Alert archive / North Carolina / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 219

May 1, 201240 counties in North Carolina; 36 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at May 1, 2012, 3:12 PM EDT for 40 counties in North Carolina; 36 counties in Virginia. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
May 1, 2012, 3:12 PM EDT (19:12 UTC)
Expired
May 1, 2012, 7:54 PM EDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 76 counties

Alamance County, NC, Alexander County, NC, Bertie County, NC, Burke County, NC, Caldwell County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Chowan County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Hertford County, NC, Iredell County, NC, Johnston County, NC, McDowell County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Perquimans County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wayne County, NC, Wilkes County, NC, Wilson County, NC, Yadkin County, NC, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Charlotte County, VA, Chesterfield County, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Suffolk, VA, Cumberland County, VA, Dinwiddie County, VA, Franklin County, VA, Greensville County, VA, Halifax County, VA, Henry County, VA, Isle of Wight County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA

The radar

The Roanoke radar (KFCX), 84 km from the middle of the area, began a volume at 19:15 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
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 1, 3:14 PM EDTSevere Thunderstorm WarningRNKHalifax, Pittsylvania76 min
May 1, 3:18 PM EDTSevere Thunderstorm WarningRNKStokes, Surry57 min
May 1, 3:28 PM EDTSevere Thunderstorm WarningRNKFranklin, Henry, Patrick, Pittsylvania, City of Martinsville62 min
May 1, 3:44 PM EDTSevere Thunderstorm WarningGSPBurke24 min
May 1, 3:47 PM EDTSevere Thunderstorm WarningRNKWilkes, Yadkin58 min
May 1, 3:50 PM EDTSevere Thunderstorm WarningRAHForsyth, Guilford35 min
May 1, 3:54 PM EDTSevere Thunderstorm WarningRNKCharlotte, Halifax, Pittsylvania66 min
May 1, 4:05 PM EDTSevere Thunderstorm WarningGSPBurke, Caldwell55 min
May 1, 4:10 PM EDTSevere Thunderstorm WarningRAHGranville, Person, Vance, Warren80 min
May 1, 4:11 PM EDTSevere Thunderstorm WarningRNKStokes, Surry, Yadkin35 min
May 1, 5:01 PM EDTSevere Thunderstorm WarningRNKYadkin29 min
May 1, 5:07 PM EDTSevere Thunderstorm WarningGSPDavie31 min
May 1, 5:13 PM EDTSevere Thunderstorm WarningAKQNorthampton47 min
May 1, 5:17 PM EDTSevere Thunderstorm WarningRAHHalifax, Warren58 min
May 1, 5:46 PM EDTSevere Thunderstorm WarningRAHDurham, Granville, Orange, Person, Wake44 min
May 1, 5:50 PM EDTSevere Thunderstorm WarningGSPBurke, McDowell22 min
May 1, 6:14 PM EDTTornado WarningRAHDurham, Granville, Orange, Wake31 min
May 1, 6:18 PM EDTSevere Thunderstorm WarningRNKStokes, Surry35 min
May 1, 6:19 PM EDTSevere Thunderstorm WarningAKQGates, Hertford41 min
May 1, 6:39 PM EDTSevere Thunderstorm WarningAKQCamden, Gates51 min
May 1, 6:43 PM EDTSevere Thunderstorm WarningRAHDurham, Franklin, Granville, Wake36 min
May 1, 7:26 PM EDTSevere Thunderstorm WarningAKQCamden, Chowan, Currituck, Gates, Pasquotank, Perquimans49 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

Roanoke, VA (KRNK), launched 12:00Z, 7.2 hours before the alert went out and 41 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, Roanoke, VA at 12:00Z on 2012-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 660 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, Roanoke, VA at 12:00Z on 2012-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 167 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
660 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
496 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
167 m²/s²
0-3 km storm-relative helicity
213 m²/s²
Significant tornado parameter
0.4
Supercell composite
3.1

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 1, 12:43 PM EDTMesoscale DiscussionSPCAlexander, Alleghany, Ashe, Avery, Burke, Caldwell and 13 more2 hr
May 1, 5:49 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Camden, Chowan, Craven, Currituck and 21 more86 min

Nearby

Severe Thunderstorm Watches in North Carolina, 2012Severe Thunderstorm Watches in Virginia, 2012Every severe thunderstorm watch in 2012

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.