Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED FOR AVIATION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
137 PM EDT SUN JUL 20 2014

.LATE MORNING UPDATE...
/ISSUED AT 1115 AM EDT SUN JUL 20 2014/
LATEST SURFACE ANALYSIS SHOWS A WARM FRONT JUST NORTH OF A LA GRANGE
TO SANDERSVILLE LINE... WITH A UNSEASONABLE COOL/CLOUDY WEDGE OF
HIGH PRESSURE NOSING IN OVER MUCH OF NORTH GA FROM THE NE. IN THE
UPPER LEVELS... WATER VAPOR IMAGERY AND SREF DATA SHOW A VORT MAX
PUSHING EAST OF THE LOWER MS VALLEY. MODELS AGREE THE WARM FRONT
WILL LIFT JUST NORTH OF ATLANTA THIS AFTERNOON AS THE UPPER
DISTURBANCE APPROACHES DURING MAX HEATING. A MODIFIED MORNING
SOUNDING FOR HIGHS IN THE LOWER 80S SHOW POSSIBLY CAPE VALUES IN THE
2500-2800 J/KG RANGE LATER THIS AFTERNOON. THIS COUPLED WITH 1.7
PW'S DOES SUGGEST AT LEAST NUMEROUS SHOWERS WITH SCATTERED EMBEDDED
THUNDERSTORMS ALONG AND SOUTH OF THE FRONT THIS AFTERNOON AND EARLY
EVENING. STILL NOT EXPECTING SEVERE AS WIND SHEAR IS WEAK WITH SUCH
A WEAK GRADIENT PREVAILING. LOCALLY HEAVY RAIN CONTINUES TO BE THE
MAIN THREAT TODAY. HAVE UPDATED ZONES TO SHOW LIKELY POPS WITH A
CHANCE OF THUNDERSTORMS UP INTO THE ATLANTA AREA THIS AFTERNOON...
AND WARMED UP DAYTIME HIGHS A WEE BIT FOR TODAY. OTHERWISE... REST
OF FORECAST IS ON TRACK AT THIS TIME. /39

.PREV DISCUSSION... /ISSUED 435 AM EDT SUN JUL 20 2014/

SHORT TERM /TODAY THROUGH MONDAY/...
SHORT TERM MODELS IN GOOD AGREEMENT OVERALL...WITH SOME
DISCREPANCIES NOTED.  THE UPPER LEVEL TROUGH CONTINUES OVER THE
EASTERN U.S. WITH A RIDGE BUILDING OVER THE DESERT SOUTHWEST BY
LATER TODAY.  AS RIDGE BUILDS A SHORT WAVE MOVING ACROSS THE
MISSISSIPPI VALLEY DEEPENS AS IT APPROACHES NORTHWEST GEORGIA
TONIGHT.  NAM IS SHOWING A CLOSED LOW OVER WEST GEORGIA BY MONDAY
AFTERNOON...HOWEVER GFS/ECMWF IN AGREEMENT WITH A SHARP TROUGH.
HAVE LEANED MORE TOWARD THE GFS/ECMWF SOLUTION FOR THIS PACKAGE. AT
THE SURFACE...THE FRONT LIFTS NORTH TODAY...HOWEVER ANOTHER WEAK
SURFACE TROUGH REMAINS ACROSS SOUTHERN PORTIONS OF FORECAST AREA
KEEPING THE OVERALL WET PATTERN WHERE BETTER INSTABILITY AND SHEAR
ARE LOCATED. EXPECT THUNDERSTORMS TO BE MAINLY DIURNALLY DRIVEN AND
ISOLATED IN COVERAGE ALTHOUGH THEY MAY BE MORE SCATTERED OVER
CENTRAL GEORGIA. EASTERLY FLOW ASSOCIATED WITH DAMMING ALONG THE
APPALACHIANS WILL CONTINUE ACROSS MUCH OF NORTH GEORGIA THROUGH THIS
AFTERNOON WHEN WINDS WILL BEGIN SHIFTING OUT OF THE SOUTH AND
SOUTHWEST AS THE SURFACE LOW APPROACHES WEST CENTRAL GA...ECMWF/GFS
LEAN TOWARD EASTERLY WINDS OVERNIGHT AS DAMMING SETS UP ONCE AGAIN.
COOL EASTERLY FLOW WILL KEEP LOW CLOUDS AROUND THROUGH MID-MORNING
ESPECIALLY ALONG A ATL-AHN LINE TODAY AND OVER NORTHEAST GA
TOMORROW. GUIDANCE TEMPERATURES ARE IN LINE AND HAVE NOT STRAYED TOO
FAR...BASED UPON YESTERDAY HAVE GONE WARMER THAN GUIDANCE AT
CSG/MCN.

