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 2 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
169,831
58,968,004
New York, NY...Philadelphia, PA...Columbus, OH...Baltimore, MD...Washington, DC...
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 2 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
162,479
42,836,255
New York, NY...Philadelphia, PA...Baltimore, MD...Newark, NJ...Lincoln, NE...
SPC AC 211710
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1210 PM CDT Tue Jul 21 2020
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC AND NORTHEAST STATES...
...SUMMARY...
Strong to severe thunderstorms capable of producing mainly damaging
winds may occur Wednesday across parts of the Northeast,
Mid-Atlantic, Ohio Valley, and vicinity. Other isolated severe
storms appear possible across parts of the central Plains.
...Ohio Valley into the Mid-Atlantic and Northeast...
A shortwave trough will move quickly northeastward through the Upper
OH Valley and Northeast on Wednesday. This shortwave is expected to
dampen throughout the day as it enters the more confluent and
stronger flow across the Northeast. Even so, the lingering
southern/southwestern periphery of the shortwave trough will help
force thunderstorms as it interacts with the moist and unstable air
mass in place from the middle OH/TN Valleys into the Mid-Atlantic
and Northeast.
Bowing line segments and clusters should be the dominant storm mode,
with damaging wind gusts as the predominant severe threat.
Deep-layer vertical shear decreases with southern extent, so the
highest potential for more organized storms, and perhaps even a few
supercells, exists from central PA into Upstate NY/Southern New
England. In this area, the stronger vertical shear suggest slightly
greater potential for hail and maybe even a tornado or two.
Antecedent cloud cover and possibly a few showers could inhibit
destabilization in the vicinity of the warm front, but the stronger
shear still merits including this area in a 15% wind probability.
...Central Plains/Central High Plains...
Isolated thunderstorms will likely be ongoing early Wednesday
morning near the western KS/NE border. An isolated hail/wind threat
will exist with this early activity before it weakens throughout the
morning. Additional storms are possible during the late
afternoon/early evening on the outflow from this early activity.
Isolated development is also possible a bit farther west along the
lee trough. Any afternoon/evening storms that do develop may be
strong enough to produce a strong wind gust or two.
...Northern CA...Southern OR...Northwest NV...
Scattered thunderstorm activity is expected Wednesday afternoon in
the vicinity of an upper low moving across northern/central CA and
into western NV. Increased mid-level moisture and enhanced mid-level
flow associated with this low will contribute to modest instability
and vertical shear. Given the deeply mixed boundary layer and
potential for a few stronger/more organized storms, a 5% severe wind
probability was introduced for portions of northern CA, southern OR,
and northwest NV.
..Mosier.. 07/21/2020
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