Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 281735
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
135 PM EDT FRI AUG 28 2015

.SYNOPSIS...
WEAK HIGH PRESSURE WILL LINGER OVER THE EAST THROUGH THE UPCOMING
WEEKEND. MOISTURE WILL GRADUALLY RETURN FROM THE SOUTHWEST THROUGH
THE WEEKEND...ALONG WITH A PASSING UPPER LEVEL DISTURBANCE BY
SUNDAY. TROPICAL SYSTEM ERIKA WILL LIKELY BE SOMEWHERE IN THE
VICINITY OF FLORIDA MONDAY THROUGH TUESDAY...WITH HIGH UNCERTAINTY
ON HER LOCATION MID TO LATE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 PM EDT FRIDAY...FAIRLY QUIET EARLY AFTERNOON ACROSS THE
REGION AS LOW STRATUS CIGS HAVE ERODED ACROSS MUCH OF THE UPPER
SAVANNAH RIVER VALLEY GIVING WAY TO A FEW LOW CLOUDS UNDER PATCHY
HIGH CIRRUS.  FURTHER NORTH ACROSS THE MTNS STARTING TO SEE BETTER
CU COVERAGE...ESPECIALLY OVER THE SW NC MTNS WHERE LATEST SPC MESO
ANALYSIS PLOTS NEARLY 1.0-1.5K J/KG SBCAPE.  THUS...OPTED NOT TO
MAKE ANY CHANGES TO THE IMMEDIATE NEAR TERM PORTION OF THE FCST
WITH THIS UPDATE AS MOST RECENT CAM GUID CONTINUES TO FAVOR WEAK
SHRA/TSRA OVER THE MTNS THIS AFTERNOON.

AS OF 315 AM...SFC HIGH PRESSURE WILL REMAIN CENTERED OVER NY/PA
TODAY...RIDGING SOUTH ACROSS THE WESTERN CAROLINAS. LLVL FLOW IS
FORECAST TO REMAIN FROM THE EAST...WITH SPEEDS GRADUALLY DECREASING
TO AFTERNOON VALUES BELOW 10 KTS. THE LLVL WINDS WILL LIKELY RESULT
IN UPSLOPE FLOW...YIELDING CLOUD COVER ACROSS THE MTNS THROUGH MOST
OF THE DAY. IN ADDITION...STRATUS OVER THE MIDLANDS ARE FORECAST TO
SLIDE OVER THE UPPER SAVANNAH RIVER VALLEY AND UPSTATE EARLY THIS
MORNING. CLOUD COVER SHOULD GRADUALLY THIN WITH THE DECREASE IN
LLVL EAST WINDS THIS AFTERNOON. FORECAST NAM SOUNDINGS AND PLAIN
VIEW OF CAPE INDICATE VERY WEAK VALUES ACROSS THE FORECAST AREA
THIS AFTERNOON. THE GREATEST CAPE VALUES SHOULD OCCUR ACROSS THE
MTNS...BUT LIKELY LESS THAN A 1000 J/KG. THE INSTABILITY WILL BE
LIMITED BY A SIGNIFICANT INVERSION AROUND H7. HOWEVER...FOLLOWING
THE NAM AND 4KM WRF...I WILL HIGHLIGHT THE MTN RIDGES WITH SCHC
TO LCHC POPS DURING THE HEAT OF THE AFTERNOON. OTHERWISE...THE
REGION WILL REMAIN DRY. HIGH TEMPERATURES SHOULD PEAK A DEGREE OR
TWO BELOW NORMALS.

