Alert archive / Georgia / Special Weather Statements in 2017

Special Weather Statement, NWS Atlanta, GA

July 22, 2017Cobb County, Georgia

NWS Atlanta, GA issued this special weather statement at Jul 22, 2017, 2:20 PM EDT for Cobb County, Georgia. It was in force for 40 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 22, 2017, 2:20 PM EDT (18:20 UTC)
Expired
Jul 22, 2017, 3:00 PM EDT
In force
40 min
Issued by
NWS Atlanta, GA
Hail
0.75 in
Wind
50

County Cobb County, GA

The radar

The Atlanta radar (KFFC), 55 km from the middle of the area, began a volume at 18:22 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.

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 6.3 hours before the alert went out and 55 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Peachtre/Fal Fld, GA at 12:00Z on 2017-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1157 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Peachtre/Fal Fld, GA at 12:00Z on 2017-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 8 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1157 J/kg
Mixed-layer CIN
-81 J/kg
Mixed-layer LCL
926 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
8 m²/s²
0-3 km storm-relative helicity
38 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Atlanta, GA wrote its last area forecast discussion before this special weather statement went out at Jul 22, 1:04 PM EDT, 1 hour 16 minutes earlier.

Area forecast discussion, Jul 22, 1:04 PM EDT, 1 hour 16 minutes before
Area Forecast Discussion
National Weather Service Peachtree City GA
104 PM EDT Sat Jul 22 2017

.UPDATE...
Updated for the 18Z Aviation Discussion.

&&

.PREV DISCUSSION... /Issued 730 AM EDT Sat Jul 22 2017/

SHORT TERM /Today through Sunday/...

The main concern for today continues to be the persistent upper
ridge and hot temperatures. Little in the way of dynamics to force
convection...but old boundaries from Friday and afternoon heating
should be able to trigger a few showers and thunderstorms. Have
broad brushed 25 to 30 percent pops for the afternoon. Thunderstorms
should diminish by 06z and Sunday looks like it will be a repeat.

Afternoon temperatures should range in the low to mid 90s for much
of the forecast area today. Dew points were tweaked up again for
today to go with persistence. Current Heat Advisory looks good
except have added another row of counties on the northern side
since these areas were showing HI values of above 105. Models
indicate somewhat lower thickness values for Sunday...however still
looking for only a slight difference in max temperatures.

41

LONG TERM /Sunday Night through Friday/...

The forecast through the extended continues to be characterized by
daily shower and thunderstorm opportunities. At the onset of the
period on Monday, an upper shortwave and approaching cold front will
serve to focus scattered convection, especially by afternoon and
evening during peak daytime heating. Given a moisture rich airmass
with PWATs around 2 inches, locally heavy rainfall can be expected.
Furthermore, as is typical during mid summer with building afternoon
instability, some strong thunderstorms will be possible.

This weakening cold front will continue to linger in the
area through midweek, which will enhance diurnal convection each
day. By late week, the upper levels transition into a northwest flow
pattern. Any disturbances riding into the area will bring additional
shower and thunderstorm chances to the state with the increased
potential for mesoscale convective systems arriving from the
northwest.

High temperatures will not stray too far from normal through the
long-term period, with highs generally near 90 in north Georgia and
into the lower 90s in central Georgia. Low temperatures, meanwhile,
will run a few degrees above normal in the mid-70s with the
exception of cooler temperatures in the mountains.

RW

&&

.AVIATION...
18Z Update...
VFR conditions will continue through the forecast. Convection will
be scattered today with most of the development across north GA.
Cu will dissipate this evening but redevelop again and a little
more numerous Sunday afternoon. Winds will be light southwest
through the forecast.

//ATL Confidence...18Z Update...
High on all elements.

17

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          97  74  94  74 /  30  20  40  30
Atlanta         94  75  92  74 /  30  20  40  30
Blairsville     89  69  88  68 /  30  20  50  50
Cartersville    94  73  92  73 /  30  20  40  40
Columbus        97  76  93  75 /  30  20  40  30
Gainesville     92  74  91  73 /  30  20  40  30
Macon           97  74  95  75 /  30  20  40  20
Rome            96  74  93  74 /  30  20  50  40
Peachtree City  93  73  92  73 /  30  20  40  30
Vidalia         95  74  94  75 /  30  20  40  20

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 6 PM EDT this evening for the following
zones: Baldwin...Bibb...Bleckley...Chattahoochee...Crawford...
Crisp...Dodge...Dooly...Emanuel...Harris...Houston...Jefferson...
Johnson...Jones...Laurens...Macon...Marion...Monroe...
Montgomery...Muscogee...Peach...Pulaski...Schley...Stewart...
Sumter...Talbot...Taylor...Telfair...Toombs...Treutlen...
Twiggs...Upson...Washington...Webster...Wheeler...Wilcox...
Wilkinson.

