Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 431
The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2021, 11:42 PM EDT for 9 counties in Georgia. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Apr 24, 2021, 11:42 PM EDT (03:42 UTC)
- Expired
- Apr 25, 2021, 1:15 AM EDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 111
Counties Brantley County, GA, Brooks County, GA, Clinch County, GA, Echols County, GA, Glynn County, GA, Lanier County, GA, Lowndes County, GA, Pierce County, GA, Ware County, GA
The radar
The Moody AFB radar (KVAX), 20 km from the middle of the area, began a volume at 03:44 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
Jacksonville, FL (KJAX), launched 00:00Z, 3.7 hours before the alert went out and 118 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
- 64 J/kg
- Mixed-layer CIN
- -157 J/kg
- Mixed-layer LCL
- 850 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 275 m²/s²
- 0-3 km storm-relative helicity
- 358 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.9
The text
As transmitted.
363
ACUS11 KWNS 250343
SWOMCD
SPC MCD 250342
GAZ000-FLZ000-250515-
Mesoscale Discussion 0431
NWS Storm Prediction Center Norman OK
1042 PM CDT Sat Apr 24 2021
Areas affected...Parts of southeastern Georgia and adjacent northern
Florida
Concerning...Severe Thunderstorm Watch 111...
Valid 250342Z - 250515Z
The severe weather threat for Severe Thunderstorm Watch 111
continues.
SUMMARY...An isolated storm or two could still intensify, mainly
near and north of the northeastern Florida/Georgia border vicinity
through about 1 AM EDT, posing a risk for locally damaging wind
gusts or perhaps a tornado. An additional watch is not anticipated.
DISCUSSION...There has been some continued veering of a fairly broad
850 mb jet to an increasing west-southwesterly component. Latest
Rapid Refresh suggests that the jet core is now in the process of
shifting east of the Georgia coast, but speeds remain on the order
of 40-50 kts, west-southwestward across northern Florida. One
associated confluent zone remains a focus for vigorous convective
development, including supercell structures, roughly along an axis
east-northeast of Tallahassee, FL into the Brunswick, GA vicinity.
Aided by inflow of seasonably moist air emanating from the
northeastern Gulf of Mexico, beneath steep lower/mid tropospheric
lapse rates, activity still appears to be supported by moderately
large CAPE on the order of 1000-2000 J/kg. Further intensification
of one or two lingering storms, with perhaps some upscale growth,
still appears possible late this evening near/north of the
northeastern Florida/Georgia border vicinity, before large-scale
forcing diminishes further by around 05-06Z.
..Kerr.. 04/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...JAX...TAE...
LAT...LON 30918364 31298252 31508155 31018142 30588308 30508383
30918364SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 24, 8:48 PM EDT | Severe Thunderstorm Watch | SPC | Appling, Atkinson, Bacon, Baker, Ben Hill, Berrien and 30 more | 4 hr |
| Apr 24, 9:02 PM EDT | Mesoscale Discussion | SPC | Baldwin, Bibb, Butts, Carroll, Clayton, Cobb and 32 more | 58 min |
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.