051
FXUS62 KGSP 091149
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 AM EST FRI JAN 9 2026
SYNOPSIS
TEMPERATURES REMAIN UNSEASONABLY WARM THROUGH SATURDAY. RAIN
CHANCES ALSO INCREASE THROUGH SATURDAY UNTIL A COLD FRONT PUSHES
THROUGH THE AREA. TEMPERATURES RETURN TO NEAR-NORMAL SUNDAY INTO
EARLY NEXT WEEK UNDER BUILDING HIGH PRESSURE.
NEAR TERM /THROUGH TONIGHT/
AS OF 6:45 AM FRIDAY:
KEY MESSAGE 1: SOME POTENTIAL FOR AREAS OF DENSE FOG THIS MORNING,
MAINLY OVER THE LOWER PIEDMONT/LAKELANDS.
AT DAYBREAK, A SFC ANALYSIS REVEALS A LINGERING POOL OF DRIER AIR
ALONG/N OF I-85 THAT WAS HINDERING THE NORTHWARD DEVELOPMENT OF
FOG. SOUTH OF I-85, FOG WAS SLOWLY DEVELOPING AND WILL BE LOCALLY
DENSE, PARTICULARLY NEAR THE LAKES. AT THIS POINT, A DENSE FOG
ADVISORY IS LOOKING LIKE LESS OF A POSSIBILITY. THE FOG POTENTIAL
WILL END BY MIDDAY DUE TO BETTER MIXING.
KEY MESSAGE 2: PRECIP CHANCES INCREASE FROM THE WEST THIS AFTERNOON
WITH THE ARRIVAL OF DEEP MOISTURE AND FORCING.
A SHORT WAVE LIFTING OUT OF THE MID/UPPER TROF OVER THE PLAINS
TODAY WILL CARRY LOW PRESSURE OVER THE GREAT LAKES AND INTO EASTERN
CANADA, WHICH IN TURN WILL DRAG A COLD FRONT ACROSS THE TN VALLEY
REGION THIS AFTERNOON. MID/UPPER FORCING WILL IMPROVE QUICKLY DURING
THE EARLY AFTERNOON AHEAD OF THE BOUNDARY AND SHOULD SPREAD EASTWARD
ACROSS OUR REGION THROUGH THE LATE AFTERNOON AND EVENING. ISENTROPIC
LIFT AT LOW AND MID-LEVELS ALSO IMPROVES ACROSS THE AREA ALONG
AND N/W OF I-85 THIS AFTERNOON WHILE DEEP LAYER MOISTURE MOVES
IN FROM THE WEST. SO, IN SPITE OF THE MEAGER PRECIP ALONG THE
BOUNDARY EARLY THIS MORNING, THE INCREASE IN FORCING SHOULD HELP
PRECIP TO BLOSSOM AHEAD OF THE FRONT ACROSS THE MTNS/FOOTHILLS AT
LEAST. PRECIP CHANCES IMPROVE FROM THE WEST AS A RESULT, BUT THIS
WAS ALREADY HANDLED FAIRLY WELL IN THE ONGOING FORECAST, SO ONLY
MINOR CHANGES WERE MADE, MAINLY TO IMPOSE A BIT OF A DELAY BASED
ON THE LATEST RUNS OF THE HRRR. THERE COULD BE A FEW RUMBLES OF
THUNDER BECAUSE OF SOME WEAK ELEVATED INSTABILITY. THE SITUATION
CONTINUES TO IMPROVE TONIGHT AS THE BOUNDARY LAYS OUT ACROSS THE
REGION, SO A HIGH PRECIP PROB STILL LOOKS WARRANTED. THE QPF LOOKS
MANAGEABLE AT THIS TIME, ESPECIALLY CONSIDERING HOW IT HAS BEEN
RELATIVELY DRY LATELY. IF THERE WOULD BE AN OUTSIDE CHANCE OF A
PROBLEM, IT WOULD BE IN THE SOUTHWEST-FACING SLOPES IN THE LITTLE
TN BASIN IN SOUTHWEST NC.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
AS OF MIDNIGHT FRIDAY MORNING:
KEY MESSAGE 1: HEAVY RAIN MAY CONTINUE SATURDAY MORNING IN THE
SOUTHWESTERN FORECAST AREA.
