Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 260537
AFDFFC

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1237 AM EST MON JAN 26 2015


.UPDATE...
/ISSUED AT 940 PM EST SUN JAN 25 2015/
HAVE UPDATED FORECAST TO BRING RAIN FARTHER SOUTH INTO WESTERN GA...AND ALSO
EXTENDED THE MENTION OF ISOLATED THUNDER INTO THOSE ZONES UNTIL AROUND 05Z.
NO CHANGES TO THE OVERNIGHT PERIOD.

41


.PREVIOUS...
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...

NO SIGNIFICANT CHANGES TO THE COMPLEX SHORT TERM FORECAST. LATEST
MODEL RUNS CONTINUE TO BE IN GOOD AGREEMENT WITH THE TRACK AND
TIMING OF STRONG UPPER TROUGH TRACKING ACROSS THE AREA TONIGHT
THROUGH EARLY MONDAY. THE MAIN CONCERNS WILL BE THE POTENTIAL FOR
WINTRY PRECIP ACROSS NORTH GEORGIA DUE TO THE COLD CORE AND STRONG
UPPER LEVEL FORCING. ALTHOUGH PORTIONS OF NORTH GEORGIA ARE
EXPECTING TO SEE 0.5-1.0 INCH OF SNOW WITH LOCALLY HIGHER AMOUNTS
/LARGELY IN THE HIGHER ELEVATIONS/ OTHER PORTIONS OF NORTH
GEORGIA WILL BE TOO WARM TO PROMOTE ANY ACCUMULATIONS.

AT THIS TIME...THE ONSET OF THE PRECIPITATION HAS NOT CHANGED
SIGNIFICANTLY. STILL ANTICIPATE LIGHT RAIN TO PUSH INTO NW GA THIS
EVENING...SPREADING EASTWARD ACROSS NORTH GEORGIA. ANTICIPATE THE
TRANSITION TO A RAIN-SNOW MIX TO OCCUR EARLY MONDAY MORNING. HIGHER
ELEVATIONS ARE EXPECTED TO SEE THE ADDITIONAL TRANSITION TO ALL SNOW
MONDAY MORNING. ANY ACCUMULATIONS WILL LIKELY BE IN AREAS ABOVE 1500
FEET AND GENERALLY 0.5 TO 1 INCH OR LESS. SOME PORTIONS OF THE
NORTHEAST GEORGIA MOUNTAINS COULD SEE HIGHER AMOUNTS. ALTHOUGH THE
PRECIP WILL EXIT NW GEORGIA BY MID MORNING MONDAY...RESIDUAL
MOISTURE REMAINS ACROSS NORTHEAST GEORGIA THROUGH THE DAY...TAPERING
OFF TO SPRINKLES OR FLURRIES BY MONDAY AFTERNOON. THERE IS A CHANCE
OF ANOTHER SHOT OF PRECIPITATION INTO TUESDAY MORNING...WHICH IS
DISCUSSED MORE IN THE LONG TERM DISCUSSION BELOW.

HAVE GONE AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR THE
EXPECTED SNOWFALL FOR THE NORTHERN TWO TIERS OF COUNTIES IN THE CWA.
THE ADVISORY MEANS THAT ACCUMULATIONS WILL BE BELOW WARNING CRITERIA
/OR BELOW 2 INCHES/ BUT THAT INCONVENIENCES ARE ANTICIPATED. FOR
NOW...THE METRO ATL AREA IS EXPECTED TO REMAIN IN THE MID TO UPPER
30S...IF NOT A DEGREE OR TWO WARMER...AND ALTHOUGH A TRANSITION FROM
RAIN TO A WINTRY MIX EARLY MONDAY MORNING IS EXPECTED /PARTICULARLY
ACROSS THE NORTHERN AND WESTERN SUBURBS/...NO ACCUMULATIONS ARE
EXPECTED.

GRADUAL CLEARING IS EXPECTED THROUGH MONDAY...THOUGH RESIDUAL
MOISTURE WILL CONTINUE TO IMPACT THE FAR NORTHERN COUNTIES INTO
TUESDAY.

AND ON AN ENTIRELY DIFFERENT NOTE...HAVE ADDED SLIGHT CHANCE THUNDER
TO THE GRIDS THROUGH LATE EVENING TONIGHT FOR PORTIONS OF FAR NORTH
GEORGIA. MODELS HAVE JUST ENOUGH INSTABILITY /100-200 J/KG/ THAT AN
ISOLATED THUNDERSTORM CAN NOT BE RULED OUT. EXPECT ANY THUNDERSTORM
POTENTIAL TO DIMINISH INTO THE OVERNIGHT HOURS AND HAVE NOT
CONTINUED THE THUNDER MENTION BEYOND 03Z. DO NOT ANTICIPATE ANY
STRONG OR SEVERE STORMS AT THIS TIME.

31


.LONG TERM /TUESDAY THROUGH SATURDAY/...

