Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 429
The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2021, 7:47 PM EDT for 18 counties in Georgia. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Apr 24, 2021, 7:47 PM EDT (23:47 UTC)
- Expired
- Apr 24, 2021, 9:45 PM EDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Appling County, GA, Atkinson County, GA, Bacon County, GA, Berrien County, GA, Brantley County, GA, Bryan County, GA, Clinch County, GA, Coffee County, GA, Cook County, GA, Glynn County, GA, Jeff Davis County, GA, Lanier County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Pierce County, GA, Ware County, GA, Wayne County, GA
The radar
The Moody AFB radar (KVAX), 99 km from the middle of the area, began a volume at 23:47 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, 11.8 hours before the alert went out and 135 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
- 984 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 180 m²/s²
- 0-3 km storm-relative helicity
- 276 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
142
ACUS11 KWNS 242347
SWOMCD
SPC MCD 242347
GAZ000-250145-
Mesoscale Discussion 0429
NWS Storm Prediction Center Norman OK
0647 PM CDT Sat Apr 24 2021
Areas affected...Parts of southeastern Georgia
Concerning...Severe potential...Watch possible
Valid 242347Z - 250145Z
Probability of Watch Issuance...40 percent
SUMMARY...Potential for strong surface gusts may remain somewhat
marginal and/or isolated in the near term, but this could increase
as upstream storms spread into the region later this evening.
DISCUSSION...A 40-50 kt southwesterly 850 mb jet is impinging on the
southwestern flank of a convectively reinforced surface cold pool,
across much of southern/eastern Georgia. As this enhances warm
advection and associated lift of moist and moderately unstable air
along the associated quasi-stationary baroclinic zone, one small,
but organized, cluster of storms has emerged and is progressing
north through northeast of the Waycross, GA area. This appears near
the core of the most stable boundary layer air, and potential for
damaging surface gusts to reach the surface remains unclear as the
cluster continues into coastal areas south of Savannah, GA through
01Z.
However, as the southerly low-level jet noses northeastward this
evening, ahead of the vigorous approaching mid-level short wave
trough, it appears that the stable boundary-layer may undergo
considerable modification. If another cluster of storms is able to
organize upstream, near the intersection of the outflow reinforced
boundary and a pre-cold frontal wind shift across southeastern
Alabama into southwestern Georgia, then there may be increasing
potential for damaging wind gusts as it overspreads a similar track
as the preceding system later this evening.
..Kerr/Thompson.. 04/24/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...JAX...FFC...TAE...
LAT...LON 31858293 31938230 32108154 31938090 31108134 30788313
31128365 31858293SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 24, 6:22 AM EDT | Tornado Watch | SPC | Baker, Ben Hill, Berrien, Brooks, Calhoun, Clay and 20 more | 9 hr |
| Apr 24, 8:29 AM EDT | Mesoscale Discussion | SPC | Baker, Ben Hill, Berrien, Brooks, Calhoun, Clay and 19 more | 91 min |
| Apr 24, 10:10 AM EDT | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Ben Hill, Berrien, Brantley and 24 more | 95 min |
| Apr 24, 10:35 AM EDT | Tornado Watch | SPC | Appling, Atkinson, Bacon, Brantley, Bryan, Camden and 15 more | 7 hr |
| Apr 24, 12:05 PM EDT | Mesoscale Discussion | SPC | Atkinson, Berrien, Brooks, Clinch, Colquitt, Cook and 10 more | 85 min |
| Apr 24, 2:22 PM EDT | Mesoscale Discussion | SPC | Chattooga, Dade, Floyd, Walker | 113 min |
| Apr 24, 4:00 PM EDT | Severe Thunderstorm Watch | SPC | Baker, Berrien, Brooks, Calhoun, Chattahoochee, Clay and 30 more | 6 hr |
| Apr 24, 4:35 PM EDT | Mesoscale Discussion | SPC | Camden, Charlton | 85 min |
| Apr 24, 5:52 PM EDT | Severe Thunderstorm Watch | SPC | Barrow, Bartow, Butts, Carroll, Chattooga, Cherokee and 26 more | 4 hr |
| Apr 24, 6:56 PM EDT | Mesoscale Discussion | SPC | Baker, Calhoun, Clay, Colquitt, Cook, Dougherty and 8 more | 94 min |
| Apr 24, 7:13 PM EDT | Mesoscale Discussion | SPC | Barrow, Bartow, Butts, Carroll, Chattooga, Cherokee and 31 more | 2 hr |
Nearby
Mesoscale Discussions in Georgia, 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.