Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 041753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1253 PM EST THU FEB 4 2016

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLIDE EAST OF THE AREA THROUGH
MORNING LIKELY STALLING ALONG THE ATLANTIC COASTLINE LATER TODAY.
THE FRONT WILL FINAL SLIDE OUT TO SEA ON FRIDAY WITH DRIER HIGH
PRESSURE PREVAILING THROUGH SATURDAY.  A COASTAL LOW COULD SPREAD
A FEW SHOWERS INTO THE AREA FROM THE SOUTHEAST ON SUNDAY BEFORE A
MORE POTENT UPPER DISTURBANCE AND ASSOCIATED SURFACE COLD FRONT
SPILL IN FROM THE NORTHWEST MONDAY MORNING LEADING TO ELEVATED
PRECIPITATION CHANCES THROUGH MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1245 PM...THE WESTERN EDGE OF THE LIGHT PRECIP HAS BEEN
SHUNTED OFF TO THE EAST...SO THE PRECIP CHANCES OVER THE EAST CAN BE
CURTAILED A BIT MORE. SATELLITE IMAGERY SHOWS SOME LOW CLOUDS BANKED
UP AGAINST THE EDGE OF THE MTNS ON THE TN BORDER. THE MTNS WERE
GENERALLY CLOUD-FREE. LOW CLOUDS HAD ALMOST MOVED OUT OF THE CLT
METRO AREA. IN BETWEEN...MID-LEVEL CLOUDS WILL CONTINUE TO STREAM UP
FROM THE S. THIS PATTERN SHOULD HOLD THRU THE AFTERNOON.

THE NEXT ISSUE IS WHAT TO DO WITH POPS...ESPECIALLY THIS EVENING AS
THAT COLD ADVECTION IS DEVELOPING. SOME OF THE GUIDANCE TENDS TO
DEVELOP A BIT OF A DEFORMATION ZONE ACROSS THE INTERIOR CAROLINAS
THIS EVENING...AS THE BASE OF THE UPPER TROUGH AND ATTENDANT
NEUTRALLY-TILTED SHORT WAVE PASSES SOUTH OF THE AREA. THIS ALLOWS
FOR A LITTLE LIGHT PRECIP TO DEVELOP AS FAR WEST AS THE MTNS. THIS
SCENARIO IS ESPECIALLY PROMINENT IN THE GFS. TAKING A LOOK AT GEFS
OUTPUT...THE OPERATIONAL GFS IS THE ONLY MEMBER THAT DEVELOPS PRECIP
OVER THE MOUNTAINS TONIGHT...WHILE THE OTHER MEMBERS ARE A LITTLE
MORE IN LINE WITH THE DETERMINISTIC MODEL EAST OF THE MTNS. THERE IS
ALSO SUPPORT FOR THIS SCENARIO FROM THE CANADIAN AND TO A LESSER
EXTENT THE ECMWF. OPTED THEREFORE TO PULL SLIGHT CHANCE POPS ALMOST
TO THE BLUE RIDGE THIS EVENING FOR A VERY LIGHT QPF EVENT. PARTIAL
THICKNESS PROGS INDICATE A RAIN/SNOW SCENARIO...WITH MOSTLY RAIN IN
THE PIEDMONT/FOOTHILLS (POSSIBLY MIXING WITH FLURRIES LATE TONIGHT).
IF PRECIP MANAGES TO DEVELOP OVER THE MTNS...IT WOULD BE SNOW.
AGAIN...THIS IS A LOW PROBABILITY/LOW QPF SITUATION. OTHERWISE...
WITH COLD ADVECTION OVERSPREADING THE AREA...MIN TEMPS ARE EXPECTED
TO BE A SOLID 5 DEGREES BELOW CLIMO TONIGHT.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 230 AM EST THURSDAY...THE SHORT TERM FCST PERIOD INITIALIZES
ON FRIDAY MORNING WITH THE UPPER PATTERN HIGHLIGHTED BY A POTENT
SHORTWAVE TROF PASSING ATOP THE MID ATLANTIC...WHILE SHORTWAVE
RIDGING BUILDS WESTWARD OVER THE MID/LOWER MS RIVER VALLEY.  AT THE
SURFACE...A QUASISTATIONARY FRONTAL AXIS WILL RESIDE ALONG THE
ATLANTIC COASTLINE...HOWEVER WILL BE ON THE MOVE RATHER QUICKLY AS
THE POTENT H5 WAVE MOVES OVERHEAD.  A BROAD REGION OF SURFACE HIGH
PRESSURE BENEATH THE A FORE MENTIONED UPPER SHORTWAVE RIDGE AXIS
WILL CONTINUE MARCHING EAST THROUGH THE DAY ON FRIDAY...EVENTUALLY
SETTLING ATOP NORTHEAST GA AND THE WESTERN CAROLINAS BY SATURDAY
MORNING.

