Severe Thunderstorm Warning 109, NWS Atlanta, GA

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
1024 PM EDT Mon May 4 2020

.UPDATE...
Continuing to monitor the inbound convection toward NW GA.
Damaging winds and hail are the main hazards.

BDL

&&

PREV DISCUSSION... /Issued 708 PM EDT Mon May 4 2020/

SHORT TERM /Tonight through Tuesday Night/...

Current satellite/radar loop shows increasing clouds across North
and Central GA with a wave moving E to SE out of the Mid MS River
Valley. This wave is expected to continue to push east and should
clip N GA late this afternoon/evening. Will see some showers and
thunderstorms as this wave pushes through mainly across N GA. The
models are showing, as this wave moves through, the best moisture
and dynamics stays north of the state so not sure just how much we
will see this evening. As the storms move across there is enough
instability developing across N GA to spark of some strong and possibly
severe storms, but any that develop will be isolated. The greatest
threats appear to be lightning strikes, Damaging winds, and some
hail. The potential for some severe storms may also continue through
the overnight hours as some hi-res models are hinting at a more
organized complex of storms moving across N GA after midnight. This
definitely isn't out of the question especially with the weak
northwest flow aloft and the wave moving through.

By Tuesday morning, a developing closed low over the central plains
will have moved east into the Mid MS river valley. This low center
is expected to continue to move E to Ne through Wed morning with its
associated cold front moving through the region Tuesday
afternoon/night. Although moisture looks to be fairly limited, there
will be ample lift with this system to continue with chance pops
across the northern zones in the evening hours. The front looks to
dry out some as it continues into central Georgia through Wed
morning. Strong to isolated severe thunderstorms will again be
possible with this front, mainly across north Georgia, due to
moderate instability and steep lapse rates. The main hazards with
any storms will again be damaging winds, lightning, and hail. SPC
has also put portions of north Georgia under a Marginal Risk for day
2.

01

LONG TERM /Wednesday through Monday/...

A series of rossby wave breaks over the north Atlantic will help
keep a block of high PV stratospheric air entrenched over the
eastern portion of North America. Within this, several tropospheric
polar vorticies (TPVs) will rotate around the edge of this and
elongate into PV streamers which will provide ascent for surface
cyclogenesis across the eastern US, keeping a somewhat active but
cooler pattern in place over the next week into early next week as
a series of quick moving lows and cold fronts move through.

By Wednesday morning, a cold front should be through most of the CWA
with the possible exception of the far southeastern counties which
may still be experiencing some precipitation. Guidance has mostly
backed off the idea of any wrap around moisture on the backside of
the low getting squeezed out over the north GA mountains, so lowered
PoPs. Cooler air moves in with the cold front for Thursday keeping
temperatures seasonable across much of the CWA.

Friday, shortwave moving out of the midwest aligns with the larger
scale trough over the eastern US and dives into our area, generating
a surface low over the Ohio River valley which quickly moves to the
northeast. Another cold front moves into the CWA with this,
providing the next opportunity for rain Friday into Friday night.
Both GFS and Euro have become a little more aggressive with
precipitation, though overall accumulations are still light given
limited moisture in the post-frontal environment that will still
exist as well as possibility of storms to the southwest preventing
much in the way of moisture return during the day. Instability is
very limited and upper-level lapse rates are not favorable, but hard
to rule out the possibility of thunder along a cold front this time
of year in Georgia. Will keep Thunder in the forecast Friday and
Friday night.

Northwest flow behind the front will bring in another reinforcing
shot of cold air. Highs will be in the upper 60s to low 70s across
the CWA over the weekend and lows down into the 40s across the area
and even upper 30s in the north Georgia mountains. Next possible
system moves by on Monday, though current guidance keeps it north of
the CWA.

Lusk

AVIATION...
00Z Update...
VFR conditions are expected to continue. Best chances for
showers and storms are over far n GA tonight.
Surface winds varying around West less than 10 kts tonight
and 8-12 kts for Tuesday with some gusts around 20 kts.

//ATL Confidence...00Z Update...
Medium to high confidence for all elements.

BDL

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          64  85  55  70 /  20  20  30   0
Atlanta         65  83  54  68 /  20  20  30   5
Blairsville     59  77  46  59 /  50  50  40   5
Cartersville    63  83  51  67 /  30  30  40   5
Columbus        63  87  59  75 /   5  10  20   5
Gainesville     62  82  53  66 /  30  30  30   0
Macon           63  87  59  75 /   0   5  10   5
Rome            63  81  51  68 /  50  40  30   5
Peachtree City  62  84  54  71 /  10  20  30   5
Vidalia         65  89  66  79 /   0   0  10   5

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Severe Thunderstorm Watch until 1 AM EDT Tuesday for the
following zones: Catoosa...Chattooga...Dade...Dawson...Fannin...
Floyd...Gilmer...Gordon...Lumpkin...Murray...Pickens...Towns...
Union...Walker...White...Whitfield.

&&

SHORT TERM...BDL
LONG TERM....Morgan
AVIATION...BDL

Hazardous Weather Outlook
National Weather Service Peachtree City GA
829 PM EDT Mon May 4 2020

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-060030-
Baldwin-Banks-Barrow-Bartow-Bibb-Bleckley-Butts-Carroll-Catoosa-
Chattahoochee-Chattooga-Cherokee-Clarke-Clayton-Cobb-Coweta-
Crawford-Crisp-Dade-Dawson-DeKalb-Dodge-Dooly-Douglas-Emanuel-
Fannin-Fayette-Floyd-Forsyth-Gilmer-Glascock-Gordon-Greene-
Gwinnett-Hall-Hancock-Haralson-Harris-Heard-Henry-Houston-Jackson-
Jasper-Jefferson-Johnson-Jones-Lamar-Laurens-Lumpkin-Macon-
Madison-Marion-Meriwether-Monroe-Montgomery-Morgan-Murray-
Muscogee-Newton-North Fulton-Oconee-Oglethorpe-Paulding-Peach-
Pickens-Pike-Polk-Pulaski-Putnam-Rockdale-Schley-South Fulton-
Spalding-Stewart-Sumter-Talbot-Taliaferro-Taylor-Telfair-Toombs-
Towns-Treutlen-Troup-Twiggs-Union-Upson-Walker-Walton-Warren-
Washington-Webster-Wheeler-White-Whitfield-Wilcox-Wilkes-
Wilkinson-
829 PM EDT Mon May 4 2020

This Hazardous Weather Outlook is for portions of North and Central Georgia.

.DAY ONE...Tonight...

The chance for severe storms has increased over portions of north
Georgia late this evening into the early morning hours. A Severe
Thunderstorm Watch has been issued accordingly until 1 AM. The
main threats will be damaging winds, large hail, and locally heavy
rainfall. An isolated brief tornado cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday...

There is a chance of thunderstorms Tuesday and Tuesday night and
again Friday and Friday night ahead of another cold front.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested but spotters are encouraged
to submit reports of severe weather through the web by going to
weather.gov/atlanta. Please relay any information about observed
severe weather to the NWS while following all local, state, and
CDC guidelines.