Area Forecast Discussion
Issued by NWS Greer, SC

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063
FXUS62 KGSP 060853
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
453 AM EDT FRI MAY 6 2016

.SYNOPSIS...
THE WEATHER WILL REMAIN UNSETTLED TODAY AS A DEEP UPPER LOW CENTER
MOVES AWAY TO THE NORTHEAST. ANOTHER FRONT IS EXPECTED TO STALL JUST
TO OUR NORTH ON SATURDAY AND SUNDAY. THE FRONT SHOULD LIFT BACK TO
THE NORTH ON MONDAY...AS HIGH PRESSURE OFF THE SOUTHEAST COAST
EXPANDS AND WARM SOUTHERLY FLOW RETURNS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM EDT...NEAR TERM WILL BE DOMINATED BY THE SLOWLY LIFTING
AND FILLING CUT OFF UPPER LOW CURRENTLY OVER VA. FOR NOW THE
UPPER LOW IS ELONGATED STRETCHING MORE NORTH-SOUTH THAN EAST-WEST
BUT AS THE SHORTWAVE AXIS ROUNDS THE BASE...THE LOW WILL LIFT TOWARD
PA/NC TODAY. ANOTHER SHORTWAVE WILL ROUND THE BASE TONIGHT...AND BY
THE END OF THE PERIOD THE UPPER TROUGH AXIS WILL BE GENERALLY OFF
THE CAROLINA COAST WITH NEGATIVE VORTICITY ADVECTION DEVELOPING OVER
THE FORECAST AREA.

EARLY-PERIOD CONCERNS REMAIN WITH SNOW IN THE HIGHER ELEVATIONS OF
THE MOUNTAINS. SEEING SOME SUBSIDENCE DRYING AROUND THE WESTERN EDGE
OF THE UPPER LOW...AS WELL AS SOME DOWNSLOPING OFF THE MOUNTAINS...
AND HAVE REALLY SEEN QUITE A BIT OF DRYING ACROSS THE AREA EARLY
THIS MORNING. STILL SEEING SOME PRECIPITATION ON WEBCAMS ACROSS THE
MOUNTAINS BUT WITH EVEN MT. MITCHELL UP TO 31 DEGREES AT AFD TIME...
IT IS OBVIOUS THE SNOW LEVELS HAVE INCREASED SOME AND PROBABLY NOT
GETTING MUCH IN THE WAY OF ANY ACCUMULATIONS BELOW 5KFT...AND
GENERALLY THINK THE CHANCE OF ANY ADDITIONAL ACCUMULATIONS ARE SLIM
AT THIS TIME. HOWEVER...THE ADVISORY IS ALREADY OUT AND WITH ONE
MORE SLUG OF MOISTURE MOVING SOUTH OF OVER THE VA MOUNTAINS...THINK
IT PRUDENT TO JUST LEAVE IT AS-IS FOR NOW.