&&

SHORT TERM...17
LONG TERM....Baker
AVIATION...17
Hazardous weather outlook, Jul 22, 1:05 PM EDT, 1 hour 15 minutes before
Hazardous Weather Outlook
National Weather Service Peachtree City GA
105 PM EDT Sat Jul 22 2017

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-231715-
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-
105 PM EDT Sat Jul 22 2017

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

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

Scattered showers and thunderstorms are expected across north and
central Georgia this afternoon and evening. A couple of strong to
severe thunderstorms will be possible. The main hazards with any
storms that develop will be strong gusty winds, heavy rainfall,
frequent lightning, and small hail.

Additionally, heat index values will be over 100 degrees for much
of north and central Georgia this afternoon and evening, with heat
index values from 105 to 108 degrees expected in much of central
Georgia. A Heat Advisory continues for areas along and south of a
Hamilton to Forsyth to Louisville line until 6 PM.

.DAYS TWO THROUGH SEVEN...Sunday through Friday...

Scattered thunderstorms are possible Sunday through Friday,
primarily in the afternoon and evening. Some strong to isolated
severe thunderstorms are possible each day.

In addition, heat index values in the 100 to 105 degree range
will again be possible for much of north and central Georgia on
Sunday.

.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.

In the hours before

Special weather statement, Jul 22, 2:20 PM EDT, 0 minutes before
Special Weather Statement
National Weather Service Peachtree City GA
220 PM EDT SAT JUL 22 2017

GAZ032-033-043-044-221900-
North Fulton GA-Douglas GA-Cobb GA-South Fulton GA-
220 PM EDT SAT JUL 22 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTH FULTON...NORTHEASTERN
DOUGLAS...SOUTHERN COBB AND NORTHERN SOUTH FULTON COUNTIES UNTIL 300
PM EDT...

At 219 PM EDT...a strong thunderstorm was over Jim R Miller Park,
moving southwest at 10 mph.

  HAZARD...40 mph wind, pea sized hail, frequent lightning 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
Atlanta, Marietta, Douglasville, Smyrna, Powder Springs, Austell,
Lithia Springs, Fair Oaks, Sweetwater Creek State Park, Vinings, Jim
R Miller Park, Six Flags Over Georgia, Dobbins Air Reserve Base and
Mableton.

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 3397 8457 3389 8444 3371 8455 3375 8469
      3386 8473 3387 8472
TIME...MOT...LOC 1819Z 037DEG 10KT 3389 8455

HAIL...0.75IN
WIND...50MPH

The office that day

Everything else NWS Atlanta, GA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 21, 8:17 PM EDTSpecial Weather StatementFFCJones28 min
Jul 22, 2:53 PM EDTSpecial Weather StatementFFCPaulding52 min
Jul 22, 3:48 PM EDTSpecial Weather StatementFFCClayton42 min
Jul 22, 3:55 PM EDTSpecial Weather StatementFFCHeard50 min
Jul 22, 4:23 PM EDTSpecial Weather StatementFFCFayette52 min
Jul 22, 4:41 PM EDTSpecial Weather StatementFFCCoweta49 min
Jul 22, 4:57 PM EDTSpecial Weather StatementFFCForsyth48 min
Jul 22, 5:03 PM EDTSpecial Weather StatementFFCButts42 min
Jul 22, 6:14 PM EDTSpecial Weather StatementFFCButts, Lamar, Spalding46 min
Jul 22, 6:23 PM EDTSpecial Weather StatementFFCLumpkin, White37 min
Jul 22, 6:52 PM EDTSpecial Weather StatementFFCLumpkin, White38 min
Jul 22, 6:54 PM EDTSpecial Weather StatementFFCPike, Spalding51 min

Nearby

Special Weather Statements in Georgia, 2017Every special weather statement in 2017

Sources

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.