ATWELL

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
WET AND ACTIVE PERIOD CONTINUES INTO THE EXTENDED PERIODS. HIGH
PRESSURE RIDGE BUILDING INTO THE CENTRAL U.S. STOPS SHORT OF THE
MISSISSIPPI RIVER...LEAVING THE SOUTHEAST TO BE INFLUENCED BY
AMPLE MOISTURE AND REMNANTS OF EARLIER WEEK SYSTEM WHICH A FEW
MODELS DEPICT AS AN UPPER LEVEL LOW. THIS COMBINATION WILL KEEP
HIGHER THAN NORMAL POPS ACROSS THE AREA THROUGH THE FIRST HALF OF
THE WEEK. BY THURSDAY...FRONT PUSHES INTO THE AREA...KEEPING RAIN
CHANCES HIGH. EXTENDED MODELS IN BETTER AGREEMENT WITH PUSHING THE
TROUGH SOUTHWARD...ALLOWING THE FRONT TO PUSH INTO SOUTH GEORGIA
BY LATE FRIDAY. WITH PREVAILING NORTHWEST FLOW ACROSS THE
REGION...EXTENDED MODELS ARE INDICATING A SERIES OF DISTURBANCES
TO IMPACT THE REGION THROUGH NEXT WEEKEND.

HAVE CONTINUED TO HIGHLIGHT THE DAYTIME PERIODS WITH THE BEST
CHANCES FOR SHOWERS AND THUNDERSTORMS WITH THE DIURNAL ENHANCEMENT
OF CONVECTION. FOR NOW...INSTABILITIES ARE HIGH ENOUGH TO WARRANT
STRONG TO POTENTIAL A BRIEF SEVERE THUNDERSTORM EACH
AFTERNOON...BUT ON THE WHOLE THE MAIN CONCERN WILL BE LOCALLY
HEAVY RAIN. MODELED PWS THROUGH THE WEEK ARE AT 1.6 TO 2
INCHES...WELL ABOVE NORMAL. WITH BREAKS ANTICIPATED DURING THE
OVERNIGHT PERIOD...FLASH FLOOD POTENTIAL IS EXPECTED TO BE
ISOLATED/LOCALIZED.

HAVE CONTINUED WITH GENERALLY NORMAL TO SLIGHTLY BELOW NORMAL
TEMPERATURES THROUGH THE EXTENDED...ESPECIALLY WITH HIGHS AS AMPLE
CLOUD COVER AND CONVECTION LIMIT INSOLATION.

31

&&

.AVIATION...
18Z UPDATE...
WARM FRONT JUST SOUTH OF ATL IS STILL EXPECTED TO DRIFT NORTH AND
ALLOW IFR/MVFR CIGS TO IMPROVE THROUGH THE AFTERNOON. THIS WILL
ALLOW CURRENT 6-8KT EASTERLY WINDS TO VEER MORE SSE THROUGH THE
AFTERNOON. AN UPPER DISTURBANCE WILL PRODUCE NUMEROUS SHOWERS WITH
SOME EMBEDDED THUNDERSTORMS THROUGH THE AFTERNOON AND EARLY EVENING.
THE GREATER COVERAGE OF CONVECTION SHOULD BE FROM ATL SOUTHWARD
THROUGH 00Z TODAY. EXPECT IFR CIGS TO SETTLE BACK IN TONIGHT AROUND
07-09Z AS A COOL EASTERLY FLOW SPREADS BACK INTO ATLANTA TAF SITES.
WARM SECTOR SPREADING BACK NORTH WILL ALLOW VFR CIGS BY 16-18Z MON.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM TO HIGH CONFIDENCE IN WINDS.
MEDIUM CONFIDENCE IN VISIBILITY/WEATHER/CIGS

