832
FXUS62 KGSP 201939
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
239 PM EST FRI DEC 20 2024
SYNOPSIS
A NORTHWEST FLOW OF MOISTURE WILL PRODUCE LIGHT SNOW ALONG
THE TENNESSEE BORDER AREAS FROM LATER TODAY THROUGH TOMORROW
MORNING. THE COLDEST DAYS ARE EXPECTED TO BE SUNDAY AND MONDAY AS
HIGH PRESSURE TAKES OVER. HOWEVER, TEMPERATURES SHOULD WARM UP A
BIT FOR CHRISTMAS.
NEAR TERM /THROUGH SATURDAY/
AS OF 155 PM EST FRIDAY: THE ALBERTA CLIPPER AND ASSOCIATED SHORT
WAVE ARE APPROACHING THE AREA EARLY THIS AFTERNOON. THE COLD FRONT
TRAILING THE CLIPPER LOW PRESSURE CROSSES THE AREA BY LATE
AFTERNOON. GUSTY WINDS ARE ALREADY DEVELOPING AHEAD OF THE FRONT AND
WILL INCREASE IN SPEED, WITH A WIND SHIFT, BEHIND THE FRONT.
REGIONAL RADAR SHOWS PRECIP APPROACHING THE MOUNTAINS FROM THE
NORTHWEST. THE COOLER AIR MASS HAS LAGGED BUT WILL SPREAD INTO THE
MOUNTAINS THROUGH THE AFTERNOON WITH RAIN CHANGING TO SNOW AT THE
HIGHER ELEVATIONS THEN TO THE VALLEY FLOORS THROUGH THE EVENING.
DEEP MOISTURE, WEAK INSTABILITY, CAA, AND NW FLOW WILL ALL LEAD TO
SNOW SHOWERS FOR THE TN BORDER COUNTIES, INCLUDING SOME LIGHT SNOW
FOR THE NORTHERN BLUE RIDGE, THE HIGH ELEVATIONS OF NORTHERN JACKSON
COUNTY AND NORTHERN BUNCOMBE COUNTY. THE SNOW SHOWERS CONTINUE
THROUGH THE EVENING THEN BEGIN TAPERING OFF SATURDAY MORNING, ENDING
BY AFTERNOON. FORECAST TRENDS STILL LOOK ON TRACK FOR AN ADVISORY
LEVEL EVENT. GENERALLY 1 TO 5 INCHES ACROSS AVERY COUNTY, AND A VERY
ELEVATION DEPENDENT 1 TO 5 INCHES FOR THE REST OF THE ADVISORY AREA.
OF COURSE, LOCALLY HIGHER AMOUNTS FOR THE LOCATIONS LIKE THE
SMOKIES, SAM'S GAP, AND ROAN AND BEECH MOUNTAINS ARE LIKELY. THE
VERY GUSTY WINDS WILL CONTINUE ACROSS THE MOUNTAINS AS WELL TONIGHT
THEN SLOWLY TAPER OFF THROUGH THE DAY. WINDS MAY GUST ABOVE 50 MPH
ACROSS LOCATIONS ABOVE 5000 FEET, BUT SHOULD REMAIN BELOW ADVISORY
LEVEL ELSEWHERE. LOWS WILL 'ONLY' BE A FEW DEGREES BELOW NORMAL, BUT
THIS WILL LIMIT ANY SIGNIFICANTLY COLD WIND CHILLS TO THE VERY HIGH
ELEVATIONS AS WELL. HIGHS SATURDAY WILL BE 10 TO 15 DEGREES BELOW
NORMAL.
ELSEWHERE, THE CAM GUIDANCE CONTINUES TO SHOW SCATTERED CONVECTION
DEVELOPING ALONG AND NEAR THE I-77 CORRIDOR LATER THIS AFTERNOON AS
THE COLD FRONT CROSSES THE AREA. THERE WILL BE WEAK INSTABILITY WITH
STEEP LAPSE RATES AND DEEP MIXING. WITH THE FREEZING LEVEL DROPPING,
THIS COULD LEAD TO GRAUPEL OR SMALL HAIL IN THE STRONGER SHOWERS,
ALONG WITH MAYBE A RUMBLE OF THUNDER OR TWO. THE GUIDANCE DOES
DIFFER ON WHERE THE STRONGER SHOWERS DEVELOP, SOME NEAR OR EVEN
SLIGHTLY WEST OF I-77, OTHERS SHOW EASTERN ROWAN/UNION NC OR EVEN
EAST OF THERE BEFORE THEY DEVELOP. SO OF COURSE, THIS WILL NEED TO
BE MONITORED. THE BOUNDARY LAYER REMAINS QUITE WARM, SO ONLY A VERY
SMALL CHANCE OF SNOW FLAKES REACHING THE GROUND. FOR NE GA AND THE
WESTERN UPSTATE, THERE WILL BE SOME CLOUDS BUT NO SHOWERS DURING THE
AFTERNOON. THE SHOWERS MOVE EAST BY EARLY EVENING WITH CLEARING
SKIES WHERE THEY HAVEN'T CLEARED EARLIER IN THE AFTERNOON. GUSTY SW
WINDS TURN NW BEHIND THE FRONT AND SLOWLY DIMINISH OVERNIGHT. LOWS
WILL BE A FEW DEGREES BELOW NORMAL. LOW END GUSTY WINDS MAY PICK
BACK UP AFTER DAYBREAK SATURDAY AS MIXING BEGINS THEN TAPER OFF
EARLY IN THE AFTERNOON. HIGHS WILL BE AROUND 5 TO 10 DEGREES BELOW
NORMAL.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
AS OF 152 PM EST FRIDAY: HEIGHTS WILL BEGIN TO RISE ON SATURDAY
EVENING AS A SPEED MAX GLIDES OVERHEAD, EMBEDDED IN NW FLOW ALOFT.
