555
FXUS62 KGSP 210308
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1008 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 953 PM EST FRIDAY: AN ARCTIC FRONT HAS CLEARED THE AREA WITH A
NOTICEABLY DRIER AND COOLER AIRMASS QUICKLY FILTERING INTO THE
REGION. AT LEAST ISOLATED TO SCATTERED SNOW SHOWERS WILL CONTINUE
ACROSS THE MOUNTAINS THROUGH MUCH OF THE OVERNIGHT WITHIN A
NORTHWEST FLOW REGIME. A SECOND SLUG OF MOISTURE MANIFESTED AS AN
AREA OF LIGHT SNOW OVER WEST VIRGINIA AND EASTERN KENTUCKY WILL DROP
INTO THE MOUNTAINS DURING THE EARLY MORNING HOURS, WHICH COULD BRING
A BRIEF UPTICK IN SNOWFALL GENERALLY BETWEEN 10-12Z. ADDITIONAL
ACCUMULATIONS OF 0.5" TO ISOLATED 2" WILL BE POSSIBLE THROUGH
DAYBREAK. POPS AND SNOW ACCUMULATIONS WERE ADJUSTED ACCORDINGLY,
OTHERWISE THE ONGOING FORECAST REMAINS ON TRACK.
OTHERWISE, AN ALBERTA CLIPPER AND ASSOCIATED SHORT WAVE ARE CROSSING
THE AREA. GUSTY WINDS ARE ALREADY DEVELOPING AHEAD OF THE FRONT AND
WILL INCREASE IN SPEED, WITH A WIND SHIFT, BEHIND THE FRONT. 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 /03Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: PREDOMINATELY VFR CONDITIONS WILL PREVAIL
THROUGH THE PERIOD AS AN ARCTIC COLD FRONT RACES ACROSS THE AREA
THIS EVENING. A BRIEF PERIOD OF -TSRA IS EXITING THE CLT AREA WITH
ANY ASSOCIATED RESTRICTIONS EXPECTED TO BE OFF TO THE EAST BY 00Z.
THE ONLY OTHER ISSUE WILL BE THE POTENTIAL FOR MVFR CEILINGS AT KAVL
THROUGH THE EVENING. OTHERWISE VFR WILL CONTINUE WITH GUSTY
NORTHWEST WINDS AT ALL TERMINALS. GUSTS WILL SUBSIDE OVERNIGHT
OUTSIDE OF THE MOUNTAINS, BUT GUSTS WILL CONTINUE AT KAVL. A FEW
GUSTS WILL BE POSSIBLE TOMORROW AS WELL, BUT NOT AS STRONG AS THIS
EVENING.
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/TW
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...TW
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