39

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          82  70  85  71 /  60  40  40  40
ATLANTA         84  70  85  72 /  60  30  30  20
BLAIRSVILLE     80  64  80  67 /  50  30  30  30
CARTERSVILLE    80  69  85  71 /  50  20  20  20
COLUMBUS        85  71  88  74 /  60  30  30  20
GAINESVILLE     82  69  82  71 /  50  40  30  40
MACON           86  70  87  72 /  60  40  40  30
ROME            83  69  86  72 /  40  20  20  20
PEACHTREE CITY  84  68  87  72 /  60  30  30  20
VIDALIA         88  72  87  73 /  60  50  50  50

&&

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

SHORT TERM...ATWELL/39
LONG TERM....31
AVIATION...39

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
534 AM EDT SUN JUL 20 2014

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-210945-
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-
534 AM EDT SUN JUL 20 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH AND CENTRAL GEORGIA.

.DAY ONE...TODAY AND TONIGHT...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY AND TONIGHT.

DISCUSSION...

AS STRONG STORM SYSTEM REMAINS ACROSS THE AREA TODAY...WIDESPREAD
SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED. THE MAIN CONCERN
WILL BE LOCALLY HEAVY RAINFALL. SOME OF THE STORMS COULD BRIEFLY
BECOME STRONG...BUT SEVERE THUNDERSTORMS ARE NOT EXPECTED.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

A WET WEEK IS EXPECTED...WITH GENERALLY SCATTERED TO WIDESPREAD
SHOWERS AND THUNDERSTORMS THROUGH SATURDAY. ISOLATED STRONG TO
BRIEFLY SEVERE STORMS CANNOT BE RULED OUT...PARTICULARLY THROUGH
THURSDAY...BUT THE MAIN THREAT WILL CONTINUE TO BE LOCALLY HEAVY
RAINFALL.

.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
1242 PM EDT SUN JUL 20 2014

GAZ066-078-201745-
1242 PM EDT SUN JUL 20 2014

...SIGNIFICANT WEATHER ADVISORY FOR HEAVY RAIN IN TROUP AND HARRIS
COUNTIES UNTIL 145 PM EDT...

AT 1239 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM STATE LINE PARK TO 15 MILES SOUTHWEST OF
WEST POINT...MOVING EAST AT 15 MPH.

RUNOFF FROM THESE STORMS WILL CAUSE MINOR FLOODING OF SMALL CREEKS
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES ACROSS
TROUP AND HARRIS COUNTIES...INCLUDING AREAS AROUND STATE LINE PARK...
WEST POINT...PIEDMONT HEIGHTS...ABBOTTSFORD...LONG CANE...
CANNONVILLE...WARES CROSSROADS...HILLCREST...JONES CROSSROADS...
SMITHS CROSSROAD...BAUGHS CROSSROADS...LAGRANGE...WHITESVILLE-PINE
LAKE...HARRISONVILLE AND LAKE HARDING. ADDITIONALLY...COUNTRY ROADS
AND FARMLANDS ALONG THE BANKS OF CREEKS AND STREAMS ARE SUBJECT TO
MINOR FLOODING.

SIGNIFICANT WEATHER ADVISORIES ARE ISSUED FOR WINDS UP TO 50
MPH...HAIL LESS THAN THE SIZE OF QUARTERS...SIGNIFICANT
CLOUD-TO-GROUND LIGHTNING...OR HEAVY RAIN.

