Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 020727
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
327 AM EDT THU OCT 2 2014

.SYNOPSIS...
DRIER HIGH PRESSURE WILL LINGER OVER THE REGION TODAY. A STRONG COLD
FRONT WILL SWEEP ACROSS THE CAROLINAS ON FRIDAY...THEN MOVING
OFFSHORE BY EARLY SATURDAY. IN THE WAKE OF THE FRONT...A COOL AND DRY
AIRMASS WILL MOVE BACK OVER THE REGION AND REMAIN IN PLACE OVER THE
WEEKEND. ANOTHER COLD FRONT WILL APPROACH THE SOUTHERN APPALACHIAN
REGION FROM THE NORTHWEST EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM...SOME FOG DEVELOPING ACROSS THE PIEDMONT...WITH MORE
FOG DEVELOPING IN EARNEST IN THE MTN VALLEYS. EXPECT MOST OF THE FOG
OUTSIDE THE MTNS TO REMAIN LIGHT...WHILE THE FOG SHOULD BE LOCALLY
DENSE IN THE MTN VALLEYS. THE FOG SHOULD REMAIN UNTIL AN HOUR OR SO
AFTER DAYBREAK. TEMPS LOOK OK.

THE MAIN CONCERN FOR THE NEAR TERM WILL BE THE APPROACH OF A COLD
FRONT DURING THE EARLY MORNING HOURS ON FRIDAY. BEFORE WE GET
THERE...ONE MORE SEASONALLY WARM EARLY AUTUMN DAY WITH MOSTLY CLEAR
SKY AND TEMPS ABOVE NORMAL. THE AXIS OF AN UPPER RIDGE WILL MOVE
OVERHEAD TODAY AND THEN OFF TO THE EAST THIS EVENING. THIS SHOULD
CARRY SURFACE HIGH PRESSURE OFF THE E COAST BY THE END OF THE DAY
THAT WILL SET THE STAGE FOR AN INFLUX OF GULF MOISTURE TONIGHT. THE
NAM CONTINUES TO DEVELOP A FEW SHOWERS UNDERNEATH A SUBSIDENCE
INVERSION AGAIN TODAY...AND ONCE AGAIN THAT LOOKS TO BE LARGELY
OVERDONE. WILL NOT RULE OUT ONE OR TWO ISOLATED SHOWERS SOMEWHERE
NEAR THE HIGHER TERRAIN...BUT THE POSSIBILITY REMAINS TOO LOW TO
INCLUDE IN THE FCST. AFTER MIDNIGHT TONIGHT...CONDITIONS WILL BECOME
INCREASINGLY FAVORABLE FOR THE DEVELOPMENT OF SHOWERS AS UPPER
DIVERGENCE ARRIVES WITH THE RIGHT ENTRANCE REGION OF THE JET
TRANSLATING EWD ACROSS THE SOUTHEAST. WARM ADVECTION AND MID LEVEL
DPVA WILL ALSO ARRIVE AFTER 06Z FRIDAY AS A PRELIMINARY SHORT WAVE
LIFTS OUT OF THE TROF AXIS TO THE WEST. THE INCREASING FORCING
SHOULD ACT UPON THE INFLUX OF MOISTURE TO DEVELOP SHOWERS TO THE
WEST THAT COULD ARRIVE OVER THE WESTERN MOUNTAINS AND NE GEORGIA/WRN
UPSTATE BY SUNRISE ON FRIDAY. WILL START TO RAMP UP PRECIP CHANCES
FROM THE W IN THE 09Z TO 12Z TIME FRAME. MIN TEMPS SHOULD BE MILD
WITH INCREASING CLOUD COVER AND WARM ADVECTION.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 315 AM THURSDAY...ON FRIDAY...A DEEP MID LEVEL CLOSED LOW WILL
TRACK SW THE WESTERN GREAT LAKE REGION. SOUTH OF THE LOW...THE AXIS OF
THE MID LEVEL TROUGH WILL DIG EAST ACROSS THE SOUTHEAST REGION. AT
THE SFC...A STRONG COLD FRONT WILL PUSH FROM MIDDLE TN 12Z FRIDAY TO
THE CAROLINA COAST BY 12Z SATURDAY. MID AND UPPER LEVEL FORCING WILL
INCREASE AS A SHORT WAVE AND BAND OF JET DIVERGENCE CROSSES THE
SOUTHERN APPALACHIANS AFTER 12Z FRIDAY. THE LOW LEVEL ENVIRONMENT
WILL FEATURE CAPES BETWEEN 500-1200 J/KG WITH HELICITY VALUES
BETWEEN 100-200 M2/S2. EHI VALUES SURGE NORTHWARD ACROSS THE REGION
AFTER MID MORNING...WITH VALUES EXCEEDING 1 M2/S2 ACROSS THE NC
PIEDMONT DURING THE MID AFTERNOON. THIS ENVIRONMENT SHOULD SUPPORT
THE DAYTIME PASSAGE OF A PRE FRONTAL BAND OF SHOWERS AND THUNDERSTORMS
ACROSS THE HIGH TERRAIN. I WILL INCREASE POPS TO CATE TO HIGH LIKELY
ACROSS THE CWA...ESPECIALLY FRIDAY AFTERNOON. GIVEN THE
ENVIRONMENT...IT IS POSSIBLE THAT WELL ORGANIZED QLCS COULD DEVELOP
FRIDAY AFTERNOON OR EVENING. HOWEVER...THE POSSIBILITY OF SVR
WEATHER APPEARS TOO LIMITED TO HIGHLIGHT IN THIS MORNINGS HWO.
TEMPERATURES WILL BE LIMITED BY THICK CLOUDS AND RAINFALL...HIGHS
SHOULD REMAIN AROUND 5 DEGREES BELOW NORMAL.

