Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 290615
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
215 AM EDT WED OCT 29 2014

.SYNOPSIS...
WARM SOUTHWEST FLOW WILL CONTINUE ACROSS THE AREA BEFORE A COLD
FRONT CROSSES THE REGION WEDNESDAY. A COLD AREA OF CANADIAN HIGH
PRESSURE WILL BUILD IN FROM THE NORTHWEST LATE IN THE WEEK AND
SLOWLY MOVE EAST...RESULTING IN BELOW NORMAL TEMPERATURES INTO EARLY
NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 215 AM...THE CWA REMAINS DRY...BAND OF RAIN ACROSS MIDDLE AND
EASTERN TN SHOWING ONLY A SLOW DRIFT EAST. I WILL UPDATE THE
FORECAST TO DELAY CHC POPS AN ADDITIONAL 2 TO 3 HOURS. IN
ADDITION...I WILL CRAFT THE POPS TO CLOSELY FOLLOW THE TIMING AND
PLACEMENT OF SOME THE CAMS. OTHERWISE...THE CURRENT FORECAST LOOKS
GOOD.

AS OF 930 PM...FCST IS BACK ON TRACK WITH THE DELAY IN PRECIP
ARRIVAL OVER THE NC MTNS. LEADING EDGE IS STILL OVER THE CUMBERLAND
PLATEAU AS OF 02Z. MILD MIN TEMPS LOOK OK.

PREVIOUS DISCUSSION...

AT 230 PM EDT TUESDAY...A CLOSED UPPER LOW OVER THE GREAT LAKES THIS
AFTERNOON WILL FILL AND MOVE INTO NORTHERN QUEBEC BY WEDNESDAY
AFTERNOON...WHILE AN ASSOCIATED UPPER TROUGH DRIFTS ACROSS THE OH
AND TN RIVER VALLEYS. A COLD FRONT NOW IN THE OH AND MID MS RIVER
VALLEYS WILL APPROACH THE MOUNTAINS OVERNIGHT...ACCOMPANIED BY
SCATTERED SHOWERS. WITH WINDS STAYING UP SOMEWHAT OVERNIGHT...FOG IS
NOT EXPECTED TO BE MUCH OF A PROBLEM...EXCEPT PERHAPS IN THE
MOUNTAIN VALLEYS OF SW NC. THIS FRONT WILL CROSS OUR AREA DURING THE
DAY ON WEDNESDAY. AT THIS POINT...INSTABILITY APPEARS RATHER
LIMITED...AND CONVECTIVE CHANCES WILL BE BEST OVER THE GA AND SC
PIEDMONT AROUND MIDDAY. PRECIPITATION IS NOT EXPECTED TO BE
ESPECIALLY GREAT...AS GRADUALLY VEERING WINDS AHEAD OF THE FRONT
INTRODUCE A LIMITED DOWNSLOPE COMPONENT...FOLLOWED BY NW DOWNSLOPE
WINDS IN THE AFTERNOON. TEMPERATURES WILL RUN ABOVE NORMAL TONIGHT
UNDER INCREASING CLOUD COVER...AND NEAR NORMAL ON WEDNESDAY.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 215 PM TUESDAY...MODELS IN GOOD AGREEMENT THAT THE COLD FRONT
WILL BE DEPARTING THE SOUTHERN/EASTERN MOST COUNTIES OF THE FORECAST
AREA CIRCA 00Z. WILL HAVE SOME LOW END POPS WED EVENING TO THE SOUTH
OF I-85 TO ACCOUNT FOR ANY LINGERING SHOWERS...BUT ANY SHOWERS
SHOULD BE GONE WELL BEFORE MIDNIGHT. WITH HIGH PRESSURE MOVING IN
FROM THE WEST OVERNIGHT...CLOUDS WILL ALSO QUICKLY CLEAR THE AREA
WITH SKC CONDITIONS BY MIDNIGHT. COLD ADVECTION BEHIND THE FRONT
WILL LOWER TEMPS INTO THE MID 30S OVER THE MOUNTAINS WITH LOW TO MID
40S ELSEWHERE. WEAK HIGH PRESSURE WILL BUILD OVER THE REGION ON
THURSDAY AND PRODUCE GENERALLY CLEAR CONDITIONS WITH MAX TEMPS SHY
OF CLIMO. GOOD RADIATIONAL COOLING CONDITIONS THU NIGHT WILL ALLOW
TEMPS TO FALL INTO THE LOWER TO MID 30S OVER THE MOUNTAINS...WITH
LOWS MAINLY IN THE LOWER 40S ELSEWHERE. CLOUDS WILL BE ON THE
INCREASE FRIDAY AS A DEEP UPPER TROUGH MOVES QUICKLY SE FROM THE
UPPER GREAT LAKES TO THE OHIO VALLEY BY LATE IN THE DAY. IMPROVING
UPPER DIVERGENCE AND THE APPROACH OF THE SURFACE COLD FRONT LATE IN
THE DAY....MAY BE ENOUGH TO PRODUCE SOME SHOWERS OVER THE NC
MOUNTAINS FRI AFTERNOON. INCREASING CLOUDS WILL KEEP MAX TEMPS BELOW
CLIMO.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 155 PM TUESDAY...THE LATEST GFS HAS COME IN MORE DYNAMICAL AND
COLDER THAN THE PREVIOUS RUN AND TRACKS A CLOSED H5 LOW OVER THE
CWFA DURING THE DAY SAT. THIS IS MORE INLINE THE 00Z ECMWF...WHICH
STILL HAS THE BETTER DYNAMICS NORTH OF THE AREA. MOISTURE LEVELS ON
THE AVAILABLE GUIDANCE HAS ALSO INCREASED WITHIN THE H85 FIELD
UPSTREAM LATE FRI THRU SAT. WITH THE EXTENDED DEEP RIDGING OVER THE
MIDWEST...THE LLVL AIRMASS WILL BE QUITE COLD BROUGHT DOWN FROM NRN
CANADA. THE BEST CAA OCCURS ACROSS THE WRN MTNS ARND 03Z SAT WITH
H85 TEMPS DROPPING INTO THE -2 C RANGE. THIS WILL SUPPORT LOWERING
FREEZING LEVELS ACROSS THE MTNS THROUGH THE MORNING...MAINTAINED
THROUGHOUT THE DAY.

