Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 311749
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
149 PM EDT MON AUG 31 2015

.SYNOPSIS...
HIGH PRESSURE WILL LINGER ACROSS THE REGION EARLY THIS WEEK. WEAK
DISTURBANCES MAY RIPPLE ACROSS THE LOWER AND MIDDLE APPALACHIAN
REGION BY MID TO LATE WEEK. A COOL AND MOIST AREA OF HIGH PRESSURE
IS EXPECTED TO SETTLE ACROSS THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA THIS WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 145 PM EDT...I HAVE UPDATED THE SKY AND POP FOR THE REST OF
THE DAY TO MATCH UP WITH LATEST TRENDS ON VIS SAT IMAGERY. IT LOOKS
LIKE THE MID LVL INVERSION MAY BE ENUF TO SUPPRESS DEEP
CONVECTION...EVEN IN THE SW NC MTNS. WHILE THE PIEDMONT LOOKS STABLE
AND POPS HAVE BEEN REDUCED. TEMPS LOOK ON TRACK.

AS OF 1030 AM EDT...CLOUDS HAVE BEEN CLEARING OUT THIS MORNING...AS
DRY AIR FILTERS IN FROM THE NORTH. THERE IS STILL ENUF LLVL MOISTURE
TO SUPPORT A DECENT FAIR WX CU DECK TODAY. BASED ON THE CURRENT
TRENDS AND LATEST GUIDANCE...THE FCST IS ON TRACK. THE BIGGEST
CHANGE WAS TO DECREASE SKY COVER...WHICH MAY CHANGE WORDING TO
MOSTLY SUNNY TO PARTLY SUNNY TODAY. AS FOR CONVECTION CHANCES THIS
AFTN...THE GUIDANCE AND CONVECTION ALLOWING MODELS AGREE ON IT BEING
CONFINED TO THE HIGH TERRAIN...AND MAINLY JUST ISOLD TO WIDELY
SCATTERED SHWRS. CANNOT RULE OUT A FEW SHWRS OUTSIDE THE MTNS...AS
THE 12Z FFC SOUNDING SHOWS A MID LVL INVERSION AROUND 550 MB...WHICH
MAY ALLOW FOR SHALLOW CONVECTION.

AS OF 700 AM EDT...REGIONAL RADARS SHOW ALL THE PRECIPITATION
ASSOCIATED WITH THE DEPARTING VORT LOBE NORTH AND EAST OF THE AREA.
HOWEVER...PLENTY OF LOW LEVEL MOISTURE IS LINGERING...WITH RATHER
PERSISTENT STRATUS EXPECTED OVER THE PIEDMONT AND PARTS OF THE
FOOTHILLS AND THE MOUNTAINS VALLEYS THROUGH THE MORNING HOURS.
LITTLE TO NO FORCING IS EXPECTED TODAY WITH MAINLY LIGHT SW FLOW
ALOFT BETWEEN A TROUGH NEAR THE MS RIVER VALLEY AND AN OFFSHORE
ATLANTIC RIDGE. ANY BETTER TROPICAL MOISTURE SHOULD ALSO REMAIN
SHUNTED TO THE COASTAL REGION. ANY ISOLD TO SCATTERED WEAK
CONVECTION TODAY SHOULD BE CONFINED MOSTLY TO THE HIGHER TERRAIN FOR
THE AFTN AND EVENING HOURS...WITH A SLIGHT SECONDARY MAXIMA POSSIBLE
IN THE ERN PIEDMONT CLOSER TO THE DEEPER COASTAL MOISTURE. PROFILES
DO NOT EXHIBIT MUCH INSTABILITY GIVEN THE EXPECTED WARM MID LEVEL
TEMPERATURES. ANOTHER ROUND OF LOW STRATUS WILL BE POSSIBLE
TONIGHT...MOST LIKELY IN THE MOUNTAIN VALLEYS. EXPECT MAXES TO REACH
NEAR CLIMO THIS AFTN ONCE THE STRATUS SCATTERS...BUT WITH MINS 1 TO
2 CATEGORIES ABOVE CLIMO TONIGHT.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 230 AM MONDAY...ON TUESDAY...THE CWA WILL REMAIN UNDER THE
WESTERN EDGE OF A DIRTY 592 DM RIDGE. FORECAST SOUNDINGS SHOWS A
LAYER OF NEARLY SATURATED AIR BETWEEN H8-H7...UNDER A WELL DEFINED
H65 INVERSION. I WILL FORECAST PARTLY TO MOSTLY CLOUDY CONDITIONS
THROUGH THE DAY. USING A BLEND OF PREFERRED MOS...HIGH TEMPERATURES
SHOULD RANGE FROM THE L80S WITHIN THE MTN VALLEYS TO UPPER 80S
EAST...VIRTUALLY NEAR NORMALS. HOWEVER...CAPES ACROSS THE REGION
SHOULD PEAK NEAR VALUES OF 1000 J/KG...WITH CIN LINGERING WELL INTO
THE AFTERNOON. PROVIDED FLOW LESS THAN 10 KTS FROM THE SFC TO 15
KFT...STORM MOTIONS AND CONVERGENCE WILL REMAIN LIMITED. I WILL
FORECAST DIURNAL CHC POPS ACROSS THE MTNS AND ADJACENT FOOTHILLS
WITH SCHC VALUES EAST.

