Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 271039
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
639 AM EDT FRI MAR 27 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE EAST OF THE AREA THIS MORNING. A TRAILING
UPPER LEVEL DISTURBANCE WILL THEN CROSS THE AREA THROUGH TONIGHT.
DRY AND SEASONALLY COLD HIGH PRESSURE WILL SETTLE IN OVER THE
WEEKEND. A LOW PRESSURE CLIPPER SYSTEM AND ASSOCIATED COLD FRONT
WILL PASS OVER THE REGION ON SUNDAY NIGHT OR MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM EDT FRIDAY...TWEAKED POPS TO ACCOUNT FOR MOST RECENT
RADAR TRENDS WHICH INDICATE SHRA EXPANSION ASSOCIATED WITH INTRUDING
UPPER TROF AXIS.  SNOW LEVELS HAVE FALLEN ENOUGH ALONG SOME OF THE
HIGHER PEAKS AND RIDGETOPS OF WESTERN NC SUCH THAT SNOW SHOWERS
COULD OCCUR...HOWEVER STILL NOT EXPECTING ANY SIGNIFICANT
ACCUMULATION AS THE BULK OF THE PRECIP WILL REMAIN JUST EAST.
OTHERWISE...TWEAKED TEMPERATURES AND DEWPOINTS TO BETTER REFLECT
OBSERVATIONAL TRENDS AND LEFT THE REMAINDER OF THE FCST AS IS.

PREVIOUS DISCUSSION...

AS OF 330 AM EDT FRIDAY...NEARLY PHASED NORTHERN/SOUTHERN STREAM
UPPER TROF PATTERN YIELDING FULL LATITUDE TROF AXIS ADVECTION ACROSS
THE CENTRAL/SOUTHERN CONUS THIS MORNING.  SURFACE WAVE OUT AHEAD
ACROSS THE MIDATLANTIC CONTINUES TO PUSH A COLD FRONT THROUGH THE
SOUTHERN APPS AT THIS TIME.  CURRENTLY...THE COLD FRONT IS SLIDING
INTO/THROUGH THE I85 CORRIDOR WHERE WINDS HAVE VEERED SHARPLY TO THE
NORTH.  THE FRONT ITSELF CAN ACTUALLY BE SEEN ON RADAR VIA THE KGSP
HALF DEGREE TILT AS IT PUSHES THROUGH THE GSP AREA.  PRECIP
ASSOCIATED WITH THIS FROPA HAS BEEN LESS THAN IMPRESSIVE TO SAY THE
LEAST DUE TO LACK OF UPPER SUPPORT AND LITTLE TO NO INSTABILITY.
THEREFORE THE FCST HAS BEEN TAILORED BACK WITH RESPECT TO POPS
ACROSS THE EASTERN TWO THIRDS OF THE FCST AREA WHERE ONLY ISOLATED
POPS ARE FEATURED THROUGH DAYBREAK...FURTHER WEST ACROSS THE HIGH
TERRAIN CATEGORICAL POPS PREVAIL.  LATEST MESO MODELS INDICATE
SHOWER EXPANSION ALONG AND SOUTH OF I85 THIS MORNING AS THE BOUNDARY
SLIDES SOUTH INTO A SLIGHTLY MORE MOIST ENVIRONMENT.  THIS ADDED
MOISTURE AND WEAK SURFACE CONVERGENCE WILL YIELD AT LEAST SOME
SCATTERED SHOWERS AROUND SUNRISE THEREFORE LIKELY POPS PERSIST
THROUGH MID MORNING OVER THESE AREAS BEFORE BEING LOWERED.  FURTHER
NORTH BEHIND THE FRONT OVER THE NC PIEDMONT...POPS REMAIN AT LIKELY
LEVELS FOR THE TIME BEING BEFORE BEING GRADUALLY REDUCED TO CHANCE
LEVELS BY MID MORNING.

