Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 301335
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
935 AM EDT SAT AUG 30 2014

.SYNOPSIS...
A WEAK NEARLY STATIONARY FRONT NORTH CAROLINA WILL DISSIPATE TODAY.
A BERMUDA HIGH WILL THEN DEVELOP AND LINGER INTO EARLY NEXT WEEK...
BRINGING TYPICAL SUMMERTIME HEAT AND HUMIDITY...WITH SCATTERED
AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM...SOME PATCHY DENSE FOG STILL HANGING IN THERE OVER
PORTIONS OF THE UPPER FRENCH BROAD VALLEY...FOOTHILLS AND EVEN THE
PIEDMONT. EXPECT THE FOG TO DISSIPATE BY ABOUT 1030 AM ALL AREAS.
OTHERWISE...THE FORECAST IS IN GOOD SHAPE. LATEST CAMPOP STILL
INDICATES THAT AT LEAST SCT CONVECTION SHOULD DEVELOP OVER WESTERN
AREAS DURING THE MID TO LATE AFTERNOON HOURS. I BLENDED IN THE
CAMPOP TO THE OFFICIAL FORECAST WHICH GENERALLY DELAYED THE ONSET OF
CONVECTION SOMEWHAT AND RAISED THE POPS FOR THIS EVENING OVER THE SW
MOUNTAINS AND NE GA. MADE ONLY MINOR ADJUSTMENTS TO OTHER FIELDS.

AS OF 630 AM EDT SATURDAY...EARLIER 2KFT STRATUS CLOUD DECK OVER
WESTERN NC HAS RECEDED TO THE NORTH ALLOWING FOR JUST ENOUGH COOLING
TO YIELD PATCHY FOG DEVELOPMENT/EXPANSION.  LATEST OBSERVATIONS
ALONG WITH SATELLITE IMAGERY INDICATE LIGHT PATCHY FOG ACROSS
PORTIONS OF THE NC PIEDMONT WHILE PATCHY DENSE FOG HAS DEVELOPED IN
THE MOUNTAIN VALLEYS AS EXPECTED.  CONDITIONS WILL IMPROVE ACROSS
THE PIEDMONT SHORTLY AFTER SUNRISE WITH THE MOUNTAIN VALLEY FOG
PERSISTING FOR AN HOUR OR SO.  OTHERWISE....TWEAKED TEMPERATURES AND
DEWPOINTS TO REFLECT LATEST OBSERVATIONS AND LEFT THE REMAINDER OF
THE FORECAST AS IT WAS.

PREVIOUS DISCUSSION...

AS OF 300 AM EDT SATURDAY...RATHER NICE DAY IN STORE ACROSS
NORTHEAST GA AND THE WESTERN CAROLINAS AS DEEP LAYER RIDGING
PREVAILS.  MEANWHILE...UPPER SHORT WAVE ENERGY TO THE WEST CONTINUES
TO PROGRESS EAST ALONG THE MEAN FLOW PROMOTING DEVELOPMENT OF
SURFACE TROF BENEATH AND SUSTAINED SOUTHERLY MOISTURE ADVECTION
REGIME.  CLOSER TO HOME...REMNANT LOW LEVEL MOISTURE AXIS FROM OLD
STATIONARY BOUNDARY CONTINUES TO PROVIDE A FOCUS FOR EXPANDING
STRATUS CLOUD DECK.  LATEST MOS GUIDANCE CONTINUES TO SUPPORT PATCHY
FOG DEVELOPMENT THIS MORNING ACROSS THE NC PIEDMONT WITH SOME AREAS
OF DENSE FOG POSSIBLE IN AND AROUND THE MOUNTAIN VALLEYS.  THAT
SAID...ABOVE MENTIONED STRATUS DECK WILL INHIBIT COOLING SOMEWHAT
THEREBY DELAYING/PREVENTING FOG DEVELOPMENT FOR AREAS OF THE NC
PIEDMONT.