ON SATURDAY...STRONG H85 CAA WILL OCCUR ACROSS THE REGION...FALLING
FROM 15C OVER AVL AT 0Z TO 2C BY 12Z. LOW TEMPERATURES ARE FORECAST
TO RANGE FROM THE 40S ACROSS THE HIGH TERRAIN TO THE MID 50S ACROSS
THE PIEDMONT. HIGH TEMPERATURES WILL LIKELY RANGE 10 TO 12 DEGREES
BELOW NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...SUNDAY SHOULD SEE THE COOLEST TEMPERATURES
OF THE PERIOD. THE CENTER SFC HIGH PRESSURE IS FORECAST TO REACH THE
AL/GA LINE BY 12Z SUNDAY. CONDITIONS ACROSS THE REGION WILL FEATURE
DRY...CALM...AND LIMITED SKY COVER. IN ADDITION...CAA MAY PUSH H85
TEMPS ACROSS THE NRN MTNS FROM 0C TO -1C. SUNDAY MORNING...MINS IN
THE MID 30S SHOULD BE COMMON ACROSS MTN RIDGES. ELSEWHERE....VALUES
ARE FORECAST TO RANGE IN THE LOW TO MID 40S.

EARLY NEXT WEEK...THE CENTER OF HIGH PRESSURE WILL PUSH OFF THE
CAROLINA COAST AS A WEAK COLD FRONT APPROACHES FROM THE WEST. THIS
PATTERN SHOULD ADVECT WARMER TEMPERATURES AND MOISTURE ACROSS THE
SOUTHERN APPALACHIAN REGION. TEMPERATURES WILL MODIFY THROUGH THE
LATE EXTENDED PERIOD...RETURN TO NEAR NORMAL BY TUESDAY AND
WEDNESDAY. IN ADDITION...I WILL MENTION DEVELOPING WIDELY SCATTERED
SHOWERS ACROSS THE MTNS AND FOOTHILLS ON TUESDAY.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT...SCATTERED VFR STRATOCUMULUS EXPECTED FOR MUCH OF THE EARLY
MORNING HOURS AS VERY WEAK UPGLIDE DEVELOPS UNDER A MID LEVEL
INVERSION. AS EXPECTED...FOG WAS DEVELOPING IN THE OUTLYING AREAS
WHICH HAD REDUCED THE VISIBILITY TO MVFR/IFR...AND EXPECT THE FOG TO
EXPAND OVER THE PIEDMONT AS IT DID LAST NIGHT. SIMILAR TO LAST
NIGHT...THE RESTRICTION SHOULD RING KCLT...BUT THE FOG WILL HAVE A
DIFFICULT TIME DEVELOPING AT THE AIR FIELD. HAVE INCLUDED A TEMPO
FOR MVFR BASED ON THE LAMP GUIDANCE...BUT CONFIDENCE IS ONLY
MODERATE. OTHERWISE...EXPECT SCT CLOUDS TO REMAIN THROUGH THURSDAY
WITH A CONTINUED VERY LIGHT SRLY FLOW THROUGH THE END PERIOD.

ELSEWHERE...THE BIG PROBLEM WILL BE MOUNTAIN VALLEY FOG AT
KAVL...WHICH WAS ALREADY LIFR AT ISSUANCE TIME. EXPECT SOME
VARIABILITY TO THE FOG RESTRICTION THROUGH DAYBREAK...BUT GENERALLY
LIFR/VLIFR. OTHER TAF SITES MAY SEE A PERIOD OF MVFR VISIBILITY AND
THAT WAS INCLUDED. THE FOG SHOULD LIFT AND BURN OFF BY 13Z TO 14Z.
OTHERWISE...SCT/FEW HIGH BASED STRATOCU AGAIN THURSDAY WITH A LIGHT
WIND FROM THE S TO SW. ANY CLOUD UP WILL REMAIN W OF THE NC MTNS
THROUGH THE END OF THE TAF PERIOD.

OUTLOOK...A COLD FRONT WILL MOVE ACROSS THE AREA ON FRI WHICH WILL
TRIGGER SHOWERS AND THUNDERSTORMS...WITH ASSOCIATED RESTRICTIONS
POSSIBLE. BEHIND THE FRONT FRI NIGHT...CLEARING WILL OCCUR WITH AN
EXTENDED PERIOD OF VFR WEATHER ANTICIPATED THROUGH EARLY NEXT WEEK.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-07Z
KCLT       HIGH  97%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  97%     HIGH  97%     HIGH 100%     HIGH 100%
KAVL       MED   63%     HIGH  85%     HIGH 100%     HIGH 100%
KHKY       HIGH  97%     HIGH  97%     HIGH 100%     HIGH 100%
KGMU       HIGH  97%     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_TABLES

&&

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

&&

$$
SYNOPSIS...NED
NEAR TERM...PM
SHORT TERM...NED
LONG TERM...NED
AVIATION...PM





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