Mesoscale Discussion 300

Issued

Mar 28, 2021, 1:24 PM EDT (17:24 UTC)

Expired

Mar 28, 2021, 3:30 PM EDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

60%

The Norfolk radar (KAKQ), 96 km from the middle of the area, began a volume at 17:27 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.

• Severe Thunderstorm Watch 68Mar 28, 3:25 PM EDT
• Severe Thunderstorm Watch 69Mar 28, 5:05 PM EDT

626 
ACUS11 KWNS 281725
SWOMCD
SPC MCD 281724 
MDZ000-DEZ000-VAZ000-NCZ000-DCZ000-281930-

Mesoscale Discussion 0300
NWS Storm Prediction Center Norman OK
1224 PM CDT Sun Mar 28 2021

Areas affected...Central and eastern Virginia into Maryland and
Delaware.

Concerning...Severe potential...Watch possible 

Valid 281724Z - 281930Z

Probability of Watch Issuance...60 percent

SUMMARY...Severe storms are forecast to develop this afternoon with
a risk for damaging wind gusts and a tornado or two. A watch may be
needed.

DISCUSSION...1720 UTC satellite and surface obs shows partly cloudy
skies and temperatures in the 70s F across much of southeastern
Virginia. To the west and north, greater cloud coverage was noted
with a line of showers along a pre-frontal trough from south-central
Virginia into northern Maryland. Gradual destabilization is
occurring to the east of these showers with SPC mesoanalysis
indicating 500-100 J/kg of MLCAPE developing associated with
low-level moist advection of dewpoints in the 60s F. Despite
increasing cloud cover, slow destabilization should continue through
the first half of the afternoon from southeastern Virginia northward
toward the southern Pennsylvania border. 

Some hi-res guidance suggests a few thunderstorms may evolve out of
the ongoing shower activity early this afternoon as the pre-frontal
trough continues eastward. Storms that develop will have the
potential to produce damaging wind gusts and perhaps a brief tornado
given strong low and mid-level flow across much of the Mid Atlantic.
However, there remains substantial uncertainty on thunderstorm
initiation early this afternoon given weak destabilization and
subtle forcing for ascent.  

A second round of thunderstorms is expected to develop along the
eastward moving cold front across central Virginia later this
afternoon. While surface conditions remain much cooler and drier,
cloud breaks across the region should allow some destabilization
through the afternoon. Forecast models show veered but elongated
hodographs supportive of damaging wind gusts with linear storms
along and ahead of the front later this afternoon and into the early
evening hours. Trends will be monitored for a possible weather watch
this afternoon/evening.

..Lyons/Thompson.. 03/28/2021

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

ATTN...WFO...PHI...AKQ...LWX...RAH...RNK...

LAT...LON   36517603 36467725 36527814 36627877 37007910 37587883
            38367832 39187739 39487665 39417575 39337547 39057524
            38697505 38327505 37937519 37337548 36917573 36617588
            36517603

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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.