Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion
National Weather Service Peachtree City GA
148 PM EDT Thu Jul 13 2017

.PREV DISCUSSION... /Issued 1057 AM EDT Thu Jul 13 2017/

UPDATE...

Temperatures are warming a bit quicker, so have updated the
hourly trends. Forecast looks on track.

PREV DISCUSSION... /Issued 719 AM EDT Thu Jul 13 2017/

PREV DISCUSSION... /issued 405 AM EDT Thu Jul 13 2017/

SHORT TERM /Today through Friday/...
Surface high pressure ridge has replaced the trough we saw a few
days ago across the region and this feature along with 594dm upper
ridge was enough to suppress activity Wed despite the presence of
high deep layer moisture. Continues to be a typical mid summer low
level environment with temps in the mid 70s and dewpoints not that
far off producing muggy overnight conditions.

For today, mid and upper level ridge to build in even further by
the afternoon hours with heights building to 595dm across east
central GA. In addition, should see a sharp decrease in
precipitable water values with 1.4 to 1.5 inches common across
both North and Central GA. It could very well be that these values
along with reduced instability will be enough to completely shut
off convection, even across the metro. Not quite ready to do that
in the grids though other than east central portions where it does
appear just sct clouds in the offing for today. Slight to low end
chance will be advertised for the remainder of the area. Given
lack of clouds and precip today, went on the higher side of
guidance with mid 90s likely for most of central GA.

Surface ridge drifts south for Friday and a slight weakening of
mid level ridge noted. Some enhanced deep layer moisture arrives
over western portions late in the day to allow for higher pops
than today but remaining in the low to mid range chance category.
Instability increases as well and with marginal mid level temps,
should see a return to isolated severe storm potential.

Deese

LONG TERM /Friday Night through Wednesday/...
Model solutions continue to delay the onset of weekend cold front
into the state. Timing varies from early Saturday to overnight
Saturday night/Sunday morning. The general consensus is more for a
Saturday afternoon/evening timing, and have ended up with good
chance pops rather than the previous likely pops due to the
uncertainty. GFS progresses the front into central and south
Georgia more quickly, with band of enhanced moisture along the
front south of the CWA by early Monday morning. ECMWF stalls the
boundary over middle Georgia, and not clearing it out of the CWA
until a secondary, dry trough axis pushes through the state on
Tuesday. Solutions still diverge with the high pressure ridge
building in mid-week and to what extent it will dominate the
region. For now, it appears we remain under the influence of
localized low pressure features/disturbances, with generally
diurnal convection persisting through next week.

Will still need to monitor the potential for Heat Advisory,
particularly late this week as heat index values near the 105
degree criteria over portions of central Georgia.

31

&&

.AVIATION...
18Z Update...

VFR conditions expected through the TAF period. However, there
will be isolated to scattered showers/thunderstorms possible
across the metro TAF sites through the afternoon. CU field around
5kft. Any precipitation activity should diminish around sunset
with convective debris clouds through the evening hours. Clear and
calm conditions expected overnight. Winds will increase with CU
development around 4kft by mid/late morning Friday. West winds
through the TAF period; although some models indicating light SSE
winds at ATL this evening. This should be brief.

//ATL Confidence...18Z Update...
Low/Medium on SSE winds at ATL.
Medium on convective coverage at metro ATL.
High on all elements.

26

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          94  73  93  73 /  20  20  20  20
Atlanta         92  74  92  74 /  20  20  30  20
Blairsville     86  67  86  67 /  30  30  30  40
Cartersville    92  72  91  72 /  20  20  30  30
Columbus        95  75  94  76 /  20  20  40  20
Gainesville     91  73  90  73 /  20  20  30  30
Macon           95  73  94  75 /  10  10  20  10
Rome            92  72  92  73 /  30  30  30  30
Peachtree City  93  72  92  72 /  20  20  40  20
Vidalia         94  74  94  75 /  20  20  20   5

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Deese
LONG TERM....31
AVIATION...26

Hazardous Weather Outlook
National Weather Service Peachtree City GA
1148 AM EDT Thu Jul 13 2017

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-141600-
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-
1148 AM EDT Thu Jul 13 2017

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

.DAY ONE...This Afternoon and Tonight...

Isolated to scattered thunderstorms are expected across north and
central Georgia this afternoon and evening, particularly north a
line from Cedartown, to Dawsonville, to Helen. Some storms may be
strong. The main hazards will be strong winds to 50 MPH, locally
heavy rainfall, and frequent lightning. Small hail will also be
possible.

Heat Index values will near 105 degrees over portions of central
Georgia this afternoon as warm temperatures combine with high
humidity. Stay hydrated and avoid prolonged periods outside if
possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday...

Scattered to numerous thunderstorms are possible each afternoon and
evening through the week and into early next week. Some more
widespread development could occur over the weekend with an
approaching front. Heat Index values will approach 105 degrees over
portions of central Georgia, generally Friday and Saturday.

.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.

Special Weather Statement
National Weather Service Peachtree City GA
215 PM EDT THU JUL 13 2017

GAZ002-003-131845-
Catoosa GA-Walker GA-
215 PM EDT THU JUL 13 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN CATOOSA AND WALKER
COUNTIES UNTIL 245 PM EDT...

At 214 PM EDT...a strong thunderstorm was near Cooper Heights, or 8
miles north of Lafayette. This storm was nearly stationary.

  HAZARD...Winds up to 40 mph...pea sized hail and heavy rain.

  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.

Some locations in the path of this storm include
Ringgold, Fort Oglethorpe, Rossville, Chickamauga, Lookout Mountain,
Noble, Wood Station, Blue Spring, Fairview, Linwood, Boynton,
Beaumont, Chattanooga  Valley, Cooper Heights and Rock Spring.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. Motorists should
slow down and be prepared for possible loss of control due to
hydroplaning.

LAT...LON 3486 8506 3484 8506 3481 8511 3482 8513
      3480 8514 3470 8530 3479 8545 3484 8545
      3498 8536 3499 8529
TIME...MOT...LOC 1814Z 224DEG 4KT 3482 8533

HAIL...0.25IN
WIND...40MPH