SHOULD SEE ANOTHER ROUND OF BELOW-NORMAL HIGHS TODAY WITH THE CAA
REGIME IN PLACE. LAPSE RATES WILL REMAIN PRETTY STEEP BUT WITH THE
SLOW NORTH/NORTHEASTWARD MOVEMENT OF THE LOW...WE START LOSING UPPER
DIFFLUENCE. THE SYSTEM BECOMES MORE MOISTURE-STARVED AS WELL WITH
QUITE A BIT OF DRYING ALOFT BY MIDDAY. HAVE LEFT SLIGHT CHANCE POPS
ACROSS EASTERN ZONES AND ALSO ACROSS THE MOUNTAINS BUT OTHERWISE
HAVE REDUCED POP TRENDS A LITTLE MORE QUICKLY. CANNOT TOTALLY RULE
OUT THUNDER CHANCES ESPECIALLY WITH THE STEEP LAPSE RATES
CONTRIBUTING TO VERY LOW CAPE VALUES /LIKE LESS THAN 200 J/KG/
ABOVE A DEEPLY MIXED SURFACE LAYER...AND LIKE YESTERDAY SOME
TEENY TINY HAIL IS MOST CERTAINLY POSSIBLE. BIGGER CONCERN...AT LEAST
AS FAR AS SENSIBLE WEATHER GOES...WILL BE THE CONTINUED LOW-END WIND
GUSTS...WELL BELOW ADVISORY CRITERIA BUT COMBINED WITH THE
BELOW-NORMAL TEMPERATURES MIGHT CONTINUE TO MAKE IT FEEL A LITTLE
COOL OUT THERE. SHOULD SEE A CLEARING TREND LATE IN THE PERIOD WITH
LOWS TONIGHT CREEPING BACK UP TO NEAR NORMAL TEMPERATURES.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 255 AM FRIDAY...THE ISSUE FOR THE WEEKEND IS HOW FAR TO THE
SOUTH A BACK DOOR COLD FRONT MAKES IT BEFORE STALLING...AND HOW MUCH
PRECIP ACTIVITY WILL DEVELOP ALONG THE BOUNDARY. BEFORE WE GET
THERE...SOME PRECIP COULD DEVELOP ALONG THE TN BORDER ON SATURDAY AS
A WEAK UPPER WAVE DROPS DOWN FROM THE NW. THIS WILL BE HANDLED WITH
A SLIGHT CHANCE...WHICH TAPERS OFF IN THE LATE AFTERNOON AFTER THE
WAVE AND DEEPER MOISTURE PASS. THE OPERATIONAL MODEL GUIDANCE IS IN
FAIRLY GOOD AGREEMENT WITH DROPPING THE BACK DOOR BOUNDARY ONLY AS
FAR SOUTH AS THE VA/NC BORDER ON SUNDAY. THE DIFFERENCE IS IN THE
DETAILS...WHERE THE GFS AND SREF DEVELOP MORE PRECIP SOUTH OF THE
BOUNDARY SUNDAY AND SUNDAY NIGHT. THE FCST FOLLOWS MORE IN LINE WITH
THE NAM/ECMWF IN KEEPING THE BETTER PRECIP CHANCES TO OUR N WITH
ONLY A TOKEN SLIGHT CHANCE/CHANCE ON THE N AND NW FRINGE OF THE FCST
AREA. UNLESS THERE IS MORE UPPER FORCING THAN INDICATED...PRECIP
SEEMS UNLIKELY E OF THE BLUE RIDGE ACROSS NORTHEAST GA AND UPSTATE
SC BECAUSE OF DOWNSLOPE DRYING. FURTHERMORE...THE UPPER RIDGE WILL
BUILD IN FROM THE WEST DURING THE DAY WHICH SHOULD MAKE THE
SITUATION LESS FAVORABLE FOR PRECIP WITH TIME. TEMPS WILL REBOUND TO
NEAR NORMAL ON SATURDAY...THEN GUIDANCE HAS HIGH TEMPS CLIMBING 5-10
DEG ABOVE NORMAL FOR SUNDAY. CONFIDENCE IS NOT GREAT THAT WE WILL
WARM UP THAT QUICKLY...BUT THE WARMUP IS GENERALLY IN LINE WITH THE
WESTERLY DOWNSLOPE BY SUNDAY AFTERNOON.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 330 AM FRIDAY...NEXT WEEK LOOKS LIKE A RETURN TO SOMETHING
MORE TYPICAL OF LATE SPRING WITH TEMPS ABOVE NORMAL AND DIURNALLY
DRIVEN CONVECTIVE PRECIP. MONDAY LOOKS LIKE THE DAY WITH THE
SMALLEST CHANCE FOR SHOWERS AS A FLAT UPPER RIDGE MOVES ACROSS THE
REGION AND WE LACK ANY MEANINGFUL MID/UPPER FORCING.  AFTER MONDAY
THOUGH...WE END UP WITH WHAT AMOUNTS TO A NEARLY ZONAL UPPER FLOW
ACROSS MOST OF THE SOUTH. HIGH PRESSURE OVER THE WESTERN ATLANTIC
WILL ALLOW FOR MOISTURE TO RETURN FROM THE GULF THROUGH MID-WEEK...
WHICH SHOULD PROVIDE THE FUEL FOR DIURNAL PRECIP DEVELOPMENT. THE
MAIN PROBLEM WILL BE THE TIMING OF ANY WEAK SHORT WAVES CAUGHT UP IN
THE ZONAL FLOW THAT WOULD MOVE THROUGH AND ENHANCE PRECIP CHANCES.
THE GFS HAS ONE MOVING THRU WEDNESDAY AND ANOTHER LATE THURSDAY...
WITH SOME SHORT WAVE RIDGING IN BETWEEN. THE ECMWF REMAINS A BIT
MORE SUBDUED IN THAT REGARD. THE PATTERN FAVORS A PRECIP CHANCE
CLOSE TO CLIMATOLOGY FOR LATE SPRING...MEANING A CHANCE OF SHOWERS
AND STORMS MAINLY IN THE AFTERNOON AND EVENING OVER THE MOUNTAINS
AND FOOTHILLS...AND A SLIGHT CHANCE OVER THE PIEDMONT. OVERALL...
FEW CHANGES WERE MADE TO THE ONGOING FORECAST. MAINLY...TEMPS WERE
RAISED A BIT LATE IN THE PERIOD.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NO CHANGES TO THE KCLT TAF FOR THE 09Z AMD.
STILL SEEING SHOWERS WORKING THEIR WAY ACROSS THE AREA ON THE BACK
SIDE OF THE UPPER LOW. INCREASING DOWNSLOPING COMPONENT WILL HELP TO
DRY THINGS OUT...THOUGH EXPECT SOME LINGERING VCSH OR -SHRA FOR A
FEW HOURS STILL. BEST CHANCE FOR MVFR CIGS REMAINS AT KHKY BUT FOR
THE MOST PART EVERYONE SHOULD BE VFR THROUGH THE PERIOD. CANNOT RULE
OUT SOME -SHRA THIS AFTERNOON BUT WITH THE UPPER LOW BEGINNING TO
MOVE AWAY CHANCES DO NOT QUITE SUPPORT PROB30...BUT WILL REEVALUATE
FOR THE 12Z TAFS. OTHERWISE... CONTINUED DEEP MIXING WITH STEEP
LAPSE RATES WILL SUPPORT ANOTHER ROUND OF GUSTY N/NNW WINDS
TODAY...WITH PEAK GUSTS 20-30KT ESPECIALLY TOWARD KAVL.


OUTLOOK...DRYING WILL CONTINUE INTO SATURDAY. A COLD FRONT WILL
APPROACH FROM THE NORTH SUNDAY...WITH ASSOCIATED PRECIPITATION
POSSIBLY APPROACHING KAVL TO KHKY BEFORE THE FRONT STALLS. WARMING
CONDITIONS WITH A RETURN TO SW FLOW ARE EXPECTED THROUGH EARLY NEXT
WEEK.

CONFIDENCE TABLE...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  94%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EDT TODAY FOR NCZ033-050.
SC...NONE.

&&

$$
SYNOPSIS...PM
NEAR TERM...TDP
SHORT TERM...PM
LONG TERM...PM
AVIATION...TDP



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