Alert archive / North Carolina / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 163

May 10, 202131 counties in North Carolina

The Storm Prediction Center issued this severe thunderstorm watch at May 10, 2021, 3:57 PM EDT for 31 counties in North Carolina. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: May 10, 2021, 3:57 PM EDT (19:57 UTC)
Expired: May 10, 2021, 10:00 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 31 counties

Alamance County, NC, Beaufort County, NC, Chatham County, NC, Craven County, NC, Cumberland County, NC, Davidson County, NC, Duplin County, NC, Durham County, NC, Edgecombe County, NC, Franklin County, NC, Greene County, NC, Guilford County, NC, Harnett County, NC, Hoke County, NC, Johnston County, NC, Jones County, NC, Lee County, NC, Lenoir County, NC, Martin County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Onslow County, NC, Orange County, NC, Pamlico County, NC, Pitt County, NC, Randolph County, NC, Sampson County, NC, Wake County, NC, Wayne County, NC, Wilson County, NC

The radar

The Raleigh/Durham radar (KRAX), 21 km from the middle of the area, began a volume at 19:58 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: 10%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
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: 50%

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
May 10, 4:02 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth, Guilford, Randolph	43 min
May 10, 4:37 PM EDT	Severe Thunderstorm Warning	RAH	Alamance, Chatham, Durham, Lee, Orange	38 min
May 10, 4:39 PM EDT	Severe Thunderstorm Warning	MHX	Carteret, Craven, Jones, Onslow	36 min
May 10, 4:45 PM EDT	Tornado Warning	RAH	Alamance, Chatham, Orange	30 min
May 10, 5:14 PM EDT	Severe Thunderstorm Warning	RAH	Chatham, Durham, Harnett, Orange, Wake	46 min
May 10, 6:14 PM EDT	Severe Thunderstorm Warning	RAH	Franklin, Nash, Wake	46 min
May 10, 9:58 PM EDT	Severe Thunderstorm Warning	RAH	Harnett, Johnston, Sampson, Wayne	60 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 8.0 hours before the alert went out and 115 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: 28 J/kg
Mixed-layer CIN: -120 J/kg
Mixed-layer LCL: 1031 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 196 m²/s²
0-3 km storm-relative helicity: 180 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

414 
WWUS20 KWNS 101955
SEL3  
SPC WW 101955
NCZ000-CWZ000-110200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 163
NWS Storm Prediction Center Norman OK
400 PM EDT Mon May 10 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Parts of central and eastern North Carolina
  Coastal Waters

* Effective this Monday afternoon and evening from 400 PM until
  1000 PM EDT.

* Primary threats include...
  Isolated damaging wind gusts to 70 mph possible
  Isolated large hail events to 1 inch in diameter possible

SUMMARY...Scattered thunderstorms will continue to develop and
spread east-southeastward across North Carolina through the
afternoon and into late evening.  The strongest storms will pose a
threat for damaging gusts and hail near 1" diameter.

The severe thunderstorm watch area is approximately along and 40
statute miles north and south of a line from 25 miles south of
Greensboro NC to 20 miles north northeast of New Bern NC. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU3).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 162...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 450. Mean storm motion vector
29025.

...Thompson

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 10, 12:51 PM EDT	Mesoscale Discussion	SPC	Alamance, Beaufort, Bertie, Bladen, Camden, Carteret and 46 more	114 min
May 10, 6:07 PM EDT	Mesoscale Discussion	SPC	Edgecombe, Franklin, Greene, Johnston, Lenoir, Martin and 5 more	53 min

Nearby

Severe Thunderstorm Watches in North Carolina, 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.