   CAROLINAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE NORTHERN HIGH PLAINS...

   ...SUMMARY...
   Severe thunderstorms capable of large hail and damaging winds will
   be possible this afternoon and tonight over portions of
   southern/central Texas northeastward into Louisiana.  Other severe
   storms may occur over parts of the upper Ohio Valley, central
   Appalachians, and Carolinas.

   ...TX/LA...
   After a very convectively active Saturday, the reservoir of extreme
   CAPE values is now restricted to portions of TX/LA.  Dewpoints in
   the 70s and strong daytime heating will yield a corridor of 4000+
   J/kg CAPE by mid/late afternoon across central and northeast TX,
   into western LA.  12z model solutions are consistent in the
   development of scattered thunderstorms along this corridor - mainly
   focused along a weak surface boundary evident in observations and
   satellite imagery.  Low-level shear is rather weak in this area, and
   deep-layer effective shear is marginal for supercell structures. 
   Nevertheless, slow-moving severe multicell to occasional supercell
   storms are expected with a risk of large hail and damaging winds. 
   This threat will last through most of the evening hours.

   ...IN/OH/Lower MI...
   A progressive mid-level shortwave trough is currently moving
   eastward across WI, and will affect the central Great Lakes region
   later today.  Scattered thunderstorms are forecast to develop from
   western Lower MI into northern IN by mid afternoon, with other
   storms building eastward along a weak warm front into northern OH. 
   CAPE/shear combinations are not particularly strong in this region,
   but cool temperatures aloft and the approaching shortwave trough may
   be sufficient for a few severe storms capable of hail and damaging
   winds.  The activity may develop eastward into western PA and
   northern WV before weakening.

   ...VA/NC...
   Visible satellite imagery shows strong heating is occurring over
   much of NC and south-central VA this morning.  Ample low level
   moisture remains in place across this area, leading to a moderately
   unstable air mass later today.  Scattered thunderstorms are expected
   to develop during the max heating period, with a few of the storms
   posing a risk of damaging wind gusts and perhaps hail.

   ...WY/SD/NE...
   Scattered thunderstorms will develop later this afternoon and early
   evening within a northwest flow regime over the Black Hills and
   surrounding region.  Steep mid-level lapse rates and sufficient CAPE
   suggest some risk of hail and gusty winds in the stronger cells.

   ..Hart/Cook.. 05/28/2017

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