Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 1185
The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2021, 4:47 PM EDT for 7 counties in Florida; 28 counties in Georgia; 4 counties in South Carolina. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jul 7, 2021, 4:47 PM EDT (20:47 UTC)
- Expired
- Jul 7, 2021, 6:45 PM EDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 342
All 39 counties
Baker County, FL, Clay County, FL, Columbia County, FL, Duval 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, Effingham County, GA, Emanuel County, GA, Evans County, GA, Glynn County, GA, Jeff Davis County, GA, Jenkins County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Montgomery County, GA, Pierce County, GA, Screven County, GA, Tattnall County, GA, Toombs County, GA, Treutlen County, GA, Ware County, GA, Wayne County, GA, Wheeler County, GA, Allendale County, SC, Beaufort County, SC, Hampton County, SC, Jasper County, SC
The radar
The Jacksonville radar (KJAX), 111 km from the middle of the area, began a volume at 20:46 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.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Jacksonville, FL (KJAX), launched 12:00Z, 8.8 hours before the alert went out and 109 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
- 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
The text
As transmitted.
241
ACUS11 KWNS 072047
SWOMCD
SPC MCD 072047
SCZ000-GAZ000-FLZ000-072245-
Mesoscale Discussion 1185
NWS Storm Prediction Center Norman OK
0347 PM CDT Wed Jul 07 2021
Areas affected...portions of far northeast Florida into southeast
Georgia and far southern South Carolina
Concerning...Tornado Watch 342...
Valid 072047Z - 072245Z
The severe weather threat for Tornado Watch 342 continues.
SUMMARY...A brief tornado or two remains possible with a primary
rain-band near the center of Elsa, and with more isolated
thunderstorms ahead of the Tropical Storm. An additional tornado
watch may be needed for South Carolina later this evening.
DISCUSSION...The center of Tropical Storm Elsa is located near the
FL/GA border, and is gradually drifting northeast along the Atlantic
Coastline. A convective rain-band, supporting occasional lightning
strikes, has been noted along a line from Ware County, GA to St.
Johns County, FL, with some confluence and occasional instances of
brief low-level rotation noted. However, this band is surrounded by
a broader region of stratiform precipitation, where temperatures are
struggling to reach or sustain above the mid 70s F, inhibiting
appreciable instability. As such, robust updrafts capable of
producing tornadoes are expected to remain quite sparse, though a
brief tornado or two cannot be ruled out.
Farther northeast of the Tropical Storm Center, more discrete storms
have developed within a broad confluence zone ahead of the
stratiform rain region, where temperatures have warmed into the 80s
F, with MLCAPE reaching 500-1000 J/kg. These storms are progressing
within an environment characterized by a weak vertical shear
profile. As such, the overall tornado threat is expected to remain
low, though a tornado or two cannot be ruled out within this regime
as well. The threat is expected to persist to 00Z, when Tornado
Watch 342 expires, at which point conditions will be monitored for a
new Tornado Watch.
..Squitieri/Guyer.. 07/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...CAE...JAX...FFC...
LAT...LON 30328294 31428282 32268287 32618275 32938228 33028150
32838085 32558050 32428046 31858080 31008111 30358121
30008129 29788149 30048235 30328294SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 6, 10:37 PM EDT | Tornado Watch | SPC | Alachua, Charlotte, Citrus, Collier, DeSoto, Gilchrist and 22 more | 9 hr |
| Jul 6, 11:59 PM EDT | Mesoscale Discussion | SPC | Charlotte, DeSoto, Hardee, Hillsborough | 2 hr |
| Jul 7, 3:03 AM EDT | Mesoscale Discussion | SPC | Charlotte, Citrus, DeSoto, Hardee, Hernando, Hillsborough and 5 more | 117 min |
| Jul 7, 5:42 AM EDT | Mesoscale Discussion | SPC | Alachua, Bradford, Charlotte, Citrus, Columbia, DeSoto and 19 more | 2 hr |
| Jul 7, 6:46 AM EDT | Tornado Watch | SPC | Baker, Bradford, Clay, Columbia, Duval, Hamilton and 4 more | 6 hr |
| Jul 7, 7:06 AM EDT | Mesoscale Discussion | SPC | Charlotte, Citrus, DeSoto, Hardee, Hernando, Highlands and 10 more | 54 min |
| Jul 7, 10:30 AM EDT | Mesoscale Discussion | SPC | Baker, Bradford, Clay, Columbia, Duval, Hamilton and 3 more | 2 hr |
| Jul 7, 12:28 PM EDT | Mesoscale Discussion | SPC | Baker, Bradford, Clay, Columbia, Duval, Nassau and 1 more | 2 hr |
| Jul 7, 1:04 PM EDT | Tornado Watch | SPC | Baker, Bradford, Clay, Columbia, Duval, Hamilton and 3 more | 7 hr |
| Jul 7, 6:12 PM EDT | Mesoscale Discussion | SPC | Brantley, Bryan, Camden, Chatham, Effingham, Evans and 6 more | 2 hr |
| Jul 7, 7:25 PM EDT | Tornado Watch | SPC | Bryan, Bulloch, Burke, Candler, Chatham, Effingham and 11 more | 11 hr |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Florida, 2021Mesoscale Discussions in South Carolina, 2021Every mesoscale discussion 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.