Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 010535
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1235 AM EST SUN MAR 1 2015

.PREV DISCUSSION... /ISSUED 733 PM EST SAT FEB 28 2015/

UPDATE...
UPDATED GRIDS FOR TONIGHT AND SUNDAY MORNING TO USE LATEST RAW
MODEL GUIDANCE. MAV/MET MOS GUIDANCE TOO WARM GIVEN STRONG CAD
EVENT SETTING UP...OFTEN SEE BUSTS OF 5 TO 10 DEGREES IN WEDGE
EVENTS WITH PRECIP FROM SAID GUIDANCE BASED ON NWS/GA TECH STUDY.
SFC WINDS ENE AT 10-15KTS TONIGHT AND PLENTY OF DRY LOW LEVEL AIR
UPSTREAM IN SC PIEDMONT. USED NAM12/GFS/SREF 2M TEMPS AND
DEWPOINTS AND UTILIZED MOST RECENT WPC QPF GUIDANCE WHICH PUTS UP
TO 0.10 INCH ICE IN WEDGE FAVORED AREAS OF NE GA. EXPANDED
FREEZING RAIN ADVISORY TO INCLUDE DAWSON AND HALL COUNTIES WHERE
THE ICE ACCUMS EXPANDED...SOUTHERN HALF OF HALL COUNTY SHOULD BE
FINE...BUT COULD SEE LIGHT ICING IN TREES EVEN IN COUNTIES JUST
OUTSIDE THE ADVISORY.

WILL BE WATCHING OBSERVED TEMPS AND PRECIP CLOSELY TONIGHT SO
FURTHER REFINEMENTS MAY BE POSSIBLE.

SNELSON

PREV DISCUSSION... /ISSUED 300 PM EST SAT FEB 28 2015/

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
SOUTHWEST FLOW ALOFT STREAMING MOISTURE ACROSS THE NORTHERN
GULF IN THE FORM OF MID/HIGH CLOUDS WITH SOME LIGHT RAIN
SPREADING NORTHWARD INTO THE FORECAST AREA THIS AFTERNOON.
STRONG HIGH PRESSURE WAS IN THE PROCESS OF BUILDING DOWN THE
APPALACHIANS AND THIS WEDGE WILL STRENGTHEN ACROSS NORTH AND
CENTRAL GA OVERNIGHT. STRONG FLOW FROM THE SOUTH AND SOUTHWEST WILL
CONTINUE TO OVERRUN THE WEDGE TONIGHT INTO SUNDAY. THIS WILL PRODUCE
LIGHT RAIN AND DRIZZLE OVER MUCH OF THE FORECAST AREA...WITH
HIGHEST POPS OVER THE EASTERN ZONES WHICH SHOULD BE DEEPER INTO THE
WEDGE. LOW CLOUDS AND RAIN COMBINED WITH EASTERLY WINDS SHOULD KEEP
DIURNAL RANGE LOW FOR TONIGHT INTO SUNDAY. HAVE LOWERED MAX
TEMPERATURES SEVERAL DEGREES AREA WIDE FOR TOMORROW. HAVE KEPT THE
FREEZING RAIN ADVISORY IN PLACE FOR THE NORTHEAST. TEMPERATURES AT
OR JUST BELOW FREEZING STILL LOOK POSSIBLE FOR THAT AREA OVERNIGHT.

41

LONG TERM /MONDAY THROUGH SATURDAY/...
ACTIVE PATTERN THROUGH THE EXTENDED IN TERMS OF PRECIPITATION.
FRONT SINKS INTO THE STATE ON MONDAY BUT WEAKENS AS IT MOVES IN.
THE MODELS ARE STILL SHOWING SOME DIFFERENCES IN TERMS OF TIMING
AND LOCATION OF PRECIPITATION WITH THE FRONT...BUT BETTER CHANCES
WILL BE ACROSS NORTH GEORGIA.

MAIN FEATURE OF THE EXTENDED IS A COLD FRONT THAT MOVES INTO THE
STATE MID WEEK. THIS WILL BRING BACK THE CHANCE OF THUNDER IN THE
TUESDAY NIGHT TO WEDNESDAY NIGHT TIME FRAME WITH THE BEST CHANCES
ON WEDNESDAY WITH MUCAPE VALUES NEAR 500 J/KG. THIS WILL BE THE
SYSTEM TO WATCH OVER THE NEXT WEEK FOR STRONG TO SEVERE WEATHER AS
AT ONE POINT...THE BETTER MUCAPE ALIGNS WITH 40KTS OF LOW LEVEL
SHEAR.

