Alert archive / North Carolina / Tornado Watches in 2020

Tornado Watch 413

August 3, 20206 counties in North Carolina; Georgetown County, Horry County, South Carolina

The Storm Prediction Center issued this tornado watch at Aug 3, 2020, 4:44 PM EDT for 6 counties in North Carolina; Georgetown County, Horry County, South Carolina. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: Aug 3, 2020, 4:44 PM EDT (20:44 UTC)
Expired: Aug 4, 2020, 12:50 AM EDT
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 80 kt

Counties Bladen County, NC, Brunswick County, NC, Columbus County, NC, New Hanover County, NC, Pender County, NC, Sampson County, NC, Georgetown County, SC, Horry County, SC

The radar

The Wilmington radar (KLTX), 30 km from the middle of the area, began a volume at 20:45 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: 50%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 5%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 40%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Aug 3, 7:49 PM EDT	Tornado Warning	ILM	Brunswick	26 min
Aug 3, 8:03 PM EDT	Tornado Warning	ILM	Brunswick, Columbus	17 min
Aug 3, 8:10 PM EDT	Tornado Warning	ILM	Brunswick, Columbus, New Hanover	35 min
Aug 3, 8:25 PM EDT	Tornado Warning	ILM	Brunswick, New Hanover	35 min
Aug 3, 8:50 PM EDT	Tornado Warning	ILM	Bladen, Brunswick, Columbus, New Hanover, Pender	25 min
Aug 3, 9:56 PM EDT	Tornado Warning	ILM	Brunswick, Columbus, New Hanover, Pender	34 min
Aug 3, 11:45 PM EDT	Flash Flood Warning Considerable damage threat	RAH	Cumberland, Harnett, Johnston, Sampson, Wayne	6 hr

Discussions around it

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

The nearest sounding before it

Charleston AFB, SC (KCHS), launched 12:00Z, 8.7 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: 1287 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 762 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -30 m²/s²
0-3 km storm-relative helicity: -56 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

955 
WWUS20 KWNS 032041
SEL3  
SPC WW 032041
NCZ000-SCZ000-CWZ000-040600-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 413
NWS Storm Prediction Center Norman OK
435 PM EDT Mon Aug 3 2020

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  southern North Carolina
  northeastern South Carolina
  Coastal Waters

* Effective this Monday afternoon and Tuesday morning from 435 PM
  until 200 AM EDT.

* Primary threats include...
  A few tornadoes possible
  Isolated significant damaging wind gusts to 90 mph possible

SUMMARY...With the landfall and inland migration of Isaias, the
potential for thunderstorms capable of producing tornadoes may begin
to develop along northeastern South Carolina coastal areas by 6-8 PM
EDT, before increasing across and inland of southern North Carolina
coastal areas through late evening.

The tornado watch area is approximately along and 60 statute miles
east and west of a line from 25 miles south southwest of Myrtle
Beach SC to 35 miles north northeast of Wilmington NC. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.

&&

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 80 knots. A few cumulonimbi with maximum tops to 400. Mean
storm motion vector 16025.

...Kerr

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 3, 3:58 PM EDT	Mesoscale Discussion	SPC	Bladen, Brunswick, Columbus, Craven, Duplin, Jones and 3 more	2 hr

Nearby

Tornado Watches in North Carolina, 2020 Tornado Watches in South Carolina, 2020 Every tornado watch in 2020

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.