Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 260
The Storm Prediction Center issued this mesoscale discussion at Mar 25, 2021, 5:31 PM EDT for 4 states. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Mar 25, 2021, 5:31 PM EDT (21:31 UTC)
- Expired
- Mar 25, 2021, 7:30 PM EDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 37 counties
Banks County, GA, Catoosa County, GA, Cherokee County, GA, Dawson County, GA, Fannin County, GA, Forsyth County, GA, Gilmer County, GA, Gordon County, GA, Habersham County, GA, Hall County, GA, Lumpkin County, GA, Murray County, GA, Pickens County, GA, Rabun County, GA, Stephens County, GA, Towns County, GA, Union County, GA, White County, GA, Whitfield County, GA, Cherokee County, NC, Clay County, NC, Graham County, NC, Jackson County, NC, Macon County, NC, Swain County, NC, Oconee County, SC, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Hamilton County, TN, Loudon County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Polk County, TN, Rhea County, TN, Sevier County, TN
The radar
The Knoxville radar (KMRX), 161 km from the middle of the area, began a volume at 21:35 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
Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 9.5 hours before the alert went out and 170 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
- 1602 m above ground
- 0-6 km bulk shear
- 53 kt
- 0-1 km storm-relative helicity
- 397 m²/s²
- 0-3 km storm-relative helicity
- 647 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
400
ACUS11 KWNS 252131
SWOMCD
SPC MCD 252131
NCZ000-SCZ000-GAZ000-TNZ000-252330-
Mesoscale Discussion 0260
NWS Storm Prediction Center Norman OK
0431 PM CDT Thu Mar 25 2021
Areas affected...northern GA...eastern TN...far western NC...extreme
upstate SC
Concerning...Severe potential...Watch possible
Valid 252131Z - 252330Z
Probability of Watch Issuance...60 percent
SUMMARY...A risk for severe thunderstorms, including the threat for
a couple of tornadoes, will likely develop over the next several
hours across northern GA and eastern TN. The risk will eventually
spread east into parts of the far western Carolinas later this
evening. The timing of an eventual watch issuance is a bit
uncertain.
DISCUSSION...Radar mosaic shows a broad rain shield across the
southern Appalachians as of 2130 UTC. A supercell over northwestern
GA, on the southern flank of the rain shield, will continue to move
east-northeast over northern GA the early evening hours. The
airmass across the southern Appalachians is currently
rain-cooled/stable but a strong moisture flux/destabilization will
likely occur during the evening hours. The richer low-level
moisture will likely reside across northern GA where lower 60s F
dewpoints are currently observed/expected this evening. In addition
to hail/wind risks with a supercell threat gradually spreading
northeastward into the area, a tornado or two is possible this
evening/tonight. For parts of southeast/eastern TN, the severe
threat will likely depend on storm development from the
west/southwest eventually moving into the region later this evening.
The expected timing of the risk will likely be delayed but begin in
a few hours.
..Smith/Grams.. 03/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GSP...MRX...FFC...
LAT...LON 34258467 35088557 35718515 35938361 35298295 34528300
33998413 34258467SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 25, 10:02 AM EDT | Mesoscale Discussion | SPC | Catoosa, Chattooga, Dade, Floyd, Polk, Walker and 1 more | 118 min |
| Mar 25, 11:12 AM EDT | Mesoscale Discussion | SPC | Dade | 3 hr |
| Mar 25, 12:26 PM EDT | Tornado Watch | SPC | Bartow, Catoosa, Chattooga, Dade, Floyd, Gordon and 4 more | 9 hr |
| Mar 25, 7:46 PM EDT | Tornado Watch | SPC | Banks, Barrow, Bartow, Carroll, Catoosa, Chattooga and 41 more | 8 hr |
| Mar 25, 3:29 PM EDT | Mesoscale Discussion | SPC | Bedford, Benton, Cannon, Cheatham, Chester, Davidson and 16 more | 2 hr |
| Mar 25, 3:33 PM EDT | Mesoscale Discussion | SPC | Dyer, Henry, Lake, Obion, Weakley | 117 min |
| Mar 25, 4:48 PM EDT | Tornado Watch | SPC | Bedford, Benton, Cannon, Carroll, Cheatham, Chester and 36 more | 7 hr |
| Mar 25, 6:52 PM EDT | Mesoscale Discussion | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Davidson and 24 more | 83 min |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in North 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.