Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 310542
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1242 AM EST SAT JAN 31 2015

.SYNOPSIS...
IN THE WAKE OF A COLD FRONT...COOL HIGH PRESSURE WILL BUILD INTO
THE REGION AND LINGER THROUGH MOST OF THE WEEKEND. MOISTURE SHOULD
RETURN LATER SUNDAY AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM...
WITH THE ASSOCIATED COLD FRONT CROSSING THE REGION EARLY MONDAY.
COLD AND DRY HIGH PRESSURE WILL THEN SET UP THROUGH THE FIRST HALF
OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
1230 AM UPDATE...HIGH PRESSURE STILL BUILDING INTO THE REGION IS
MAINTAINING THE PRS GRADIENT ALONG THE MTN CHAIN. WINDS REMAIN GUSTY
AT THE OBS SITES...BUT EVEN ON THE ECONET MTN PEAK SITES THE WINDS
CAME DOWN BELOW ADVY CRITERIA BY MIDNIGHT. THE ADVISORY WAS ALLOWED
TO EXPIRE. SKIES REMAIN CLEAR AND TEMPS MORE OR LESS ON TRACK. HAVE
REVISED SKY AND WINDS THRU THE DAY TODAY...KEEPING SKIES CLEAR THRU
LATE MRNG WHEN MODEL PROGS INDICATE CIRRUS BEGIN TO INCREASE SLOWLY.

AS OF 230 PM EST FRIDAY...A TIGHT SURFACE PRESSURE GRADIENT OVER THE
REGION BETWEEN A LOW OFF THE MID-ATLANTIC COAST AND A 1035MB CP HIGH
CENTERED OVER THE MIDWEST HAS RESULTED IN GUSTY N/NW WINDS ACROSS
MUCH OF OUR CWA TODAY. STRONGER WIND GUSTS OF 40-50 MPH WILL
CONTINUE TO AFFECT THE NORTHERN NC MTNS THRU TONIGHT. HENCE...WILL
CONTINUE THE WIND ADVISORY FOR AVERY...MITCHELL AND YANCEY COUNTIES
THROUGH MID-NIGHT. THE WINDS SHOULD DIE DOWN TOWARDS THE LATE
EVENING AS THE PRESSURE GRADIENT RELAXES OVER THE AREA. ANY
LINGERING SNOW SHOWERS ALONG THE TN LINE SHOULD TAPER OFF THRU THE
LATE AFTERNOON HOURS AS APPRECIABLE LLVL DRYING CONTINUES. WITH
STOUT CAA NWLY FLOW...OVERNIGHT TEMPS WILL DROP INTO THE 10S/LOW20S
ACROSS THE MTS/VALLEY ZONES...L20/M20S OVER THE NC PIEDMONT/EASTERN
UPSTATE SC AND M20/U20S ELSEWHERE.

TOMORROW...A RATHER FLAT UPPER RIDGE WILL BUILD IN FROM THE WEST
ALLOWING THE SURFACE HIGH TO SETTLE ACROSS THE REGION.
THEREFORE...WE WILL SEE CONTINUED DRY WEATHER AND TEMPS SHOULD STAY
3-5 DEGREES BELOW NORMAL FOR MOST LOCATIONS. MOSTLY CLEAR SKIES
TOMORROW MORNING WILL GIVE WAY TO PARTLY TO MOSTLY CLOUDY SKIES
TOWARDS THE LATE AFTERNOON AS CONSIDERABLE MID/HIGH CLOUDS AHEAD OF
AN APPROACHING UPPER TROUGH FROM THE ROCKIES OVERSPREAD THE AREA.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 245 PM FRIDAY...SHORT RANGE MODELS INDICATE THAT LOW PRESSURE
WILL LIKELY ORGANIZE ACROSS THE CENTRAL MISSISSIPPI RIVER VALLEY
SUNDAY MORNING. MOISTURE IS EXPECTED TO INCREASE FROM THE TOP DOWN
SUNDAY AM...BUT FORCING AND MOISTURE APPEAR TOO LIMITED TO SUPPORT
MEASURABLE PRECIP BEFORE MID MORNING. BASED ON A BLEND OF THE
MODELS...I WILL INCREASE RAPIDLY INTO THE LIKELY RANGE BY MID
DAY...REACH CATE ACROSS THE MTNS BY EVENING. THE TIMING OF THE POPS
SHOULD ALLOW FREEZING MORNING TEMPERATURES TO WARM WELL ABOVE
FREEZING BEFORE PRECIP ONSET. HIGH TEMPERATURES ON SUNDAY SHOULD
RANGE FROM MID 40S TO NEAR 50 ACROSS THE MTNS TO LOW 50S EAST.

