755
FXUS62 KGSP 210843
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
343 AM EST SAT DEC 21 2024
SYNOPSIS
A NORTHWEST FLOW OF MOISTURE WILL PRODUCE LIGHT SNOW ALONG THE
TENNESSEE BORDER AREAS EARLY IN THE DAY, BUT THE MOISTURE SHOULD
PULL OUT BY EARLY AFTERNOON. MEANWHILE, COLD AIR WILL CONTINUE TO
FILTER INTO THE AREA. THE COLDEST DAYS ARE EXPECTED TO BE SUNDAY
AND MONDAY AS HIGH PRESSURE TAKES OVER. HOWEVER, TEMPERATURES ARE
EXPECTED TO TREND BACK TOWARD NORMAL FOR CHRISTMAS.
NEAR TERM /THROUGH TONIGHT/
AS OF 3:05 AM EST SATURDAY: COLDER AND DRIER AIR CONTINUES TO SPREAD
OVER OUR AREA IN THE WAKE OF A ROBUST COLD FRONT THAT IS NOW WELL TO
OUR EAST. SKIES ARE CLEAR OUTSIDE OF THE NC MTNS, BUT REMAIN BKN TO
OVC OVER THE MTNS IN THE NW FLOW. ISOLATED TO SCT SNOW SHOWERS CON-
TINUE ALONG THE NC/TN BORDER REGION WITH ANOTHER SLUG OF MOISTURE
STILL EXPECTED TO DROP OVER THAT AREA OVER THE NEXT FEW HOURS AND
BRING A BRIEF UPTICK IN SNOWFALL. AS SUCH, ADDITIONAL SNOW ACCUMS
OF ROUGHLY HALF AN INCH TO ISOLATED 2+ INCHES WILL BE POSSIBLE THRU
DAYBREAK. LOWS SHOULD BE A FEW DEGREES BELOW CLIMATOLOGY FOR MOST
LOCATIONS THIS MORNING.
OTHERWISE, THE UPPER TROF AXIS WILL LIFT FURTHER OFF THE ATLANTIC
COAST AND WELL NE OF OUR AREA TODAY. HEIGHTS WILL INCREASE VERY
BRIEFLY, HOWEVER THE EASTERN CONUS WILL REMAIN UNDER VERY BROAD
UPPER TROFING THRU THE NEAR-TERM PERIOD. AT THE SFC, BROAD CANADIAN
HIGH PRESSURE WILL CONTINUE TO SPREAD OVER THE AREA FROM THE NORTH
TODAY AND TONIGHT AND KEEP THINGS DRY WITH MOSTLY CLEAR SKIES AND
BELOW NORMAL TEMPERATURES. LIGHT SNOW SHOWERS WILL LIKELY CONTINUE
ALONG THE NC/TN BORDER THIS MORNING BUT SHOULD FIZZLE OUT DURING
THE AFTERNOON AS THE BOUNDARY LAYER BECOMES TOO DRY TO SUPPORT ANY
MORE PRECIP. THE GUSTY WINDS WILL ALSO CONTINUE ACROSS THE NC MTNS
THIS MORNING, BUT SHOULD GRADUALLY TAPER OFF AS THE DAY WEARS ON.
IN ADDITION, THERE'S A DECENT CHANCE THAT OUR NC PIEDMONT ZONES
AND POSSIBLY OUR UPSTATE ZONES COULD SEE ANOTHER BRIEF ROUND OF
LOW-END GUSTS THIS AFTERNOON AS AN EMBEDDED UPPER SHORTWAVE ROUNDS
THE BASE OF THE BROADER UPPER TROF RIGHT OVER OUR CWA. REGARDLESS,
THE GUSTS SHOULD DISSIPATE BY THE EVENING. HIGH TEMPS TODAY WILL BE
ROUGHLY 5 TO 15 DEGREES BELOW NORMAL, WITH THE MTNS BEING THE MOST
BELOW NORMAL.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
AS OF 115 AM EST SATURDAY: THE SECOND HALF OF THE WEEKEND AND THE
START OF THE BRIEF WORK WEEK STILL LOOKS LIKE TYPICAL WINTER, AT
LEAST IN TERMS OF THE CHILLY TEMPS THAT WILL RUN ABOUT TEN DEGREES
BELOW NORMAL IN SPITE OF MOSTLY CLEAR SKY. THE CULPRIT WILL BE
A LARGE CONTINENTAL SFC HIGH THAT MOVES STEADILY FROM SW QUEBEC
ON SUNDAY, ACROSS UPSTATE NY AND NRN NEW ENGLAND SUNDAY NIGHT,
TO THE NEW ENGLAND COAST MONDAY, THEN OFFSHORE ON TUESDAY. THIS
HIGH WILL RIDGE DOWN THE EAST SIDE OF THE MTNS AND DOWN ACROSS
OUR REGION THROUGH MONDAY IN A COLD AIR DAMMING CONFIGURATION,
BUT WITH A SIGNIFICANT LACK OF MOISTURE, YOU WILL SCARCELY NOTICE
IT OTHER THAN THE COLD NORTHEASTERLY BREEZE. THINGS GET A LITTLE
INTERESTING, MAYBE, ON MONDAY NIGHT AS THE GFS DEVELOPS A WAVE
ON THE OLD ARCTIC FRONT OFF THE SOUTHEAST COAST AND SPREADS SOME
MOISTURE NORTHWARD TOWARD THE WESTERN PIEDMONT. BY THAT TIME, A
NRN STREAM WAVE WILL CUT US OFF FROM THE PARENT HIGH OFFSHORE AND
LEAVE BEHIND A WEAK HIGH OVER THE MTNS, KEEPING LOW TEMPS BELOW
FREEZING. HOWEVER, THE GEFS DOESN'T SHOW MUCH SUPPORT AND THE
OTHER OPERATIONAL RUNS ARE DRY. SO, WE WILL KEEP THE COOL TEMPS,
LESS CLOUD COVER, AND NO PRECIP IN THE FORECAST, RATHER THAN THE
PROBLEMATIC LIGHT PRECIP OF THE OPERATIONAL GFS.
