Mesoscale Discussion 1901

Issued

Oct 25, 2021, 6:41 PM EDT (22:41 UTC)

Expired

Oct 25, 2021, 8:45 PM EDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Dover AFB radar (KDOX), 95 km from the middle of the area, began a volume at 22:41 UTC, the scan nearest the moment this went out.

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387 
ACUS11 KWNS 252242
SWOMCD
SPC MCD 252241 
NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-260045-

Mesoscale Discussion 1901
NWS Storm Prediction Center Norman OK
0541 PM CDT Mon Oct 25 2021

Areas affected...portions of northern Maryland and northern Delaware
into southeast Pennsylvania and southern into central New Jersey

Concerning...Severe potential...Watch unlikely 

Valid 252241Z - 260045Z

Probability of Watch Issuance...20 percent

SUMMARY...A couple damaging gusts remain possible with some of the
stronger storms over the next couple of hours. The severe threat
should gradually diminish later this evening with boundary-layer
stabilization. A WW issuance is not expected given the short-lived
nature of the severe threat.

DISCUSSION...A west-east oriented band of convection has become
established along a confluence zone across central MD/DE over the
past couple of hours. While mainly pulse cellular and brief
multicellular storms comprise the convective band, a couple of the
stronger storm cores have produced damaging gusts within the past
hour, particularly across Fairfax County, VA. This convective band
is progressing northward across a reservoir of 500+ J/kg MLCAPE and
35-45 kts of effective bulk shear (driven primarily by sfc-500 mb
speed shear within a unidirectional southerly vertical wind
profile). As such, a couple damaging gusts remain possible with the
longer lasting cells/clusters given the available buoyancy. However,
RAP forecast soundings suggest that the aforementioned buoyancy is
driven primarily by a heated/mixed boundary layer. Given nocturnal
cooling already underway, the boundary layer is expected to
stabilize. As such, the ongoing damaging gust threat is expected to
be relatively brief (i.e. continuing for only a few more hours
before diminishing), and a WW issuance is not anticipated.

..Squitieri/Hart.. 10/25/2021

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

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

LAT...LON   38907522 38987631 38977694 38987731 38987769 39157771
            39597747 40357648 40827598 40867569 40737524 40557475
            40337443 39877411 39447421 39097460 38887491 38907522

Mesoscale Discussions in Maryland, 2021Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in Pennsylvania, 2021Every mesoscale discussion in 2021

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.