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.
Baltimore, MD...Washington, DC...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...
Probabilistic Large Hail 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
5 %
57,335
22,623,792
Baltimore, MD...Washington, DC...Virginia Beach, VA...Miami, FL...Norfolk, VA...
SPC AC 111955
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Sun Apr 11 2021
Valid 112000Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE SOUTHERN
FLORIDA PENINSULA AND FLORIDA KEYS...
...SUMMARY...
Damaging winds, a tornado or two, and isolated large hail are
expected this afternoon/evening across southern Florida. The threat
for a few damaging gusts and isolated large hail will shift into the
Florida Keys late tonight.
...20Z Update...
Storms have moved south of the enhanced area and the risk is
expected to lessen with southern extent as outflow has already
started to surge ahead of the storms with most activity on the cool
side of the boundary. Therefore, the enhanced area in Florida has
been removed.
Expanded the slight risk area to cover the Florida Keys for storms
late tonight. Storms on the western edge of the ongoing MCS that
extends from the Florida Peninsula into the central Gulf will move
into the Keys after 06Z. There is some question whether outflow
ahead of current storms in southern Florida may disrupt the
environment in the Keys. However, the last several runs of the HRRR
suggest at least some recovery. An environment with strong
instability in excess of 2000 J/kg (MLCAPE) and effective shear
around 40 knots would be sufficient for a damaging wind
threat/isolated hail threat in the Keys as this activity moves
through.
No changes to the marginal area in the mid-Atlantic as a few strong
to isolated severe storms remain possible this afternoon/evening.
..Bentley/Gleason.. 04/11/2021
.PREV DISCUSSION... /ISSUED 1129 AM CDT Sun Apr 11 2021/
...Central/south FL this afternoon/evening...
A large cluster of thunderstorms that formed early this morning
across the northeast Gulf of Mexico is evolving into a bowing MCS as
it moves onshore near Tampa. The storms will likely move along an
outflow boundary across central FL through the day, with the storms
forcing the outflow southward with time. Surface heating and
increases in low-level moisture south of the boundary, along with 50
kt west-southwesterly midlevel flow, will support the threat for
swaths of damaging gusts with the bowing segments. A tornado or two
may also occur with embedded circulations where the bowing segments
interact with the east-west oriented outflow boundary.
The threat for at least isolated damaging winds will shift southward
with time along the outflow boundary, spreading into south FL this
afternoon/evening.
...Eastern NC into the Mid-Atlantic this afternoon/evening...
A lead shortwave trough is rotating northeastward over the
Mid-Atlantic as of midday, with little forcing for ascent (or weak
subsidence) in its wake. Given surface heating and lingering
low-level moisture along and ahead of a cold front, a few storms may
still develop this afternoon, with the more probable area from VA
into south central PA. There will be marginally sufficient vertical
shear and buoyancy for a low-end threat for damaging winds and/or
large hail with the strongest storms this afternoon/evening.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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