Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 2090
The Storm Prediction Center issued this mesoscale discussion at Dec 31, 2021, 6:40 PM EST for 27 counties in Georgia; Abbeville County, McCormick County, South Carolina. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Dec 31, 2021, 6:40 PM EST (23:40 UTC)
- Expired
- Dec 31, 2021, 8:15 PM EST
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 29 counties
Banks County, GA, Barrow County, GA, Cherokee County, GA, Clarke County, GA, Cobb County, GA, Dawson County, GA, DeKalb County, GA, Elbert County, GA, Forsyth County, GA, Franklin County, GA, Gilmer County, GA, Gwinnett County, GA, Habersham County, GA, Hall County, GA, Hart County, GA, Jackson County, GA, Lincoln County, GA, Lumpkin County, GA, Madison County, GA, Oconee County, GA, Oglethorpe County, GA, Pickens County, GA, Stephens County, GA, Union County, GA, Walton County, GA, White County, GA, Wilkes County, GA, Abbeville County, SC, McCormick County, SC
The radar
The Greer radar (KGSP), 133 km from the middle of the area, began a volume at 23:43 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 nearest sounding before it
Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 11.7 hours before the alert went out and 136 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
- 1182 m above ground
- 0-6 km bulk shear
- 62 kt
- 0-1 km storm-relative helicity
- 134 m²/s²
- 0-3 km storm-relative helicity
- 234 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
523
ACUS11 KWNS 312340
SWOMCD
SPC MCD 312340
SCZ000-GAZ000-010115-
Mesoscale Discussion 2090
NWS Storm Prediction Center Norman OK
0540 PM CST Fri Dec 31 2021
Areas affected...portions of northern Georgia
Concerning...Severe potential...Watch unlikely
Valid 312340Z - 010115Z
Probability of Watch Issuance...5 percent
SUMMARY...A brief tornado cannot be ruled out over the next few
hours as weak supercells approach a stationary boundary and enhanced
low-level shear.
DISCUSSION...As of 2335 UTC, several showers and weak thunderstorms
showing transient low-level mesocyclones were identified across
portions of northern Georgia. Ongoing within a marginally unstable
airmass (MLCAPE around 500 J/kg) ahead of a weak mid-level shortwave
trough, limited forcing for ascent and buoyancy will likely limit
the spatial coverage and longevity of ongoing convection. However,
enhanced low-level shear (0-1km SRH of 150-200 m2/s2) in proximity
to a diffuse quasi-stationary front may continue to support a brief
tornado threat with any marginal supercells structures. Gradual
weakening of the convection should continue through the next several
hours with the loss of daytime heating. Given the uncertainty on the
coverage and longevity of the severe threat a weather watch is
unlikely.
..Lyons/Guyer.. 12/31/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CAE...GSP...FFC...
LAT...LON 33618320 33718428 34008489 34758449 34898390 34798323
34488260 34138227 33818223 33558237 33618320SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 31, 1:48 PM EST | Mesoscale Discussion | SPC | Carroll, Haralson, Polk | 57 min |
Nearby
Mesoscale Discussions in Georgia, 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.