815
FXUS62 KGSP 210846
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
346 AM EST THU NOV 21 2024
SYNOPSIS
A COLD FRONT WILL DRIFT OFF THE CAROLINA COAST TODAY AS COLD HIGH
PRESSURE BRINGS BELOW NORMAL TEMPERATURES AND DRY CONDITIONS THROUGH
THE WEEKEND. LIGHT SNOW WILL FALL MAINLY ALONG THE TENNESSEE BORDER
TONIGHT INTO FRIDAY. THERE WILL BE A WARMING TREND BEGINNING LATE
IN THE WEEKEND THROUGH EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 325 AM EST THURSDAY...STILL SEEING WIND GUSTS WORTHY OF
KEEPING THE WIND ADVISORY GOING AT THIS HOUR ACROSS AT LEAST
THE NRN MOUNTAINS/FOOTHILLS, SO WE PREFER TO LET THE ADVISORY
RIDE UNTIL SUCH A TIME AS THE WIND DIMINISHES. OTHERWISE, TEMPS
CONTINUE TO COOL AT VARIABLE RATES WITH THE COLD ADVECTION BEING
NON-UNIFORM. NOT GOING TO GIVE UP ON THE LOW TEMP FCST AT THIS
POINT. SKY WILL REMAIN CLEAR, BUT A LOOK UPSTREAM REVEALS THE CLOUDS
AND PRECIP CROSSING THE OH RIVER AND MOVING IN THE DIRECTION OF
THE NC MTNS.
STILL LOOKS LIKE OUR FIRST TASTE OF WINTER ACROSS THE NC MOUNTAINS
NEAR THE TN BORDER STARTING LATER TODAY AND CONTINUING OVERNIGHT
TONIGHT. AN UPPER LOW OVER THE MIDWEST IS EXPECTED TO WOBBLE IN
OUR DIRECTION AS A POWERFUL SHORT WAVE/VORT LOBE ROTATES AROUND
THE LOW AND DIVES SOUTHEAST TOWARD THE SRN APPALACHIANS THIS
MORNING. GUIDANCE HAS THE DPVA ASSOCIATED WITH THIS FEATURE REACHING
THE NC BORDER BETWEEN 18Z AND 21Z THIS AFTERNOON ALONG WITH THE
SLUG OF MOISTURE SEEN IN THE SATELLITE IMAGERY NOTED ABOVE. PRECIP
CHANCES RAMP UP ALONG THE TN BORDER FROM AVERY DOWN TOWARD THE
SMOKIES FROM MID-AFTERNOON INTO THE EVENING. EXPECT AN INITIAL BURST
OF PRECIP, POSSIBLY BEGINNING AS A WINTRY MIX WHICH IS TYPICAL, BUT
CHANGING FAIRLY QUICK TO SNOW SHOWERS. PRECIP PROBS ALONG THE BORDER
RAMP UP FURTHER INTO THE LIKELY AND CATEGORICAL RANGE THIS EVENING
AS THE DEEPER MOISTURE MOVES IN AFTER 00Z, DEEP ENOUGH TO REACH
INTO THE DENDRITIC GROWTH ZONE ANYWAY. THE BEST ACCUM POTENTIAL
WILL PROBABLY BE BETWEEN MIDNIGHT AND DAYBREAK FRIDAY. THOUGHTS
ABOUT SNOW AMOUNTS HAVEN'T CHANGED APPRECIABLY SO WE APPEAR TO BE
ON THE TRACK TO AN ADVISORY. NOTE THAT ISOLATED LOCATIONS ABOVE 5K
FEET WILL PROBABLY MAKE IT TO WARNING CRITERIA, BUT OVERALL THE
ZONE AVERAGES INDICATE SNOW ACCUMS IN THE ADVISORY RANGE. TEMPS
TONIGHT WILL FEEL WINTRY, ESPECIALLY WITH SOME RESIDUAL WIND FROM
THE NW, AND SHOULD BOTTOM OUT 5-10 DEGREES BELOW NORMAL. BUT...NOT
COOL ENOUGH TO GET ANYWHERE CLOSE TO AN ADVISORY FOR THE COLD TEMPS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/
AS OF 221 AM EST THURSDAY: AS DRIER AIR FILTERS INTO THE MOUNTAINS
ON FRIDAY AND WARMING ALOFT CUTS OFF ICE NUCLEATION, SNOW SHOULD
TAPER OFF THROUGH MOST OF THE DAY. THERE MAY BE A RESURGENCE
LATE IN THE DAY AS A WEAK VORT LOBE ROTATES ACROSS THE NORTHERN
ZONES AND BRIEFLY COOLS THE MID-LEVELS...RE-INCITING ACTIVITY
ALONG THE NORTHERN BLUE RIDGE. THE BIGGER STORY ON FRIDAY WILL
LIKELY BE WINDS, WHICH WILL REMAIN ELEVATED THROUGH MUCH OF THE
DAY. ESPECIALLY ACROSS THE HIGH TERRAIN, BOTH THE HREF AND THE
COMPARATIVELY-SUBDUED NBM DEPICT ~75% ODDS OF ADVISORY-CRITERIA
WINDS THROUGH THE FIRST HALF OF FRIDAY. TEMPERATURES WILL ONLY
CLIMB INTO THE LOW 50S, EVEN ACROSS THE LOW TERRAIN.
