Mesoscale Discussion 1661

Issued

Aug 31, 2021, 2:03 PM EDT (18:03 UTC)

Expired

Aug 31, 2021, 4:00 PM EDT

In force

117 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Atlanta radar (KFFC), 114 km from the middle of the area, began a volume at 18:05 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.

610 
ACUS11 KWNS 311803
SWOMCD
SPC MCD 311803 
GAZ000-SCZ000-312000-

Mesoscale Discussion 1661
NWS Storm Prediction Center Norman OK
0103 PM CDT Tue Aug 31 2021

Areas affected...Northeast Georgia...far western South
Carolina...and far northeastern Alabama

Concerning...Severe potential...Watch unlikely 

Valid 311803Z - 312000Z

Probability of Watch Issuance...20 percent

SUMMARY...A risk for a brief tornado or two and some damaging winds
remain possible with storms ongoing associated with the remnants of
Tropical Cyclone Ida. Uncertainty remains high on the coverage of
any tornado/wind threat this afternoon.

DISCUSSION...As of 1800 UTC, the remnant low of TC Ida was located
across northern Alabama with a loosely organized convective band
extending east/southeastward from the center across central Georgia.
Within this line, lightning has tended to increase over the last
hour as storms have progressed eastward toward areas of lower cloud
coverage across far northeastern Georgia and western South Carolina.
Here, SPC mesoanalysis indicates insolation has increased MLCAPE
values to 500-1000 J/kg. However, this area of greater buoyancy is
somewhat displaced from stronger low-level shear associated with
Ida's decaying wind field. With smaller low-level hodographs and
effective SRH, the tornado threat maybe somewhat muted despite
greater instability. Enough overlap of buoyancy and shear may
overlap to support a low-end risk for one or two brief tornadoes and
some damaging wind gusts over the next couple of hours as storms
continue to the north/northeast.

Behind the leading convective band, water vapor and visible imagery
show a pocket of clearing where dry mid-level air has intruded along
the Alabama Georgia border. Weak insolation through cloud breaks is
supporting some additional destabilization within the tropical
airmass. A few weak showers/thunderstorms have recently developed
within this area. Low-level wind fields nearer Ida's center remain
stronger and marginally supportive of a low-end supercell/tornado
risk despite surface obs tending to veer with time as Ida lifts to
the northeast. A tornado remains possible with any storms able to
become established this afternoon. Given the low confidence and
limited overlap of strong low-level shear and buoyancy a watch is
unlikely.

..Lyons/Grams.. 08/31/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CAE...GSP...FFC...

LAT...LON   34948387 34998302 34918257 34698219 34308205 33938205
            33568211 33248221 32828232 32668245 32678297 33288318
            33518332 33558357 33318389 33108409 33008435 32988461
            33098481 33378510 33928506 34348471 34948387

Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in South Carolina, 2021Every mesoscale discussion in 2021

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.