Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 844
The Storm Prediction Center issued this mesoscale discussion at Jun 3, 2021, 1:46 PM EDT for 6 states. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Jun 3, 2021, 1:46 PM EDT (17:46 UTC)
- Expired
- Jun 3, 2021, 3:45 PM EDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 102 counties
Kent County, DE, New Castle 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, Talbot County, MD, Washington County, MD, Gloucester County, NJ, Salem County, NJ, Adams County, PA, Chester County, PA, Delaware County, PA, Lancaster County, PA, Montgomery County, PA, Philadelphia County, PA, York County, PA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Petersburg, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Henrico County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah 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), 59 km from the middle of the area, began a volume at 17:49 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, 5.8 hours before the alert went out and 58 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
- 73 J/kg
- Mixed-layer CIN
- -52 J/kg
- Mixed-layer LCL
- 511 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 116 m²/s²
- 0-3 km storm-relative helicity
- 118 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
534
ACUS11 KWNS 031746
SWOMCD
SPC MCD 031746
PAZ000-NJZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-031945-
Mesoscale Discussion 0844
NWS Storm Prediction Center Norman OK
1246 PM CDT Thu Jun 03 2021
Areas affected...southern and central Virginia northeastward to
southeastern Pennsylvania and vicinity
Concerning...Severe potential...Watch possible
Valid 031746Z - 031945Z
Probability of Watch Issuance...60 percent
SUMMARY...Locally strong/severe storms are expected to develop this
afternoon along and east of the higher terrain. A WW may be
required.
DISCUSSION...Latest visible satellite imagery shows a recent
increase in vertical cumulus growth in the vicinity of the Blue
Ridge, as rather thin/broken high cloudiness continues to permit
gradual heating. While rather weak lapse rates will limit
destabilization potential to some degree, 500 to 1000 J/kg
mixed-layer CAPE is now indicated across central and northern
Virginia. This will support a continued, gradual increase in
convective coverage and intensity this afternoon, as large-scale
ascent ahead of the eastward-moving Ohio Valley trough continues to
spread across the region.
Aiding in local convective intensification will be amply strong
0-6km shear, supported by a belt of mid-level southwesterly flow
around 40 kt atop the area. As such, a few multicell
clusters/bands, and even a couple of storms with mid-level rotation,
are expected. This gradual ramp-up in convective coverage/intensity
-- and associated risk for primarily damaging wind gusts -- will
likely require some consideration for WW issuance this afternoon.
..Goss/Guyer.. 06/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...
LAT...LON 37567981 37768003 39447818 40337645 40467526 39837503
38487583 37427661 37077758 37047901 37567981SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 3, 2:48 PM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 6 hr |
| Jun 3, 4:47 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 88 min |
Nearby
Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in Maryland, 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.