MAIN CHANGE FROM THIS TIME YESTERDAY HAS BEEN THE DEVELOPMENT OF A
SECONDARY TROUGH TO MOVE THROUGH...THE RESULT OF A LOBE OF UPPER
LEVEL ENERGY THAT ROTATES INTO NORTH GEORGIA. INDICATIONS ARE THAT
THIS COULD RESULT IN ADDITIONAL SNOW SHOWERS ACROSS FAR NORTH
GEORGIA THAT WOULD NOT BE LIMITED TO JUST THE MOUNTAINS AS
PROFILES ARE MORE THAN COLD ENOUGH TO SUPPORT SNOW. QPF HOWEVER IS
VERY MEAGER WITH THIS SYSTEM AND JUST NOT SEEING ANY ACCUMULATIONS
PAST 12Z TUE. MORE CONCERNING WILL BE RESIDUAL MOISTURE ON ROADS
AND THE QUICK TRANSITION TO BELOW FREEZING TEMPS. ELEVATED WINDS
WILL HELP IN THE DRYING PROCESS BUT CONTINUED LOW CLOUDS WILL
NOT...NOT TO MENTION ANY RESIDUAL PRECIPITATION AS WELL. MAY BE
THAT A TIER OF COUNTIES WILL NEED TO BE ADDED TO CURRENT ADVISORY
EVENTUALLY FOR BLACK ICE POTENTIAL AND THAT OVERALL ADVISORY IS
EXTENDED IN TIME THROUGH TUESDAY MORNING.

OTHERWISE...LIMITED CHANGES TO THE EXTENDED WITH CONTINUED
ADVERTISEMENT OF LIGHT RAIN/SNOW OVER THE NORTHERN TIER ONCE AGAIN
ON THU NIGHT.

DEESE


&&

.PREV DISCUSSION... /ISSUED 139 PM EST SUN JAN 25 2015/

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...

OTHERWISE ACTIVE PATTERN CONTINUES THROUGH REST OF LONG TERM WITH
SEVERAL OTHER SHORTWAVE DISTURBANCES TRAVERSING ALONG THE STUBBORN
BROAD UPPER TROUGH THAT JUST CANNOT SEEM TO SHAKE THE EAST CONUS.
HOWEVER...LARGE DISCREPANCIES EXIST IN THE MODELS WITH TIMING AND
AMPLITUDE OF DISTURBANCES. THE NEXT BEST CHANCE OF PRECIP FOR NOW
LOOKS TO BE THURSDAY INTO THURSDAY NIGHT...THEN AGAIN LATE SATURDAY.
THE THURSDAY SYSTEM LOOKS TO BE A BIT BETTER ORGANIZED AND MORE OF A
CLIPPER SYSTEM /ECMWF MUCH MORE BULLISH AND LESS PROGRESSIVE THAN
THE GFS/...WHILE THE SATURDAY NIGHT IMPULSE HAS MUCH LESS AMPLITUDE
AND MORE OF A TRAILING COLD FRONT INTO THE NORTH. COLUMN TEMPS BOTH
PERIODS SUPPORT POSSIBLE SNOW MIXING INTO THE FAR NORTH SO HAVE
INCLUDED LOW CHANCE MENTION AT THE MOMENT. CONFIDENCE IS VERY LOW AT
THE MOMENT AND FUTURE CHANGES ARE LIKELY DUE TO THE AFOREMENTIONED
DIFFERENCES SEEN IN THE SOLUTIONS. PLEASE CONTINUE TO CLOSELY
MONITOR THE FORECAST.

BAKER

&&

.AVIATION...
06Z UPDATE...
EXPECT PREVAILING VFR CIGS WITH A TEMPO MVFR CIGS THRU 09Z... THEN
MVFR CIGS ARE EXPECTED TO SETTLE IN THRU THE REST OF THE MORNING.
PATCHES OF -RA WILL OCCASIONALLY MOVE ACROSS THE TAF SITES THIS
MORNING... BUT NO VSBY RESTRICTIONS ARE EXPECTED. IN THE NORTH
ATLANTA TAF SITES...MIXED WINTRY PRECIP MAY BE POSSIBLE BETWEEN 10-
14Z THIS MORNING... BUT NO ACCUMULATIONS OR IMPACTS TO AVIATION ARE
EXPECTED AS THE LOWEST 2-3KFT OF THE ATMOSPHERE WILL BE ABOVE
FREEZING. EXPECT IMPROVEMENT TO VFR CIGS BY 18Z... THEN VFR
CONDITIONS PREVAIL THRU REST OF TAF PERIOD. CURRENT WSW WINDS 5-8KTS
WILL SHIFT NW BY 09-10Z THIS MORNING... THEN INCREASE TO AROUND 12-
15KTS WITH GUSTS TO 20-25KT BY 14-15Z THIS MORNING.

//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON MVFR CIGS AND MIXED PRECIPITATION.
MEDIUM TO HIGH ON REMAINING ELEMENTS.

39

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          57  38  51  32 /  10  20  20   5
ATLANTA         56  40  47  33 /  10  30  20   5
BLAIRSVILLE     51  36  41  27 /  30  60  40  20
CARTERSVILLE    57  37  45  30 /  30  50  20   5
COLUMBUS        60  41  51  34 /   5  10  10   0
GAINESVILLE     53  38  46  31 /  20  40  40  10
MACON           60  40  53  32 /   5  10  10   0
ROME            56  37  44  29 /  40  50  20   5
PEACHTREE CITY  58  37  48  29 /   5  30  10   0
VIDALIA         61  42  55  36 /   5  10  10   0

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 AM TO 7 PM EST MONDAY FOR THE
FOLLOWING ZONES: CATOOSA...CHATTOOGA...DADE...DAWSON...FANNIN...
GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...
WALKER...WHITE...WHITFIELD.

&&

$$

SHORT TERM...41/39
LONG TERM....DEESE
AVIATION...39


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