Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 746
The Storm Prediction Center issued this mesoscale discussion at May 26, 2021, 1:21 PM EDT for 5 states. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- May 26, 2021, 1:21 PM EDT (17:21 UTC)
- Expired
- May 26, 2021, 2:45 PM EDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 53 counties
Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Washington County, MD, Wicomico County, MD, Worcester County, MD, Cape May County, NJ, Cumberland County, NJ, 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, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Jefferson County, WV
The radar
The Sterling radar (KLWX), 72 km from the middle of the area, began a volume at 17:21 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 5.4 hours before the alert went out and 64 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
- 478 J/kg
- Mixed-layer CIN
- -132 J/kg
- Mixed-layer LCL
- 922 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 35 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
206
ACUS11 KWNS 261721
SWOMCD
SPC MCD 261721
NJZ000-MDZ000-DEZ000-VAZ000-DCZ000-PAZ000-WVZ000-261845-
Mesoscale Discussion 0746
NWS Storm Prediction Center Norman OK
1221 PM CDT Wed May 26 2021
Areas affected...northern VA...MD...DE and far southern NJ
Concerning...Severe potential...Watch possible
Valid 261721Z - 261845Z
Probability of Watch Issuance...40 percent
SUMMARY...Locally damaging winds are possible with thunderstorms
this afternoon into early evening.
DISCUSSION...Strong heating through early afternoon has allowed
temperatures to warm into the 80s to low 90s amid upper 60s to low
70s surface dewpoints. This is aiding in weak to moderate
destabilization with up to 1500 J/kg MLCAPE present across the
region. Isolated convection is developing over the higher terrain of
WV and a cluster of thunderstorms is expected to form over the next
couple of hours across northern VA/western MD. Effective shear will
remain weak over the area, with around 20-25 kt currently forecast.
Nevertheless, very steep low level lapse rates will promote strong
downdraft potential. Should cold pool development occur, there is
some potential that a better organized cluster could develop and
grow upscale as it shifts across the Chesapeake Bay toward the
DE/southern NJ coast early this evening. Convective trends will be
monitored and a watch may be needed in the next couple of hours.
..Leitman/Hart.. 05/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...
LAT...LON 39697687 39677594 39677559 39497519 39257483 39027477
38767476 38417494 38257520 38107571 37957616 38077760
38157789 38257824 38417844 38637852 39007844 39357827
39567803 39737752 39697687SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 26, 2:48 PM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 7 hr |
| May 26, 4:41 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 64 min |
| May 26, 6:34 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 116 min |
| May 26, 12:16 PM EDT | Mesoscale Discussion | SPC | Brooke, Hancock, Ohio | 119 min |
| May 26, 12:59 PM EDT | Severe Thunderstorm Watch | SPC | Brooke, Hancock, Marion, Marshall, Monongalia, Ohio and 3 more | 7 hr |
Nearby
Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in Maryland, 2021Mesoscale Discussions in Delaware, 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.