677
FXUS62 KGSP 050533
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1233 AM EST MON JAN 5 2026
SYNOPSIS
HIGH PRESSURE KEEPS TEMPERATURES ABOVE NORMAL AND RAIN CHANCES LOW
UNTIL A COLD FRONT ARRIVES AT THE END OF THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 1106 PM SUNDAY:
KEY MESSAGE #1: DENSE FOG AND LOW STRATUS LIKELY OVERNIGHT INTO
MONDAY MORNING. CLOUDS AND FOG GRADUALLY CLEAR THROUGH THE MORNING,
BUT MAY LINGER INTO THE AFTERNOON ACROSS THE FOOTHILLS. OTHERWISE,
TEMPERATURES WILL BE NEAR NORMAL WITH QUIET CONDITIONS.
A BROAD ZONE OF WESTERLIES AND ENVELOPED MUCH OF THE COUNTRY FROM
THE DESERT SOUTHWEST TO THE APPALACHIANS. A FEW WEAK PERTURBATIONS
ARE EMBEDDED WITHIN THIS MODEST FLOW REGIME, BUT WILL BE OF NO
IMPACT TO THE AREA TODAY. THE MAIN FOCUS FOR THE FORECAST WILL BE
THE POTENTIAL FOR DENSE FOG, POTENTIALLY WIDESPREAD, TO DEVELOP
DURING THE PRE-DAWN HOURS AND PERSIST INTO LATE MORNING TO EVEN
EARLY AFTERNOON. SURFACE HIGH PRESSURE OVER THE OHIO VALLEY WILL
SHIFT INTO THE MID-ATLANTIC OVERNIGHT AND INTO THE MORNING WITH WEAK
SOUTHERLY FLOW RETURNING ACROSS THE SOUTHEAST STATES. A PLUME OF
MOISTURE IS PROGGED TO POOL UP AGAINST THE ESCARPMENT IN CONCERT
WITH WEAK ISENTROPIC ASCENT. SKY COVER WILL CLEAR OVER THE NEXT
SEVERAL HOURS AS A BATCH OF MID-LEVEL STRATUS SHIFTS EAST. ONCE THAT
HAPPENS, CONDITIONS SHOULD BECOME PRIME FOR EFFICIENT RADIATIONAL
COOLING AS MOISTURE RETURN COMMENCES. THIS WILL IN TURN FOSTER THE
DEVELOPMENT OF WIDESPREAD FOG AND LOW STRATUS WITH WIDESPREAD DENSE
FOG NOT OUT OF THE QUESTION, ESPECIALLY EAST OF THE MOUNTAINS FROM
THE UPSTATE THROUGH MUCH OF THE PIEDMONT AND FOOTHILLS. A DENSE FOG
ADVISORY MAY BE NEEDED LATER TONIGHT. FOG WILL BE SLOW TO MIX OUT IN
THE MORNING AND WILL BE RATHER ENTRENCHED. WITH TIME, THE EDGES OF
THE FOG WILL MIX OUT FROM SOUTH TO NORTH. THIS WILL LEAVE LOCATIONS
ALONG AND NORTH OF I-40 FOGGED IN THROUGH MUCH OF THE MORNING AND
PERHAPS EVENT INTO THE EARLY AFTERNOON BEFORE FINALLY MIXING OUT.
THEREAFTER, TEMPERATURES WILL BE NEAR SEASONAL NORMALS WITH SOME
SUNSHINE ACROSS THE MOUNTAINS AND SOUTHERN PORTIONS OF THE AREA
WHERE THE FOG/STRATUS CLEAR EARLIEST. ANOTHER BOUT OF FOG/STRATUS
COULD MATERIALIZE INTO TUESDAY MORNING, BUT CONFIDENCE IN COVERAGE
REMAINS LOW AT THIS TIME.
SHORT TERM /TUESDAY THROUGH WEDNESDAY/
AS OF 1100 PM SUN:
KEY MESSAGE: TEMPERATURES TREND WARMER TUESDAY AND WEDNESDAY WITH
RAIN CHANCES REMAINING VERY LOW.
A DEEP DRY INVERSION WILL PERSIST OVER THE AREA THROUGH WEDNESDAY.
SOUTHWESTERLY WAA CONTINUES BETWEEN WESTERN ATLANTIC RIDGE AND WEAK
TROUGH CROSSING THE MID-MS AND OH VALLEYS TUESDAY, WITH WINDS THEN
VEERING AS THE ASSOCIATED WEAK COLD FRONT PASSES EARLY WEDNESDAY.