ALTHOUGH THE BEST FRONTOGENETIC FORCING STILL IS LIKELY TO OCCUR OVER
THE MOUNTAINS AND UPPER SAVANNAH RIVER VALLEY PRIOR TO 12Z SATURDAY,
850MB WINDS WILL REMAIN IN A FAVORABLE SW'LY DIRECTION THROUGH THE
MORNING AND MAY ACTUALLY INCREASE IN SPEED BETWEEN DAYBREAK AND NOON,
CONTINUING TO PROVIDE UPSLOPE FORCING INTO THE SOUTHWEST FACING
MOUNTAIN RIDGES AND TO SOME DEGREE THE ESCARPMENT. 900MB
FRONTOGENESIS (BASICALLY VERY NEAR SURFACE FOR THE HIGHER MOUNTAINS)
IS SHOWN TO INCREASE ON THE NAM AND GFS AFTER 12Z, SO THE POTENTIAL
FOR HEAVY RAINFALL WILL PERSIST, WITH STEERING FLOW ORIENTED ROUGHLY
PARALLEL TO THAT AXIS. PWATS STILL WILL BE NEAR THEIR PEAK VALUE (+3
SD PER ENSEMBLE MEAN) OVER THE AREA. HENCE ANY BANDS OF HEAVY RAIN
ONGOING AT DAYBREAK WILL TAKE TIME TO DIMINISH, AND NEW BANDS COULD
DEVELOP. OF NOTE, THE HIGHER RES DETERMINISTIC MODELS ARE NOT SHOWING
MUCH POTENTIAL FOR RATES GREATER THAN AN INCH PER HOUR; THE MAIN
CONCERN IS FOR A LONGER DURATION RAIN EVENT WITH TOTALS SLOWLY
BUILDING AND CAUSING RISES ON CREEKS AND STREAMS, AND THAT APPEARS
MOST LIKELY IN OUR FAR SW NC COUNTIES AND THE ADJACENT PORTION OF
GA/SC. IN LIGHT OF RECENT DRY WEATHER BEING A BIG MITIGATING FACTOR
FOR FLOOD RISK, THE WPC MARGINAL RISK LOOKS APPROPRIATE FOR THE
WESTERN CWA AND EMBEDDED SLIGHT FOR THE MOUNTAINS NEAR AND SOUTHWEST
OF THE GREAT SMOKIES. NOT CONFIDENT ENOUGH FOR A FLOOD WATCH AT THIS
TIME.
KEY MESSAGE 2: CONVECTION SATURDAY AFTERNOON COULD POSE
AN ISOLATED RISK OF DAMAGING WINDS.
SURFACE COLD FRONT LOOKS UNLIKELY TO CROSS THE MOUNTAINS UNTIL
SATURDAY EVENING, BUT DEEP SATURATION CONTINUES TO BE SHOWN OVER THE
AREA THROUGH THE DAY, SO LAPSE RATES REMAIN POOR, ALTHOUGH STRONG
SOUTHWESTERLY WAA IS EXPECTED TO BRING TEMPS TO THE UPPER 60S OVER
MOST LOWER ELEVATIONS NORTHWEST OF I-85, AND LOWER 70S SOUTHEAST.
