Alert archive / North Carolina / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 157
The Storm Prediction Center issued this severe thunderstorm watch at Apr 22, 2017, 3:17 PM EDT for 18 counties in North Carolina; 18 counties in Virginia. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 22, 2017, 3:17 PM EDT (19:17 UTC)
- Expired
- Apr 22, 2017, 7:04 PM EDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 36 counties
Alamance County, NC, Caswell County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Rockingham County, NC, Stokes County, NC, Vance County, NC, Warren County, NC, Yadkin County, NC, Brunswick County, VA, Campbell County, VA, Charlotte County, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Martinsville, VA, Dinwiddie County, VA, Greensville County, VA, Halifax County, VA, Henry County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nottoway County, VA, Pittsylvania County, VA, Prince Edward County, VA, Southampton County, VA, Sussex County, VA
The radar
The Raleigh/Durham radar (KRAX), 116 km from the middle of the area, began a volume at 19:20 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
- 2%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 22, 3:31 PM EDT | Severe Thunderstorm Warning | AKQ | Greensville, Southampton, Sussex | 29 min |
| Apr 22, 3:44 PM EDT | Severe Thunderstorm Warning | AKQ | Lunenburg, Mecklenburg | 46 min |
| Apr 22, 3:48 PM EDT | Severe Thunderstorm Warning | AKQ | Northampton | 27 min |
| Apr 22, 3:50 PM EDT | Tornado Warning | AKQ | Lunenburg, Mecklenburg | 25 min |
| Apr 22, 3:57 PM EDT | Severe Thunderstorm Warning | AKQ | Southampton, Sussex | 19 min |
| Apr 22, 4:05 PM EDT | Tornado Warning | AKQ | Brunswick, Lunenburg, Mecklenburg | 25 min |
| Apr 22, 4:06 PM EDT | Severe Thunderstorm Warning | AKQ | Hertford, Northampton | 24 min |
| Apr 22, 4:06 PM EDT | Tornado Warning | RNK | Charlotte, Halifax | 24 min |
| Apr 22, 4:22 PM EDT | Tornado Warning | AKQ | Brunswick, Mecklenburg | 23 min |
| Apr 22, 4:26 PM EDT | Severe Thunderstorm Warning | AKQ | Southampton, City of Suffolk | 30 min |
| Apr 22, 4:37 PM EDT | Tornado Warning | AKQ | Brunswick, Greensville, City of Emporia | 23 min |
| Apr 22, 4:53 PM EDT | Severe Thunderstorm Warning | AKQ | Brunswick, Greensville, Southampton, Sussex, City of Emporia | 24 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, 7.3 hours before the alert went out and 90 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.
- Mixed-layer CAPE
- 28 J/kg
- Mixed-layer CIN
- -103 J/kg
- Mixed-layer LCL
- 755 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 131 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 22, 11:57 AM EDT | Mesoscale Discussion | SPC | Alleghany, Ashe, Caswell, Granville, Person, Rockingham and 6 more | 2 hr |
| Apr 22, 4:12 PM EDT | Mesoscale Discussion | SPC | Alamance, Caswell, Durham, Edgecombe, Forsyth, Franklin and 12 more | 2 hr |
| Apr 22, 7:40 PM EDT | Mesoscale Discussion | SPC | Cherokee | 65 min |
Nearby
Severe Thunderstorm Watches in North Carolina, 2017Severe Thunderstorm Watches in Virginia, 2017Every severe thunderstorm 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.