Mesoscale Discussion 1805

Issued

Oct 6, 2021, 1:26 PM CDT (18:26 UTC)

Expired

Oct 6, 2021, 4:00 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Atlanta radar (KFFC), 83 km from the middle of the area, began a volume at 18:28 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.

• Tornado Watch 513Oct 6, 2:50 PM CDT

023 
ACUS11 KWNS 061826
SWOMCD
SPC MCD 061826 
GAZ000-TNZ000-ALZ000-062100-

Mesoscale Discussion 1805
NWS Storm Prediction Center Norman OK
0126 PM CDT Wed Oct 06 2021

Areas affected...portions of AL...TN...and GA.

Concerning...Severe potential...Watch possible 

Valid 061826Z - 062100Z

Probability of Watch Issuance...40 percent

SUMMARY...A few strong/severe storms may pose a risk for damaging
wind gusts and or a brief tornado this afternoon. Convective
evolution remains uncertain given cloud cover and previous
convection.

DISCUSSION...As of 1815 UTC, surface observations and WV imagery
showed a vertically stacked low centered across northeastern
Arkansas. To the east of this low, broad ascent was supporting
several bands of convection from TN southward, into eastern AL and
western/central GA. Partly to mostly cloudy skies with a few breaks
are ongoing across much of AL and GA with the arrival of mid-level
dry air east of the low. As surface temperatures warm into the upper
70s and 80s F, weak-moderate buoyancy (750-1500 J/kg of MLCAPE)
should develop given heating of the very moist airmass with surface
dewpoints near 70 F. Southerly flow through much of the lower and
middle troposphere will support deep veering wind profiles favorable
for organized storms. Low-level backing of surface winds (0-1km srh
of 50-75 m2/s2) is also present on VWP data from FCC where several
small supercells have been noted. With favorable buoyancy and
effective shear in place, a few weak supercells may have the
potential to produce damaging wind gusts and or a brief tornado as
they move to the north this afternoon. 

Uncertainty remains on the evolution of storms across GA given dense
cloud cover and little surface forcing for ascent. Latest HRRR and
other hi-res guidance suggests a cluster of strong storms may
materialize out of the ongoing CU field and weak confluence across
west-central GA and eastern AL. Weak low-level UH tracks align well
with the potential for low-end supercells to track north and east
into northern AL/GA and southern TN into this evening. While
uncertainty remains, increasing storm coverage and favorable
kinematics will likely support some severe threat this afternoon and
early evening. Conditions will be monitored for a possible weather
watch.

..Lyons/Guyer.. 10/06/2021

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...

LAT...LON   35688569 35768643 35418689 34618696 34028660 33568603
            33138526 32808487 32608446 32628375 32798350 32958338
            33298342 33588353 33778382 34188403 34948444 35478502
            35688569

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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.