SUNDAY NIGHT...THE CENTER OF THE LOW IS TIMED TO PASS ACROSS THE MID
ATLANTIC STATES AROUND DAYBREAK. A STRONG COLD FRONT ASSOCIATED WITH
THE LOW IS FORECAST TO SWEEP EAST ACROSS THE CWA EARLY MONDAY. EAST
OF THE FRONT...TEMPERATURES ACROSS THE MTNS SHOULD REMAIN ABOVE
FREEZING SUNDAY NIGHT...SUPPORTING GENERALLY RAINFALL.
HOWEVER...STRONG CAA BEHIND THE FRONT SHOULD RESULT IN A FAST
TRANSITION TO SNOW AROUND SUNRISE MONDAY. IN FACT...TEMPERATURES
ACROSS THE MTNS ARE FORECAST TO CONTINUE TO FALL THROUGH THE
DAYLIGHT HOURS. THE PRECIP WILL BECOME SUPPORTED BY MOIST AND COLD
NW WINDS ALONG THE TN BORDER BY MID DAY MON. AREAS EAST...SHOULD
EXPERIENCE STRONG DOWNSLOPING FLOW WITH DECREASING MOISTURE. IT
APPEARS THAT THE BEST OVERLAP OF MOISTURE...WINDS...AND SNOW
SUPPORTING TEMPERATURES WILL OCCUR DURING THE EARLY DAYLIGHT
HOURS...THEN GRADUALLY DECREASE THROUGH THE REST OF THE DAY. THE
LATER ARRIVE OF COLD AIR WILL RESULT IN A DECREASE IN STORM TOTAL
SNOWFALL...HOWEVER...WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 255 PM FRIDAY...THERE IS GOOD AGREEMENT AT THE START OF THE
PERIOD AS COLD AND DRY HIGH PRESSURE BUILDS INTO THE AREA TUE. BELOW
NORMAL TEMPS ARE EXPECTED.

AFTER TUESDAY...CONFIDENCE DROPS SIGNIFICANTLY. GUIDANCE STILL SHOWS
A PATTERN WHERE AN UPPER LOW OVER THE BAJA PENINSULA OPENS UP AND
MOVES TOWARD THE SERN CONUS IN THE SRN STREAM FLOW TOWARD MID-
WEEK...WHILE A SHORT WAVE DROPS INTO ACROSS THE AREA IN THE NRN
STREAM FLOW TOWARD THE END OF THE PERIOD. HOWEVER...THE SFC PATTERN
DIFFERS GREATLY WITH THE GFS BRINGING A MILLER-A TYPE LOW TO THE FL
PANHANDLE GULF COAST WED AND MOVING TO CAPE HATTERAS WED NITE...
BRINGING WIDESPREAD MOISTURE AND PRECIP TO THE AREA. THE LOW MOVES
NE AWAY FROM THE AREA THU...AS COLD HIGH PRESSURE BUILDS IN FROM THE
NE THRU FRI. LOW LEVEL MOISTURE AND ISENTROPIC LIFT OVER THE
DEVELOPING CAD THEN PRODUCE WIDESPREAD PRECIP ACROSS THE AREA FROM
LATE THU INTO FRI MORNING. THE ECMWF ON THE OTHER HAND...HAS A GULF
LOW. HOWEVER...IT IS MUCH FARTHER SOUTH...KEEPING ANY MOISTURE AND
PRECIP WELL SOUTH OF THE CWFA. IT BRINGS A COLD FRONT ACROSS THE
AREA THU...WITH MAYBE SOME NW FLOW PRECIP...BUT MAINLY A MUCH COLDER
AIR MASS. THE GEFS ENSEMBLE MEAN DOES HAVE PRECIP DURING THIS
TIME...BUT IT IS LIMITED TO THE LOW CHC RANGE. THEREFORE...HAVE
TAKEN THIS TRACK AND LIMITED POP TO LOW CHC FOR LATE WED AND WED
NITE...WITH SLIGHT CHC ON THU. PRECIP IS LATE ENUF AND TEMPS ARE
WARM ENUF FOR THE WED PRECIP TO BE MAINLY RAIN. TEMPS ARE COLD ENUF
ON THE BACK SIDE OF THE PRECIP TO BE SNOW...BUT PRECIP ENDING WOULD
LIMIT ANY SNOW OUTSIDE OF THE MTNS. TEMPS WILL BE NEAR NORMAL WED
AND THU...BUT BACK BELOW NORMAL FOR FRI.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...VFR THRU THE PERIOD. AS HIGH PRESSURE
CONTINUES TO BUILD INTO THE REGION EARLY THIS MRNG THE PRESSURE
GRADIENT WILL BE FAIRLY STRONG ACRS THE MTNS. THE SETUP IS FAVORABLE
FOR A GUSTY GAP WIND AT KAVL AND TO AT LEAST KEEP KGSP/KGMU WITH A
LIGHT NORTHERLY BREEZE THRU SUNRISE. WINDS WILL REMAIN LIGHT AND
MOSTLY BACK INTO THE SW QUAD DURING THE DAY...BUT KAVL WILL INSTEAD
SEE SOME VARIABILITY AND EVENTUALLY PREVAIL NW. CIRRUS WILL SLOWLY
SPREAD IN AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. CALM WINDS
PREVAIL BY LATE TONIGHT.

OUTLOOK...MOISTURE BEGINS TO RETURN SUNDAY AHEAD OF ANOTHER LOW
PRESSURE SYSTEM...WHICH IS LIKELY TO BRING PRECIP AND RESTRICTIONS.
DRYING IS EXPECTED BY LATE MONDAY IN THE WAKE OF THAT SYSTEM.
ANOTHER MOIST LOW PRES SYSTEM MAY AFFECT THE REGION DURING THE
MIDDLE OF NEXT WEEK.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  94%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     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_TABLES

&&

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

&&

$$
SYNOPSIS...CSH
NEAR TERM...JOH/WIMBERLEY
SHORT TERM...NED
LONG TERM...RWH
AVIATION...WIMBERLEY


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