CONDITIONS WILL IMPROVE BEYOND DAYBREAK AS HEATING WORKS TO ERODE
LOW STRATUS/FOG PRESENT ACROSS THE REGION.  LIGHT/CALM SURFACE FLOW
WILL GRADUALLY INCREASE OUT OF THE SOUTHEAST TO AROUND 5-10MPH BY
MID/LATE AFTERNOON.  SOUNDINGS CONTINUE TO INDICATE JUST ENOUGH LOW
LEVEL MOISTURE TO SUPPORT MINIMAL COVERAGE OF FAIR WX CU AS LAPSE
RATES STEEPEN WITH HEATING THIS AFTERNOON.  CONVECTION TO THE WEST
ASSOCIATED WITH WAA CONVEYOR BELT AND SURFACE TROFFING WILL ALSO
LIKELY PROMOTE SOME MID/HIGH LEVEL CIRRUS STREAMING ALOFT.  SPEAKING
OF MOISTURE ADVECTION PATTERN...POPS WILL REMAIN NON MENTIONABLE
THROUGH MUCH OF THE MORNING BEFORE GRADUALLY INCREASING TO NEAR
LIKELY LEVELS ACROSS THE WESTERN MOST ZONES...TAPERING TO SLIGHT
CHANCE LEVELS FOR PORTIONS OF THE WESTERN UPSTATE AND NC FOOTHILLS
BY LATE EVENING.  THIS IS IN RESPONSE TO BOTH THE MOISTURE AXIS
APPROACHING AND ALSO PROXIMITY OF SOUTHEAST RIDGE LEADING TO WEAKER
INHIBITION FURTHER WEST.  THAT SAID...PROFILES SUPPORT ONLY MINIMAL
CAPE AND WOULD LIKELY NOT YIELD ROBUST UPDRAFTS LEADING TO SUSTAINED
CONVECTION.  THUS...ONLY EXPECTING GENERAL THUNDERSTORMS AT BEST
WITH CLOUD TO GROUND LIGHTNING BEING A PRIMARY THREAT WHICH WILL BE
MENTIONED IN THE HWO.  POPS WILL REMAIN AT SOLID CHANCE LEVELS
ACROSS THE HIGH TERRAIN THROUGH THE OVERNIGHT HOURS TO ACCOUNT FOR
CONTINUED SOUTHERLY UPSLOPE ENHANCED SHOWERS.  TEMPERATURES ON
SATURDAY WILL WARM TO ABOVE NORMAL LEVELS ACROSS THE MAJORITY OF THE
FORECAST AREA AS STRONG UPPER RIDGE PREVAILS.  ALTHOUGH STILL ABOVE
NORMAL...TEMPERATURES COULD BE SLIGHTLY COOLER ACROSS THE MOUNTAINS
AS BETTER SKY COVER LIMITS HEATING.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 215 AM SATURDAY...A WEAKENING SHORT WAVE TROUGH EJECTING FROM
THE GREAT PLAINS WILL PHASE WITH A SHORT WAVE CROSSING THE GREAT
LAKES AND NUDGE THE SERN CONUS ANTICYCLONE OFF THE SE COAST EARLY IN
THE SHORT TERM. A SECONDARY WEAK WAVE MOVES ACROSS THE AREA MONDAY
AS THE ANTICYCLONE DROPS TO THE GA COAST AND RETROGRADES INTO GA MON
NITE. AT THE SFC...A WEAKENING FRONTAL ZONE MOVES ACROSS THE AREA
SUNDAY IN ASSOCIATION WITH THE SHORT WAVE. THERE WILL ALSO BE SOME
UPPER DIVERGENCE AS THE RIGHT ENTRANCE REGION OF A JET STREAK MOVES
THRU. HOWEVER...ALL GUIDANCE HAS BACKED OFF ON THE AMOUNT OF
INSTABILITY DEVELOPING SUNDAY...AT LEAST OUTSIDE OF THE MTNS. CAP
DOES ERODE DURING THE DAY...SO EXPECT CONVECTION TO DEVELOP.
HOWEVER...POP HAS BEEN LOWERED OUTSIDE OF THE MTNS IN LINE WITH
GUIDANCE CONSENSUS...BUT KEPT IN THE SCT RANGE AS THERE WILL BE SOME
FORCING ALONG WITH WEAK INSTABILITY. WITH THE CONTINUED MODERATE
INSTABILITY EXPECTED OVER THE MTNS...LIKELY POP IS RETAINED THERE.
GUIDANCE ALSO IN AGREEMENT SHOWING LOWER PW VALUES THAN PREVIOUSLY
FCST...LEADING TO ONLY ISOLATED POTENTIAL FOR HEAVY RAINFALL. ANY
SVR STORMS SHUD BE ISOLATED AS WELL WITH WEAK SHEAR. TEMPS WILL BE
NEAR TO SLIGHTLY ABOVE NORMAL.

