Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 543
The Storm Prediction Center issued this mesoscale discussion at May 5, 2021, 1:03 PM EDT for 5 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 5, 2021, 1:03 PM EDT (17:03 UTC)
- Expired
- May 5, 2021, 3:30 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 85 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, 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, Wicomico County, MD, Worcester County, MD, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Lancaster County, PA, Accomack County, VA, Amelia County, VA, Arlington County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Williamsburg, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Powhatan County, VA, Prince George County, VA, Prince William County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA
The radar
The Sterling radar (KLWX), 97 km from the middle of the area, began a volume at 17:04 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, 5.1 hours before the alert went out and 89 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
- 99 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 709 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 75 m²/s²
- 0-3 km storm-relative helicity
- 191 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
818
ACUS11 KWNS 051704
SWOMCD
SPC MCD 051703 COR
NJZ000-MDZ000-DEZ000-PAZ000-VAZ000-DCZ000-051930-
Mesoscale Discussion 0543
NWS Storm Prediction Center Norman OK
1203 PM CDT Wed May 05 2021
Areas affected...Far Southeast PA...Far Southern NJ...Delmarva
Peninsula...DC...Central/Eastern MD...Eastern VA
Concerning...Severe potential...Watch unlikely
Valid 051703Z - 051930Z
CORRECTED FOR INCORRECT TEMPERATURE REFERENCE IN FIRST PARAGRAPH.
Probability of Watch Issuance...20 percent
SUMMARY...Isolated damaging wind gusts are possible this afternoon
as thunderstorms developing along a southeastward-moving cold front.
DISCUSSION...Recent surface analysis places a low over east-central
PA, with a cold front extending southwestward across central MD and
through central and southwest VA. Air mass ahead of this front
continues to gradually destabilize as temperatures rise into the
upper 70s and low 80s across MD and VA. Slightly cooler temperatures
are in place across southeast PA where cloudiness has limited
heating. This diurnal heating is occurring amid mid 60s dewpoints,
resulting in moderate instability despite the modest mid-level lapse
rates.
General expectation is for isolated to widely scattered
thunderstorms to develop along the front as it continues
southeastward this afternoon. Low-level flow is relatively modest
but deep-layer flow remains strong, contributing to fast storm
motion and the potential for a few strong, convectively augmented
downdrafts.
..Mosier/Grams.. 05/05/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...
LAT...LON 39537710 40097629 39727508 38587495 37377570 36817633
36817788 37887865 39537710Nearby
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.