Alert archive / North Carolina / Tornado Watches in 2017

Tornado Watch 194

May 4, 201719 counties in North Carolina; 15 counties in South Carolina

The Storm Prediction Center issued this tornado watch at May 4, 2017, 8:49 PM EDT for 19 counties in North Carolina; 15 counties in South Carolina. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
May 4, 2017, 8:49 PM EDT (00:49 UTC)
Expired
May 5, 2017, 3:00 AM EDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
60 kt
All 34 counties

Bladen County, NC, Brunswick County, NC, Carteret County, NC, Columbus County, NC, Craven County, NC, Cumberland County, NC, Duplin County, NC, Harnett County, NC, Hoke County, NC, Johnston County, NC, Jones County, NC, Lenoir County, NC, New Hanover County, NC, Onslow County, NC, Pender County, NC, Robeson County, NC, Sampson County, NC, Scotland County, NC, Wayne County, NC, Berkeley County, SC, Charleston County, SC, Clarendon County, SC, Darlington County, SC, Dillon County, SC, Dorchester County, SC, Florence County, SC, Georgetown County, SC, Horry County, SC, Lee County, SC, Marion County, SC, Marlboro County, SC, Orangeburg County, SC, Sumter County, SC, Williamsburg County, SC

The radar

The Wilmington radar (KLTX), 57 km from the middle of the area, began a volume at 00:49 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
10%
One or more gusts of 65 knots or more
10%
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
30%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 4, 8:52 PM EDTTornado WarningCAEClarendon, Orangeburg23 min
May 4, 9:16 PM EDTTornado WarningCAEClarendon, Orangeburg44 min
May 4, 10:36 PM EDTTornado WarningILMFlorence, Marion39 min
May 4, 11:41 PM EDTTornado WarningILMHorry34 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

Charleston AFB, SC (KCHS), launched 00:00Z, 0.8 hours before the alert went out and 173 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, Charleston AFB, SC at 00:00Z on 2017-05-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 401 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, Charleston AFB, SC at 00:00Z on 2017-05-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 278 square meters per square second.19395878Sfc1 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
401 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
781 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
278 m²/s²
0-3 km storm-relative helicity
329 m²/s²
Significant tornado parameter
0.6
Supercell composite
8.3

Open this sounding in Storm Lab

The text

As transmitted.

479 
WWUS20 KWNS 050047
SEL4  
SPC WW 050047
NCZ000-SCZ000-CWZ000-050700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 194
NWS Storm Prediction Center Norman OK
850 PM EDT Thu May 4 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southeastern North Carolina
  Eastern South Carolina
  Coastal Waters

* Effective this Thursday night and Friday morning from 850 PM
  until 300 AM EDT.

* Primary threats include...
  A few tornadoes possible

SUMMARY...Tornado threat has become greater than isolated over the
area, with the potential for additional supercells to form both in
the main band of thunderstorms moving northeastward, and activity
moving inland from the Atlantic.  Outlook probabilities are being
upgraded accordingly as well.

The tornado watch area is approximately along and 55 statute miles
either side of a line from 55 miles south southwest of Florence SC
to 30 miles east northeast of Jacksonville NC. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU4).

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 193...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 22030.

...Edwards

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 4, 11:24 PM EDTMesoscale DiscussionSPCBladen, Brunswick, Columbus, Duplin, Greene, Jones and 7 more66 min
May 5, 2:28 AM EDTMesoscale DiscussionSPCAlamance, Beaufort, Bertie, Bladen, Camden, Caswell and 43 more92 min
May 5, 3:09 AM EDTTornado WatchSPCAlamance, Anson, Bladen, Brunswick, Carteret, Chatham and 37 more6 hr
May 5, 5:56 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Camden, Chowan, Currituck, Dare and 12 more94 min
May 5, 6:25 AM EDTTornado WatchSPCBeaufort, Bertie, Camden, Chowan, Currituck, Dare and 9 more5 hr
May 5, 8:27 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Camden, Carteret, Chowan, Craven and 9 more93 min
May 5, 6:15 PM EDTMesoscale DiscussionSPCHalifax, Hertford, Northampton90 min

Nearby

Tornado Watches in North Carolina, 2017Tornado Watches in South Carolina, 2017Every tornado watch in 2017

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.