MEANWHILE...SPLIT FLOW OVER THE PLAINS STATES WILL ATTEMPT TO
PHASE INTO A SINGLE FULL LATITUDE TROF...LIKELY MOVING OVER THE
ARKLATEX BY DAYBREAK ON SATURDAY.  THIS BROAD AREA OF H5 HEIGHT
FALLS WILL ADVECT EAST ALL THE WHILE CONTINUING TO DEEPEN AS IT
SPREADS OVER THE NORTHEAST GULF COAST INTO MIDDAY SATURDAY.  AT THAT
TIME...GUIDANCE FAVORS SIGNIFICANT SFC PRESSURE FALLS ACROSS THE FL
PENINSULA THEN EASTWARD OVER THE WATERS OF THE WESTERN ATLANTIC.
SAID SURFACE LOW PRESSURE WILL DEEPEN THROUGH THE OVERNIGHT INTO
SUNDAY MORNING WITH SOME MODEL DISCONTINUITY PRESENT AS TO ITS
EVENTUAL TRACK...AND HOW THAT RELATES TO THE SOUTHERN APPALACHIANS.
ECMWF/CMC SOLUTIONS ARE WETTER AND SIGNIFICANTLY FURTHER INLAND THAN
THAT OF THE GFS...WHICH IF WAS TO VERIFY...WOULD YIELD NOTHING MORE
THAN INCREASED CLOUDINESS.  HOWEVER...THE FORMER WOULD FAVOR LOW
END PRECIP CHANCES ALONG/EAST OF THE I77 CORRIDOR THROUGH MIDDAY
SUNDAY...WITH THERMAL PROFILES BARELY SUPPORTING A RASN MIX AT
PRECIP ONSET.  THUS THE FCST FAVORS SUCH SOLUTION WITH SLIGHT
CHANCE POPS HIGHLIGHTED WITH A BRIEF SHOT AT A FEW FLURRIES.
THE ENTIRE SYSTEM LOOKS TO EJECT EAST THROUGH THE DAYLIGHT HOURS
ON SUNDAY ALLOWING FOR DRYING AND ANOTHER BRIEF ROUND OF HIGH
PRESSURE INTO SUNDAY NIGHT.  TEMPERATURES THROUGH THE SHORT TERM
PERIOD WILL REMAIN JUST A FEW DEGREES BELOW CLIMO ON AVERAGE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 AM EST THURSDAY...THE MEDIUM RANGE FCST PERIOD KICKS
OFF ON SUNDAY NIGHT AS A BRIEF ROUND OF DEEP LAYER RIDGING SETS
UP ATOP THE SOUTHERN APPALACHIANS AS A POTENT H5 SHORTWAVE EJECTS
INTO THE WESTERN ATLANTIC.  HOWEVER...A FAST MOVING CLIPPER TYPE
SYSTEM DIVING THROUGH THE UPPER MIDWEST WILL SWEEP INTO THE SOUTHERN
APPALACHIANS BY MONDAY MORNING PACKING A MODEST AMOUNT OF MOISTURE
ALONG ITS SURFACE COLD FRONT.  BEYOND THIS POINT...AND REALLY
THROUGH THE REMAINDER OF THE PERIOD...THE PATTERN REMAINS DOMINATED
BY A BROAD/DEEP LONGWAVE TROF WHILE A SERIES OF REINFORCING H5
SHORTWAVES PASS THROUGH THE MEAN FLOW ALOFT.  THIS WILL LIKELY
SPELL A FAIRLY PROLONGED NWFS SETUP ACROSS THE SOUTHERN APPS WITH
SOME OF THE A FORE MENTIONED FRONTAL MOISTURE BREAKING CONTAINMENT
INTO THE NC/SC PIEDMONT AS WELL AS NE GA LEADING TO A FEW SN
SHOWERS...SPECIFICALLY ON MONDAY INTO TUESDAY.  ANY NWFS COULD
PERSIST FOR A FEW DAYS LEADING TO MODEST ACCUMULATIONS ACROSS THE
MTNS AS FLOW/MOISTURE ARE CONTINUOUSLY REINFORCED.  ALONG WITH THE
PRECIP...THE AIRMASS ASSOCIATED WITH THIS SYSTEM LOOKS RATHER COLD
AS BOTH THE GFS/ECMWF SHOVE ANY CRITICAL THICKNESS VALUES WELL
