Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion
National Weather Service Peachtree City GA
541 PM EDT Wed Apr 6 2022

.UPDATE...

Updated for the expansion of the Flood Watch.

.PREV DISCUSSION... /Issued 500 PM EDT Wed Apr 6 2022/

UPDATE...

Updated to add the TOR watch for north Georgia.

PREV DISCUSSION... /Issued 301 PM EDT Wed Apr 6 2022/

.Afternoon Area Forecast Discussion...

SHORT TERM /Tonight through Thursday Night/...

No major changes to thinking in the short term forecast, so have
included very in-depth previous discussion from Thiem.

Mesoanalysis shows very saturated environment under FEW/SCT cloud
deck, allowing for ample insolation with temps climbing into the
80s, with Tds in the 70s. This sets the stage with SBCAPE values
3000+ j/kg, ample instability for any storms that fire, in tandem
with impressive mid- lvl lapse rates and mid-lvl flow. Current
hazards for central Georgia remain large hail, gusty to damaging
winds from downbursts, tornadoes and bouts of heavy rain.

Stratus and Fog remain resilient over N GA, with metro Atlanta
seeing cloud decks as low as 1000ft, with FG/DZ and lowered
visibilities just now lifting, hindering CAPE development. This
has setup a pseudo-front along the I-20 corridor with large temp
disparity. However, looking to this evening, although CAMS have
been all over the place in spatial coverage and timing of frontal
passage. However, severe weather potential for N GA remains on
track with some form of a QLCS to enter NW GA by 23-02z. As
mentioned, see previous discussion for additional info:

Morgan

Previous Short Term Discussion Below...

One Enhanced Risk Severe Weather Outlook down, one more to go!

Despite a strong quasi-linear convective system sweeping through the
forecast area today, with widespread reports of wind damage and over
a dozen noted tornadic debris signatures, the area remains in a
general warm sector regime with abundant low-level warmth and
moisture. In the mid-layers (500-700 hPA), very dry air was left
behind following the storm system, which is helping to keep
scattered light sprinkles/showers from growing more upscale,
however, by noon broad southwesterly flow will increase moisture in
these levels as well and boosting PWATs from near an inch in this
morning's special 06Z sounding to back over an inch and a half by
the afternoon for Central Georgia, setting the stage for another
potential round of severe weather.

Central Georgia, this afternoon into the early evening...

Abundant moisture return by the afternoon in the low- to mid-levels,
is going to be timed with a northward moving coastal, baroclinic
boundary and a very weak mid-level shortwave trough. This setup will
result in a rather abnormal setup for severe weather for this
region, but one that has worrisome combination of severe parameters:

* A weak shortwave will provide lower-level lift across the region,
  which will act as a trigger mechanism for convective development
  and will cool the mid-levels between 500-700 hPa, creating lapse
  rates near 7 C/km.
* With zonal-flow in place in the mid-levels with the rapid invasion
  of the shortwave later in the afternoon, offsetting effects of
  advection warmer mid-level air won't be as present as they
  otherwise would in a more classic Southeastern SVR setup.
* Cooling in the mid-levels, combined with warm and very moist air
  advecting in off the Gulf will create surface-based CAPE values
  between 2000-3000 J/kg this afternoon.
* In general, wind profiles aloft are rather weak (0-6 km shear
  values are below 30 kts) due to the weak nature of the shortwave
  likely resulting in shorter-lived, popcorn-like cells that
  collapse on themselves after approx an hour with very little wind
  shear between 2-6 km.
* However, in the lowest 2 km, wind shear is decent with quarter-
  circle hodographs providing good streamwise vorticity into
  developing right-moving storms and increasing the potential for
  rotating thunderstorms and spin-up circulations.

The result of all this in an environment in Central Georgia this
afternoon with no strong organizing trigger mechanism typical for a
more organized severe thunderstorm development, although mesoscale
boundaries or bands may change this. However, the parameters are
good for shorter-lived (1-2 hours) storms capable of large hail and
rapidly developing short-lived tornadic circulations. This threat
followed by cooler, drier air in the mid-levels allowing evaporative
cooling which combined with water loading will present
downburst/microburst potential as storm updrafts collapse.
Additionally, with 1-3 inches of rain previously fallen, a flooding
threat will be present anywhere heavier rain persists for prolonged
periods of time.

