Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
721 AM EDT Tue Jul 4 2017

.UPDATE...
For 12z TAFs.

&&

.PREV DISCUSSION... /Issued 355 AM EDT Tue Jul 4 2017/

SHORT TERM /Today through Wednesday/...
Latest G16 WV satellite imagery shows a decaying upr wave moving
east across northern Alabama & middle Tennessee at this time,
accompanied by a few showers and embedded thunderstorms. It is this
feature that will be the focus for convective initiation across
mainly north Georgia today.

Challenging forecast centers around coverage of showers/storms and
how far south they develop, considering Hi-res models are in a bit
of disagreement. The HRRR/RAP and 00z NAM keep most of the
convection north of I-20 and I-85 while our local WRF/ARW models
(which initialize off the GFS) are farther south (south of I-20 /
along a LaGrange to Griffin to Greensboro line). Regardless of
outcome, with the exception of the higher elevations of northeast
Georgia, confidence is medium to high that any showers/storms will
dissipate after 8PM and hopefully not impact many outdoor
(Independence Day) activities. Out ahead of aforementioned upr wave,
narrow belt of 20-25kt West-Southwest low lvl (sfc-h85) flow over
north GA, along with moderate instability AOA 2K J/KG could support
a few stronger storms this afternoon. Mid lvl dry air intrusion
evident on Water Vapor could enhance isolated downburst winds of
50 to 60 mph. However, widespread severe weather is not expected.

Tuesday night into Wednesday, shortwave ridge looks to set up across
the forecast area behind Tuesday's upr lvl system and upstream wave
over Missouri/Arkansas. This should help to limit convection while
warming temps up into the lower to mid 90s across much of central
GA. Heat indices could exceed 100F from Americus to Dublin to
Swainsboro.

DJN.83

LONG TERM /Wednesday Night through Monday/...

Extended period begins with a shortwave trof apprchng within
a broader 500mb trof anchored over the eastern half of the US that
remains anchored for the entire extended period. Pops expected to
peak across far north GA Thursday aftn/eve with the approach of
the shortwave trof. Will likely see a north to south gradient of
tstm coverage from Thursday to Friday as the shortwave exits and
forces a weak boundary southward through the CWA on Friday.
Uncertainty increases through the weekend as the eastern US trof
sharpens and becomes more conducive for NW flow MCS type systems.
Both the ECMWF and GFS in general agreement on the NW flow pattern
and the potential for something more organized to develop and
head south on Saturday...which would appear to emanate from an
overnight MCS in Missouri on Friday AM. Too early to determine
anything other than recognize the potential.

GFS and ECMWF diverge thereafter with ECM bringing in some drier
air by Sunday thru Tuesday whereas the GFS hangs a boundary up and
keeps pop chances normal to above normal through the extended.
Running the model blends in the extended yield near normal pops
overall with and near normal temps. Given the uncertainty of the
weekend...would expect confidence to decrease with time.
In summary...looking for increased pop targets of Thursday in north
GA...Friday in Central/South GA and Saturday from North to South
with potential MCS.

KS.30

&&

.AVIATION...
12Z Update...
VFR conditions expected to prevail over ATL and surrounding TAF
sites, despite some patchy shallow ground fog. Challenges today
center around placement and coverage of convection as an upper lvl
disturbance moves east across middle Tennessee. Hi-res models are
having a difficult time resolving feedback issues. Feeling is that
isolated to widely scattered SHRA/TSRA will develop within moist
plume/narrow enhanced westerlies and new rain-induced cold pool
across north Georgia. Some of this activity has the potential to
reach ATL and surrounding sites after 20z. Outside of storms,
westerly sfc winds will prevail today with SCT cumulus btwn
040-050. These will dissipate after 00z this evening.

//ATL Confidence...12Z Update...
Low to Medium with convection timing and coverage.
High with all other elements.

DJN.83

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          90  71  91  72 /  30  20  20   5
Atlanta         89  73  90  73 /  30  20  20   5
Blairsville     81  66  84  67 /  40  30  30  30
Cartersville    88  71  89  72 /  30  20  20  10
Columbus        94  74  94  74 /  10   5   5   5
Gainesville     86  71  88  72 /  30  20  20  10
Macon           94  73  95  74 /  10  10  10   5
Rome            88  71  90  72 /  40  20  30  20
Peachtree City  90  71  91  71 /  20  20  10   5
Vidalia         95  75  95  76 /  10  10  20   5

&&

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

SHORT TERM...DJN.83
LONG TERM....30
AVIATION...DJN.83

Hazardous Weather Outlook
National Weather Service Peachtree City GA
454 AM EDT Tue Jul 4 2017

GAZ001>009-011>016-019>025-027-030>039-041>062-066>068-070>073-
075-050900-
Baldwin-Banks-Barrow-Bartow-Butts-Carroll-Catoosa-Chattooga-
Cherokee-Clarke-Clayton-Cobb-Coweta-Dade-Dawson-DeKalb-Douglas-
Fannin-Fayette-Floyd-Forsyth-Gilmer-Glascock-Gordon-Greene-
Gwinnett-Hall-Hancock-Haralson-Heard-Henry-Jackson-Jasper-Jones-
Lamar-Lumpkin-Madison-Meriwether-Monroe-Morgan-Murray-Newton-
North Fulton-Oconee-Oglethorpe-Paulding-Pickens-Pike-Polk-Putnam-
Rockdale-South Fulton-Spalding-Taliaferro-Towns-Troup-Union-
Walker-Walton-Warren-White-Whitfield-Wilkes-
454 AM EDT Tue Jul 4 2017

This Hazardous Weather Outlook is for portions of central Georgia...east central Georgia...north central Georgia...northeast Georgia...northwest Georgia AND west central Georgia.

