Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED FOR WATCH
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
113 PM EDT WED JUN 15 2011

.UPDATE FOR WATCH...
A WEAK WARM FRONT WILL DRIFT EASTWARD ACROSS NORTH GA THIS AFTERNOON
AND EARLY EVENING. BEHIND THE WARM FRONT...EXPECT A SURGE OF WARM...
MOIST AND UNSTABLE AIR TO SPREAD OVER THE REGION DURING MAX HEATING.
THIS COUPLED WITH A STRONG UPPER DISTURBANCE WILL BRING A GOOD
CHANCE OF THUNDERSTORMS TO MUCH OF NORTH GA THIS AFTERNOON AND
THROUGH THE EVENING. A FEW OF THESE STORMS COULD BECOME SEVERE...
WITH STRONG DOWNBURST WINDS TO 60 MPH AND LARGE HAIL THE MAIN
THREATS. THE GREATER THREAT OF SEVERE STORMS APPEARS TO BE GENERALLY
ALONG AND NORTH OF A ROME TO JASPER TO HELEN LINE WHERE A SEVERE
THUNDERSTORM WATCH HAS BEEN POSTED UNTIL 8 PM THIS EVENING. ALTHOUGH
THE WATCH AREA HAS THE GREATER POTENTIAL FOR STRONG STORMS... ALL
COUNTIES ACROSS NORTH GA WILL BE VULNERABLE TO ISOLATED
THUNDERSTORMS THROUGH THE EVENING. MODELS SUGGEST SHOWERS WITH
POSSIBLE A FEW EMBEDDED THUNDERSTORMS COULD LINGER ACROSS MUCH OF
NORTH GA OVERNIGHT...BUT THE THREAT OF STRONG TO SEVERE STORMS IS
EXPECTED TO GREATLY DIMINISH BY MID-LATE EVENING WITH LOSS OF
DAYTIME HEATING AND THE STRONGER UPPER DISTURBANCE PUSHING EAST.
/39

&&

.PREV DISCUSSION... /ISSUED 715 AM EDT WED JUN 15 2011/

SHORT TERM /TODAY THROUGH FRIDAY/...
MODELS CONTINUE TO SHOW AN INCREASE IN DEEPER MOISTURE ACROSS MUCH
OF THE COUNTY WARNING AREA THIS AFTERNOON INTO TONIGHT AS A WEAK
FRONTAL BOUNDARY STRETCHING ACROSS SOUTH CENTRAL GEORGIA DRIFTS
NORTHWARD AND A SHORTWAVE MOVES SOUTHEAST FROM THE OH-TN VALLEY
REGION. BEST PRECIP COVERAGE STILL EXPECTED ACROSS NORTH GEORGIA
WHERE BETTER UPPER SUPPORT NOTED...AND WILL CONTINUE GOOD CHANCE
TO LIKELY POPS THERE. STRONG TO SEVERE STORMS POSSIBLE...ESPECIALLY
ACROSS EXTREME NORTHERN COUNTIES WHERE BEST CAPE AND SHEAR VALUES
EXPECTED. STORM PREDICTION CENTER ALSO OUTLOOKING PORTIONS OF THIS
AREA IN SLIGHT RISK OF SEVERE...WITH DAMAGING WINDS AND HAIL BEING
THE MAIN THREATS. BY THURSDAY...BEST UPPER SUPPORT SHIFTS EAST OF
THE STATE BUT WITH REMNANTS OF WEAK BOUNDARY STILL IN THE AREA
SLIGHT CHANCE TO CHANCE POPS STILL SEEM IN ORDER. MODELS SIMILAR
WITH ANOTHER WEAK IMPULSE TRACKING ACROSS THE OH-TN VALLEY REGION
FRIDAY AND WILL HOLD ON TO SLIGHT CHANCE POPS FOR MUCH OF OUR
AREA. TEMPS WILL BE A CHALLENGE. IN SPITE OF INCREASED CLOUD
COVERAGE AND PRECIP CHANCES...WARM TEMPS CONTINUING ESPECIALLY
ACROSS CENTRAL GEORGIA WHERE MID TO UPPER 90S EXPECTED.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
UPPER RIDGE BUILDS BACK ACROSS THE AREA OVER THE WEEKEND...
CONTINUING INTO EARLY NEXT WEEK. LESSENING CHANCES FOR PRECIP AND
WARMER TEMPERATURES WILL BE THE RULE. WILL HOLD ON TO SLIGHT
CHANCE POPS...MAINLY IN THE MOUNTAINS WHERE TERRAIN WILL HAVE
SOME AFFECT.

