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 %
90,902
34,462,657
New York, NY...Boston, MA...Newark, NJ...Jersey City, NJ...Yonkers, NY...
SPC AC 230523
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 AM CDT Thu Jul 23 2020
Valid 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
NORTHEAST...AND OVER PARTS OF THE NORTHERN HIGH PLAINS...
...SUMMARY...
Scattered strong to severe storms are expected this afternoon over
parts of the Northeast, with damaging wind gusts and isolated hail.
Severe storms are also possible from eastern Montana into western
North Dakota late in the day. Isolated activity, including a few
strong wind gusts, is possible over much of the Appalachians and Mid
Atlantic, and across Idaho.
...Synopsis...
Cyclonic flow aloft will exist from the Great Basin northward across
the Pacific Northwest and northern Rockies, with various embedded
waves. A leading shortwave trough will lift northeast across WY, MT
and ND, with storms forming within the northern High Plains surface
trough. Farther east, a positive-tilt shortwave trough will move
east across the Great Lakes and into New England, with a weak
surface reflection approaching I-95 by late afternoon.
...Northeast...
A surface trough will develop during the day from ME southwestward
into PA/NJ, beneath modest westerly winds aloft as a positive-tilt
shortwave trough approaches the St. Lawrence Valley. Mid to upper
60s F dewpoints will exist across the region, with heating leading
to 1500 J/kg MLCAPE across eastern PA, NY and southern New England.
Storms are likely to form around 18Z near the surface trough, and
will spread east/northeast through the afternoon. Unidirectional
wind profiles should be sufficient to support cellular storm mode,
with both wind and hail threat. Any wind threat will increase should
storms merge into larger clusters or lines.
...Northern High Plains...
Storms are likely to form near the surface trough/front after 21Z
across eastern MT, and possibly into northwest SD, where low-level
lapse rates will be steep. Backed southeast surface winds will
maintain 60s F dewpoints downshear into the Dakotas where
instability will be strong, but capped. CAMs suggest initial cells
(which will likely produce hail) may develop into an MCS/bow during
the evening, with damaging-wind threat across western ND.
...Central MT into ID...
Storms are forecast to form relatively early across central ID
(~18Z), and will shift east across much of southwest MT during the
afternoon. This may hamper heating in some areas. However, cool
temperatures aloft may support marginal hail or wind. Other storms
are likely to form where heating will be stronger, from northern NV
into southern ID, with a few hail or wind reports possible. Weak
shear will be a limiting factor across this area.
..Jewell/Cook.. 07/23/2020
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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