LONG TERM /TUESDAY THROUGH FRIDAY/
AS OF 231 AM EST SATURDAY: THE REST OF THE FORECAST PERIOD CONTINUES
TO LOOK LIKE A LOW-CONFIDENCE AFFAIR, AS A DEVELOPING BLOCKING
PATTERN SEEMS TO BE GIVING FITS TO THE MODELS. IF THERE IS ANY
CONSISTENCY, IT WOULD BE THAT SOME WEAK CONSENSUS THAT AFTER A
NRN STREAM WAVE MOVES PAST, WE SLIP RIGHT BACK INTO A COLD AIR
DAMMING REGIME ON TUESDAY AS A MEAN MID/UPPER RIDGE AXIS SETS UP
OVER THE EAST COAST AND PERSISTS FOR THE REST OF THE WEEK. THIS
ACTS TO DEFLECT A SERIES OF DAMPENING SHORT WAVES PAST TO OUR NW,
ONE PERHAPS ON WEDNESDAY AND THE NEXT PERHAPS FRIDAY, LEAVING
US WITH ONLY WEAK FORCING AND MOISTURE, SUGGESTING THAT ANY
SIGNIFICANT WEATHER WILL BE SOMEWHERE OTHER THAN HERE. THE MODEL
BLEND RESULTS IN PRECIP CHANCES CREEPING UP INTO THE CHANCE RANGE,
IN DEFERENCE TO THE WETTER SOLUTIONS INCLUDING THE CANADIAN, BUT THE
PROBS ARE LIMITED TO THE 30-40 PERCENT RANGE AT BEST. FORTUNATELY,
THE SITUATION SUPPORTS TEMPS RUNNING SLIGHTLY ABOVE NORMAL, SO ANY
PRECIP IS MOST LIKELY TO BE RAIN, WITH THE EXCEPTION OF PERHAPS
THE MTN PEAKS ABOVE 6K FEET WHICH WOULD HAVE THE POTENTIAL FOR
SOME WET SNOW AT TIMES. HOPEFULLY THE NEXT FEW DAYS WILL PROVIDE
SOME MUCH NEEDED CLARITY.
AVIATION /09Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: EXPECT MOSTLY VFR CONDITIONS TO PREVAIL
THRU THE 06Z TAF PERIOD AS AN ARCTIC COLD FRONT MOVES EAST OF
OUR AREA OVERNIGHT. THE ONLY RESTRICTIONS ARE THE ONGOING MVFR
CIGS AT KAVL FROM THE PERSISTENT NW FLOW CLOUD COVER. EXPECT
THESE CLOUDS TO EVENTUALLY SCT OUT LATER IN THE MORNING, BUT
AS IS TYPICAL IN THESE SITUATIONS, IT MIGHT TAKE A BIT LONGER.
OTHERWISE, BESIDES A FEW HIGH CLOUDS, SKIES WILL BE MOSTLY CLEAR
THRU THE PERIOD. WINDS WILL CONTINUE TO FAVOR A NWLY TO NLY DI-
RECTION THRU THE TAF PERIOD WITH GUSTS HAVING SUBSIDED AT MOST
SITES OUTSIDE OF THE MTNS ALREADY. KCLT AND KHKY WILL LIKELY SEE
ANOTHER ROUND OF LOW-END GUSTS THIS AFTN/EVENING, WITH GUSTS
DISSIPATING AGAIN LATER IN THE EVENING. THE UPSTATE TERMINALS
COULD ALSO SEE SOME MORE LOW-END GUSTS THIS AFTN/EVENING, BUT
THEY WOULD LIKELY BE MORE SPORADIC, SO I DID NOT INCLUDE THEM
IN THE TAFS. AT KAVL, LOWER-END GUSTS WILL LIKELY CONTINUE THRU
THE MORNING AND AFTN, AND SHOULD EVENTUALLY DIE OFF LATER IN
THE EVENING WITH WINDS REMAINING NWLY.
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 THIS AFTERNOON FOR
NCZ033-048>052.
SC...NONE.
SYNOPSIS...PM
NEAR TERM...JPT
SHORT TERM...PM
LONG TERM...PM
AVIATION...JPT
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