Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 220
The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2021, 6:32 AM CDT for 12 counties in Florida; 34 counties in Georgia. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- Mar 18, 2021, 6:32 AM CDT (11:32 UTC)
- Expired
- Mar 18, 2021, 7:30 AM CDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 46 counties
Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Taylor County, FL, Wakulla County, FL, Atkinson County, GA, Baker County, GA, Ben Hill County, GA, Berrien County, GA, Brooks County, GA, Calhoun County, GA, Coffee County, GA, Colquitt County, GA, Cook County, GA, Crisp County, GA, Decatur County, GA, Dodge County, GA, Dooly County, GA, Dougherty County, GA, Early County, GA, Grady County, GA, Irwin County, GA, Lanier County, GA, Lee County, GA, Lowndes County, GA, Miller County, GA, Mitchell County, GA, Pulaski County, GA, Randolph County, GA, Seminole County, GA, Sumter County, GA, Telfair County, GA, Terrell County, GA, Thomas County, GA, Tift County, GA, Turner County, GA, Webster County, GA, Wilcox County, GA, Worth County, GA
The radar
The Tallahassee radar (KTLH), 43 km from the middle of the area, began a volume at 11:36 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
Tallahassee Rgnl, FL (KTLH), launched 00:00Z, 11.5 hours before the alert went out and 43 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
- 1019 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 126 m²/s²
- 0-3 km storm-relative helicity
- 171 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
764
ACUS11 KWNS 181133
SWOMCD
SPC MCD 181132
GAZ000-FLZ000-ALZ000-181230-
Mesoscale Discussion 0220
NWS Storm Prediction Center Norman OK
0632 AM CDT Thu Mar 18 2021
Areas affected...Portions of the FL Panhandle...extreme southeastern
AL...and southern GA
Concerning...Severe potential...Watch likely
Valid 181132Z - 181230Z
Probability of Watch Issuance...80 percent
SUMMARY...A few tornadoes and damaging wind gusts remain possible in
the short term across Tornado Watch 38, and a downstream watch is
likely.
DISCUSSION...Multiple low-level circulations have developed with
storms both in the FL Panhandle and southeastern AL over the past
hour or so. At least two of these circulations were likely tornadoes
with corresponding CC minimums. The low-level flow across parts of
the FL Panhandle and southwestern GA has become backed to a more
southeasterly direction due to surface pressure falls, likely due to
the development of a meso-low in southeastern AL. This is enhancing
hodograps and low-level shear across this region, and a few
tornadoes will remain possible through the morning hours with either
QLCS circulations and embedded low-topped supercells as the airmass
downstream remains sufficiently unstable to support surface-based
storms. Damaging straight-line winds, like the Panama City FL gust
to 64 kt, will also remain a possibility. Given recent radar trends,
downstream watch issuance appears likely.
..Gleason/Thompson.. 03/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAX...FFC...TAE...
LAT...LON 30028564 30678560 31158522 31558501 32198443 32328369
32208300 32088280 31308286 30208323 29828361 30008399
29858435 29538504 29678542 30028564SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 10:15 PM CDT | Mesoscale Discussion | SPC | Escambia, Okaloosa, Santa Rosa | 90 min |
| Mar 17, 11:02 PM CDT | Tornado Watch | SPC | Bay, Calhoun, Escambia, Holmes, Jackson, Okaloosa and 3 more | 9 hr |
| Mar 18, 1:52 AM CDT | Mesoscale Discussion | SPC | Escambia, Holmes, Okaloosa, Santa Rosa | 83 min |
| Mar 18, 4:28 AM CDT | Mesoscale Discussion | SPC | Bay, Calhoun, Holmes, Jackson, Walton, Washington | 92 min |
| Mar 18, 6:53 AM CDT | Tornado Watch | SPC | Dixie, Franklin, Gadsden, Gulf, Jefferson, Lafayette and 5 more | 5 hr |
| Mar 18, 10:05 AM CDT | Mesoscale Discussion | SPC | Columbia, Dixie, Hamilton, Jefferson, Lafayette, Madison and 2 more | 115 min |
| Mar 18, 10:42 AM CDT | Tornado Watch | SPC | Alachua, Baker, Bradford, Clay, Columbia, Duval and 7 more | 6 hr |
| Mar 18, 9:34 AM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Clarke, Elbert, Franklin, Habersham and 5 more | 2 hr |
| Mar 18, 1:08 PM CDT | Tornado Watch | SPC | Elbert, Lincoln | 4 hr |
| Mar 18, 2:10 PM CDT | Mesoscale Discussion | SPC | Elbert | 3 hr |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Florida, 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.