Aug 23, 2017 0100 UTC Day 1 Convective Outlook
Updated: Wed Aug 23 01:00:25 UTC 2017 (20170823 0100Z Day 1 shapefile | 20170823 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170823 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 54,315 14,324,150 Worcester, MA...Springfield, MA...Paterson, NJ...Hartford, CT...Manchester, NH...
MARGINAL 122,893 28,989,088 New York, NY...Philadelphia, PA...Baltimore, MD...Boston, MA...Oklahoma City, OK...
Probabilistic Tornado Graphic
20170823 0100 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 % 23,897 3,851,646 Albany, NY...Scranton, PA...Schenectady, NY...Troy, NY...Pittsfield, MA...
2 % 52,171 23,077,014 Newark, NJ...Jersey City, NJ...Yonkers, NY...Worcester, MA...Springfield, MA...
Probabilistic Damaging Wind Graphic
20170823 0100 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 % 54,437 14,226,105 Springfield, MA...Paterson, NJ...Hartford, CT...Manchester, NH...Waterbury, CT...
5 % 122,995 28,553,372 New York, NY...Baltimore, MD...Boston, MA...Oklahoma City, OK...Newark, NJ...
Probabilistic Large Hail Graphic
20170823 0100 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
No Risk Areas Forecast
   SPC AC 230100

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0800 PM CDT Tue Aug 22 2017

   Valid 230100Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
   PA...NORTHERN NJ...SOUTHEAST NY INTO NEW ENGLAND...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   NORTHEAST U.S. SLIGHT RISK AREA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   MIDDLE AND EASTERN TN INTO NORTHERN AL...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PART OF THE
   SOUTHERN PLAINS...

   ...SUMMARY...
   Scattered strong to severe storms remain a threat across eastern
   Pennsylvania into parts of New England this evening and perhaps to
   the early overnight.

   ...Northeast States...
   Although instability will be weakening, given loss of daytime
   heating, storms will continue to spread across eastern PA into
   northern NJ and southeast NY to parts of New England this evening to
   the early overnight, as strong forcing for ascent should compensate
   for the weaker instability in the short term.  Strongly sheared
   environment, as deep-layer winds strengthen into New England, will
   continue to favor storm organization with low-level rotation
   remaining possible for a tornado or two.

   ...Portions of middle and eastern TN and northern AL...
   A band of storms will continue to advance to the south-southeast
   through middle into parts of eastern TN, and perhaps northern AL yet
   this evening.  Although instability will undergo further weakening,
   given the loss of daytime heating, forcing for ascent attendant to
   the southern extent of the Great Lakes/OH Valley may compensate
   allowing for an additional strong to severe storm.  Weak effective
   bulk shear will preclude storm organization, though water-loaded
   downdrafts per precipitable water ranging from 1.5-2.0 inches and
   cold pool development could locally enhance the threat for
   stronger/damaging wind gusts.  This threat should wane by late
   evening, as surface-based inhibition will become too strong to
   overcome for stronger momentum air to reach the ground.

   ...Southern Plains...
   Storm mergers across northwest/west-central TX and across OK will
   continue to pose a threat for locally strong/damaging wind gusts,
   given residual moderate instability, high precipitable water of
   1.5-2.0 inches, and some cold pool development enhancing this
   isolated severe threat this evening.

   ..Peters.. 08/23/2017

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