MEANWHILE THE PRIMARY UPPER TROF AXIS WILL BE SLIDING INTO THE
REGION TOWARD DAYS END WITH ABUNDANT COLD ADVECTION PATTERN RIDING
ALONG.  LATEST GUIDANCE FAVORS THE TROF BASE SLIDING ATOP THE TN
VALLEY REGION LATE IN THE DAY TODAY YIELDING INCREASED NW FLOW OVER
THE HIGH TERRAIN AS BROAD CHANNELED VORTICITY BAND MOVES IN.
THUS...KEEPING POPS ELEVATED OVER THE MTNS TO ACCOUNT FOR SNOW
SHOWERS THROUGH THE OVERNIGHT HOURS...WHERE SUB ADVISORY LEVEL
SNOWFALL IS FCST.  THE OTHER CONCERN FOR THE OVERNIGHT PERIOD IS THE
STRENGTH OF THE COLD ADVECTION LEADING TO SUBFREEZING TEMPERATURES
ACROSS THE MTNS...AND NEAR FREEZING LEVELS OUTSIDE OF THE MTNS.  AS
THE FROST/FREEZE PROGRAM HAS BEEN ACTIVATED ACROSS SOUTHWEST
NC...WILL BE ISSUING FREEZE WARNING TO ACCOUNT FOR THREATENING
TEMPERATURES TONIGHT.  REGARDING FROST ACROSS NORTHEAST GA AND THE
NC/SC PIEDMONT...EXPECTING WINDS OVERNIGHT TO INCREASE TO LEVELS
NOT SUPPORTIVE OF FROST DEVELOPMENT THEREFORE NO FROST PRODUCTS WILL
BE ISSUED.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 315 AM FRIDAY...THE MAIN STORY FOR THE SHORT RANGE WILL BE THE
HIGH AMPLITUDE UPPER TROF THAT SETTLES BRIEFLY OVER THE EAST...WHICH
WILL MAKE IT FEEL MUCH MORE LIKE WINTER THAN EARLY SPRING. AFTER
SOME LINGERING NW FLOW SNOW SHOWER ACTIVITY ENDS AFTER DAYBREAK
SATURDAY...THE REST OF THE DAY SHOULD BE QUIET AS A TRAILING SHORT
WAVE IS CHANNELED AND HAS LITTLE MOISTURE TO WORK WITH. HIGH
PRESSURE WILL BUILD DOWN FROM THE NORTH AND WILL KEEP HIGH TEMPS
CLOSE TO WHAT IS NORMAL FOR MID JANUARY. THE HIGH WILL SETTLE OVER
TOP OF THE WESTERN CAROLINAS BY SUNDAY MORNING AND SHOULD PROVIDE
FOR EXCELLENT RADIATIONAL COOLING CONDITIONS. EXPECT THAT THE ENTIRE
FCST AREA WILL BE BELOW FREEZING BY DAYBREAK SUNDAY. BEING THAT
SATURDAY NIGHT IS THE FOURTH PERIOD OF THE FCST...PREFER TO WAIT FOR
ONE MORE MODEL CYCLE BEFORE ISSUING A FREEZE WATCH...JUST IN CASE
THE MODEL GUIDANCE CHANGES. THE UPPER RIDGE MOVES OVERHEAD SUNDAY
AND THAT SHOULD PUSH THE SFC HIGH OFF TO THE EAST. TEMPS WILL NOT
MODERATE MUCH...THOUGH...AND WILL REMAIN WELL BELOW NORMAL. THE NEXT
SHORT WAVE WILL DIVE DOWN AND ACROSS THE FCST AREA SUNDAY NIGHT AND
MONDAY MORNING. THERE APPEARS TO BE MORE MODEL CONSENSUS WITH THE
TIMING OF THIS FEATURE AND THE ASSOCIATED SFC COLD FRONT...REACHING
THE MTNS SUNDAY NIGHT AND CROSSING THE REGION THRU MIDDAY MONDAY.
THAT WILL ALLOW FOR ELIMINATING THE PRECIP CHANCES FROM THE N/NW
MONDAY AFTERNOON. PARTIAL THICKNESS/FCST SOUNDINGS SHOW LOW
POTENTIAL FOR ANYTHING OTHER THAN RAIN...SO THE MIN TEMP FCST FOR
SUNDAY NIGHT WILL BE KEPT ABOVE FREEZING. HAVE LOWERED HIGH TEMPS ON
MONDAY BASED ON A CONSENSUS OF THE GUIDANCE SUPPORTED BY AN EARLIER
FRONTAL PASSAGE.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 230 AM FRIDAY...THE UPPER AIR PATTERN THRU THE MEDIUM RANGE
STILL LOOKS PROGRESSIVE. AN UPPER TROF AXIS OFF THE EAST COAST
MONDAY NIGHT WILL MOVE OFF TO THE EAST. THAT WILL ALLOW SURFACE HIGH
PRESSURE TO BUILD IN FROM THE WEST THRU TUESDAY AS A DEAMPLIFYING
UPPER RIDGE APPROACHES. THINK MONDAY NIGHT AND MOST OF TUESDAY WILL
BE DRY AS A RESULT. THE PROBLEM WILL BE A WEAK SRN STREAM SHORT WAVE
UNDERCUTTING THE DEAMPLIFYING RIDGE ON TUESDAY AND TUESDAY NIGHT.
THE OPERATIONAL GFS AND ECMWF KEEP THE SHORT WAVE WELL TO THE WEST
THRU TUESDAY EVENING...WHICH SUGGESTS THAT MOISTURE RETURN FROM THE
W/SW WILL BE DELAYED UNTIL PERHAPS TUESDAY NIGHT. PRECIP WAS REMOVED
FOR TUESDAY BASED ON THIS CONSENSUS. THE REST OF THE MEDIUM RANGE
LOOKS UNSETTLED AS FIRST THE SHORT WAVE PASSAGE BRINGS UPPER SUPPORT
FOR PRECIP DEVELOPMENT ON WEDNESDAY AND WEDNESDAY NIGHT...THEN A NRN
STREAM WAVE PUSHES A COLD FRONT DOWN FROM THE NW ON THURSDAY TO BE
THE FOCUS FOR ADDITIONAL PRECIP DEVELOPMENT. NO CHANGES WERE MADE
TO THE MEDIUM RANGE FROM WEDNESDAY ONWARD.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR/MVFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD.
INITIALIZED TAF AT MVFR LEVELS WITH -SHRA AND GUSTY NORTHERLY WINDS.
THIS WILL CARRY THROUGH MIDDAY AS THE PRIMARY UPPER TROF AXIS SLIDES
THROUGH THE REGION WITH LOW LEVEL MOISTURE REMAINING SUPPORTIVE OF
MVFR CIG RESTRICITONS THROUGH EARLY/MID AFTERNOON.  LOW VFR RETURNS
AFTER THE 21Z TIMEFRAME AMIDST LIGHT NORTHERLY FLOW AT THE SURFACE.
HIGH LEVEL CIRRUS WILL DOMINATE LATE IN THE PERIOD.

