Alert archive / Georgia / Tornado Watches in 2021

Tornado Watch 342

July 7, 20219 counties in Florida; 21 counties in Georgia

The Storm Prediction Center issued this tornado watch at Jul 7, 2021, 1:04 PM EDT for 9 counties in Florida; 21 counties in Georgia. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Jul 7, 2021, 1:04 PM EDT (17:04 UTC)
Expired
Jul 7, 2021, 8:00 PM EDT
In force
7 hr
Issued by
the Storm Prediction Center
Strongest gust expected
60 kt
All 30 counties

Baker County, FL, Bradford County, FL, Clay County, FL, Columbia County, FL, Duval County, FL, Hamilton County, FL, Nassau County, FL, Saint Johns County, FL, Union County, FL, Appling County, GA, Bacon County, GA, Brantley County, GA, Bryan County, GA, Bulloch County, GA, Camden County, GA, Candler County, GA, Charlton County, GA, Chatham County, GA, Clinch County, GA, Echols County, GA, Effingham County, GA, Evans County, GA, Glynn County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Pierce County, GA, Tattnall County, GA, Ware County, GA, Wayne County, GA

The radar

The Jacksonville radar (KJAX), 110 km from the middle of the area, began a volume at 17:05 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
10%
Ten or more severe wind reports
5%
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
20%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 7, 4:04 PM EDTTornado WarningCHSBulloch, Candler26 min
Jul 7, 4:32 PM EDTTornado WarningJAXDuval, Saint Johns28 min
Jul 7, 4:54 PM EDTTornado Warning Tornado observedJAXDuval, Nassau36 min
Jul 7, 5:42 PM EDTTornado WarningJAXCamden33 min
Jul 7, 6:11 PM EDTTornado Warning Tornado observedJAXCamden, Glynn, Wayne21 min
Jul 7, 7:01 PM EDTFlash Flood WarningJAXCamden, Glynn119 min
Jul 7, 7:53 PM EDTFlash Flood WarningJAXGlynn78 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

Jacksonville, FL (KJAX), launched 12:00Z, 5.1 hours before the alert went out and 108 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, Jacksonville, FL at 12:00Z on 2021-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1540 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Jacksonville, FL at 12:00Z on 2021-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 103 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
1540 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
838 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
103 m²/s²
0-3 km storm-relative helicity
144 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

982 
WWUS20 KWNS 071701
SEL2  
SPC WW 071701
FLZ000-GAZ000-CWZ000-080000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 342
NWS Storm Prediction Center Norman OK
105 PM EDT Wed Jul 7 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Northeast Florida
  Southeast Georgia
  Coastal Waters

* Effective this Wednesday afternoon and evening from 105 PM
  until 800 PM EDT.

* Primary threats include...
  A couple tornadoes possible

SUMMARY...Strong low-level winds on the periphery of Elsa along with
a warm/moist air mass will continue to allow for the possibility of
transient supercells capable of a couple of brief tornadoes.

The tornado watch area is approximately along and 55 statute miles
east and west of a line from 35 miles north northwest of Savannah GA
to 40 miles west southwest of St Augustine FL. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 341...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 14015.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 6, 10:37 PM EDTTornado WatchSPCAlachua, Charlotte, Citrus, Collier, DeSoto, Gilchrist and 22 more9 hr
Jul 6, 11:59 PM EDTMesoscale DiscussionSPCCharlotte, DeSoto, Hardee, Hillsborough2 hr
Jul 7, 3:03 AM EDTMesoscale DiscussionSPCCharlotte, Citrus, DeSoto, Hardee, Hernando, Hillsborough and 5 more117 min
Jul 7, 5:42 AM EDTMesoscale DiscussionSPCAlachua, Bradford, Charlotte, Citrus, Columbia, DeSoto and 19 more2 hr
Jul 7, 6:46 AM EDTTornado WatchSPCBaker, Bradford, Clay, Columbia, Duval, Hamilton and 4 more6 hr
Jul 7, 7:06 AM EDTMesoscale DiscussionSPCCharlotte, Citrus, DeSoto, Hardee, Hernando, Highlands and 10 more54 min
Jul 7, 10:30 AM EDTMesoscale DiscussionSPCBaker, Bradford, Clay, Columbia, Duval, Hamilton and 3 more2 hr
Jul 7, 12:28 PM EDTMesoscale DiscussionSPCBaker, Bradford, Clay, Columbia, Duval, Nassau and 1 more2 hr
Jul 7, 4:47 PM EDTMesoscale DiscussionSPCBaker, Clay, Columbia, Duval, Nassau, Saint Johns and 1 more118 min
Jul 7, 6:12 PM EDTMesoscale DiscussionSPCBrantley, Bryan, Camden, Chatham, Effingham, Evans and 6 more2 hr
Jul 7, 7:25 PM EDTTornado WatchSPCBryan, Bulloch, Burke, Candler, Chatham, Effingham and 11 more11 hr

Nearby

Tornado Watches in Georgia, 2021Tornado Watches in Florida, 2021Every tornado 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.