Alert archive / Georgia / Tornado Watches in 2017
Tornado Watch 485
The Storm Prediction Center issued this tornado watch at Sep 11, 2017, 1:46 PM EDT for 13 counties in Georgia; 11 counties in South Carolina. It was in force for 10 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 11, 2017, 1:46 PM EDT (17:46 UTC)
- Expired
- Sep 12, 2017, 12:00 AM EDT
- In force
- 10 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 24 counties
Bryan County, GA, Bulloch County, GA, Burke County, GA, Candler County, GA, Chatham County, GA, Effingham County, GA, Evans County, GA, Jenkins County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Screven County, GA, Tattnall County, GA, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Beaufort County, SC, Berkeley County, SC, Charleston County, SC, Colleton County, SC, Dorchester County, SC, Hampton County, SC, Jasper County, SC, Orangeburg County, SC
The radar
The Charleston,SC radar (KCLX), 23 km from the middle of the area, began a volume at 17:47 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
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 5%
- 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
- 60%
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 |
|---|---|---|---|---|
| Sep 11, 1:49 PM EDT | Tornado Warning | CHS | Charleston, Colleton, Dorchester | 26 min |
| Sep 11, 1:53 PM EDT | Tornado Warning | CHS | Charleston, Dorchester | 24 min |
| Sep 11, 2:45 PM EDT | Tornado Warning | CHS | Beaufort, Colleton | 30 min |
| Sep 11, 2:46 PM EDT | Tornado Warning | CHS | Berkeley, Charleston, Dorchester | 16 min |
| Sep 11, 3:10 PM EDT | Flash Flood Warning | CHS | Berkeley, Colleton, Dorchester | 7 hr |
| Sep 11, 6:56 PM EDT | Tornado Warning | CAE | Bamberg, Barnwell | 34 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 12:00Z, 5.8 hours before the alert went out and 105 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 547 m above ground
- 0-6 km bulk shear
- 62 kt
- 0-1 km storm-relative helicity
- 902 m²/s²
- 0-3 km storm-relative helicity
- 1081 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
805 WWUS20 KWNS 111738 SEL5 SPC WW 111738 GAZ000-SCZ000-CWZ000-120200- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 485 NWS Storm Prediction Center Norman OK 140 PM EDT Mon Sep 11 2017 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Eastern Georgia Southeast South Carolina Coastal Waters * Effective this Monday afternoon and evening from 140 PM until 1000 PM EDT. * Primary threats include... A couple tornadoes possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Isolated tornadoes and/or waterspouts will remain possible through the afternoon and early evening across the watch area as thunderstorms over the ocean move ashore. The tornado watch area is approximately along and 60 statute miles either side of a line from 45 miles southwest of Savannah GA to 40 miles northeast of Charleston SC. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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. && 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 500. Mean storm motion vector 11050. ...Hart
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 10, 10:33 PM EDT | Mesoscale Discussion | SPC | Brantley, Camden, Charlton, Clinch, Echols, Glynn and 1 more | 87 min |
| Sep 10, 11:50 PM EDT | Tornado Watch | SPC | Brantley, Bryan, Camden, Charlton, Chatham, Glynn and 6 more | 14 hr |
| Sep 11, 4:58 AM EDT | Mesoscale Discussion | SPC | Brantley, Bryan, Camden, Charlton, Chatham, Glynn and 6 more | 2 hr |
| Sep 11, 8:49 AM EDT | Mesoscale Discussion | SPC | Brantley, Bryan, Camden, Charlton, Chatham, Effingham and 7 more | 116 min |
| Sep 11, 5:45 PM EDT | Mesoscale Discussion | SPC | Beaufort, Berkeley, Charleston, Colleton, Dorchester | 60 min |
Nearby
Tornado Watches in Georgia, 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.