.DAY ONE...Today and Tonight...

There is a chance of a few showers and thunderstorms today and
into this evening.  The best chances for storms will be
between the hours of noon and 6 pm generally across the
North Georgia Mountains....however a scattered shower or thunderstorm
cannot be ruled out in any location along and north of Interstate
20. Frequent lightning...gusty winds...and locally heavy rainfall
will be the primary hazards.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

There is a chance of showers and thunderstorms each day, mainly
during the afternoon and evening hours. A few storms could be
strong to possibly severe with gusty winds as well as locally
heavy rain. The best chances of isolated strong to severe storms
will come on Thursday and Friday as a weak front moves across the
region.

Due to the heavy rain, brief localized flooding of poor drainage
areas is possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

GAZ069-074-076-078>086-089>098-102>113-050900-
Bibb-Bleckley-Chattahoochee-Crawford-Crisp-Dodge-Dooly-Emanuel-
Harris-Houston-Jefferson-Johnson-Laurens-Macon-Marion-Montgomery-
Muscogee-Peach-Pulaski-Schley-Stewart-Sumter-Talbot-Taylor-
Telfair-Toombs-Treutlen-Twiggs-Upson-Washington-Webster-Wheeler-
Wilcox-Wilkinson-
454 AM EDT Tue Jul 4 2017

This Hazardous Weather Outlook is for portions of central Georgia...east central Georgia...southeast Georgia AND west central Georgia.

.DAY ONE...Today and Tonight...

While an isolated shower or thunderstorm is possible this
afternoon and evening...chances are forecast to be less than 20
percent today. However, the combination of the high temperatures
and the dewpoint will cause the the heat index to approach and
exceed 100 degrees during the afternoon hours today. Drink plenty
of water and watch for signs of heat exhaustion if you are
outdoors today.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

There is a chance of showers and thunderstorms each day, mainly
during the afternoon and evening hours. A few storms could be
strong to possibly severe with gusty winds as well as locally
heavy rain. The best chances of isolated strong to severe storms
will come on Thursday and Friday as a weak front moves across the
region.

Due to the heavy rain, brief localized flooding of poor drainage
areas is possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

Special Weather Statement
National Weather Service Peachtree City GA
614 AM EDT TUE JUL 4 2017

GAZ001>003-041115-
Catoosa GA-Walker GA-Dade GA-
614 AM EDT TUE JUL 4 2017

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN CATOOSA...WALKER AND DADE
COUNTIES UNTIL 715 AM EDT...

At 613 AM EDT...a cluster of thunderstorms were over Cloudland Canyon State
Park, or near Trenton...moving east at 25 mph.

  HAZARD...Heavy rain up to 1.5 inches per hour.

  IMPACT...Heavy rain may cause temporary street flooding especially
           in poor drainage areas.

Some locations in the path of this storm include
Ringgold, Trenton, Fort Oglethorpe, Rossville, Chickamauga, Lookout
Mountain, Blue Spring, Fairview, Chattanooga  Valley, Cloudland
Canyon State Park, Hooker, Cooper Heights, Rock Spring, Rising Fawn,
Noble, Lakeview, Indian Springs, Wood Station, Graysville and Cole
City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Motorists should slow down and be prepared for possible loss of
control due to hydroplaning.

LAT...LON 3499 8514 3477 8515 3469 8555 3498 8560
TIME...MOT...LOC 1013Z 247DEG 22KT 3482 8552

Special Weather Statement
National Weather Service Peachtree City GA
725 AM EDT TUE JUL 4 2017

GAZ001>003-041230-
Catoosa GA-Walker GA-Dade GA-
725 AM EDT TUE JUL 4 2017

...SIGNIFICANT WEATHER ADVISORY FOR CATOOSA...WALKER AND DADE
COUNTIES UNTIL 830 AM EDT...

At 723 AM EDT...a northeast to southwest line of showers and storms
was over Trenton to Ringgold...individual storms were moving east at
30 mph.

  HAZARD...Heavy rain...up to 1.5 inches has already fallen in portions
           of Dade County in the past 2 hours...with additional
           rainfall expected.

  IMPACT...Heavy rain may cause temporary street flooding especially
           in poor drainage areas.

Some locations in the path of this storm include
Ringgold, Trenton, Fort Oglethorpe, Rossville, Chickamauga, Lookout
Mountain, Blue Spring, Fairview, Chattanooga  Valley, Cloudland
Canyon State Park, Hooker, Cooper Heights, Rock Spring, Rising Fawn,
Noble, Lakeview, Indian Springs, Wood Station, Graysville and Cole
City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Motorists should slow down and be prepared for possible loss of
control due to hydroplaning.

LAT...LON 3499 8503 3498 8503 3483 8507 3481 8512
      3482 8513 3480 8514 3464 8554 3498 8560
TIME...MOT...LOC 1123Z 250DEG 24KT 3488 8549