921
FXUS62 KFFC 201717
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1217 PM EST WED FEB 20 2019
UPDATE
A FLASH FLOOD WATCH HAS BEEN ISSUED FOR MOST OF NORTH GEORGIA,
INCLUDING THE ATLANTA METRO AREA, REPLACING THE PREVIOUSLY ISSUED
AREAL FLOOD WATCH. A LINE OF STORMS IS EXPECTED TO MOVE THROUGH
THE AREA LATER THIS AFTERNOON AND EVENING WHICH COULD BRING
BETWEEN 1 TO 3 INCHES OF RAINFALL IN A SHORT AMOUNT OF TIME, AN
INCREASE FROM PREVIOUS ESTIMATES. LOCALLY HIGHER AMOUNTS WILL ALSO
BE POSSIBLE WHERE TRAINING OCCURS. GIVEN PREVIOUS ACCUMULATIONS
AND SATURATED GROUNDS, THIS AMOUNT OF RAINFALL WILL PRODUCE
SIGNIFICANT RUNOFF AND FLOODING OF CREEKS AND RIVERS, AS WELL AS
EXTENSIVE STREET FLOODING AND ROAD PONDING.
THIEM
PREV DISCUSSION
/ISSUED 346 AM EST WED FEB 20 2019/
SHORT TERM /TODAY THROUGH THURSDAY/...
NO MAJOR CHANGES TO THE OVERALL PATTERN AS MODELS CONTINUE IN GOOD
AGREEMENT THROUGH THE SHORT TERM. THE SOUTHWEST FLOW ALOFT WILL
CONTINUE TO BRING ABUNDANT GULF MOISTURE OVER THE CWA. THE MAIN
FOCUSING MECHANISM TODAY WILL BE UPGLIDE ALONG A WARM FRONT THAT
WILL PUSH ACROSS NORTH GEORGIA THIS AFTERNOON AND EVENING. UNTIL
THEN, LOW CLOUDS, DRIZZLE AND INTERMITTENT RAIN WILL CONTINUE ACROSS
NORTH GEORGIA THROUGH THIS EVENING. THE HIGH WINDS EXPERIENCED
EARLIER ARE DIMINISHING AND THE WIND ADVISORY WILL BE ALLOWED TO
EXPIRE AT 12Z TODAY.
AS THE WARM FRONT PUSHES NORTHEAST THIS AFTERNOON AND EVENING, THE
ATMOSPHERE WILL DESTABILIZE ENOUGH TO ALLOW MUCAPES OF 500-800 TO
SPREAD ACROSS THE CWA. THIS WILL BE ENOUGH FOR ISOLATED TSRA
DEVELOPMENT THIS AFTERNOON AND TONIGHT.
A COLD FRONT WILL MOVE INTO THE NORTH GEORGIA THURSDAY.
GFS/NAM/ECMWF WANT TO PUSH IT THROUGH MOST OF THE CWA BY 00Z FRI.
WITH A PARALLEL FLOW ALOFT, THE FRONT MAY NOT BE ABLE TO MAKE IT
THROUGH THE CWA. SOME OF THE HI-RES MODELS KEEP THE FRONT ACROSS
NORTH GA THURSDAY AND THEN LIFT IT NORTH INTO TENNESSEE LATE
THURSDAY AFTERNOON. DUE TO THE UNCERTAINTY, WILL CONTINUE WITH THE
BEST CHANCES OF SHOWERS/ISOLATED TSRA ACROSS NORTH GA.
QPF VALUES BY MODELS AND WPC HAVE COME DOWN A LITTLE, BUT AT THIS
TIME DO NOT WANT TO MAKE ANY CHANGES TO THE CURRENT WATCH TIMING AND
CONFIGURATION AS THIS IS A PROLONGED EVENT.
17
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM PERIOD BEGINS WITH A FRONT STALLED IN THE VICINITY AS
MULTIPLE WAVES OF PRECIPITATION IMPACT THE AREA. AS SUCH HAVE KEPT
LIKELY TO CATEGORICAL POPS ACROSS NORTHERN GEORGIA THROUGH SATURDAY.
AS HIGH PRESSURE MOVES OFF THE EAST COAST AND NOSES DOWN THE
APPALACHIANS, A WEDGE BUILDS IN ON FRIDAY AND LOOKS TO REMAIN UNTIL
SATURDAY. THIS WILL HELP TO ENHANCE PRECIPITATION ACROSS THE AREA.
