Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 222
The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2021, 11:05 AM EDT for 8 counties in Florida; 43 counties in Georgia; Hampton County, Jasper County, South Carolina. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Mar 18, 2021, 11:05 AM EDT (15:05 UTC)
- Expired
- Mar 18, 2021, 1:00 PM EDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 39
All 53 counties
Columbia County, FL, Dixie County, FL, Hamilton County, FL, Jefferson County, FL, Lafayette County, FL, Madison County, FL, Suwannee County, FL, Taylor County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Ben Hill County, GA, Berrien County, GA, Brantley County, GA, Brooks County, GA, Bryan County, GA, Bulloch County, GA, Candler County, GA, Charlton County, GA, Chatham County, GA, Clinch County, GA, Coffee County, GA, Cook County, GA, Dodge County, GA, Echols County, GA, Effingham County, GA, Emanuel County, GA, Evans County, GA, Glynn County, GA, Irwin County, GA, Jeff Davis County, GA, Jenkins County, GA, Lanier County, GA, Laurens County, GA, Liberty County, GA, Long County, GA, Lowndes County, GA, McIntosh County, GA, Montgomery County, GA, Pierce County, GA, Screven County, GA, Tattnall County, GA, Telfair County, GA, Tift County, GA, Toombs County, GA, Treutlen County, GA, Turner County, GA, Ware County, GA, Wayne County, GA, Wheeler County, GA, Wilcox County, GA, Hampton County, SC, Jasper County, SC
The radar
The Moody AFB radar (KVAX), 12 km from the middle of the area, began a volume at 15:06 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, 3.1 hours before the alert went out and 125 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
- 162 J/kg
- Mixed-layer CIN
- -183 J/kg
- Mixed-layer LCL
- 888 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km storm-relative helicity
- 183 m²/s²
- 0-3 km storm-relative helicity
- 220 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.5
The text
As transmitted.
904
ACUS11 KWNS 181506
SWOMCD
SPC MCD 181505
SCZ000-GAZ000-FLZ000-181700-
Mesoscale Discussion 0222
NWS Storm Prediction Center Norman OK
1005 AM CDT Thu Mar 18 2021
Areas affected...Central into eastern Georgia and southern South
Carolina...and far northern Florida
Concerning...Tornado Watch 39...
Valid 181505Z - 181700Z
The severe weather threat for Tornado Watch 39 continues.
SUMMARY...Severe storms remain possible within WW 39, with a tornado
or damaging wind threat shifting east into the afternoon. An
additional watch is likely downstream of WW 39.
DISCUSSION...A line of storms currently extends from central and
southern GA into the eastern FL Panhandle. This activity has been a
bit disorganized, with only brief areas of rotation or shear zones
noted on radar. One notable cluster of storms was located over
Laurens County GA as of 15Z.
While these storms currently exist near the instability axis with
MLCAPE at or above 500 J/kg, objective analysis shows only weak
instability downstream into eastern GA and SC. With time, this area
will destabilize as well as dewpoints rise and if pockets of heating
develop. An axis of 200-300 m2/s2 effective SRH is forecast to
remain ahead of the developing dryline, and will support a supercell
and tornado threat later today.
..Jewell.. 03/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...JAX...FFC...TAE...
LAT...LON 29598303 29418336 29598351 29858373 30028399 30018417
30048425 30698391 31318372 31728364 32158346 32508312
32928155 32848109 32508077 31898083 31148143 30318255
29598303SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 11:15 PM EDT | Mesoscale Discussion | SPC | Escambia, Okaloosa, Santa Rosa | 90 min |
| Mar 18, 12:02 AM EDT | Tornado Watch | SPC | Bay, Calhoun, Escambia, Holmes, Jackson, Okaloosa and 3 more | 9 hr |
| Mar 18, 2:52 AM EDT | Mesoscale Discussion | SPC | Escambia, Holmes, Okaloosa, Santa Rosa | 83 min |
| Mar 18, 5:28 AM EDT | Mesoscale Discussion | SPC | Bay, Calhoun, Holmes, Jackson, Walton, Washington | 92 min |
| Mar 18, 7:32 AM EDT | Mesoscale Discussion | SPC | Bay, Calhoun, Franklin, Gadsden, Gulf, Jackson and 6 more | 58 min |
| Mar 18, 7:53 AM EDT | Tornado Watch | SPC | Dixie, Franklin, Gadsden, Gulf, Jefferson, Lafayette and 5 more | 5 hr |
| Mar 18, 11:42 AM EDT | Tornado Watch | SPC | Alachua, Baker, Bradford, Clay, Columbia, Duval and 7 more | 6 hr |
| Mar 18, 10:34 AM EDT | Mesoscale Discussion | SPC | Banks, Barrow, Clarke, Elbert, Franklin, Habersham and 5 more | 2 hr |
| Mar 18, 2:08 PM EDT | Tornado Watch | SPC | Elbert, Lincoln | 4 hr |
| Mar 18, 3:10 PM EDT | Mesoscale Discussion | SPC | Elbert | 3 hr |
| Mar 18, 5:57 PM EDT | Mesoscale Discussion | SPC | Chesterfield, Lancaster, Marlboro | 63 min |
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.