Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 230830
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
430 AM EDT WED APR 23 2014

.SYNOPSIS...
DRY HIGH PRESSURE WILL BUILD OVER THE AREA TODAY AND LINGER THROUGH
THURSDAY. A WEAK COLD FRONT WILL CROSS THE FORECAST AREA ON
FRIDAY...WITH A REINFORCING FRONT STALLING IN THE VICINITY OF THE
REGION OVER THE WEEKEND. A WET AND POSSIBLY STORMY PATTERN WILL SET
UP FOR EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 430 AM...FOR THE 0830 UTC UPDATE...THE COLD FRONT HAS PUSHED
INTO THE FOOTHILLS...AND SHUD CROSS THE I-85 CORRIDOR WITHIN THE
NEXT HOUR OR SO. I UPDATED THE TEMP/DWPT/WIND/WX GRIDS THRU DAYBREAK
TO MATCH UP WITH THE TRENDS.

AS OF 300 AM...THE COLD FRONT IS FINALLY SHOWING SIGNS OF CROSSING
THE NC MTNS...AS KAVL HAS A NW WIND. EAST OF THE MTNS...PATCHY FOG
CONTINUES TO INCREASE IN COVERAGE...AND EVEN LOCALLY DENSE IN A
COUPLE SPOTS. I STILL EXPECT THE DRY AIR AND CAA TO WIN OUT...AND NO
WIDESPREAD DENSE FOG IS EXPECTED.

TODAY...DEEP LAYER NWLY FLOW WILL RESULT IN A SUNNY DAY WITH
SEASONABLE TEMPS. DRY SFC HIGH PRES FILTERS IN FROM THE
NORTH...WHICH WITH A LITTLE MIXING...WILL DROP DWPTS INTO THE 20 AND
30S...RESULTING IN CRITICAL RH ACRS MOST OF THE AREA. GUSTY NW WINDS
WILL LINGER INTO THE AFTN ACRS THE NC ZONES...SO THE FIRE DANGER
STATEMENT LOOKS GOOD.

TONIGHT...THE AXIS OF SFC HIGH PRES WILL SETTLE ACRS THE SOUTHERN
APPALACHIANS...WHILE A LITTLE BIT OF NE FLOW WILL LINGER ACRS THE
PIEDMONT. MOS GUIDANCE HINTS AT TEMPS IN THE MID 30S ACRS MUCH OF
THE NC MTNS AND NORTHERN FOOTHILLS. RADIATIONAL COOLING CONDITIONS
LOOK GOOD...SO FROST WILL BE MENTIONED IN THE THESE AREAS.
HOWEVER...THERE IS STILL ENUF UNCERTAINTY ON THESE MIN TEMPS TO HOLD
OFF ON A FROST ADVISORY UNTIL THE DAY SHIFT CAN ASSESS THE LATEST
GUIDANCE.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 230 AM EDT WED...500 MB RIDGING WILL CROSS THE FORECAST AREA
ON THU AS WEAK SFC HIGH PRES MOVES OFFSHORE. SRLY RETURN FLOW
MOISTURE WILL GRADUALLY DEVELOP AT LOW LEVELS BY LATE DAY AND THEN
IMPROVE AND DEEPEN THROUGH THU NIGHT. MEANWHILE...A DEAMPLIFYING
UPPER WAVE EXTENDING SWD FROM A GREAT LAKES H5 LOW CENTER WILL SWING
EASTWARD AND CROSS THE APPALACHIANS FRI MORNING. A WEAK SURFACE COLD
FRONT ASSOCIATED WITH THIS SYSTEM WILL CROSS THE WRN HALF FRI
MORNING AND THEN GENERALLY CLEAR ERN SECTIONS MID AFTN. ALTHOUGH
MOISTURE AND LIFT WITH THE FRIDAY SYSTEM ARE EXPECTED TO DECAY EAST
OF THE MTNS...SFC BASED CAPE VALUES OF 1000 TO 1500 J/KG WILL BE
POSSIBLE ACROSS PIEDMONT SECTIONS FRI AFTN. SFC TO 3 KM SHEAR VALUES
SHOULD BE FAIRLY UNIMPRESSIVE AT 20 TO 30 KT...WHICH WOULD LIMIT THE
SEVERE THUNDERSTORM POTENTIAL. MAX TEMPS WILL BE A COUPLE OF DEGREES
BELOW CLIMO MOST AREAS THU AFTN...BUT ABOUT A CATEGORY OR BETTER
ABOVE CLIMO ON FRI.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM EDT WED...A FLAT FLOW REGIME OVER THE CENTRAL/ERN CONUS
EARLY SAT WILL GIVE WAY TO AN AMPLIFIED FLOW PATTERN LATE IN THE
WEEKEND AS A CLOSED SYSTEM MOVES FROM THE ROCKIES TO THE PLAINS. A
BACKDOOR COLD FRONT APPROACHING FROM THE N ON SAT WILL LIKELY STALL
SOMEWHERE IN OR NEAR THE FORECAST AREA ON SUNDAY. W TO NW DOWNSLOPE
FLOW AHEAD OF THE BACKDOOR FRONT SHOULD KEEP MOST OF THE AREA DRY
SAT...BUT WITH MAINLY MTN POPS ENCROACHING ON SUNDAY AFTN IN
DEVELOPING SRLY FLOW. EXPECT MAXES TO RUN 1 TO 2 CATEGORIES ABOVE
NORMAL.