THUS...WITH DYNO/MECH LIFT AND AVAIL MOISTURE...THE -SHRA WILL
QUICKLY TURN INTO -SNSH AFT 03Z. POPS HAVE BEEN BUMPED UP ACROSS THE
WRN NC MTNS TO THE HIGH CHANCE RANGE FRI NIGHT...WITH MID CHANCE
POPS PERSISTING TIL 00Z SUN. SNOW AMOUNTS SHOULD REACH HIGH END ADV
RANGE...ALTHOUGH QPF/FCST AMOUNTS COULD AND PROBABLY WILL CHANGE AS
WE NEAR THE EVENT. LOWER END SNOWFALL ACCUMS ARE ALSO POSSIBLE
ACROSS THE NC FTHILLS AND NC NW PIEDMONT SAT AS THE STRONG MLVL FLOW
AND DYNAMICS MAINTAIN COLD MOIST COLUMNS EAST.

MODEL SOUNDINGS DROPPED ACROSS THE NC SPINE FRI NIGHT SHOW AVG WINDS
IN THE SFC-1KM LAYER ON THE ORDER OF 25 KTS...WITH CAA GUST
POTENTIALS REACHING 40-45 KTS. ENOUGH WIND FOR A FUTURE HIGHER END
WIND ADV OR WARNING. ON SUN...MIN TEMPS SAT MORNING ACRS THE
NON/MTNS WILL BE IN THE FROST RANGE WITH FREEZING LEVELS OVER THE NC
FTHILLS. MINS ON SUN MORNING WILL REACH FREEZING LEVELS ACRS ALL
NON/MTN ZONES. WITH THE COLDEST AIR OF THE SEASON REINFORCED OVER
THE WEEKEND...MAX TEMPS SAT AND SUN WILL BE HELD ARND 15 DEGREES
BELOW NORMAL.

DRY WX FOR MON/TUE AS A STRONG UPPER HIGH BUILDS OVER THE SE CONUS.
MAX TEMPS WILL STILL STRUGGLE TO REACH NORMAL LEVELS...LIKELY
REMAINING A COUPLE CATS OR SO BELOW EACH DAY.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...BANDS OF HIGH CLOUDS AND LIGHT SW WINDS WILL CONTINUE
ACROSS THE TERMINAL THROUGH THE MORNING HOURS. SOUTHWEST WINDS ARE
FORECAST TO STRENGTHEN TO AROUND 10 KTS BY LATE MORNING. THE SFC
COLD FRONT MAY PUSH WEST TO EAST ACROSS THE TERMINAL BETWEEN 17Z TO
21Z. AS THE FRONT APPROACHES...CLOUD BASES WILL LIKELY LOWER TO
SCT020 BKN035 WITH ISOLATED SHOWERS. IT IS POSSIBLE THAT PERIODS OF
MVFR CEILINGS MAY OCCUR NEAR THE FRONT. AFTER 23Z...WINDS SHOULD
STEADILY VEER FROM THE NNW WITH VFR CLOUDS.

ELSEWHERE...A SLOW MOVING BAND OF RAIN MAY REACH THE TN/NC LINE BY
12Z. THE BAND SHOULD REMAIN OVER THE MTNS THROUGH THE
MORNING...SHIFTING EAST ACROSS THE FOOTHILLS AND PIEDMONT WHILE
THINNING THROUGH THE AFTERNOON. I WILL TIME VCSH OR -SHRA AS THE
COLD FRONT APPROACHES FROM THE WEST. TIMING OF THE -SHRA ACROSS THE
MTNS IS 16 TO 18Z...TO 18-20Z ACROSS THE I-85 CORRIDOR. AFTER
FROPA...WINDS SHOULD VEER FROM THE NNW AND CLOUDS WILL DISSIPATE.

OUTLOOK...HIGH PRESSURE AND VFR CONDITIONS RETURN FOR THURSDAY.
ANOTHER FRONT APPROACHES ON FRIDAY...BRINGING CLOUDS COVER OVER THE
AREA THROUGH SATURDAY...BUT CONFIDENCE IS MARGINAL ON RESTRICTIONS
ASSOCIATED WITH THIS SYSTEM.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...SBK
NEAR TERM...NED/PM
SHORT TERM...LG
LONG TERM...SBK
AVIATION...NED



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