Alert archive / North Carolina / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 398

July 28, 202135 counties in North Carolina; 5 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Jul 28, 2021, 2:19 PM EDT for 35 counties in North Carolina; 5 counties in Virginia. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jul 28, 2021, 2:19 PM EDT (18:19 UTC)
Expired
Jul 28, 2021, 8:32 PM EDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 40 counties

Beaufort County, NC, Bertie County, NC, Camden County, NC, Carteret County, NC, Chowan County, NC, Craven County, NC, Cumberland County, NC, Currituck County, NC, Dare County, NC, Duplin County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Greene County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Hyde County, NC, Johnston County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Sampson County, NC, Tyrrell County, NC, Wake County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, City of Emporia, VA, City of Franklin, VA, Greensville County, VA, Southampton County, VA, Sussex County, VA

The radar

The Morehead City radar (KMHX), 100 km from the middle of the area, began a volume at 18:20 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
5%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
40%
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
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 28, 2:35 PM EDTSevere Thunderstorm WarningAKQCamden, Pasquotank, Perquimans40 min
Jul 28, 3:02 PM EDTSevere Thunderstorm WarningRAHHarnett43 min
Jul 28, 3:36 PM EDTSevere Thunderstorm WarningRAHChatham, Harnett, Lee, Wake39 min
Jul 28, 3:42 PM EDTSevere Thunderstorm WarningAKQChowan, Perquimans18 min
Jul 28, 3:57 PM EDTSevere Thunderstorm WarningMHXHyde, Tyrrell, Washington63 min
Jul 28, 4:16 PM EDTSevere Thunderstorm WarningAKQNorthampton29 min
Jul 28, 4:37 PM EDTSevere Thunderstorm WarningMHXBeaufort, Craven, Pitt38 min
Jul 28, 4:42 PM EDTSevere Thunderstorm WarningRAHJohnston, Nash, Wake, Wayne, Wilson63 min
Jul 28, 4:55 PM EDTSevere Thunderstorm WarningMHXBeaufort, Hyde, Tyrrell, Washington65 min
Jul 28, 5:37 PM EDTSevere Thunderstorm WarningMHXBeaufort, Craven, Hyde, Pamlico53 min
Jul 28, 5:43 PM EDTSevere Thunderstorm WarningRAHEdgecombe, Wilson47 min
Jul 28, 5:45 PM EDTSevere Thunderstorm WarningRAHCumberland, Hoke, Sampson45 min
Jul 28, 5:47 PM EDTSevere Thunderstorm WarningMHXBeaufort, Craven, Greene, Jones, Lenoir, Pitt58 min
Jul 28, 6:27 PM EDTSevere Thunderstorm WarningRAHCumberland, Sampson27 min
Jul 28, 6:39 PM EDTSevere Thunderstorm WarningMHXCraven, Duplin, Greene, Jones, Lenoir, Onslow and 2 more66 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

Newport, NC (KMHX), launched 12:00Z, 6.3 hours before the alert went out and 99 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-pSkew-T log-p diagram, Newport, NC at 12:00Z on 2021-07-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2446 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Newport, NC at 12:00Z on 2021-07-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 61 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2446 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
613 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
61 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0

Open this sounding in Storm Lab

The text

As transmitted.

259 
WWUS20 KWNS 281816
SEL8  
SPC WW 281816
NCZ000-VAZ000-CWZ000-290100-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 398
NWS Storm Prediction Center Norman OK
220 PM EDT Wed Jul 28 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Eastern North Carolina
  Southeast Virginia
  Coastal Waters

* Effective this Wednesday afternoon and evening from 220 PM
  until 900 PM EDT.

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

SUMMARY...Clusters of thunderstorms will develop and spread across
the watch area through the afternoon.  Very hot/humid conditions and
favorable winds aloft will promote a risk of damaging wind gusts and
hail in the strongest cells.

The severe thunderstorm watch area is approximately along and 60
statute miles either side of a line from 65 miles east of Roanoke
Rapids NC to 35 miles west of Jacksonville NC. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).

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
33025.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 28, 12:36 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Camden, Chowan, Craven and 28 more114 min
Jul 28, 4:16 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Camden, Chowan, Craven, Cumberland and 23 more119 min
Jul 28, 6:07 PM EDTMesoscale DiscussionSPCAnson, Bladen, Brunswick, Columbus, Cumberland, Duplin and 8 more83 min

Nearby

Severe Thunderstorm Watches in North Carolina, 2021Severe Thunderstorm Watches in Virginia, 2021Every 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.