Mesoscale Discussion 8

Issued

Jan 1, 2021, 12:42 PM EST (17:42 UTC)

Expired

Jan 1, 2021, 2:45 PM EST

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Robins AFB radar (KJGX), 91 km from the middle of the area, began a volume at 17:43 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 1Jan 1, 3:30 PM EST

706 
ACUS11 KWNS 011743
SWOMCD
SPC MCD 011742 
SCZ000-GAZ000-011945-

Mesoscale Discussion 0008
NWS Storm Prediction Center Norman OK
1142 AM CST Fri Jan 01 2021

Areas affected...Parts of the Georgia and adjacent South Carolina
Piedmont

Concerning...Severe potential...Watch unlikely 

Valid 011742Z - 011945Z

Probability of Watch Issuance...20 percent

SUMMARY...There appears at least some potential for strengthening
convection with embedded supercell structures which could pose
increasing potential for damaging wind gusts and/or a couple of
tornadoes through 3-5 PM EST.  It is not yet certain that a severe
weather watch will be needed, but trends are being monitored for
this possibility.

DISCUSSION...Likely due to relatively warm temperatures aloft and
weak mid/upper forcing for ascent, there has been little, if any,
recent lightning with a narrow, remnant pre-cold frontal line of
convection advancing east of the Georgia/Alabama state border
vicinity.  This convection appears supported by lift associated with
low-level convergence along a confluence zone aligned with a 40-50
kt southerly low-level jet (around 850 mb), which is forecast to
continue shifting eastward across the remainder of Georgia through
20-22Z.

Along and south of a developing warm frontal zone across the Georgia
into South Carolina Piedmont, now north of Macon into the Augusta
vicinity, at least weak warming of a relatively moist boundary layer
(including surface dew points in the mid/upper 60s F) is
contributing to weak boundary-layer CAPE.  This may be as high as
500 J/kg, but there appears little in the way of mid-level cooling
and lift to augment potential for intensifying thunderstorm
development through the remainder of the afternoon.

However, as a segment of the ongoing convective line now advancing
across and east of the Greater Atlanta Metro area (and extending
southward to around Columbus) progresses eastward this afternoon,
and encounters strengthening low-level warm advection along the warm
frontal zone, there appears at least some potential for
intensification.  If this occurs, large clockwise-curved low-level
hodographs along the frontal zone, beneath strong west-southwesterly
high-level flow, may contribute to environment conducive to
supercell structures posing a risk for damaging winds and/or
tornadoes.

..Kerr/Hart.. 01/01/2021

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

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

LAT...LON   33758417 33848295 33968189 33348162 32968291 32998434
            33328442 33758417

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.