DEWPOINTS ALREADY WILL BE IN THE UPPER 50S IN THE MORNING AND SHOULD
PUSH PAST 60 BY MIDDAY. SBCAPE REMAINS SMALL, NO BETTER THAN 200-300
J/KG, IN MOST GUIDANCE SOLUTIONS, THOUGH THE PROBABILITY OF NONZERO
SBCAPE HAS INCREASED IN RECENT CYCLES OF SEVERAL MODELS. SCREAMING
40-50 KT WINDS AT 850 MB WILL OFFER SUFFICIENT 0-3KM BULK SHEAR TO
ANTICIPATE A SMALL THREAT OF DAMAGING WINDS WITH LOW-TOPPED
CONVECTIVE STORMS, EVEN IF NO THUNDER RESULTS (THOUGH THUNDER CHANCES
HAVE INCREASED WITH THE MEAN SBCAPE). THE ORIENTATION OF THE SHEAR
VECTORS IS LESS THAN IDEAL W.R.T. THE EXPECTED ORIENTATION OF THE
FRONT, AND THE CAMS THAT GO OUT THRU SATURDAY ARE NOT PRODUCING MUCH
IN THE WAY OF UPDRAFT HELICITY. WE ALSO LACK THE STRONG 500MB TROUGH
THAT IS KNOWN TO BE AN IMPORTANT FACTOR IN HIGH-SHEAR LOW-CAPE
TORNADO THREAT. NEVERTHELESS, SPC HAS A MARGINAL RISK AREA
ENCOMPASSING THE CWA SATURDAY, AND THAT LOOKS REASONABLE. EVEN IF
CONVECTION DOES NOT PRODUCE A SPIN-UP, HAVE INCLUDED FORECAST WIND
GUSTS ABOVE NBM ON THE ASSUMPTION THAT RAIN OR CONVECTIVE DOWNDRAFTS
COULD BRING DOWN STRONG WINDS OF 30-40 MPH.
KEY MESSAGE 3: COLD FRONT WILL BRING WINDY CONDITIONS SATURDAY NIGHT
AND SUNDAY, WHICH COULD OVERLAP WITH LOW RELATIVE HUMIDITY SUNDAY
AFTERNOON.
CAA WILL SET IN SATURDAY NIGHT WITH LEADING VORT AXIS BLOWING THRU
THE AREA, AND SFC GRADIENT BEGINS TO INCREASE ACROSS THE MOUNTAINS,
AND HIGH ELEVATIONS WILL SEE GUSTS PICK UP ACCORDINGLY, POTENTIALLY
REACHING ADVISORY CRITERIA BY DAYBREAK SUNDAY. ENOUGH MOISTURE COULD
LINGER ALONG THE TN BORDER FOR FLURRIES WITH VERY LIGHT SNOW ACCUMS
NOT OUT OF THE QUESTION IN HIGH ELEVATIONS THRU MIDDAY. THE MAIN
SHORTWAVE PASSES DURING THE DAY SUNDAY, WHICH USHERS IN A SECONDARY
FRONT AND VEERS WINDS SOLIDLY NW. TEMPS IN THE HIGHER MOUNTAINS
SHOULD REMAIN NEARLY STEADY THROUGH THE DAY OR FALL SLIGHTLY, WHILE
AREAS EAST OF THE MOUNTAINS WILL SEE A NORMAL DIURNAL CURVE, WITH
COLDER AIR OFFSET BY DOWNSLOPING. DEWPOINTS WILL TANK FOLLOWING THE
TROUGH AXIS, AND GUSTS TO NEARLY 30 MPH ARE LIKELY AT TIMES IN THE
PIEDMONT. THERE COULD BE A BRIEF PERIOD OF OVERLAP BETWEEN THE WIND
AND LOW RH, THOUGH BOTH CONDITIONS BECOME LESS CONCERNING FOR FIRE WX
QUICKLY WITH SUNSET IN THE PIEDMONT, THOUGH IT WOULDN'T TAKE MUCH TO
WORSEN CONDITIONS DURING THE AFTERNOON. WE'LL BE COMING OUT OF THE
RAINY PERIOD, SO FUEL MOISTURE MAY NOT BE QUITE LOW ENOUGH TO WARRANT
ANY FIRE WEATHER HEADLINES AS IT IS, BUT THAT IS SOMETHING THAT WILL
NEED TO BE MONITORED SUNDAY.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 1250 AM FRI:
KEY MESSAGE: DRY AND SEASONABLY COLD MONDAY AND TUESDAY. PASSING
TROUGH BRINGS BACK CHANCES FOR PRECIP WEDNESDAY AND THURSDAY.
