703
FXUS62 KFFC 271950
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
350 PM EDT WED OCT 27 2021
...AFTERNOON AFD: WIND ADVISORY IN EFFECT TOMORROW FOR NORTH
GEORGIA...
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
ENJOY THE BEAUTIFUL WEATHER TODAY WHILE IT LASTS, AS TODAY MIGHT BE
THE LAST FOR THE NEXT FEW FOR A GOOD CHUNK OF THE NORTHERN CWA
WITHOUT CHANCES OF RAIN AND CLOUD COVER. TEMPS ACROSS THE AREA HAVE
MADE IT INTO THE UPPER 60S TO LOWER 70S WITH MOSTLY LIGHT AND
VARIABLE WINDS. THAT ALL CHANGES TONIGHT AS A DYNAMIC SYSTEM
APPROACHES THE AREA. CURRENTLY, SHARP UPPER LEVEL TROUGH IS LOCATED
OVER THE GREAT PLAINS WITH MOISTURE SURGING INTO THE AREA ALL THE
WAY FROM THE GULF INTO FORMING SURFACE CYCLONE AROUND EASTERN OK.
STRONG MCS IS NOTED ALONG THE SOUTHERN END OF THIS SURGE OF MOISTURE
WHERE BETTER MOISTURE AND INSTABILITY RESIDES NEAR THE GULF. THIS
SYSTEM IS SET TO GET A BOOST OF LIFE FROM A POSITIVE PV ANOMALY
ALONG THE DYNAMIC TROPOPAUSE THAT WILL BE DIVING INTO THE TROUGH
TONIGHT. THE RESULT WILL BE A RAPID BOOST TO CYCLOGENESIS AS THE
TROPOPAUSE PV GRADIENT TIGHTENS, CREATES A JET STREAK, AND ALLOWS
THE CURRENT SFC CYCLONE TO CONTINUE DEEPENING THROUGH MASS
DIVERGENCE ALOFT ALONG THE LEFT EXIT REGION.
THE RESULT WILL BE A CONTINUED SURGE IN THE ONGOING MOISTURE PLUME
TOWARDS THE CWA. TIMING HAS SLOWED A LITTLE WITH THE CONVECTIVE
GUIDANCE, SO THE BULK LOOKS TO ARRIVE IN THE MORNING TO EARLY
AFTERNOON HOURS FOR THE CWA. THE GOOD NEWS IS THE SEVERE POTENTIAL
IS STILL LOW. PREVIOUS FRONT HAS SCOURED MOST OF THE MOISTURE AND
LEFT A MOSTLY COOL CONTINENTAL AIRMASS IN PLACE DESPITE SOME AIRMASS
MODIFICATION TODAY. ADDITIONALLY, LARGE SURFACE LOW WILL STILL BE
OFF THE COAST OF NEW ENGLAND TOMORROW MORNING AND FLOW AROUND IT IS
HELPING TO SUSTAIN A WEAK WEDGE OVER A LARGE PORTION OF THE CWA.
FINALLY, WHILE SOME OF THE HI RES GUIDANCE (THE NAM NEST, FOR
INSTANCE) SHOWS SOME MUCAPE, MID-LEVEL LAPSE RATES ARE STILL SMALL
THANKS TO SLOW PROGRESSION OF THE UPPER LEVEL TROUGH WHICH QUICKLY
CUTS OFF, AND ANY CAPE IS ELEVATED ABOVE A SURFACE INVERSION
EVERYWHERE EXCEPT FAR SOUTH CENTRAL GA. SPC CONTINUES TO MAINTAIN A
MARGINAL RISK OVER JUST FAR SOUTH CENTRAL GA AS A RESULT, WITH
GENERAL THUNDER EVERYWHERE ELSE. WON'T RULE OUT SEVERAL RUMBLES OF
THUNDER AND HAVE MAINTAINED AT LEAST SLIGHT CHANCE THUNDER IN THE
GRIDS ACROSS MOST OF THE CWA FOR AT LEAST THE INITIAL SURGE.
SOME WAA AND MOISTURE RETURN WILL STILL BE POSSIBLE AFTER THE
PASSAGE OF THE INITIAL LINE IN THE MORNING TO EARLY AFTERNOON, SO
AREAS IN CENTRAL GEORGIA COULD SEE AN AFTERNOON STORM OR TWO BEFORE
THE MAIN SURGE OF THE COLD FRONT IN THE EVENING. THE HRRR, HIRESFV3,
AND ONE OR TWO OTHER HI-RES HAVE CONSISTENTLY SHOWN AN ISOLATED
STORM OR TWO IN THE AFTERNOON TO EVENING IN THIS AREA. THE OTHER
AREA TO WATCH WILL BE NORTH GA, WHERE ELEVATED MOISTURE WRAPPING
AROUND THE QUICKLY STACKING UPPER AND LOWER LEVEL LOWS MAY BE ABLE
TO SQUEEZE OUT SOME ADDITIONAL RAINFALL AND EVEN A RUMBLE OF THUNDER
OR TWO ON THURSDAY NIGHT. WHERE CLEARING HAPPENS DOWN IN CENTRAL GA,
SOME PATCHY FOG WILL ALSO BE POSSIBLE PROVIDED WINDS COME DOWN
ENOUGH.
