Mesoscale Discussion 1667

Issued

Sep 1, 2021, 4:01 AM EDT (08:01 UTC)

Expired

Sep 1, 2021, 6:00 AM EDT

In force

119 min

Issued by

the Storm Prediction Center

Concerning

Tornado watch 481

Counties New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Queen Anne's County, MD, Chester County, PA, Delaware County, PA, Lancaster County, PA, York County, PA

The Dover AFB radar (KDOX), 114 km from the middle of the area, began a volume at 08:03 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

051 
ACUS11 KWNS 010801
SWOMCD
SPC MCD 010801 
NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-011000-

Mesoscale Discussion 1667
NWS Storm Prediction Center Norman OK
0301 AM CDT Wed Sep 01 2021

Areas affected...Maryland...Southeast Pennsylvania

Concerning...Tornado Watch 481...

Valid 010801Z - 011000Z

The severe weather threat for Tornado Watch 481 continues.

SUMMARY...An isolated tornado threat will likely continue for a few
more hours. The threat is expected to become marginal near daybreak.
For that reason, a new weather watch will probably not be needed.

DISCUSSION...The latest radar imagery shows an isolated supercell in
central and northern Washington D.C. The storm is located along as
surface front and on the northwestern edge of a corridor of moderate
instability, with the RAP estimating MLCAPE in the 1000 to 1200 J/kg
range. In addition, the LWX WSR-88D VWP has veering winds with
height in the boundary layer and some speed shear in the low to
mid-levels. This wind profile will support continued supercell
development over the next 2 to 3 hours. A tornado threat will be
possible as the ongoing supercell moves northeastward toward the
Pennsylvania state line. The supercell is expected to weaken around
daybreak as it moves away from the stronger instability and more to
the cool side of the surface front.

..Broyles.. 09/01/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PHI...CTP...LWX...

LAT...LON   39657697 39177730 38977706 38907658 39047600 39527550
            39997517 40177531 40287613 40047663 39657697

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.