49

&&

.AVIATION...
/ISSUED AT 715 AM EDT WED JUN 15 2011/
12Z UPDATE...
AGAIN MAIN CONCERN THIS TAF VALID PERIOD WILL BE STRONG CONVECTION
EXPECTED IN THE 20Z-05Z TIME FRAME. STRONG NW FLOW SHORT WAVE
TRAVERSING THE AREA LATE TODAY IMPINGING ON MODERATE SHEAR AND HIGH
INSTABILITY. ACCOMPANYING MCS LIKELY. HAVE LEANED HEAVILY TOWARD THE
WRF CONVECTIVE PROGS...SHOWING LINE OF STRONG-SEVERE TSRA REACHING
ATL AROUND 23Z THEN MOVING TO AHN/MCN BETWEEN 02Z-04Z. GFS/NAM
SLIGHTLY SLOWER...HENCE REASON FOR HOLDING ONTO CONVECTION ACROSS SE
AREAS UNTIL 05Z. IFR VSBY/MVFR CIGS/AND NW WIND GUSTS TO 27KTS WITH
POSSIBLE WITH MCS. NATURE OF ORGANIZED MCS LEADS TO HIGH CONFIDENCE
IN STRONG/GUSTY NW WINDS RATHER THAN VRB WITH TYPICAL PULSE
CONVECTION. NOT EXPECTING MUCH IF ANY PRE-MCS CONVECTION WITH VFR
CIGS/VSBYS PREVAILING PRIOR TO ARRIVAL OF LATE AFTERNOON/EVENING
TSRA. WIND DIR PROBLEMATIC AGAIN TODAY...EVEN LESS DEFINED THAN
PREVIOUS DAYS. NE WINDS THROUGH MID-DAY WILL BECOME VRB...WITH
MODELS PROGGING DIR ANYWHERE FROM SE-NW BY 18Z. OTHER THAN
ATL...HAVE SHOWN VRB AT MID-DAY. FOR ATL...HAVE GONE WITH NAM/GFS
SHOWING SSW-SW BY 18Z. BEHIND CONVECTION...WINDS AGAIN VRB
OVERNIGHT. WIND DIR WILL NEED ADJUSTMENT WITH LATER TAFS.

//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE IN CIG AND VSBY.
HIGH CONFIDENCE IN WIND SPEED.
LOW CONFIDENCE IN WIND DIRECTION THROUGH TAF VALID PERIOD.
HIGH CONFIDENCE IN AFTERNOON/EVENING THUNDERSTORMS AND ASSOCIATED
STRONG/GUSTY NW WINDS.

19

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          92  69  92  68 /  20  30  30  10
ATLANTA         91  72  92  72 /  20  40  20  10
BLAIRSVILLE     83  63  85  61 /  30  60  30  10
CARTERSVILLE    91  66  93  63 /  30  60  20  10
COLUMBUS        96  72  95  72 /  20  30  20  20
GAINESVILLE     89  68  91  68 /  20  50  30  10
MACON           96  70  94  69 /  10  30  20  10
ROME            92  68  95  65 /  30  60  20  10
PEACHTREE CITY  92  66  92  65 /  20  30  20  10
VIDALIA         97  75  95  73 /  10  30  40  20

&&

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

20

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1255 PM EDT WED JUN 15 2011

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-161100-
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-
1255 PM EDT WED JUN 15 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT
SCATTERED SEVERE THUNDERSTORMS EXPECTED ACROSS NORTH AND CENTRAL
GEORGIA LATE THIS AFTERNOON AND TONIGHT.

.SYNOPSIS...
STRENGTHENING NORTHWEST FLOW ALOFT WAS NOTED ACROSS THE REGION AS
A STRONG UPPER-LEVEL DISTURBANCE WAS MOVING FROM THE CENTRAL
PLAINS TOWARD THE TENNESSEE VALLEY. A WEAK WARM FRONT ACROSS SOUTH
GEORGIA WILL DRIFT BACK NORTH INTO NORTH GEORGIA TODAY.