ON WEDNESDAY...SHORT RANGE MODELS INDICATE THAT THE CWA WILL FALL
WITHIN A WEAKNESS WITHIN THE MID LEVEL RIDGE. IN FACT...A S/W IS
EXPECTED TO RIPPLE ACROSS THE MID APPALACHIANS DURING THE
AFTERNOON....POSSIBLY BRUSHING THE REGION WITH MID LEVEL FORCING.
NAM FORECAST SOUNDINGS INDICATE THE CAPE VALUES WILL INCREASE TO
1500-2000 J/KG BY THE HEAT OF THE AFTERNOON. IN ADDITION...HIGH
TEMPERATURES ARE FORECAST TO RISE AROUND 2 DEGREE ABOVE VALUES
EXPECTED FOR TUESDAY. GIVEN THE LARGE FIELD OF INSTABILITY AND
PASSING DISTURBANCE ACROSS THE MID APPALACHIANS...A BROKEN BAND OF
TSRA MAY DEVELOP OVER THE VA/WV DURING THE AFTERNOON...SPREADING SE
DURING THE LATE AFTERNOON AND EVENING. I WILL FORECAST CHC POPS
ACROSS THE MTNS AND NC FOOTHILLS...WITH SCHC EAST OF I-85.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
AS OF 310 AM MONDAY...MID LEVEL HEIGHTS ARE FORECAST TO DECREASE
ACROSS THE CWA DURING THE EXTENDED PERIOD. BY THE END OF THE
WEEK...THE CENTER OF A 595 DM RIDGE WILL SETTLE OVER THE NORTHEAST
CONUS...WITH A BROAD WEAKNESS OVER THE SOUTHEAST. THIS PATTERN
SHIFT WILL PROVIDE NEAR NORMAL TEMPERATURES DURING THE
WEEKDAYS...WITH A COOLING TREND DURING THE WEEKEND. I WILL
FORECAST SCHC TO CHC DIURNAL POPS WEDNESDAY THROUGH FRIDAY FOR
SHOWERS/THUNDERSTORMS...COVERAGE FAVORING THE MTNS. HOWEVER...THE
SFC PATTERN BY SAT NIGHT...ESPECIALLY ON THE 0Z GFS...APPEARS TO
SHOW A DEVELOPING AREA OF CAD. THE GFS INDICATES THAT BROAD AND
WEAK ISENTROPIC LIFT AND UPSLOPE FLOW WILL BE POSSIBLE ACROSS THE
REGION ON SUNDAY. I DID NOT WANT TO SINK HIGH TEMPS TO CAD
LEVELS...BUT DID ADJUST A LITTLE COOLER. IN ADDITION...I HAVE
MOSTLY CLOUDY CONDITIONS THROUGH MOST OF THE WEEKEND. POPS WILL
REMAIN IN THE CHC RANGE EACH DAY THIS WEEKEND.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...A STRATOCU DECK HAS DEVELOPED ACRS THE KCLT AREA...WITH
BASES GRADUALLY LIFTING ABOVE MVFR RANGE BY 18Z. THE FCST SNDGS SHOW
THE CLOUDS SETTLING AROUND 4000 FT BY MIDAFTERNOON. FROM
THERE...GUIDANCE DIVERGES...WITH SOME KEEPING POTENTIAL LOW CLOUDS
AROUND THRU TONIGHT...WITH BASES LOWERING BACK TO MVFR. WHILE OTHERS
INDICATE MOST OF THE CLOUDS DISSIPATING AFTER SUNSET. GIVEN THE WEAK
FLOW AND EXPECTED LACK OF PRECIP TODAY...I LEANED TOWARD LESS
CLOUDS. HOWEVER...TOWARD DAYBREAK TUESDAY...STRATUS MAY DEVELOP IF
THERE IS ENUF FLOW/MOISTURE TO ALLOW DEVELOPMENT. I KEPT A FEW020
AROUND 10Z TO SHOW THAT POSSIBILITY. THE WINDS WILL BE LIGHT THRU
THE PERIOD...SO THERE IS ALSO SOME FOG POTENTIAL TUE MORNING.
OTHERWISE...VFR CONDITIONS ARE EXPECTED.

ELSEWHERE...THE UPSTATE SITES ARE MOSTLY CLEAR WITH LIGHT WINDS AT
TIME OF TAF ISSUANCE...WHILE MORE CLOUDS CAN BE SEEN OVER KAVL AND
KHKY (WITH BASES AROUND 4000-5000 FT). TONIGHT...I EXPECT MOST OF
THE CUMULUS CLOUDS TO DISSIPATE...LEAVING MOSTLY CLEAR SKIES WITH
LIGHT TO CALM WINDS. ENUF MOISTURE MAY EXIST FOR FOG AND STRATUS
POTENTIAL AGAIN TOWARD DAYBREAK...MAINLY AT KAVL. THE ATMOSPHERE IS
ONLY WEAKLY UNSTABLE IN THE MTNS...SO WHILE A FEW SHRA OR TSRA MAY
DEVELOP...I LEFT OUT ANY MENTION FROM THE KAVL TAF.

OUTLOOK...A PLUME OF GULF AND ATLANTIC MOISTURE WILL CONTINUE TO
WRAP UP ALONG THE SE COAST...GENERALLY JUST SOUTHEAST OF THE
TERMINAL FORECAST AREA...THROUGH THE WEEK. RESTRICTIONS ARE POSSIBLE
DURING PERIODS OF ANY SCATTERED SHOWERS OR THUNDERSTORMS. IN
ADDITION...LOW CLOUDS AND FOG MAY DEVELOP EACH NIGHT...ESPECIALLY IN
THE MOUNTAIN VALLEYS.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  83%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH  83%     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 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...NED
NEAR TERM...ARK/HG
SHORT TERM...NED
LONG TERM...NED
AVIATION...ARK


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.