North Georgia, this evening into the overnight hours...

In north Georgia, a strong cold front from a more organized
synoptic system is expected to surge into for northwest Georgia just
before sunset. This will provide a stout triggering mechanism for
storm development, with stronger winds aloft more supportive of
longer-lived supercell development. The dynamics for north Georgia
during this time is everything that's missing for Central Georgia
during the afternoon. However, despite the better dynamics the
thermodynamics are more lacking.

* The moisture return for north Georgia will be less abundant
  resulting in PWATs just above an inch for the area, likely
  resulting in convective storms struggling to become more robust.
* Storms in the south earlier in the day may rob some surface-based
  instability in the region. With that said, forecast values of
  surface-based CAPE are still expected to be above 2000 J/kg, but
  begin falling after 6 PM.
* The timing of the cold front may keep storms elevated after 8 PM,
  limiting severe potential.
* With these factors in mind, low-level wind profiles are much more
  favorable to tornadic supercells if they can overcome the drier
  air aloft. Hodographs show sickle-cell structures through 4-6 km,
  with decent, but not perfect, storm-relative streamwise vorticity.
* Dry air in the mid levels, could cause strong evaporative
  cooling fueled downbursts in any robust storms that do form.
  These winds combined with the storm motion could create several
  instances of damaging wind gusts.

All in all, please stay aware of any watches or warnings issued for
your area through the day and into tonight. Please have a plan of
action ready in case it is needed.

Following the cold front tonight, more tranquil weather is in store
with clearing skies, breezy NW winds, and highs generally in the 60s
by Thursday.

Thiem

LONG TERM /Friday through Wednesday/...

Anomalous temperatures still on track for the weekend. Temps should
begin to slowly moderate towards normal on Sunday. Friday and
Saturday night's lows should be 5 to 15 degrees below normal.
Saturday's highs will range from 15 to 25 degrees below normal for
this time of year.

Frost/Freeze products will likely be needed Friday night and
Saturday night.

Previous Long Term Discussion Below...

The impressive, expansive upper trough that fueled our final round
of active weather continues to dig further down across the
southeast, with a tight pressure gradient on its outer edge (~20-22
mb difference across GA). As such, gusty gradient winds will be
possible through Saturday afternoon when the trough begins to lift
across the mid-Atlantic states. Several shortwave disturbances
rounding the inner edge of the trough will lead to increased cloud
cover and brief bursts of rain across north GA on Friday into
Saturday. A surface high from over the Gulf and stout upper ridging
break the active pattern as they settle in across the southeast on
Sunday to round off the weekend and take us through the beginning of
the work week.

Temperatures will be quite cool for April standards following the
cold frontal passage on Thursday night. Have added the potential for
areas of frost on Sunday morning, when minimum temperatures are
coolest and winds begin to calm. Highs will stall out in the mid-50s
to 60s, 12-15 degrees below average; lows through the weekend will
be in the 30s, about 5-10 degrees below average. As the surface high
begins to drift across the southeast Sunday, winds shift to be
primarily from the southeast, and temperatures recover to seasonable
highs in the 70s-80s and lows in the 40s.

96

AVIATION...
18Z Update...

Metro TAF sites socked in stubborn LIFR/IFR cigs, expecting
gradual improvement through the afternoon as daytime mixing
occurs. Have SHRA starting at 18z as precip overspreads the area
along a shortwave, with low-end potential of TS, but confidence is
too low at this time to include. TSRA will be possible again tonight
after 00z as a cold front pushes through metro TAF sites. After
frontal passage, winds turn NW by 08z tonight, remaining elevated
between 9-13kts. Should go VFR cigs/vsbys tomorrow between 11-14z
as drier air rushes in.

//ATL Confidence...18Z Update...

