Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 221
The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2021, 10:34 AM EDT for 11 counties in Georgia; 7 counties in North Carolina; 10 counties in South Carolina. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 18, 2021, 10:34 AM EDT (14:34 UTC)
- Expired
- Mar 18, 2021, 1:00 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 28 counties
Banks County, GA, Barrow County, GA, Clarke County, GA, Elbert County, GA, Franklin County, GA, Habersham County, GA, Hall County, GA, Hart County, GA, Jackson County, GA, Madison County, GA, Stephens County, GA, Cabarrus County, NC, Cleveland County, NC, Gaston County, NC, Lincoln County, NC, Mecklenburg County, NC, Rowan County, NC, Stanly County, NC, Abbeville County, SC, Anderson County, SC, Cherokee County, SC, Greenville County, SC, Laurens County, SC, Oconee County, SC, Pickens County, SC, Spartanburg County, SC, Union County, SC, York County, SC
The radar
The Greer radar (KGSP), 23 km from the middle of the area, began a volume at 14:39 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
Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 2.6 hours before the alert went out and 244 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
- 486 m above ground
- 0-6 km bulk shear
- 67 kt
- 0-1 km storm-relative helicity
- 470 m²/s²
- 0-3 km storm-relative helicity
- 562 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
859
ACUS11 KWNS 181434
SWOMCD
SPC MCD 181434
NCZ000-SCZ000-GAZ000-181700-
Mesoscale Discussion 0221
NWS Storm Prediction Center Norman OK
0934 AM CDT Thu Mar 18 2021
Areas affected...northern Georgia into west-central North Carolina
Concerning...Severe potential...Watch possible
Valid 181434Z - 181700Z
Probability of Watch Issuance...60 percent
SUMMARY...At least isolated strong to severe storms are expected to
develop along the warm front, in a corridor from northern Georgia
into west-central North Carolina.
DISCUSSION...Surface analysis shows a warm front extending from
northern GA eastward into northern SC, with dewpoints into the lower
60s F to the south. Meanwhile, a dryline was developing across
western GA in association with the midlevel dry slot. Surface
observations also show an area of pressure falls, up to 1 mb/hr,
just ahead of the dryline/warm front intersection. This is also
where a line of thunderstorms currently exists, just east/northeast
of the Atlanta area.
As the warm front lifts north today, gradual destabilization is
expected, mainly through advection early, but also with heating this
afternoon as breaks in the clouds develop. Despite poor midlevel
lapse rates south of the midlevel jet core, a favorable corridor of
lift and low-level shear may support severe storms, including the
threat of tornadoes and damaging wind gusts. Effective SRH exceeds
300 m2/s2 as of late morning, and although forecast to decrease
throughout the day, will still be sufficient for tornadoes with
150-250 m2/s2 concentrated in the lowest 1km near the warm front.
..Jewell/Grams.. 03/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...RAH...CAE...GSP...FFC...
LAT...LON 34268234 33808355 33918391 34308401 34618363 35788080
35808038 35548001 35248007 34708136 34268234SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 11:15 PM EDT | Mesoscale Discussion | SPC | Quitman | 90 min |
| Mar 18, 12:02 AM EDT | Tornado Watch | SPC | Baker, Bibb, Butts, Calhoun, Carroll, Chattahoochee and 38 more | 9 hr |
| Mar 18, 2:52 AM EDT | Mesoscale Discussion | SPC | Chattahoochee, Clay, Marion, Quitman, Randolph, Stewart and 1 more | 83 min |
| Mar 18, 5:28 AM EDT | Mesoscale Discussion | SPC | Clay, Early, Seminole | 92 min |
| Mar 18, 7:32 AM EDT | Mesoscale Discussion | SPC | Atkinson, Baker, Ben Hill, Berrien, Brooks, Calhoun and 28 more | 58 min |
| Mar 18, 7:53 AM EDT | Tornado Watch | SPC | Baker, Ben Hill, Berrien, Bleckley, Brooks, Calhoun and 32 more | 5 hr |
| Mar 18, 11:05 AM EDT | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Ben Hill, Berrien, Brantley and 37 more | 115 min |
| Mar 18, 11:42 AM EDT | Tornado Watch | SPC | Appling, Atkinson, Bacon, Brantley, Bryan, Bulloch and 21 more | 6 hr |
| Mar 18, 2:08 PM EDT | Tornado Watch | SPC | Elbert, Lincoln | 4 hr |
| Mar 18, 3:10 PM EDT | Mesoscale Discussion | SPC | Elbert | 3 hr |
| Mar 18, 4:45 PM EDT | Tornado Watch | SPC | Alamance, Anson, Chatham, Cumberland, Davidson, Durham and 20 more | 4 hr |
| Mar 18, 5:09 PM EDT | Tornado Watch | SPC | Bertie, Camden, Chowan, Currituck, Gates, Hertford and 3 more | 6 hr |
| Mar 18, 5:57 PM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Beaufort, Bertie, Cabarrus, Camden and 45 more | 63 min |
| Mar 18, 7:49 PM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Chatham, Cumberland, Durham, Edgecombe and 21 more | 56 min |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in South Carolina, 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.