MODEL PROFILES DEPICT SWIFT DRYING, EVEN AT THE SURFACE, SUCH
THAT BY THE OVERNIGHT HOURS SATURDAY NIGHT AND LEADING INTO SUNDAY
MORNING, BASICALLY EVERYWHERE SHOULD BE DRY, EVEN ALONG THE NC-TN
BORDER ZONES. SUNDAY SHOULD BE A PLEASANT DAY, AS DRY AIR COMES
DOWN THE BLUE RIDGE ESCARPMENT, AND DOWNSLOPE WARMING COUNTERACTS
POSTFRONTAL CAA.
ON MONDAY, HIGH PRESSURE CENTERED OVER NEW ENGLAND WILL RIDGE
DOWN THE EASTERN SEABOARD...SETTING US UP FOR A CLASSICAL CAD
CONFIGURATION. THIS'LL KEEP TEMPS 8-10 DEGREES BELOW NORMAL GOING
INTO MONDAY NIGHT.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
AS OF 211 PM EST FRIDAY: WEDGING WILL CONTINUE INTO MONDAY NIGHT,
BUT WEAKEN...WHILE A COMPACT UPPER LOW DIGS ACROSS THE MIDWEST.
THIS'LL INCITE SOME AMOUNT OF LOW-LEVEL WAA ON MONDAY NIGHT AND
TUESDAY, BEFORE A BROAD BAROCLINIC ZONE SETS UP ACROSS THE EASTERN
CONUS LATER IN THE WEEK. THERE REMAINS POOR CONSISTENCY AMONG
MODEL ENSEMBLES, THOUGH IN GENERAL IT LOOKS LIKE WEDNESDAY AND
BEYOND SHOULD BECOME MORE ACTIVE.
AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: MVFR CIGS CONTINUE TO SCATTER OUT OUTSIDE OF
THE MOUNTAINS WITH CLEARING TAKING PLACE FROM WEST TO EAST. LOW VFR
WILL MOVE BACK INTO THE MOUNTAINS THROUGH THE AFTERNOON AND LINGER
OVER PORTIONS OF THE FOOTHILLS AND PIEDMONT. CAM GUIDANCE SHOWS
SCATTERED SHOWERS DEVELOPING NEAR KCLT THIS AFTERNOON AND MOVING
EAST BY EVENING. CAN'T RULE OUT AN IN CLOUD LIGHTNING FLASH OR
GRAUPEL/PEA HAIL BUT CHANCE TOO LOW FOR THE TAF. HAVE A PROB30
IN PLACE FOR THAT. KHKY HAS A LOWER CHANCE WITH NO CONVECTION
EXPECTED ELSEWHERE. WINDS WILL START OUT WSW AND TURN NW AND BECOME
GUSTY THROUGH THE AFTERNOON INTO THE EVENING. SKIES CLEAR OVERNIGHT
WITH DIMINISHING NW WINDS. N WIND PICKS BACK UP, WITH LOW END GUSTS
POSSIBLE SATURDAY MORNING.
AT KAVL: GUSTY NNW WINDS DEVELOP THIS AFTERNOON, PICK UP SPEED
THROUGH THE EVENING AND OVERNIGHT, THEN SLOWLY DIMINISH SATURDAY.
LOW VFR CLOUDS RETURN THROUGH THE AFTERNOON WITH MVFR CIGS
DEVELOPING BY EVENING THEN SCATTERING OUT ON SATURDAY. CAN'T RULE
OUT FLURRIES OR EVEN A BRIEF LIGHT SNOW SHOWER, BUT CHANCE TOO LOW
FOR THE TAF.
OUTLOOK: EXPECT BROAD HIGH PRESSURE AND MOSTLY DRY CONDITIONS TO
PERSIST THRU EARLY NEXT WEEK. PRECIPITATION CHANCES AND ASSOCIATED
RESTRICTIONS INCREASE BY MID WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 1 PM EST SATURDAY FOR NCZ033-
048>052.
SC...NONE.
SYNOPSIS...MPR
NEAR TERM...RWH
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...RWH
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