ONLY WEAK INSTABILITY IS FORECAST ON MONDAY WITH LITTLE IN THE WAY
OF FORCING. HAVE DROPPED POP ACROSS THE BOARD...BUT KEPT IN THE
SCATTERED RANGE. STILL...THE BEST MOISTURE AND INSTABILITY WILL BE
OVER THE MTNS...SO POP SLIGHTLY HIGHER THERE. TEMPS WILL WARM A FEW
DEGREES MONDAY AND MONDAY NITE.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 335 AM SATURDAY...A LOW AMPLITUDE TROF MOVES EAST ACROSS THE
ERN CONUS TUE KEEPING THE UPPER ANTICYCLONE SUPPRESSED ACROSS THE
GULF COAST STATES. AS THE TROF MOVES EAST OFF SHORE WED...RIDGING
DEVELOPS OVER THE SERN CONUS. THIS RIDGING REMAINS IN PLACE THU AND
FRI. AT THE SFC...A WEAK COLD FRONT DROPS SOUTH TOWARD THE AREA AS
THE TROF MOVES EAST TUE. THE FRONT STALLS NORTH OF THE AREA WED...
BUT A LEE TROF DEVELOPS OVER THE CWFA. THE FRONT DISSIPATES THU BUT
LEAVES A WEAK CONVERGENCE ZONE WHICH MOVES IN ON THU AND REMAINS IN
PLACE FRI. THIS PATTERN WILL KEEP LOW LEVEL MOISTURE AND INSTABILITY
ACROSS THE AREA. EVEN WITH THE RIDGE IN PLACE...THE SFC BOUNDARY
WILL HELP PROVIDE ENOUGH FORCING TO TAP THE ELEVATED INSTABILITY
ACROSS THE AREA. THIS WILL LEAD TO GENERALLY SCT DIURNAL CONVECTION
EACH DAY...WITH COVERAGE SLIGHTLY FAVORING THE MTNS THRU THE PERIOD.
TEMPERATURES WILL REMAIN ABOVE NORMAL UNTIL FRI WHEN THEY DROP TO
NEAR NORMAL.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL THROUGH THE PERIOD AS DEEP LAYER RIDGING
PREVAILS LEADING TO DRY WEATHER AND MOSTLY SUNNY SKIES.  LIGHT WINDS
INITIALLY WILL INCREASE OUT OF THE SOUTH BY MID/LATE MORNING WITH
AFTERNOON FEW LOW VFR CU AND SCT HIGH LEVEL CIRRUS BEING THE
DOMINATE SKY COVER.  AS UPPER WAVE AND ASSOCIATED MOISTURE ADVECTION
AXIS CONTINUES TO SLIDE EAST THROUGH THE DAY...SKIES WILL FILL IN
FROM THE WEST.  THUS...10Z FM GROUP CARRIES LIGHT SOUTHERLY WINDS
UNDER LOW VFR CU AT BKN045.

ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE MAJORITY OF THE
FORECAST PERIOD WITH THE EXCEPTION OF IFR/MVFR LEVEL FOG/STRATUS
THIS MORNING AT KHKY AND KAVL.  EARLIER MVFR LEVEL STRATUS DECK HAS
RECEDED SOMEWHAT GIVING WAY TO FOG DEVELOPMENT AS COOLING RESUMES.
ALL SITES WILL RETURN TO VFR LEVELS BY MID MORNING WITH ABOVE
MENTIONED DEEP LAYER RIDGING DOMINATING THE WEATHER FOR THE DAY.
INITIAL LIGHT WINDS WILL INCREASE INTO THE 5-8KTS RANGE OUT OF THE
SOUTH BY LATE MORNING TO EARLY AFTERNOON.  LOW VFR CU WILL HIGHLIGHT
THE SKIES BY LATE MORNING BENEATH OCCASIONAL HIGH LEVEL CIRRUS.
EXPECTING OVERALL COVERAGE OF SKY COVER TO INCREASE LATE IN THE
PERIOD AS DEEPER MOISTURE ADVECTS IN FROM THE WEST.  AS THIS
MOISTURE AXIS INTRUDES...SHRA/TSRA CHANCES WILL INCREASE BY LATE
AFTERNOON LASTING INTO THE EARLY EVENING AT KAND AND KAVL.  DUE TO
LOW PROBABILITIES AND EFFECTS OF CAPPING CONTINUING TO PLAY A
ROLE...OPTED FOR VCTS/VCSH MENTION INSTEAD OF PREVAILING WX.

OUTLOOK...MOISTURE ADVECTION BEGINNING TONIGHT WILL LEAD TO
INCREASING CHANCES FOR ISOLATED/SCATTERED DIURNAL SHRA/TSRA THROUGH
MIDWEEK WITH THE GREATEST PROBABILITIES RESIDING ALONG THE HIGH
TERRAIN. IN ADDITION...MORNING FOG/STRATUS WILL BE POSSIBLE WITH THE
MOUNTAINS ONCE AGAIN HAVING THE GREATEST CHANCES AT RESTRICTIONS.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-13Z
KCLT       HIGH  99%     HIGH 100%     HIGH 100%     HIGH  91%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
KAVL       HIGH  92%     HIGH 100%     HIGH 100%     HIGH  94%
KHKY       HIGH  91%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  87%

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

&&

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

&&

$$
SYNOPSIS...RWH
NEAR TERM...CDG/LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CDG





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