189  
FXUS62 KGSP 211154  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
654 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 6:15 AM EST SATURDAY: WE REMAIN CLEAR OUTSIDE OF THE NC MTNS  
WITH BKN TO OVC STRATUS OVER THE MTNS IN THE NW FLOW. ANOTHER ROUND  
OF SCT SNOW SHOWERS IS ONGOING ALONG THE NC/TN BORDER AS ANOTHER SLUG  
OF BETTER MOISTURE HAS BEEN MOVING OVER THAT AREA THAT PAST COUPLE OF  
HRS. AS SUCH, ADDITIONAL SNOW ACCUMS OF ROUGHLY 0.5 INCHES TO ISOLATED  
2 INCHES WILL BE POSSIBLE THRU MID-MORNING. THE WINTER WX ADVISORY FOR  
A PORTION OF OUR NC MTNS REMAINS IN EFFECT UNTIL 1 PM TODAY.  
 
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 /12Z SATURDAY THROUGH WEDNESDAY/  
 
AT KCLT AND ELSEWHERE: EXPECT MOSTLY VFR CONDITIONS TO PREVAIL  
THRU THE 12Z TAF PERIOD. THE ONLY RESTRICTIONS ARE THE ONGOING  
MVFR CIGS AT KAVL FROM THE PERSISTENT NW FLOW CLOUD COVER. EXPECT  
THESE CLOUDS TO EVENTUALLY LIFT/SCT OUT LATER THIS MORNING, BUT  
AS IS TYPICAL IN THESE SITUATIONS, IT MIGHT TAKE A BIT LONGER  
THAN ANTICIPATED. OTHERWISE, BESIDES A FEW HIGH CLOUDS, SKIES  
WILL BE MOSTLY CLEAR THRU THE PERIOD. WINDS WILL CONTINUE TO  
FAVOR A NWLY TO NLY DIRECTION THRU THIS EVENING AND THEN VEER  
TO A MORE NELY DIRECTION LATER TONIGHT. THERE'S A DECENT CHANCE  
THAT KCLT WILL SEE A FEW MORE HRS OF LOW-END GUSTS LATER THIS  
MORNING/AFTN. THIS WAS HANDLED WITH A TEMPO FROM 15 TO 19Z.  
KHKY AND THE UPSTATE TERMINALS COULD ALSO SEE SOME MORE LOW-  
END GUSTS, BUT THEY WOULD LIKELY BE MORE SPORADIC, SO I DID  
NOT INCLUDE THEM IN THE TAFS. AT KAVL, GUSTS WILL LIKELY CON-  
TINUE THRU THE MORNING AND AFTN, BUT 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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