170
FXUS62 KGSP 180552
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1252 AM EST TUE NOV 18 2025
SYNOPSIS
COOL DRY HIGH PRESSURE WILL MOVE OFF THE EAST COAST TODAY AS A WARM
FRONT BRINGS ABOVE NORMAL TEMPERATURES FROM WEDNESDAY THROUGH THE
WEEKEND. MOISTURE INCREASES LATE THIS WEEK AS LOW PRESSURE TRIES TO
ORGANIZE TO WEST OF THE AREA, WHICH GRADUALLY INCREASE RAIN CHANCES.
NEAR TERM /THROUGH TONIGHT/
AS OF 1220 AM TUESDAY: WEAK LOW LEVEL RETURN FLOW WILL STEADILY
BECOME ESTABLISHED ACROSS THE REGION TODAY...IN RESPONSE TO HEIGHT
FALLS ASSOCIATED WITH A COMPACT UPPER LOW THAT WILL OPEN UP AND
WEAKEN AS IT EXPEDITES FROM THE CENTRAL GREAT PLAINS EARLY THIS
MORNING TO THE MID-ATLANTIC COAST BY THE END OF THE PERIOD. THE
S/SW FLOW AND MORE SHALLOW MIXING INDICATES DEWPOINTS SHOULD NOT
CRATER AS MUCH THIS AFTERNOON AS IN THE PREVIOUS TWO DAYS...BUT
THE AIR MASS WILL REMAIN VERY DRY JUST OFF THE SURFACE, AND IT
STANDS TO REASON THAT SOME OF THAT WILL MIX TO THE SURFACE THIS
AFTERNOON...LIKELY RESULTING IN MARGINALLY CRITICAL RH. SEE THE
FIRE WX DISCUSSION FOR ADDITIONAL DETAILS. MAX TEMPS ARE FORECAST
TO BE A COUPLE OF DEGREES WARMER THAN ON MONDAY IN MOST AREAS...MORE
THAN 5 DEGREES ABOVE CLIMO.
AS HEIGHT FALLS OVERSPREAD THE OHIO VALLEY LATE TODAY THROUGH
TONIGHT...RESPONDING LOW LEVEL FRONTOGENESIS WILL RESULT IN
WIDESPREAD SHOWER DEVELOPMENT TO OUR NW THROUGHOUT TODAY...WITH
SOME OF THIS ACTIVITY MAKING A RUN TOWARD THE NC MOUNTAINS AS WELL
AS THE I-40 CORRIDOR OVERNIGHT. HAVING SAID THAT, PASSAGE OF THE
DEEPER FORCING TO OUR NORTH, A LACK OF APPRECIABLE INSTABILITY TO
SUPPORT SHOWER MAINTENANCE, AND UNDERWHELMING MOISTURE PROFILES
SUGGEST SHOWERS WILL HAVE DIFFICULTY MAKING INROADS INTO THE CWA. 60-
80 POPS (FOR LOW QPF MOSTLY OF .25" OR LESS) ARE ADVERTISED FOR THE
NC COUNTIES BORDERING TN TONIGHT, BUT CHANCES QUICKLY DIMINISH TO
THE SOUTH AND EAST, WITH <20% CHANCES FOR THE I-85 CORRIDOR AND
POINTS SE. IN LIGHT OF WEAK, ELEVATED CAPE, CAN'T RULE OUT A STRAY
THUNDERSTORM IN THE WESTERN ZONES, BUT CHANCES ARE ONLY 10-20%. MIN
TEMPS WILL BE AROUND 10 DEGREES ABOVE NORMAL IN THE RELATIVELY
MOIST/RELATIVELY WELL-MIXED WARM SECTOR REGIME.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 1207 AM EST TUESDAY: ACTIVE SOUTHERN STREAM JET STREAM WILL BE
DRAPED FROM THE SOUTHERN PLAINS THROUGH THE MIDWEST AND OH VALLEY
DURING THE FORECAST PERIOD. LEADING SHORTWAVE WILL BE IN THE MIDST
OF EXITING THE MID-ATLANTIC COAST AT THE BEGINNING OF THE FORECAST
PERIOD. A WEAK, DIFFUSE FRONTAL BOUNDARY LOOKS TO SAG SOUTH OVER THE
AREA WEDNESDAY, WITH AN OROGRAPHIC COMPONENT CAPABLE OF SPARKING
A FEW SHOWERS ALONG THE NC/TN BORDER, WHILE THE BETTER FORCING
FOR ASCENT AND MOISTURE REMAINS NORTH OF THE CWFA. A CLOSED UPPER
LOW GRADUALLY SHIFTS FROM SOUTHERN CALIFORNIA TO THE FOUR CORNERS
DURING THE SHORT TERM AND HELPS TO SHARPEN THE JET STREAK, WHICH
ALLOWS AN UPPER RIDGE TO BUILD OVER THE AREA BEHIND THE DEPARTING
SHORTWAVE. DEEP LAYER SOUTHWESTERLY FLOW FROM THE SOUTHERN PLAINS
THROUGH THE MIDWEST WILL BRING DEEP MOISTURE ACROSS THIS REGION,
INFLUENCED BY AN EMBEDDED BAROCLINIC ZONE AND FORCING FOR ASCENT. A
FEW SHOWERS MAY SCRAPE BY THE MOUNTAINS BY THURSDAY NIGHT ONCE THIS
SETUP BECOMES FULLY ESTABLISHED, BUT UPPER RIDGING WILL CONTROL
THE OVERALL PATTERN AND SUPPRESS MUCH IN THE WAY OF QPF RESPONSE
ACROSS THE REST OF THE CWFA. RISING HEIGHTS FROM THE BUILDING
UPPER RIDGE OVER THE EASTERN CONUS WILL LEAD TO AFTERNOON HIGHS ON
