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
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 %
30,083
30,796,883
New York, NY...Philadelphia, PA...Virginia Beach, VA...Newark, NJ...Norfolk, VA...
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 %
31,791
13,045,411
Philadelphia, PA...Baltimore, MD...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...
SPC AC 211234
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Wed Apr 21 2021
Valid 211300Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
NORTHEAST...
...SUMMARY...
Isolated to scattered damaging winds are possible across the coastal
Mid-Atlantic States into southern New England between 1 to 6 PM EDT.
...Mid-Atlantic to New England...
Surface temperatures have begun warming through the 50s into the 60s
from southeast PA to southern New England south. However, surface
dew points largely remain in the 40s north of coastal VA and this
will limit buoyancy today. Robust boundary-layer heating will be
necessary to support meager MLCAPE to around 500 J/kg.
A surface cyclone over south-central PA will deepen as it tracks
towards southwest ME. An attendant cold front will sweep east and
reach the Mid-Atlantic Coastal Plain midday to early afternoon. As
it impinges on the destabilizing air mass, scattered to broken
low-topped convective development is anticipated. Given the
amplifying wave, strengthening of low to mid-level southwesterlies
should yield upscale evolution to a short-lived QLCS spreading into
southern New England. More broken cells should be maintained farther
south where a few transient supercells are expected. A well-mixed
boundary layer with an inverted-v thermodynamic profile and pressure
rise/fall couplet may support strong to isolated severe gusts with
scattered damaging winds as the primary hazard. Farther south,
marginally severe hail is possible where storm mode can remain
semi-discrete before convection quickly spreads off the coast.
..Grams/Dial.. 04/21/2021
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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