TONIGHT...A BROAD MID LEVEL LOW IS EXPECTED TO REMAIN NEAR THE
MISSISSIPPI DELTA...AS A SLIGHT S/W RIDGE INCREASED FROM THE EAST
ACROSS THE CAROLINAS. H925 FLOW IS FORECAST TO VEER FROM SOUTHEAST
THIS EVENING TO SOUTH BY 12Z SAT. SKY COVER MAY INCREASE FROM
SOUTH TO NORTH DURING THE LATE NIGHT HOURS. I WILL KEEP POPS IN
THE SINGLE DIGITS TONIGHT. MIN TEMPERATURES ARE FORECAST TO RANGE
FROM 2 TO 4 DEGREES BELOW NORMAL.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 255 AM FRIDAY...NRN STREAM ENERGY WILL MOVE ACROSS THE GREAT
LAKES ON SATURDAY AND REACH NEW ENGLAND LATE IN THE WEEKEND.
MEANWHILE...A SRN STREAM TROUGH WILL LINGER OVER THE MID AND DEEP
SOUTH WEST OF THE APPALACHIANS. A PIECE OF THIS SRN STREAM LOW...AND
AN ASSOCIATED UPPER JETLET...WILL LIKELY LIFT NWD THROUGH THE BASE
OF THE SRN APPALACHIANS SAT NIGHT INTO SUNDAY. AHEAD OF THIS
FEATURE...MOISTURE WILL START INCREASING FROM THE SW LATE
SATURDAY...WITH THE DEEPEST MOISTURE AND FORCING THEN CROSSING THE
REGION SATURDAY NIGHT INTO SUNDAY. WILL ADVERTISE MAINLY INCREASING
CLOUDS ON SATURDAY...WITH THE BEST SHOWER CHANCES ARRIVING FROM THE
SW SAT NIGHT INTO SUNDAY MORNING. DEWPOINTS WILL STEADILY RECOVER
ALONG WITH THUNDER CHANCES THROUGH SUNDAY. WILL FEATURE A SLIGHTLY
SMALLER THAN GUIDANCE DIURNAL RANGE ON TEMPS GIVEN THE ANTICIPATED
CLOUDS OVER THE WEEKEND.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 255 AM FRIDAY...A RESURGENT RIDGE AXIS IS EXPECTED TO DEVELOP
EARLY NEXT WEEK FROM THE SRN SHORES OF THE GREAT LAKES TO THE MID
ATLANTIC COAST...AS NRN STREAM ENERGY DEPARTS NEW ENGLAND...AND THE
REMAINING SRN STREAM LOW RETROGRADES WEST INTO THE SRN PLAINS/TX.
THE RESULTING RIDGE AXIS OVER THE EASTERN UNITED STATES WILL MAKE
FOR HIGH UNCERTAINTY IN THE TRACK OF TROPICAL SYSTEM ERIKA THROUGH
THE MEDIUM RANGE PERIOD. THERE IS REASONABLY GOOD CLUSTERING OF THE
MODEL SOLUTIONS IN THE VICINITY OF FLORIDA MON INTO TUE...BUT THEN
HIGH UNCERTAINTY BEYOND THAT. WILL THUS KEEP A MAINLY DIURNAL
PATTERN OF SLIGHTLY ABOVE CLIMO POPS GOING MON THROUGH THU GIVEN THE
ANTICIPATED MID ATLANTIC BLOCKING RIDGE AND POSSIBILITY OF GRADUALLY
INCREASING TROPICAL MOISTURE WITH THE ERIKA CIRCULATION...BUT WITH
HIGH UNCERTAINTY AT THIS POINT.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...VFR THROUGH THE PERIOD.  HIGH PRESSURE TO THE NORTH
WILL ALLOW DRIER CONDITIONS TO PERSIST DURING THIS TAF CYCLE.
INITIALIZED TAF WITH ENE WINDS WITH SOME ESE FLOW POSSIBLE THEREBY
SETTING UP CROSSWIND ISSUES AROUND THE 22Z-02Z TIMEFRAME THIS
AFTERNOON/EVENING.  OTHERWISE...HIGH LEVEL CIRRUS WILL PREVAIL
THROUGH THE OVERNIGHT BEFORE LLV MOISTURE ADVECTS IN FROM THE
SOUTH THUS POSSIBLY YIELDING A SCT/BKN STRATUS DECK AT 020-030.
HELD OFF ON ANY MVFR CIGS WITH A FORE MENTIONED STRATUS AS SOME
GUIDANCE HAS TRENDED A TAD DRIER.  EXPECTING ANY LOW STRATUS TO
PERSIST THROUGH DAYBREAK INTO MID/LATE MORNING BEFORE BL HEATING
ERODES SUCH GIVING WAY TO HIGH LEVEL CIRRUS ATOP LIGHT ENE FLOW.

ELSEWHERE...VERY SIMILAR TO THAT OF KCLT ABOVE HOWEVER WITH
BETTER CHANCES FOR MVFR RESTRICTIONS AT SITES FURTHER WEST WHERE
DEEPER LLV MOISTURE PLUME IS EXPECTED TO ADVECT IN BY MORNING.
THUS...INITIALIZED ALL TAFS VFR AT SCT 040-050 BEFORE IMPROVING TO
HIGH LEVEL CIRRUS AT 25K BY EARLY EVENING.  MODELS DO CONTINUE TO
HINT AT SOME FOG ISSUES IN AND AROUND THE MTN VALLEYS BY SATURDAY
MORNING...THUS DID INCLUDE...HOWEVER KEPT AT MVFR LEVELS FOR KAVL.
WINDS THROUGH THE PERIOD WILL REMAIN SE AT KAVL AND ENE/ESE FOR ALL
SC SITES AT AROUND 6-10KTS THIS AFTERNOON BEFORE CALMING TONIGHT.

OUTLOOK...CHANCES FOR DIURNALLY FAVORED SHOWERS AND THUNDERSTORMS
WILL CONTINUE TO INCREASE AS MOISTURE ADVECTS IN FROM THE SOUTHEAST
THROUGH THE WEEKEND YIELDING POSSIBLE RESTRICTIONS.  EARLY MORNING
STRATUS/FOG RESTRICTIONS COULD ALSO OCCUR FOR AREAS THAT RECEIVED
PREVIOUS RAINFALL LEADING TO ENHANCED MOISTURE IN THE BL.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   58%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     LOW   58%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     LOW   58%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%

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

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...CDG/NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...CDG



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