Alert archive / Maryland / Mesoscale Discussions in 2021
Mesoscale Discussion 1054
The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2021, 6:15 PM EDT for 5 states. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2021, 6:15 PM EDT (22:15 UTC)
- Expired
- Jun 21, 2021, 7:15 PM EDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 302...304
All 32 counties
Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Caroline County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Prince George's County, MD, Queen Anne's County, MD, Talbot County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Mercer County, NJ, Monmouth County, NJ, Ocean County, NJ, Salem County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Lancaster County, PA, Montgomery County, PA, Philadelphia County, PA, Arlington County, VA, City of Falls Church, VA
The radar
The Dover AFB radar (KDOX), 68 km from the middle of the area, began a volume at 22:14 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.
The nearest sounding before it
Wallops Is Stn, VA (KWAL), launched 12:00Z, 10.3 hours before the alert went out and 166 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 525 J/kg
- Mixed-layer CIN
- -38 J/kg
- Mixed-layer LCL
- 630 m above ground
- 0-6 km bulk shear
- 7 kt
- 0-1 km storm-relative helicity
- 4 m²/s²
- 0-3 km storm-relative helicity
- -14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
249
ACUS11 KWNS 212216
SWOMCD
SPC MCD 212215
NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-212315-
Mesoscale Discussion 1054
NWS Storm Prediction Center Norman OK
0515 PM CDT Mon Jun 21 2021
Areas affected...Portions of the Mid Atlantic and East Coast
Concerning...Severe Thunderstorm Watch 302...304...
Valid 212215Z - 212315Z
The severe weather threat for Severe Thunderstorm Watch 302, 304
continues.
SUMMARY...A line of thunderstorms with a history of damaging wind
gusts will track east over the next couple of hours. A continued
threat for damaging gusts appears likely before storms move offshore
around 00z.
DISCUSSION...2215Z radar imagery showed a line of strong/severe
thunderstorms and short bowing segments across portions of
northeastern VA, MD, and southern PA. Several reports of tree and
property damage have been received with this convective line over
the last few hours. Recent lightning and satellite trends suggests
some weakening of the line is occurring given lower flash rates and
warmer cloud tops. This is likely the result of interference from
the cooler maritime airmass near the Chesapeake Bay. However, SPC
mesoanalysis shows a broad area of locally greater buoyancy
(2000-2500 J/kg of MLCAPE) exists to the east across DE and southern
NJ. While some weakening of the ongoing line will likely continue,
damaging wind gusts from strong outflow winds will remain a threat.
Some resurgence may occur after storms cross into more favorable
thermodynamic profile east of the bay across WW302 and southern
portions of 304. This threat will continue before storms move
offshore around 00z.
..Lyons.. 06/21/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...
LAT...LON 38607464 38567508 38667644 38897726 39617687 40337649
40427538 40407437 40227367 39587388 39137419 38607464SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 1:51 PM EDT | Mesoscale Discussion | SPC | New Castle | 114 min |
| Jun 21, 4:33 PM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 6 hr |
| Jun 21, 2:20 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Cecil and 9 more | 6 hr |
| Jun 21, 6:50 PM EDT | Mesoscale Discussion | SPC | Passaic, Sussex, Warren | 55 min |
| Jun 21, 11:59 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 12 more | 91 min |
| Jun 21, 12:31 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Cambria, Cameron and 19 more | 7 hr |
| Jun 21, 3:45 PM EDT | Severe Thunderstorm Watch | SPC | Bradford, Lackawanna, Luzerne, Pike, Susquehanna, Wayne and 1 more | 7 hr |
| Jun 21, 3:47 PM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Cambria, Cameron, Clearfield, Elk and 6 more | 58 min |
| Jun 21, 5:59 PM EDT | Mesoscale Discussion | SPC | Scott, City of Bristol | 91 min |
Nearby
Mesoscale Discussions in Maryland, 2021Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in Pennsylvania, 2021Every mesoscale discussion in 2021
Sources
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.