THEREAFTER, FORCING WILL BE LOST AS THE UPPER TROUGH PULLS
NORTHEASTWARD OVERNIGHT, GIVING WAY TO QUASI-ZONAL FLOW ALOFT
AND DRY HIGH PRESSURE AT THE SURFACE. THE SFC PRESSURE GRADIENT
WILL SLACKEN ACROSS THE MOUNTAINS, ALLOWING WINDS TO DIE DOWN.
LOWS IN THE MID 30S CAN BE EXPECTED JUST ABOUT EVERYWHERE OVERNIGHT,
BEFORE THEY CLIMB INTO THE UPPER 50S ON SATURDAY. THEY'LL FALL
INTO THE MID- OR EVEN LOWER-30S AGAIN SATURDAY NIGHT, WHICH LOOKS
TO BE THE BEST NIGHT FOR CALM WINDS, CLEAR SKIES, AND EXCELLENT
RADIATIVE COOLING.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
AS OF 231 AM EST THURSDAY: UNPERTURBED FLOW ALOFT WILL CONTINUE
THROUGHOUT MOST OF THE EXTENDED. ILL-DEFINED CYCLOGENESIS LOOKS TO
TAKE HOLD AT SOME POINT MID-WEEK, ALTHOUGH THE DETAILS ARE UNCLEAR.
THE GFS AND ITS ENSEMBLES TEND TO DEVELOP IT AROUND WEDNESDAY OVER
THE OZARKS, THEN HAVE IT TRACK NORTHEASTWARD. THE GEPS ENSEMBLES
TEND TO TAKE THE SAME TRACK, BUT DEPICT ITS DEVELOPMENT LATER.
ENS MEMBERS AS WELL AS THE 00Z DETERMINISTIC ECMWF DEPICT A CYCLONE
DEVELOPING OVER THE UPPER MIDWEST MID-WEEK...SUCH THAT ANY IMPACTS
THE CAROLINAS SEE WILL BE THROUGH THE PASSAGE OF A COLD FRONT NEAR
THE END OF THE PERIOD, AS OPPOSED TO ANY WARM FRONTAL ACTIVATION
MIDWEEK. SO...INITIALLY-DRY CONDITIONS WILL GIVE WAY TO WARMER,
WETTER CONDITIONS MID- TO LATE-WEEK, BUT THERE'S JUST NOT MUCH
FORECAST CONFIDENCE YET.
AVIATION /09Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR AT ALL TERMINALS THROUGH THE PERIOD,
WITH SKY CLEAR AND NO RESTRICTIONS. THAT LEAVES US WITH A GUSTY NW
WIND OVERNIGHT THAT SLOWLY DIMINISHES OUTSIDE THE MTNS BUT REMAINS
STRONG OVER THE RIDGETOPS. GUIDANCE INDICATES THE DEVELOPMENT OF A
LEE TROF EARLY IN THE DAY, SUCH THAT EAST OF THE MTNS THE DIRECTION
SHOULD COME AROUND TO WSW SHORTLY AFTER DAYBREAK IF NOT BEFORE. DEEP
MIXING WILL PERMIT FREQUENT GUSTS THROUGH THE BETTER PART OF THE
DAY. WIND SHOULD DIMINISH AND WE LOSE THE GUSTS AROUND SUNSET.
OUTLOOK: VFR OUTSIDE OF THE MOUNTAINS THROUGH MONDAY. GUSTY W/NW
WINDS MAY LINGER THROUGH FRIDAY. KAVL MAY SEE SOME LOW VFR OR MVFR
CIGS AS MOISTURE PUSHES UP THE VALLEY THROUGH FRIDAY NIGHT WITH
VFR RETURNING THROUGH MONDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ033-049-
050-052-053-059-062>065-501-503-505-507-509.
WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR NCZ033-048>052.
SC...NONE.
SYNOPSIS...MPR
NEAR TERM...PM
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...PM
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