CONTINUOUS HIGH PWS AND INSTABILITY WILL RESULT IN PERIODS OF
THUNDERSTORMS AND HEAVY RAINFALL ACROSS THE AREA THROUGH SATURDAY.
WITH MULTIPLE RIVERS ACROSS NORTHERN GEORGIA ALREADY IN FLOOD,
CONCERNS FOR RIVER FLOODING AND FLASH FLOODING WILL CONTINUE AS
THESE ROUNDS OF PRECIPITATION IMPACT THE AREA, ESPECIALLY ACROSS
PORTIONS OF NORTHERN GEORGIA. THE FLOOD WATCH REMAINS IN EFFECT
THROUGH SATURDAY MORNING. MAKE SURE TO STAY UPDATED TO THE FORECAST
FOR ANY CHANGES TO THE WATCH.
THE NEXT SYSTEM IS FORECAST TO IMPACT THE AREA LATE SATURDAY INTO
SUNDAY AS A SURFACE LOW DEVELOPS ACROSS THE MIDWEST AND PUSHES A
COLD FRONT THROUGH THE STATE ON SUNDAY. PW'S REMAIN HIGH SO PERIODS
OF HEAVY RAINFALL MAY BE POSSIBLE. OVERALL, INSTABILITY ISN'T AS
IMPRESSIVE AS PREVIOUS SHIFTS, BUT CHANCES FOR THUNDER REMAIN IN THE
FORECAST. THE GOOD NEWS IS WE SHOULD SEE SOME DRIER WEATHER ON
MONDAY BEFORE CHANCES FOR RAIN RETURN ON TUESDAY.
TEMPERATURES THROUGH THE WEEKEND ARE EXPECTED TO BE MOSTLY ABOVE
AVERAGE IN THE 60S AND 70S, ASIDE FROM THOSE WITHIN THE WEDGE WHERE
HIGHS ARE EXPECTED TO BE CLOSER TO THE 50S. AFTER THE WEEKEND
SYSTEM, HIGH TEMPERATURES ARE EXPECTED TO BE CLOSER TO SEASONAL
NORMS.
REAVES
AVIATION...
12Z UPDATE...
A MIX OF IFR/LIFR CIGS WILL CONTINUE THROUGH THE FORECAST. WINDS
WILL BE EASTERLY WITH A FEW GUSTS EARLY THIS MORNING. WINDS WILL
BECOME SOUTH TO SOUTHWEST TONIGHT AS THE WARM FRONT LIFTS NORTH OF
ATL/AHN. BEST CHANCES OF RAIN WILL BE NORTH OF ATL/AHN, HOWEVER
AS THE COLD FRONT APPROACHES TONIGHT, CHANCES OF RAIN WILL
INCREASE. THERE IS A RISK OF TSRA THIS AFTERNOON AND TONIGHT,
HOWEVER RISK IS TOO LOW TO MENTION IN THE TAF.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE.
17
PRELIMINARY POINT TEMPS/POPS
ATHENS 47 46 62 54 / 50 60 60 70
ATLANTA 51 50 64 55 / 50 70 60 60
BLAIRSVILLE 48 46 59 51 / 70 80 80 70
CARTERSVILLE 52 50 60 52 / 60 80 70 70
COLUMBUS 65 60 76 62 / 40 50 50 60
GAINESVILLE 45 44 60 53 / 60 80 70 70
MACON 60 57 77 61 / 30 30 50 50
ROME 53 50 58 51 / 80 90 70 70
PEACHTREE CITY 56 53 68 56 / 40 60 60 60
VIDALIA 67 61 80 63 / 30 10 30 30
FFC WATCHES/WARNINGS/ADVISORIES
FLASH FLOOD WATCH THROUGH THURSDAY EVENING FOR THE FOLLOWING
ZONES: BANKS...BARROW...BARTOW...CARROLL...CATOOSA...CHATTOOGA...
CHEROKEE...CLAYTON...COBB...COWETA...DADE...DAWSON...DEKALB...
DOUGLAS...FANNIN...FAYETTE...FLOYD...FORSYTH...GILMER...GORDON...
GWINNETT...HALL...HARALSON...HEARD...JACKSON...LUMPKIN...
MURRAY...NORTH FULTON...PAULDING...PICKENS...POLK...SOUTH
FULTON...TOWNS...UNION...WALKER...WHITE...WHITFIELD.
SHORT TERM...KING
LONG TERM....THIEM
AVIATION...KING
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