Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 119
The Storm Prediction Center issued this mesoscale discussion at Feb 18, 2021, 10:23 AM EST for 5 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 18, 2021, 10:23 AM EST (15:23 UTC)
- Expired
- Feb 18, 2021, 1:30 PM EST
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 96 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, 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, Alamance County, NC, Caswell County, NC, Davidson County, NC, Durham County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Vance County, NC, Warren County, NC, Cape May County, NJ, Cumberland County, NJ, Salem County, NJ, Albemarle County, VA, Amelia County, VA, Appomattox County, VA, Arlington County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Petersburg, VA, City of Richmond, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Sussex County, VA, Westmoreland County, VA
The radar
The Norfolk radar (KAKQ), 79 km from the middle of the area, began a volume at 15:25 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, 3.4 hours before the alert went out and 148 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
- 604 m above ground
- 0-6 km bulk shear
- 86 kt
- 0-1 km storm-relative helicity
- 77 m²/s²
- 0-3 km storm-relative helicity
- 421 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
396
ACUS11 KWNS 181523
SWOMCD
SPC MCD 181523
NJZ000-DEZ000-MDZ000-VAZ000-NCZ000-DCZ000-181830-
Mesoscale Discussion 0119
NWS Storm Prediction Center Norman OK
0923 AM CST Thu Feb 18 2021
Areas affected...portions of the mid-Atlantic into central Virginia
and northern North Carolina
Concerning...Freezing rain
Valid 181523Z - 181830Z
SUMMARY...Sleet and freezing rain continues from the mid-Atlantic
southward into northern North Carolina. The precipitation will
gradually come to an end from west to east through the morning and
early afternoon.
DISCUSSION...Persistent cold air damming in the lee of the
Appalachians has maintained upper 20s to low 30s temperatures as far
south as northern North Carolina. Surface observations in this area
have shown ice accretion as high as 0.1" per hour recently. The
greatest freezing rain accumulation has been across central and
southern Virginia where temperatures remain in the upper 20s to low
30s and precipitation is mostly falling as freezing rain. Farther
north, temperatures are cold enough at the top of the boundary layer
(as seen on IAD 12Z RAOB) to support mostly sleet. Isentropic ascent
will shift northeastward by early afternoon which should bring an
end to precipitation across much of this region by 19-20Z.
..Bentley.. 02/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...LWX...RAH...RNK...GSP...
LAT...LON 35458016 35658059 36308008 37187919 37817878 38017871
38937784 39717695 39717582 39607502 39337447 39197442
38887455 38787508 38787552 38507580 38277584 37717674
37347691 36487713 36127789 36017852 35757924 35497976
35458016SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 18, 4:28 AM EST | Mesoscale Discussion | SPC | Charles | 6 hr |
| Feb 18, 9:47 AM EST | Mesoscale Discussion | SPC | Bergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more | 4 hr |
Nearby
Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in Maryland, 2021Mesoscale Discussions in North Carolina, 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.