Alert archive / South Carolina / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 276
The Storm Prediction Center issued this severe thunderstorm watch at May 11, 2011, 1:41 AM EDT for 11 counties in South Carolina. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 2011, 1:41 AM EDT (05:41 UTC)
- Expired
- May 11, 2011, 5:00 AM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
Counties Berkeley County, SC, Charleston County, SC, Darlington County, SC, Dillon County, SC, Dorchester County, SC, Florence County, SC, Georgetown County, SC, Horry County, SC, Marion County, SC, Marlboro County, SC, Williamsburg County, SC
The radar
The Wilmington radar (KLTX), 98 km from the middle of the area, began a volume at 05:44 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
- 70%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 1:43 AM EDT | Severe Thunderstorm Warning | ILM | Darlington, Dillon, Florence, Marlboro | 62 min |
| May 11, 2:31 AM EDT | Severe Thunderstorm Warning | CHS | Berkeley, Charleston, Dorchester | 59 min |
| May 11, 2:39 AM EDT | Severe Thunderstorm Warning | ILM | Darlington, Florence, Horry, Marion, Williamsburg | 51 min |
| May 11, 2:43 AM EDT | Severe Thunderstorm Warning | ILM | Dillon, Horry, Marion | 51 min |
| May 11, 3:02 AM EDT | Severe Thunderstorm Warning | ILM | Florence, Georgetown, Horry, Marion, Williamsburg | 73 min |
| May 11, 3:27 AM EDT | Severe Thunderstorm Warning | CHS | Berkeley, Charleston, Colleton, Dorchester | 63 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, 5.7 hours before the alert went out and 136 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
- 2852 J/kg
- Mixed-layer CIN
- -45 J/kg
- Mixed-layer LCL
- 899 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 110 m²/s²
- 0-3 km storm-relative helicity
- 221 m²/s²
- Significant tornado parameter
- 3.0
- Supercell composite
- 14.5
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 10, 9:01 PM EDT | Mesoscale Discussion | SPC | Alexander, Alleghany, Anson, Ashe, Avery, Bladen and 46 more | 59 min |
| May 10, 10:18 PM EDT | Mesoscale Discussion | SPC | Alexander, Ashe, Avery, Buncombe, Burke, Caldwell and 16 more | 27 min |
| May 10, 10:42 PM EDT | Severe Thunderstorm Watch | SPC | Alexander, Avery, Buncombe, Burke, Caldwell, Catawba and 13 more | 4 hr |
| May 11, 12:14 AM EDT | Mesoscale Discussion | SPC | Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 17 more | 61 min |
| May 11, 2:37 AM EDT | Mesoscale Discussion | SPC | Alexander, Ashe, Avery, Buncombe, Burke, Caldwell and 14 more | 23 min |
| May 11, 6:06 PM EDT | Mesoscale Discussion | SPC | Buncombe, Haywood, Henderson, Jackson, Polk, Transylvania | 54 min |
| May 11, 12:41 AM EDT | Severe Thunderstorm Watch | SPC | Aiken, Bamberg, Barnwell, Calhoun, Chesterfield, Clarendon and 11 more | 3 hr |
| May 11, 1:35 AM EDT | Mesoscale Discussion | SPC | Berkeley, Charleston, Darlington, Dorchester, Florence, Georgetown and 2 more | 25 min |
| May 11, 3:34 AM EDT | Mesoscale Discussion | SPC | Berkeley, Charleston, Chesterfield, Colleton, Darlington, Dillon and 7 more | 56 min |
Nearby
Severe Thunderstorm Watches in South Carolina, 2011Every severe thunderstorm watch in 2011
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.