Low to medium on all elements

Morgan

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          55  68  43  61 /  70   0   0   5
Atlanta         52  66  43  58 /  90   0   0   5
Blairsville     45  62  36  52 / 100   5   5  40
Cartersville    47  66  41  57 /  90   0   0  10
Columbus        55  69  44  64 /  70   5   0   0
Gainesville     52  65  43  57 /  90   0   0  10
Macon           57  72  43  67 /  70   5   0   0
Rome            49  66  41  57 /  90   0   0  10
Peachtree City  50  67  41  60 /  80   0   0   5
Vidalia         63  72  48  68 /  90  30   5   0

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday morning for the following zones:
Baldwin...Bibb...Bleckley...Butts...Chattahoochee...Crawford...
Crisp...Dodge...Dooly...Emanuel...Glascock...Greene...Hancock...
Harris...Houston...Jasper...Jefferson...Johnson...Jones...
Lamar...Laurens...Macon...Marion...Meriwether...Monroe...
Montgomery...Morgan...Muscogee...Oglethorpe...Peach...Pike...
Pulaski...Putnam...Schley...Stewart...Sumter...Talbot...
Taliaferro...Taylor...Telfair...Toombs...Treutlen...Troup...
Twiggs...Upson...Warren...Washington...Webster...Wheeler...
Wilcox...Wilkes...Wilkinson.

Tornado Watch until 10 PM EDT this evening for the following
zones: Baldwin...Bibb...Bleckley...Butts...Catoosa...
Chattahoochee...Chattooga...Clayton...Coweta...Crawford...
Crisp...Dade...Dodge...Dooly...Emanuel...Fannin...Fayette...
Gilmer...Glascock...Gordon...Greene...Hancock...Harris...Heard...
Henry...Houston...Jasper...Jefferson...Johnson...Jones...Lamar...
Laurens...Macon...Marion...Meriwether...Monroe...Montgomery...
Morgan...Murray...Muscogee...Newton...Peach...Pike...Pulaski...
Putnam...Schley...Spalding...Stewart...Sumter...Talbot...
Taliaferro...Taylor...Telfair...Toombs...Treutlen...Troup...
Twiggs...Upson...Walker...Warren...Washington...Webster...
Wheeler...Whitfield...Wilcox...Wilkes...Wilkinson.

&&

SHORT TERM...NListemaa
LONG TERM....96
AVIATION...Morgan

Hazardous Weather Outlook
National Weather Service Peachtree City GA
1226 AM EDT Thu Apr 7 2022

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-080430-
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-
1226 AM EDT Thu Apr 7 2022

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

...A FLOOD WATCH REMAINS IN EFFECT UNTIL 8 AM EDT THIS MORNING FOR
PORTIONS OF CENTRAL GEORGIA...

.DAY ONE...Tonight...

One final round of showers and thunderstorms are expected to move
through eastern and central Georgia through the night. The primary
threat will be flash flooding with saturated soils receiving an
additional half to one and a half inches of rainfall. Other
threats will include frequent lightning and strong gusty winds.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday...

No hazardous weather is expected at this time.

.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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1230 AM EDT THU APR 07 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0803 PM     TSTM WND DMG     3 WNW DUBLIN            32.55N  82.96W
04/06/2022                   LAURENS            GA   AMATEUR RADIO

            TREE DOWN ON POWERLINES ALONG SPRINGDALE RD BETWEEN
            WAVERLY DR AND BEAVER RUNN.

&&

EVENT NUMBER FFC2200373

LUSK

Special Weather Statement
National Weather Service Peachtree City GA
1245 AM EDT Thu Apr 7 2022

GAZ046>049-054>057-070515-
Morgan GA-Fayette GA-Walton GA-Rockdale GA-Clayton GA-Spalding GA-
Newton GA-Henry GA-
1245 AM EDT Thu Apr 7 2022

...Strong thunderstorms will impact portions of Spalding,
southeastern Rockdale, southeastern Fayette, west central Morgan,
Henry, south central Walton, south central Clayton and Newton
Counties through 115 AM EDT...

At 1245 AM EDT, a line of strong thunderstorms was along a line
extending from Almon to near Lovejoy to Digbey, and moving east at 45
mph.

HAZARD...Up to 40 mph wind, frequent cloud to ground lightning and
         heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

Locations impacted include...
Griffin, McDonough, Conyers, Covington, Stockbridge, Hampton,
Lovejoy, Locust Grove, Social Circle, Oxford, Porterdale, Rutledge,
Brooks, Woolsey, Sunny Side, East Griffin, Blacksville, Ola, Walker
Mill and Luella.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning. Motorists
should slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 3326 8450 3345 8431 3366 8393 3368 8355
      3345 8393 3345 8394 3322 8418 3321 8450
TIME...MOT...LOC 0445Z 260DEG 38KT 3364 8393 3345 8425 3324 8449

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

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