&&

LAT...LON 3320 8498 3286 8496 3267 8510 3269 8512
      3273 8512 3275 8515 3278 8513 3281 8517
      3283 8517 3284 8516 3287 8519 3311 8524
TIME...MOT...LOC 1642Z 270DEG 13KT 3304 8523 3286 8522
          3274 8537

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
145 PM EDT SUN JUL 20 2014

GAZ066-078-201830-
145 PM EDT SUN JUL 20 2014

...SIGNIFICANT WEATHER ADVISORY FOR HEAVY RAIN IN TROUP AND HARRIS
COUNTIES UNTIL 230 PM EDT...

AT 142 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER WEST POINT...MOVING NORTHEAST AT 10 MPH.

RUNOFF FROM THESE STORMS WILL CAUSE MINOR FLOODING OF SMALL CREEKS
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES ACROSS
TROUP AND HARRIS COUNTIES...INCLUDING AREAS AROUND WEST POINT...
WHITESVILLE-PINE LAKE...LONG CANE...CANNONVILLE...JONES CROSSROADS...
BAUGHS CROSSROADS...BIG SPRINGS...HILLCREST...WARES CROSSROADS...
LAGRANGE AND SMITHS CROSSROAD. ADDITIONALLY...COUNTRY ROADS AND
FARMLANDS ALONG THE BANKS OF CREEKS AND STREAMS ARE SUBJECT TO MINOR
FLOODING.

SIGNIFICANT WEATHER ADVISORIES ARE ISSUED FOR WINDS UP TO 50
MPH...HAIL LESS THAN THE SIZE OF QUARTERS...SIGNIFICANT
CLOUD-TO-GROUND LIGHTNING...OR HEAVY RAIN.

&&

LAT...LON 3314 8504 3297 8486 3294 8486 3271 8512
      3273 8512 3275 8515 3278 8513 3281 8517
      3283 8517 3284 8516 3287 8519 3295 8521
TIME...MOT...LOC 1745Z 234DEG 10KT 3288 8514

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
234 PM EDT SUN JUL 20 2014

GAZ093-104>106-201915-
234 PM EDT SUN JUL 20 2014

...SIGNIFICANT WEATHER ADVISORY FOR HEAVY RAIN AND LIGHTNING IN
SUMTER...MACON...CRISP AND DOOLY COUNTIES UNTIL 315 PM EDT...

AT 233 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM CLEARVIEW TO COBB...MOVING NORTHEAST AT 25
MPH.

RUNOFF FROM THESE STORMS WILL CAUSE MINOR FLOODING OF SMALL CREEKS
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES ACROSS
SUMTER...MACON...CRISP AND DOOLY COUNTIES...INCLUDING AREAS AROUND
PENNINGTON...LAMAR...COBB...METHVINS...NEW ERA...ANDERSONVILLE...
ANDERSONVILLE NATIONAL HISTORIC SITE...FLINT RIVER WMA...CLEARVIEW...
DRAYTON...MONTEZUMA...OGLETHORPE...WHITEWATER STATE PARK...DOOLING
AND LILLY. ADDITIONALLY...COUNTRY ROADS AND FARMLANDS ALONG THE BANKS
OF CREEKS AND STREAMS ARE SUBJECT TO MINOR FLOODING.

THESE STORMS ARE NOT EXPECTED TO REACH SEVERE THUNDERSTORM
CRITERIA...WHICH IS HAIL THE SIZE OF QUARTERS OR LARGER OR DAMAGING
WIND GUSTS OF 58 MPH OR HIGHER.

&&

LAT...LON 3192 8400 3204 8411 3211 8424 3216 8421
      3216 8419 3221 8418 3251 8400 3251 8398
      3249 8388 3247 8385 3239 8384 3236 8386
      3229 8385 3229 8369 3220 8367
TIME...MOT...LOC 1834Z 213DEG 21KT 3225 8409 3215 8400
          3197 8394