THE OTHER STORY WITH THIS SYSTEM IS THE WIND ADVISORY. STRONG LOW-
LEVEL JET WILL BE NOTED WITH THIS MOISTURE SURGE ALONG THE WARM
CONVEYER BELT, AND HI-RES MODELS SHOW 30 KT WINDS DOWN TO EVEN 950
MB, WELL INTO THE INVERSION. FOR THE MOUNTAINS, THIS MEANS WE WILL
LIKELY SEE STRONG WINDS MIXING DOWN EASILY OVER THE TERRAIN,
ALLOWING FOR WIND GUSTS UP TO 45 MPH (AND IT WOULD NOT SURPRISE ME
TO SEE SOMETHING ISOLATED A LITTLE HIGHER). FOR AREAS TO THE SOUTH,
STRONG WIND GUSTS WILL BE POSSIBLE WHERE THEY CAN MIX DOWN, AND
RAINFALL WILL MAKE THAT EASIER. HOWEVER, STILL NOT EXPECTING TO MEET
ADVISORY CRITERIA OF 35 MPH ACROSS A WIDESPREAD AREA TAKING INTO
CONSIDERATION FRICTIONAL EFFECTS, SO HAVE LEFT ADVISORY ALONE. WILL
LET FUTURE SHIFTS CONTINUE TO EVALUATE, AND WILL NOT RULE OUT
EXPANSION STILL. THROUGH THE DAY ON THURSDAY, STRONG WINDS MAY STILL
BE POSSIBLE AS DRY SLOT MOVES IN ALOFT, HENCE WHY WIND ADVISORY
CARRIES THROUGH THE EVENING.
LUSK
LONG TERM /FRIDAY THROUGH WEDNESDAY/
COOL, RAW START TO THE EXTENDED FORECAST PERIOD AS THE LARGE/DEEP
UPPER LOW LINGERS OVER THE REGION THROUGH FRIDAY. LOW STARTS LIFTING
NORTHEAST GOING INTO THE WEEKEND WITH THE UPPER FLOW FLATTENING TO
NEARLY ZONAL ACROSS THE SOUTHERN U.S. BY SUNDAY, CONTINUING THROUGH
THE FIRST HALF OF THE WORKWEEK. FLOW DOES BEGIN TURNING SOMEWHAT
SOUTHWESTERLY BY THE MIDDLE OF NEXT WEEK AS THE UPPER PATTERN BEGINS
AMPLIFYING ONCE AGAIN. LARGELY A DRY EXTENDED FORECAST RIGHT NOW.
WILL SEE SOME LINGERING SHOWERS FRIDAY AND SATURDAY ACROSS THE FAR
NORTH WITH THE UPPER LOW STILL IN PLACE, AND MAY SEE PRECIPITATION
CHANCES CREEPING BACK IN AS THE UPPER FLOW TURNS SOUTHWESTERLY AT
THE END OF THE PERIOD.
TEMPERATURES START OUT NOTICEABLY BELOW SEASONAL NORMALS, ESPECIALLY
HIGH TEMPERATURES, BUT MODERATE TO NEAR NORMAL BY THE BEGINNING OF
NEXT WEEK THROUGH THE BALANCE OF THE EXTENDED FORECAST PERIOD.
20
AVIATION
18Z UPDATE...
VFR EXPECTED UNTIL THURS MORNING CLOSE TO 12Z. EXPECT A FALL TO
MVFR W/ A POTENTIAL EXTENDED PERIOD OF IFR CIGS IN THE MORNING
INTO THE AFTERNOON AS SHRA AND SOME POTENTIAL TSRA MOVE THROUGH
THE METRO. WINDS NOW ARE VRB AROUND THE AIRPORT, BUT SHOULD MOVE
TO SE BY WED EVENING, PICKING UP FROM 5-8 KTS THIS EVENING TO
10-15 KTS BY THURSDAY MORNING, W/ GUSTS UP TO 25 KTS THROUGH
AFTERNOON. EXPECT TO BOUNCE BACK TO MVFR CIGS BY THURSDAY
EVENING.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE IN EXACT TIMING OF CIGS/PRECIP, HIGH ALL OTHERS.
LUSK
PRELIMINARY POINT TEMPS/POPS
ATHENS 49 62 51 60 / 40 100 70 50
ATLANTA 52 64 52 58 / 60 100 50 60
BLAIRSVILLE 46 55 47 54 / 40 100 90 80
CARTERSVILLE 52 61 50 58 / 60 90 70 80
COLUMBUS 57 74 53 60 / 80 90 20 30
GAINESVILLE 49 58 51 57 / 50 100 80 70
MACON 54 71 53 63 / 60 100 30 30
ROME 53 63 52 59 / 70 90 80 80
PEACHTREE CITY 52 68 50 58 / 70 80 40 50
VIDALIA 54 72 57 67 / 30 80 40 20
FFC WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY FROM 2 AM TO 6 PM EDT THURSDAY FOR THE FOLLOWING
ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...
FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...
POLK...TOWNS...UNION...WALKER...WHITE...WHITFIELD.
SHORT TERM...LUSK
LONG TERM....20
AVIATION...LUSK
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