.PRIMARY HAZARDS...
THE PRIMARY HAZARD FROM THUNDERSTORMS THIS AFTERNOON AND TONIGHT
WILL BE DAMAGING WINDS. FREQUENT LIGHTNING CAN ALSO BE EXPECTED.
SOME OF THE THUNDERSTORMS ACROSS NORTH GEORGIA WILL ALSO BE CAPABLE
OF PRODUCING QUARTER-SIZED HAIL. THUNDERSTORMS ARE EXPECTED TO MOVE
INTO NORTHWEST GEORGIA AROUND 1 PM EDT...AND MOVE SOUTHEAST REACHING
ATLANTA AROUND 6 PM EDT AND MACON BY 10 PM EDT. THE MOST LIKELY AREA
FOR SEVERE THUNDERSTORMS WILL BE NORTH OF A LINE FROM CEDARTOWN...TO
ALPHARETTA...TO GAINESVILLE BETWEEN 1 PM AND 10 PM EDT.

.DISCUSSION...
A STRONG SHORT WAVE...EMBEDDED WITHIN WEST-NORTHWEST FLOW
ALOFT...WILL MOVE FROM THE CENTRAL PLAINS TOWARD THE EASTERN
TENNESSEE VALLEY AND MID-ATLANTIC REGION DURING THE NEXT 24 HOURS.
UNUSUALLY STRONG SHEAR FOR MID-JUNE WILL ACCOMPANY THIS SYSTEM. BY
EVENING...35 TO 40 KNOTS OF LOW-LEVEL SHEAR IS EXPECTED TO TRAVERSE
THE NORTHERN SECTION OF THE STATE. WITH HIGH TEMPERATURES AGAIN WELL
INTO THE 90S AND DEWPOINTS RISING INTO THE MID 60S...CAPE VALUES
WILL EXCEED 3000 J/KG ACROSS PARTS OF NORTH CENTRAL AND NORTHWEST
GEORGIA BY LATE AFTERNOON. LIFTED INDICES WILL DROP TO AS LOW AS -8
IN THIS SAME REGION. THIS COMBINATION OF PARAMETERS WILL SUPPORT
SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
SEVERE THUNDERSTORMS WILL REMAIN POSSIBLE ACROSS EAST CENTRAL AND
MIDDLE GEORGIA EARLY THURSDAY...WITH ISOLATED SEVERE THUNDERSTORMS
POSSIBLE ACROSS THE EASTERN SECTIONS OF MIDDLE GEORGIA THURSDAY
AFTERNOON. OTHERWISE...THERE IS A CHANCE OF THUNDERSTORMS EACH DAY
FRIDAY THROUGH TUESDAY...PRIMARILY DURING THE AFTERNOON AND EVENING
HOURS.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS AND EMERGENCY MANAGERS ACROSS NORTH GEORGIA SHOULD BE
PREPARED FOR ACTIVATION AFTER 3 PM EDT...AND ACROSS CENTRAL GEORGIA
AFTER 7 PM EDT TODAY. SPOTTERS CAN ALSO SUBMIT REPORTS OF SEVERE
WEATHER ONLINE AT WEATHER.GOV/ATLANTA.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
126 PM EDT WED JUN 15 2011

GAZ001>003-151815-
126 PM EDT WED JUN 15 2011

...SIGNIFICANT WEATHER ADVISORY FOR 40 MPH WINDS IN WALKER...CATOOSA
AND DADE COUNTIES UNTIL 215 PM EDT...

AT 120 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER LOOKOUT MOUNTAIN...MOVING EAST AT 40 MPH.

WIND GUSTS OF 40 MPH ARE LIKELY AS THIS STORM MOVES ACROSS WALKER...
CATOOSA AND DADE COUNTIES THROUGH 215 PM EDT. SOME LOCATIONS IN THE
PATH OF THE STORM INCLUDE CHATTANOOGA VALLEY...FAIRVIEW...LOOKOUT
MOUNTAIN...WILDWOOD...FORT OGLETHORPE...LAKEVIEW...BOYNTON...INDIAN
SPRINGS...GRAYSVILLE...RINGGOLD AND SALEM.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT. CONTINUE TO MONITOR
NOAA WEATHER RADIO...WEATHER.GOV OR OTHER MEDIA OUTLETS FOR FURTHER
STATEMENTS OR POSSIBLE WARNINGS ON THESE STORMS.

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

&&

LAT...LON 3498 8498 3497 8499 3492 8501 3490 8542
      3499 8543 3499 8498
TIME...MOT...LOC 1725Z 265DEG 33KT 3503 8532