MODELS DIFFER AS TO HOW LONG NOCTURNALLY GENERATED STRATUS LINGERS
INTO THE DAY TUESDAY; THE MOIST LAYER IS QUITE SHALLOW, TRAPPED UNDER
THE INVERSION, SO THINKING IS IT WILL BURN OFF DURING THE MORNING. AS
SUCH, STILL FAVORING AN APPRECIABLY WARMER DAY COMPARED TO MONDAY,
SUPPORTED NOT ONLY BY THE FASTER CLEARING BUT ALSO THICKNESSES
INCREASING. SOME BUST POTENTIAL DOES EXIST IF THE LOW CLOUDS ARE MORE
STUBBORN THAN FORECAST. WINDS WILL BE BREEZY AS WE MIX INTO
PREFRONTAL LLJ. CIRRUS WILL BE ON THE INCREASE WITH ARRIVAL OF UPPER
JET AND APPROACH OF FRONT FROM THE WEST, AND A LAYER OF STRATOCU IS
SUGGESTED TO REACH THE MOUNTAINS LATE IN THE DAY WITH A VERY SHALLOW
LAYER OF INSTABILITY UNDER THE INVERSION. WE STILL FEATURE A LOW
15-30% CHANCE OF PRECIP ALONG THE TN BORDER AND UPPERMOST SAVANNAH
VALLEY TUE NIGHT, THOUGH GIVEN THE SHALLOW NATURE AND LACK OF
APPRECIABLE DYNAMIC FORCING, THERE APPEARS NO NEED TO MENTION PRECIP
ANY FURTHER EAST. ANY PRECIP SHOULD BE RAIN WITH OVERNIGHT LOWS 10-15
ABOVE NORMAL.
850MB FLOW TURNS WESTERLY TUE NIGHT; THE MOUNTAIN POPS DIMINISH. FLOW
THEN TURNS NORTHWESTERLY WED, WITH CAA TECHNICALLY ONGOING BUT
DOWNSLOPING AND AIRMASS MODIFICATION OVERCOMING THAT--MAX TEMPS HIT
THE UPPER 60S AND LOWER 70S, STILL NEAR THE RECORD AT GSP BUT NOT THE
OTHER SITES WHERE THE DAILY RECORDS ARE HIGH OUTLIERS. DRIER AIR
BEHIND THE FRONT MEANS RH MAY BOTTOM OUT CLOSER TO 30 PERCENT THOUGH
WINDS LOOK TO BE FAIRLY LIGHT.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 1145 PM SUN:
KEY MESSAGE 1: DESPITE MORE CLOUD COVER COMPARED TO THE FIRST HALF OF
THE WEEK, TEMPERATURES REMAIN CONSIDERABLY ABOVE NORMAL UNTIL A COLD
FRONT PASSES SATURDAY.
COLD FRONT LOOKS TO STALL SOUTH OF THE CWA EITHER WEDNESDAY NIGHT OR
THURSDAY. BY THAT TIME, SHORTWAVES WILL BE COMING INTO PHASE OVER OR
JUST EAST OF THE ROCKIES; AHEAD OF THE INCIPIENT TROUGH THE FRONT
WILL REACTIVATE, INITIALLY IN THE LOWER MS VALLEY BUT EVENTUALLY
ACROSS SOUTHERN AL/GA/SC. AGAIN THE MOIST LAYER LOOKS TO REMAIN
SHALLOW UNDER A DEEP INVERSION, SO DESPITE ONSET OF CLOUD COVER IN
THE AREA LATE WED NIGHT OR THU, POPS TAKE LONGER TO DEVELOP AND
MAINLY OCCUR WHERE SW'LY FLOW LEADS TO MECHANICAL LIFT ALONG/SOUTH OF
THE BLUE RIDGE, I.E., THE NW HALF OF THE CWA. THE WARMING TREND LOOKS
TO BE TEMPERED BY THE ARRIVAL OF THE CLOUDS, BUT GIVEN THE ANOMALOUS
HEIGHTS AND TEMPS ALOFT, TEMPS REMAIN 15-20 ABOVE NORMAL OVERALL.
FORECAST MINS FRIDAY MORNING ACTUALLY ARE A TAD HIGHER THAN NORMAL
MAXES.