ELSEWHERE...POST FRONTAL PRECIP CONTINUES TO SLIDE THROUGH THE
REGION LEADING TO MVFR CONDITIONS.  INITIALIZED ALL TAFS VFR/MVFR
THROUGH MID/LATE MORNING WITH CONDITIONS IMPROVING EARLIEST ACROSS
THE WEST...THEREFORE LEADING TO EARLIER VFR ONSET AT KAVL.  THE
REMAINING SITES WILL IMPROVE ONCE SHRA EXITS THE REGION NEAR
MIDDAY.  LOW VFR WILL DOMINATE THROUGH EARLY EVENING BEFORE LOW
CLOUDS SCT LEADING TO ONLY HIGH LEVEL CIRRUS AMONGST LIGHT/MODERATE
NORTHERLY FLOW.  LASTLY...EXPECTING LIGHT SHSN ALONG THE TN LINE
ASSOCIATED WITH CAA PATTERN...THUS WOULD NOT BE SURPRISED TO SEE A
FEW FLURRIES AT KAVL NEAR PERIODS END HOWEVER LEFT ANY MENTION OUT
OF TAF FOR THIS ISSUANCE.

OUTLOOK...DRY HIGH PRESSURE PREVAILS THROUGH SUNDAY...THEN ANOTHER
FRONT MOVES IN WITH PRECIPITATION ON MONDAY.  RESTRICTIONS LOOK
MOST LIKELY IN AND AROUND THE MOUNTAIN VALLEYS THUS AFFECTING
KAVL.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       MED   62%     HIGH  96%     HIGH 100%     HIGH 100%
KGSP       MED   61%     HIGH  93%     HIGH 100%     HIGH 100%
KAVL       LOW   58%     HIGH  93%     HIGH 100%     HIGH  95%
KHKY       LOW   57%     MED   78%     HIGH 100%     HIGH 100%
KGMU       LOW   58%     MED   78%     HIGH 100%     HIGH 100%
KAND       LOW   58%     MED   78%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.CLIMATE...
RECORD MINIMUM TEMPERATURES FOR MARCH 28TH...

GSP  26  1982
CLT  25  1982
AVL  11  1887

RECORD MINIMUM TEMPERATURES FOR MARCH 29TH...

GSP  26  1899
CLT  26  2013
AVL  19  1982

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FREEZE WARNING FROM MIDNIGHT TONIGHT TO NOON EDT SATURDAY FOR
     GAZ010.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO NOON EDT SATURDAY FOR
     NCZ048-051>053-058-059-062>065-507-509.
SC...NONE.

&&

$$
SYNOPSIS...PM
NEAR TERM...CDG
SHORT TERM...PM
LONG TERM...PM
AVIATION...CDG
CLIMATE...


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