FOR WEDNESDAY NIGHT...THE RAIN CONTINUES ACROSS CWA...HOWEVER
TEMPS AROUND OR JUST BELOW FREEZING ARE FORECAST TO MOVE INTO
PARTS OF THE NW FOR THE SECOND HALF OF THE NIGHT. BASED ON GFS
BUFR DATA HAVE INCLUDED MENTION OF FREEZING/RAIN SLEET ACROSS THE
FAR NW ACROSS A VERY SMALL AREA OF THE CWA...BUT WITH CLOUDS AND
PRECIPITATION ALREADY OCCURRING...FORECAST AND MODEL GUIDANCE
TEMPERATURES MAY BE A LITTLE ON THE COOL SIDE. PRECIPITATION
ASSOCIATED WITH THE FRONT SHOULD PUSH OUT BY FRIDAY.

PREVIOUS DISCUSSION FOLLOWS.

11

PREVIOUS LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
WARMER PATTERN SETTING UP ACROSS THE REGION FOR THE MAJORITY OF THE
EXTENDED FORECAST PERIOD WITH PERSISTENT SOUTHWESTERLY UPPER FLOW.
THIS PATTERN ALSO LEANS WETTER. MINOR FOCUS FOR MORE ORGANIZED
PRECIPITATION MONDAY AS A WEAK FRONTAL BOUNDARY SAGS INTO THE STATE
AND WASHES OUT. LITTLE UPPER SUPPORT AND MINIMAL INSTABILITY SO I AM
INCLINED TO REMOVE THE SLIGHT CHANCE FOR THUNDER WE CURRENTLY HAVE
FOR THE DAYTIME PERIOD MONDAY. BETTER CHANCES FOR THUNDER WEDNESDAY
INTO WEDNESDAY NIGHT AS A MUCH STRONGER FRONT SWEEPS INTO THE STATE
AHEAD OF A FAIRLY STRONG SHORT WAVE. INSTABILITY IS NOTICEABLY
BETTER WITH THIS SYSTEM...AND WITH A STRONG LOW-LEVEL JET PROGGED
ACROSS THE SOUTHEASTERN U.S. WE WILL NEED TO KEEP AN EYE OUT FOR
POSSIBLE SEVERE WEATHER WITH THIS SYSTEM. COOLER WEATHER FILLS IN
BEHIND THIS SYSTEM HEADING INTO NEXT WEEKEND...BUT FLATTENING UPPER
PATTERN SHUNTS THE BEST COLD AIR EAST WELL NORTH OF THE STATE.

20

&&

.AVIATION...
06Z UPDATE...
LATEST PLOT OF FLIGHT CATEGORIES ACROSS THE AREA SHOWS IFR ACROSS
MOST OF SOUTH GEORGIA MOVING INTO THE CSG AND MCN PORTIONS OF
MIDDLE GEORGIA WITH ALL MVFR TO THE NORTH OF THIS. ALONG WITH THE
IFR IS A GOOD DEAL OF -RA AND DZ ACROSS THE AREA. ALL THIS
ACTIVITY WILL SHIFT NORTH TO AFFECT THE ATL TERMINALS LATER THIS
MORNING. EXPECTING LIFR TO IFR FOR MOST ALL OF THE DAY NOW AS
LATEST GUIDANCE A LITTLE MORE PESSIMISTIC ON IMPROVEMENT. COULD BE
A BRIEF IMPROVEMENT LATE THIS EVENING AS EDGE ERODES AND NEXT
FRONT APPROACHES BUT PROSPECTS FOR THIS IMPROVEMENT LOOK LOW.
ADDITIONAL LOW CLOUD FOR SUN NIGHT WITH MORE CHANCE OF SEEING
REDUCED VSBY AS WELL WITH SOME GUIDANCE INDICATING VLIFR POSSIBLE.
WILL HOLD TAFS AT LIFR FOR NOW AND EVALUATE AGAIN WITH NEXT TAF
SET.

//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON VLIFR POTENTIAL SUN NIGHT.
HIGH ON REMAINING ELEMENTS.

DEESE

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          42  39  63  46 /  70  20  40  50
ATLANTA         45  43  59  48 /  50  40  40  40
BLAIRSVILLE     47  42  54  42 /  60  50  50  50
CARTERSVILLE    46  44  54  45 /  40  50  50  40
COLUMBUS        52  47  66  53 /  40  40  30  30
GAINESVILLE     43  41  58  45 /  60  30  40  50
MACON           47  45  67  52 /  70  20  30  40
ROME            48  44  52  44 /  30  40  50  50
PEACHTREE CITY  48  44  60  48 /  50  40  40  40
VIDALIA         50  49  69  55 /  70  10  20  30

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY UNTIL 8 AM EST THIS MORNING FOR THE
FOLLOWING ZONES: DAWSON...FANNIN...HALL...LUMPKIN...TOWNS...
UNION...WHITE.

&&

$$

SHORT TERM...DEESE
LONG TERM....20
AVIATION...DEESE



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