WEDNESDAY AND THURSDAY TOPPING OUT IN THE LOW TO UPPER 70S, WITH
A FEW LOCATIONS LIKELY REACHING 80. OVERNIGHT LOWS WILL INDUCE A
WARMING TREND AS WELL WITH A WARM AND MOIST AIR MASS SETTLING IN,
KEEPING DEWPOINTS ELEVATED IN THE 50S. IN THIS CASE, OVERNIGHT
LOWS ON WEDNESDAY AND THURSDAY WILL RUN 12-18 DEGREES ABOVE NORMAL.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 1242 AM EST TUESDAY: AN AMPLIFIED SYNOPTIC PATTERN WILL
BE UNDERWAY DURING THE EXTENDED FORECAST PERIOD AS THE CLOSED
UPPER LOW FROM THE SHORT-TERM OVER THE FOUR CORNERS REGION EJECTS
WITHIN THE AFOREMENTIONED SOUTHERN STREAM JET AND OPENS UP OVER THE
CENTRAL CONUS ON FRIDAY. FLOW BECOMES STEADILY MORE COMPLEX AND
SPLIT AS A SECOND CLOSED UPPER LOW DIGS OVER THE DESERT SOUTHWEST
AND A CLOSED UPPER LOW SHIFTS INTO EASTERN CANADA WITH THE NORTHERN
STREAM JET. AS A RESULT, THE SOUTHERN STREAM JET LOOSELY SHIFTS SOUTH
AS ACTIVE SHORTWAVES MOVE WITHIN THE MEAN FLOW OF THE JET. MODEL
GUIDANCE STILL HAVE A HARD TIME COMING TO A REAL CONSENSUS ON
THE SENSIBLE WEATHER FOR THE CWFA DUE TO THE COMPLEXITY OF THE
PATTERN. THE MAIN SHORTWAVE THAT TRAVERSES TOWARDS AND OVER THE
AREA SEEMS TO OCCUR SOMETIME OVER THE WEEKEND. POPS HAVE ESCALATED
AS THE NBM PICKS UP ON BETTER AGREEMENT FOR PRECIP, BUT OVERALL
TIMING AND AMOUNTS VARY A GOOD BIT. THE LATTER HALF OF THE EXTENDED
WILL FALL ON WHAT HAPPENS TO THE SECOND CLOSED UPPER LOW OVER THE
SOUTHWESTERN CONUS AND HOW FAR SOUTH OR NORTH IT TRAVELS ONCE IT
DEPARTS FROM THIS REGION AND ENCROACHES THE EASTERN CONUS BY THE
VERY END OF THE FORECAST PERIOD. ANOMALOUSLY HIGH HEIGHTS REMAIN IN
PLACE THROUGH MUCH OF THE EXTENDED PERIOD, RESULTING IN TEMPERATURES
10-15 DEGREES ABOVE NORMAL THROUGH THE EARLY PART OF NEXT WEEK.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: A VERY DRY AIR MASS WILL SUPPORT CONTINUED
VFR/MOSTLY SKC CONDITIONS ACROSS THE TERMINAL FORECAST AREA THROUGH
THIS FORECAST PERIOD. CALM OR LIGHT/VARIABLE WINDS EARLY THIS
MORNING WILL BECOME S/SW AT 5-10 KTS BY EARLY AFTERNOON...DECREASING
SLIGHTLY DURING THE EVENING.
OUTLOOK: A WEAKENING FRONTAL ZONE WILL BRING SHOWERS AND
POSSIBLE RESTRICTIONS TUE NIGHT AND EARLY WED...MAINLY TO THE
MOUNTAINS. OTHERWISE, MOSTLY VFR, ALBEIT WITH INCREASING POTENTIAL
FOR EARLY MORNING FOG/LOW STRATUS...MAINLY ACROSS THE MOUNTAIN
VALLEYS. THE NEXT FRONT COULD BRING SHOWERS AND RESTRICTIONS EARLY
IN THE WEEKEND.
FIRE WEATHER
HUMIDITY AND TEMPERATURES STEADILY INCREASE TONIGHT THROUGH MID-
WEEK, BUT ONE MORE AFTERNOON OF NEAR CRITICAL RH IS LIKELY TODAY,
WITH MINIMUMS OF AROUND 25% EXPECTED FOR MUCH OF THE AREA. WINDS
WILL BE WELL BELOW CRITICAL LEVELS, BUT THE OCCASIONAL GUST OF
15-20 MPH IS POSSIBLE THIS AFTERNOON. PER COLLABORATION WITH
LAND MANAGEMENT AGENCIES AND THE NC WEATHER FORECAST OFFICES,
A FIRE DANGER STATEMENT HAS BEEN ISSUED TO ENCOMPASS MUCH OF OUR
NC ZONES FOR THIS AFTERNOON FOR LOW RH AND THE VERY DRY ANTECEDENT
CONDITIONS. ALTHOUGH RH SHOULD REMAIN ABOVE CRITICAL LEVELS FOR THE
REMAINDER OF THE WEEK, VERY WARM TEMPERATURES WILL RETURN. THIS
COULD CREATE A LOW-END WILDFIRE RISK GIVEN LOW 10-HOUR FUEL
MOISTURE VALUES.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...INCREASED FIRE DANGER FROM 11 AM EST THIS MORNING THROUGH THIS
AFTERNOON FOR NCZ035>037-048>050-053-056-057-065-068>072-
082-501>510.
SC...NONE.
SYNOPSIS...CAC
NEAR TERM...JDL
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...JDL
FIRE WEATHER...JDL
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