Alert archive / Virginia / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 535

October 25, 2021Calvert County, Charles County, Saint Mary's County, Maryland; 12 counties in North Carolina; 44 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Oct 25, 2021, 6:26 PM EDT for Calvert County, Charles County, Saint Mary's County, Maryland; 12 counties in North Carolina; 44 counties in Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Oct 25, 2021, 6:26 PM EDT (22:26 UTC)
Expired: Oct 25, 2021, 10:40 PM EDT
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 59 counties

Calvert County, MD, Charles County, MD, Saint Mary's County, MD, Alamance County, NC, Caswell County, NC, Durham County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Orange County, NC, Person County, NC, Rockingham County, NC, Stokes County, NC, Vance County, NC, Warren County, NC, Amelia County, VA, Appomattox 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 Colonial Heights, VA, City of Danville, VA, City of Fredericksburg, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Goochland County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Westmoreland County, VA

The radar

The Norfolk radar (KAKQ), 79 km from the middle of the area, began a volume at 22:28 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

15 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Oct 25, 6:29 PM EDT	Severe Thunderstorm Warning	RNK	Franklin, Henry, Pittsylvania, City of Martinsville	61 min
Oct 25, 6:48 PM EDT	Tornado Warning	RNK	Henry, Pittsylvania, City of Martinsville	27 min
Oct 25, 6:57 PM EDT	Severe Thunderstorm Warning	RAH	Forsyth, Guilford	48 min
Oct 25, 7:05 PM EDT	Tornado Warning	RAH	Guilford	25 min
Oct 25, 7:22 PM EDT	Severe Thunderstorm Warning	RNK	Appomattox, Buckingham, Campbell, Charlotte	53 min
Oct 25, 7:23 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Orange, Spotsylvania	21 min
Oct 25, 7:27 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth, Guilford, Randolph	48 min
Oct 25, 7:38 PM EDT	Severe Thunderstorm Warning	RNK	Campbell, Charlotte, Halifax, Pittsylvania	37 min
Oct 25, 7:42 PM EDT	Severe Thunderstorm Warning	RAH	Alamance	33 min
Oct 25, 8:06 PM EDT	Tornado Warning	RNK	Halifax, Pittsylvania	39 min
Oct 25, 8:16 PM EDT	Severe Thunderstorm Warning	RNK	Caswell	29 min
Oct 25, 8:19 PM EDT	Severe Thunderstorm Warning	RNK	Charlotte, Halifax	42 min
Oct 25, 8:37 PM EDT	Severe Thunderstorm Warning	RAH	Alamance, Chatham, Durham, Granville, Orange, Person	38 min
Oct 25, 8:44 PM EDT	Severe Thunderstorm Warning	AKQ	Lunenburg, Mecklenburg	61 min
Oct 25, 9:07 PM EDT	Severe Thunderstorm Warning	RAH	Franklin, Granville, Vance, Wake, Warren	38 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 10.4 hours before the alert went out and 161 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1208 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 106 m²/s²
0-3 km storm-relative helicity: 41 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

310 
WWUS20 KWNS 252222
SEL5  
SPC WW 252222
MDZ000-NCZ000-VAZ000-CWZ000-260500-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 535
NWS Storm Prediction Center Norman OK
625 PM EDT Mon Oct 25 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Eastern Maryland
  North Central North Carolina
  Central and Northeast Virginia
  Coastal Waters

* Effective this Monday night and Tuesday morning from 625 PM
  until 100 AM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...Thunderstorms are expected to intensify late this
afternoon over parts of central Virginia into northern North
Carolina, then spread eastward across the watch area.  The strongest
cells will pose a risk of damaging wind gusts, hail, and possibly a
tornado or two.

The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 20 miles west northwest
of Patuxent River MD to 20 miles east southeast of Greensboro NC.
For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU5).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
25030.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 25, 6:41 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Carroll, Cecil, Frederick, Harford and 5 more	2 hr
Oct 25, 3:01 PM EDT	Mesoscale Discussion	SPC	Alamance, Alexander, Caswell, Chatham, Davidson, Davie and 19 more	119 min

Nearby

Severe Thunderstorm Watches in Virginia, 2021 Severe Thunderstorm Watches in North Carolina, 2021 Severe Thunderstorm Watches in Maryland, 2021 Every severe thunderstorm watch 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.