Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 945
The Storm Prediction Center issued this mesoscale discussion at Jun 13, 2021, 12:32 PM EDT for 9 counties in Maryland; 19 counties in Virginia; Berkeley County, Jefferson County, West Virginia. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jun 13, 2021, 12:32 PM EDT (16:32 UTC)
- Expired
- Jun 13, 2021, 2:30 PM EDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 30 counties
Anne Arundel County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Washington County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, King George County, VA, Loudoun County, VA, Prince William County, VA, Rappahannock County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV
The radar
The Sterling radar (KLWX), 8 km from the middle of the area, began a volume at 16:34 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
Washington/Dulle, VA (KIAD), launched 12:00Z, 4.5 hours before the alert went out and 5 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 664 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 54 m²/s²
- 0-3 km storm-relative helicity
- 56 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
671
ACUS11 KWNS 131632
SWOMCD
SPC MCD 131632
MDZ000-VAZ000-DCZ000-WVZ000-131830-
Mesoscale Discussion 0945
NWS Storm Prediction Center Norman OK
1132 AM CDT Sun Jun 13 2021
Areas affected...central Maryland into northern Virginia
Concerning...Severe potential...Watch unlikely
Valid 131632Z - 131830Z
Probability of Watch Issuance...20 percent
SUMMARY...A few damaging gusts may accompany the leading line of
storms. A WW issuance is not currently expected given the sparse
nature of the severe threat.
DISCUSSION...KLWX and MRMS mosaic radar imagery have shown a recent
uptick in intensity along the leading line of an MCS that has been
in progress for the past few hours. This line has likely been
elevated, however, the associated cold pool is now propagating into
a 75-80 F surface airmass, where the boundary-layer should have
mixed to some degree (based on modified RAP forecast soundings). A
transition to a more surface-based MCS is likely over the next
couple of hours, where wet downbursts may support a few damaging
gusts. However, troposheric winds and deep-layer ascent are both
quite weak, and buoyancy is expected to be limited (generally below
500 J/kg MLCAPE) given poor low/mid-level lapse rates and mid to
upper 60s F dewpoints. As such, damaging gusts are expected to
remain isolated and a WW issuance is not currently anticipated.
..Squitieri/Grams.. 06/13/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...LWX...
LAT...LON 39077855 39497816 39657778 39657721 39477672 38977645
38537641 38227663 38127706 38197757 38587818 39077855SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 13, 12:13 PM EDT | Mesoscale Discussion | SPC | Allegany, Garrett | 2 hr |
| Jun 13, 3:26 PM EDT | Mesoscale Discussion | SPC | Garrett | 94 min |
| Jun 13, 4:56 PM EDT | Severe Thunderstorm Watch | SPC | Alleghany, Bath, Bland, Botetourt, Buchanan, Craig and 7 more | 5 hr |
| Jun 13, 7:05 PM EDT | Mesoscale Discussion | SPC | Alleghany, Bath, Botetourt, Craig, Giles, Roanoke and 3 more | 85 min |
| Jun 13, 12:50 PM EDT | Severe Thunderstorm Watch | SPC | Barbour, Braxton, Brooke, Cabell, Calhoun, Clay and 30 more | 7 hr |
| Jun 13, 4:31 PM EDT | Mesoscale Discussion | SPC | Boone, Cabell, Clay, Fayette, Jackson, Kanawha and 13 more | 89 min |
Nearby
Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in Maryland, 2021Mesoscale Discussions in West Virginia, 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.