THE PINWHEELING PLAINS SYSTEM WILL GRADUALLY MIGRATE EWD MON THROUGH
TUE. IT DOES NOT APPEAR THAT THE LINGERING SFC HIGH TO THE N EARLY
IN THE WEEK WILL BE STRONG ENOUGH TO CREATE MUCH CAD UNDER THE
RETURNING MOISTURE. ANY WEAK CAD WOULD BE POSSIBLE MAINLY MON...BUT
WITH MOST OF THE REGION MORE SOLIDLY INTO THE WARM SECTOR BY
TUESDAY...WITH CONSIDERABLE INSTABILITY RESULTING. THE SLOWLY MOVING
BLOCKED PATTERN COULD PRODUCE ABUNDANT RAINFALL THROUGH MID WEEK.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
KCLT...ONLY A TRACE OF RAIN WAS REPORTED AT THE TERMINAL ASOS THIS
EVENING...SO CONFIDENCE ON GROUND FOG DEVELOPMENT IS LOW. THE DEWPT
DEPRESSION AT TIME OF 06Z TAF ISSUANCE WAS 2F...AND WINDS ARE LIGHT
WITH CLEAR SKIES. WITH THAT SAID...DRIER AIR IS WORKING IN ACRS THE
NC PIEDMONT...AND A COLD FRONT SHUD PUSH THRU BEFORE DAYBREAK. SO
WHILE FOG IS POSSIBLE...I THINK CHANCES ARE TOO LOW TO PUT IN THE
TAF. TRENDS WILL BE MONITORED CLOSELY...HOWEVER. OTHERWISE...IT SHUD
BE A QUIET TAF PERIOD...WITH CLEAR SKIES AND A LIGHT NW WIND THAT
MAY APPROACH 10 KTS THIS AFTN.

ELSEWHERE...BASED ON THE LIGHT RAIN THAT FELL YESTERDAY...ONLY KGSP
SEEMS TO HAVE THE RIGHT CONDITIONS FOR GROUND FOG AT THE TERMINAL.
THE OTHER SITES HAVE DEWPT DEPRESSIONS 4-10F...EXCEPT 2F AT KAVL.
HOWEVER...A COLD FRONT SHUD PUSH THRU OVERNIGHT...AND ADVECT DRY AIR
AND SOME MIXING...ESP AT KAVL WHERE CHANNELED VALLEY WINDS SHUD PICK
UP TO ABOUT 10 KTS WITH GUSTS BY DAYBREAK. KAVL WAS CALM AT TIME OF
TAF ISSUANCE...SO A BRIEF PERIOD OF FOG CANNOT BE RULED OUT...BUT
CONFIDENCE TOO LOW TO MENTION IN THE TAF. OTHERWISE...VFR CONDITIONS
ARE EXPECTED WITH NW WINDS.

OUTLOOK...DRY HIGH PRES WILL DOMINATE THRU THU. ANOTHER COLD FRONT
WITH POTENTIAL FOR SHOWERS/TSTMS IS THEN EXPECTED TO CROSS THE
REGION FRIDAY...DRYING OUT BY SATURDAY.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-08Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  85%     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  83%     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_TABLES

&&

.FIRE WEATHER...
A DRY AND SEASONABLY WARM AIR MASS WILL MOVE INTO THE AREA TODAY
BEHIND A DEPARTING COLD FRONT. THE COMBINATION OF WARM TEMPERATURES
AND LOW DEW POINTS WILL LEAD TO RELATIVE HUMIDITY VALUES AT OR BELOW
25 PERCENT ACROSS MOST OF THE AREA. GUSTY NORTHWEST WINDS WILL
LINGER THIS MORNING INTO THE AFTN ACROSS THE MTNS NC PIEDMONT. WITH
ONLY LIGHT PRECIPITATION YESTERDAY...FUELS SHOULD QUICKLY DRY OUT
TODAY. A FIRE DANGER STATEMENT WAS COORDINATED WITH LAND MANAGERS
YESTERDAY...AND NO CHANGES WERE MADE TO THAT THIS MORNING.

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...ARK
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK
FIRE WEATHER...






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