SOUTH OF THE CWFA...MORE SPECIFICALLY...THE 540DM LINE LOOKS TO
PUSH AS FAR SOUTH AS JACKSONVILLE FL.  CLOSER TO HOME...GUIDANCE
IS STARTING TO SHOW SIGNS OF THE RETURN TO WINTER LIKE TEMPERATURES
AS A CONSENSUS OF HIGHS BY MIDWEEK RANGE FROM THE MID 30S TO LOWER
40S ON AVERAGE...WITH LOWS BY WEDNESDAY/THURSDAY MORNINGS IN THE
TEENS TO MID 20S ON AVERAGE.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...BKN MVFR CEILING REMAINED ACROSS THE WRN PIEDMONT...BUT
DRIER AIR WAS SLOWLY FILTERING IN FROM THE WEST. THINK THAT BY MID
AFTERNOON THE LOW CLOUDS WILL SCATTER AND VFR WILL PREVAIL WITH A
MAINLY MID-LEVEL CEILING. HAVE KEPT A TEMPO FOR THE MVFR CEILING
THRU THE AFTERNOON...BUT THIS COULD BE FOR TOO LONG OF A PERIOD.
WIND SHOULD REMAIN NE TO N INTO THE MID EVENING. THINGS GET MURKY
LATER THIS EVENING. AS AN AREA OF LOW PRESSURE ORGANIZES AND DEEPENS
OFF THE COAST THIS EVENING IN RESPONSE TO THE ARRIVAL OF A STRONG
SHORT WAVE ALOFT...THE MODELS INDICATE THE DEVELOPMENT OF SOME LIGHT
PRECIP ACROSS THE PIEDMONT. DEEP LAYER FORCING LOOKS ADEQUATE FOR
PRECIP PRODUCTION FROM MAINLY A VFR CLOUD DECK. THIS SHOULD BE IN A
LIQUID FORM IF IT HAPPENS BEFORE 06Z WHEN THE STRONGEST FORCING
MOVES THRU AND TEMPS HAVE NOT COOLED EXCESSIVELY IN THE BOUNDARY
LAYER. IF ANY PRECIP PERSISTS PAST 06Z...IT WOULD BE IN THE FORM OF
SNOW SHOWERS. FOR THE TIME BEING...THE CHANCE OF PRECIP DOES NOT
APPEAR TO BE HIGH ENOUGH TO INCLUDE IN THE TAF. HOWEVER...A FEW SNOW
SHOWERS ARE WITHIN THE REALM OF POSSIBILITIES AT KCLT BETWEEN 06Z
AND 12Z FRIDAY. SKY SHOULD CLEAR QUICKLY AROUND DAYBREAK.
THEREAFTER...WITH A DEEPENING BOUNDARY LAYER AND COLD ADVECTION...WE
SHOULD HAVE A STRONG AND GUSTY NW WIND.

ELSEWHERE...VFR THRU THE PERIOD. CLOUDS MAY REDEVELOP THIS EVENING
BUT SHOULD HAVE BASES AT LEAST 050. WIND WILL COME AROUND TO N AND
NW. ON FRIDAY...EXPECT A STRONG AND GUSTY NW WIND.

OUTLOOK...LARGE HIGH PRESSURE WILL SLOWLY BUILD ACROSS THE REGION
THROUGH THE WEEKEND...GRADUALLY PUSHING OUT THE LINGERING MOISTURE
LATE THU INTO EARLY FRIDAY. UNRESTRICTED CONDITIONS ARE THEN
EXPECTED THROUGH THE WEEKEND. A STRONG UPPER AIR DISTURBANCE COULD
BRING ENOUGH MOISTURE TO WRING OUT A FEW RAIN OR SNOW SHOWERS ON
MONDAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       MED   79%     HIGH  92%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     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...NONE.
SC...NONE.

&&

$$
SYNOPSIS...CDG
NEAR TERM...JDL/PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...PM



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