MOSTLY CLEAR WITH WINDS BECOMING LIGHT MONDAY AS SFC HIGH CENTERS
OVER THE GULF/ATLANTIC COASTAL PLAIN. MAX TEMPS END UP ABOUT A
CATEGORY BELOW NORMAL FOR THE FIRST TIME IN A WHILE. RH LIKELY TO
BOTTOM OUT AT OR BELOW 30 PERCENT IN MUCH OF THE AREA THAT AFTERNOON,
THOUGH WITH THE LIGHT WINDS FIRE WX CONCERN MAY BE MITIGATED. SW FLOW
DEVELOPS TUESDAY; TEMPS AND DEWPOINTS REBOUND ALTHOUGH LOW RH AGAIN
MAY OCCUR. HEIGHT FALLS ARE REINFORCED ALOFT AS CLIPPER-LIKE TROUGH
DIGS INTO THE UPPER MIDWEST CIRCA TUESDAY. MODELS CONTINUE TO SHOW
THIS TROUGH DEEPENING NEAR THE GREAT LAKES AND BRINGING ANOTHER COLD
FRONT TO THE SOUTHERN APPALACHIANS WED OR THU. MOST MODELS STILL
SHOW THE TROUGH ACTIVATING THE COASTAL FRONT, AND WHILE THE
DETERMINISTIC GFS/EC/GDPS NOW DEPICT THE INCIPIENT LOW DISTANT ENOUGH
FROM OUR AREA TO PRECLUDE PRECIP IN OUR PORTION OF THE PIEDMONT, A
FEW ENSEMBLE MEMBERS FROM EACH MODEL STILL DO, AND SO NBM REFLECTS
SMALL POPS THERE. TEMPERATURES WOULD BE WARM ENOUGH FOR ONLY RAIN
OUTSIDE THE MOUNTAINS, WHERE SNOW WOULD BE PREDOMINANT WHERE TEMPS
ARE COLD ENOUGH. LIGHT MOUNTAIN ACCUMS APPEAR POSSIBLE.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: A SOUTHERLY FLOW OF MOISTURE RETURNING
FROM THE GULF CONTINUES TO FORCE THE DEVELOPMENT OF A LOW CLOUD
DECK THAT WAS STEADILY DROPPING DOWN INTO THE IFR TO LIFR RANGE
FROM SOUTH TO NORTH. THE ATMOSPHERE HAS REVEALED A PREFERENCE FOR
A CEILING RESTRICTION INSTEAD OF A VIS RESTRICTION BECAUSE OF A
LINGERING POOL OF DRIER AIR ALONG/N OF I-85 AT DAYBREAK, SO WE
HAVE CUT BACK ON THE FOG AT MOST TERMINALS WITH THE EXCEPTION OF
KAND. MOST TERMINALS SHOULD PREVAIL IFR FOR THE BETTER PART OF THE
MORNING, WITH TEMPORARY LIFR. RADAR SHOWS A FEW LIGHT RETURNS OVER
THE UPSTATE, AND A LARGER AREA OF PRECIP WELL OFF TO THE WEST. THE
LATEST GUIDANCE SUGGESTS THAT PRECIP WILL BE DELAYED A BIT INTO
THE MID/LATE AFTERNOON, SO WE RAMP UP WITH A PROB30 FOLLOWED BY A
TEMPO FOR RAIN RESTRICTIONS AFTER 20-22Z OR SO. DURING THIS TIME,
GUIDANCE SUGGESTS THAT THE CEILING WILL LIFT TO VFR FOR A FEW
HOURS, WHICH SEAMS REASONABLE. WIND SHOULD BEND MORE SW FOR THE
AFTERNOON. AROUND SUNSET, THE LOW CLOUDS WILL RETURN ALONG WITH
THE ARRIVAL OF THE STEADY PRECIP. AT SOME POINT IN THE EVENING,
AN MVFR TO IFR CEILING WILL RETURN, WITH WIDESPREAD RAIN AND
RESTRICTIONS FROM LATE EVENING ONWARD.
OUTLOOK: RESTRICTIONS WILL PERSIST THRU MOST OF SATURDAY. FLIGHT
CONDITIONS IMPROVE LATE SATURDAY INTO SUNDAY BEHIND THE FRONT.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JCW
NEAR TERM...PM
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...PM
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