Alert archive / North Carolina / Tornado Watches in 2018

Tornado Watch 381

September 16, 20186 counties in North Carolina; Horry County, South Carolina

The Storm Prediction Center issued this tornado watch at Sep 16, 2018, 11:01 PM EDT for 6 counties in North Carolina; Horry County, South Carolina. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Sep 16, 2018, 11:01 PM EDT (03:01 UTC)
Expired: Sep 17, 2018, 5:00 AM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Strongest gust expected: 60 kt

Counties Bladen County, NC, Brunswick County, NC, Columbus County, NC, Cumberland County, NC, Robeson County, NC, Sampson County, NC, Horry County, SC

The radar

The Wilmington radar (KLTX), 67 km from the middle of the area, began a volume at 03:02 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: 30%
One or more EF2 to EF5 tornadoes: 10%
Ten or more severe wind reports: 5%
One or more gusts of 65 knots or more: 5%
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: 20%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 16, 11:45 PM EDT	Severe Thunderstorm Warning	ILM	Bladen	33 min
Sep 16, 11:59 PM EDT	Tornado Warning	ILM	Bladen	18 min
Sep 17, 12:03 AM EDT	Flash Flood Warning	ILM	Horry	3 hr
Sep 17, 12:10 AM EDT	Tornado Warning	RAH	Cumberland, Sampson	35 min
Sep 17, 12:22 AM EDT	Tornado Warning	ILM	Horry	23 min
Sep 17, 12:31 AM EDT	Flash Flood Warning	ILM	Robeson	6 hr
Sep 17, 12:50 AM EDT	Tornado Warning	RAH	Sampson, Wayne	14 min
Sep 17, 1:02 AM EDT	Tornado Warning	ILM	Columbus	28 min
Sep 17, 2:39 AM EDT	Tornado Warning	ILM	Columbus	23 min
Sep 17, 3:14 AM EDT	Tornado Warning	ILM	Bladen, Columbus	31 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 00:00Z, 3.0 hours before the alert went out and 150 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: 851 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 708 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 59 m²/s²
0-3 km storm-relative helicity: 77 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

552 
WWUS20 KWNS 170258
SEL1  
SPC WW 170258
NCZ000-SCZ000-170900-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 381
NWS Storm Prediction Center Norman OK
1100 PM EDT Sun Sep 16 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southeast North Carolina
  Far northeast South Carolina

* Effective this Sunday night and Monday morning from 1100 PM
  until 500 AM EDT.

* Primary threats include...
  A couple tornadoes possible

SUMMARY...A couple of probable tornadoes have occurred over the past
1-2 hours along the North Carolina/South Carolina border vicinity. A
moist low-level influx in the presence of residually strong
low-level winds will likely continue to yield transient supercells
with some tornado risk into the overnight, although the overall
tornado potential should gradually diminish by daybreak Monday.

The tornado watch area is approximately along and 35 statute miles
east and west of a line from 25 miles east northeast of Fayetteville
NC to 80 miles south of Fayetteville NC. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU1).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 380...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 16040.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 16, 8:55 PM EDT	Mesoscale Discussion	SPC	Anson, Bladen, Columbus, Cumberland, Harnett, Hoke and 8 more	2 hr
Sep 17, 4:11 AM EDT	Mesoscale Discussion	SPC	Bladen, Brunswick, Columbus, Cumberland, Duplin, Harnett and 8 more	2 hr

Nearby

Tornado Watches in North Carolina, 2018 Tornado Watches in South Carolina, 2018 Every tornado watch in 2018

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.