CYCLOGENESIS IS SHOWN TO OCCUR GENERALLY NEAR OKLAHOMA THURSDAY AND
MAJOR MODEL CONSENSUS STILL DEPICTS THE NEW SYSTEM TRACKING TO NEAR
LAKE MICHIGAN THROUGH FRIDAY. WHEREAS IT HAD APPEARED POSSIBLE THE
LOW'S TRACK WOULD BE FARTHER SOUTH AND BRING THE COLD FRONT TO OUR
AREA FRIDAY, MOST RUNS NOW FAVOR THE FRONT NOT CROSSING THE SOUTHERN
APPS UNTIL SATURDAY MORNING. POPS THUS ARE DELAYED OVER THE EASTERN
HALF OF THE CWA UNTIL LATER FRIDAY, WITH PEAK CHANCES FOR ALL ZONES
BEING FRIDAY NIGHT OR SATURDAY MORNING. IN THAT PERIOD, FORCING WILL
BE PROVIDED MAINLY BY 45-50 KT LLJ AND RIGHT-REAR QUAD OF JET STREAK
IN THE EXIT REGION OF THE UPPER TROUGH. ENSEMBLE PWATS RISE TO AROUND
2 SD ABOVE CLIMO, SUGGESTING POTENTIAL FOR VERY GOOD RAINFALL RATES,
THOUGH GFS AND ECMWF ENSEMBLE PROBS OF 1"/6H ARE ACTUALLY QUITE LOW
EAST OF THE MOUNTAINS. DEEP SATURATION SEEN ON PROG SOUNDINGS OVER
THE WESTERN CWA IS NOT SEEN FARTHER EAST, BUT LAPSE RATES ARE POOR IN
BOTH AREAS. THESE MAY BE RESPONSIBLE FOR THE LOW LIKELIHOOD OF
SIGNIFICANT RAINFALL. THE LACK OF CAPE WOULD APPEAR TO KEEP OUR
SEVERE THREAT LOW, THOUGH LREF SUGGESTS DEWPOINTS ARE LIKELY TO REACH
60F IN OUR EASTERN I-85 CORRIDOR SATURDAY AFTERNOON. BULK SHEAR WILL
BE STRONG, AND IF ANY INSTABILITY DOES DEVELOP A FINE LINE OF
CONVECTION POSING A SEVERE WIND THREAT COULD RESULT, ESPECIALLY IN
THAT AREA.
KEY MESSAGE 2: AS TEMPERATURES RETURN TO NEAR NORMAL, LIGHT NORTHWEST
FLOW SNOW IS POSSIBLE IN THE MOUNTAINS SATURDAY NIGHT AND/OR SUNDAY
NIGHT.
TEMPS TREND COOLER ONLY A FEW DEGREES ON SATURDAY--STILL WELL ABOVE
NORMAL--WITH CAA ONCE AGAIN OFFSET BY DOWNSLOPING. POPS DIMINISH FROM
AFTERNOON ONWARD, BUT DUE TO MODEL SPREAD REMAIN SLIGHT-CHANCE OR
GREATER ACROSS MOST OF THE AREA UNTIL SUNDAY MORNING. TEMPS COOL TO
NEAR NORMAL OVER THE MOUNTAINS BY THAT TIME, AND THE PATTERN SUPPORTS
AT LEAST A BRIEF CHANGE TO SNOW IN THE NW FLOW PRONE AREAS. TEMPS
NEAR NORMAL IN THE PIEDMONT SUNDAY BUT BELOW NORMAL IN THE MOUNTAINS.
BASE OF SHORTWAVE PASSING THE MOUNTAINS NEXT SUNDAY NIGHT MAY RESULT
IN ANOTHER BRIEF SHOT OF NW FLOW SNOW.
AVIATION /06Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: A MYRIAD OF RESTRICTIONS ARE EXPECTED AT MOST
TERMINALS THROUGH THE OVERNIGHT AND INTO MONDAY MORNING. FOG AND LOW
STRATUS IS ALREADY DEVELOPING BENEATH A MID-LEVEL CLOUD DECK. WITH
TIME, FOG AND STRATUS IS EXPECTED TO EXPAND IN COVERAGE AS THE MID-
LEVEL CLOUDS SHIFT EAST OF THE AREA AND WINDS SHIFT TO OUT OF THE
SOUTH ALLOWING SHALLOW MOISTURE TO POOL UP EAST OF THE MOUNTAINS.
WIDESPREAD DENSE FOG WILL BE POSSIBLE AND COULD LAST BEYOND THE
USUAL SUNRISE DISSIPATION WINDOW. THIS WILL RESULT IN WIDESPREAD IFR
TO LIFR CONDITIONS WITH ACCOMPANYING LOW STRATUS AS WELL. FOG WILL
BE SLOW TO MIX OUT WITH STRATUS SLOW TO SCATTER AS WELL RESULTING IN
LINGERING IFR OR LOWER RESTRICTIONS BEYOND SUNRISE. SOME TERMINALS
MAY NOT SEE A RETURN TO VFR UNTIL LATER IN THE AFTERNOON HOURS. ALL
LOCATIONS SHOULD HAVE A RETURN TO VFR BY MID TO LATE AFTERNOON,
WHICH SHOULD CONTINUE INTO THE EVENING. ANOTHER ROUND OF LOW
STRATUS/FOG CANNOT BE DISCOUNTED INTO EARLY TUESDAY MORNING, BUT
CONFIDENCE IS MUCH LOWER AT THIS TIME.
OUTLOOK: DRY, VFR CONDITIONS EXPECTED THROUGH MUCH OF THE WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...TW
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...TW
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