Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 300604
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
204 AM EDT MON MAR 30 2015

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE SOUTHEAST COAST TONIGHT. A LOW
PRESSURE CLIPPER SYSTEM AND ASSOCIATED COLD FRONT WILL THEN PASS
OVER THE AREA EARLY MONDAY MORNING. HIGH PRESSURE WILL RETURN FOR
MIDWEEK...WITH ANOTHER COLD FRONT APPROACHING THE REGION BY THE END
OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 530 AM...WE ARE SEEING AN INCREASE IN PRECIP COVERAGE TO THE
WEST WHERE THE FRONTAL BOUNDARY WAS INTERCEPTING THE STRONGER LOW
LEVEL JET AND MOISTURE PLUME ACROSS TN/NRN MS. A FEW SHOWERY
ELEMENTS WERE NOTED OVER ERN TN...BUT THIS WAS PROBABLY NOT REACHING
THE GROUND. WILL PUT OFF THE ONSET OF PRECIP FOR ANOTHER HOUR OR
TWO...WHICH HAS THE ADDED BENEFIT OF ALLOWING WARM ADVECTION TO
BRING THE TEMPS UP ABOVE FREEZING AT THE PEAKS OF THE NC MTNS. ALL
INDICATIONS REMAIN THAT PRECIP WILL IN FACT BLOSSOM TO THE WEST THRU
THE PRE-DAWN HOURS AND REACH THE WESTERN CAROLINAS BY/AROUND
DAYBREAK. WE SHALL SEE. SOME SKEPTICISM REMAINS.

REMAINDER OF PREVIOUS DISCUSSION...

THE SHORT TERM AND CONVECTION ALLOWING MODELS CONTINUE TO INDICATE
CONVECTION WILL EXPAND QUICKLY ACROSS PORTIONS OF THE MISS AND TENN
VALLEYS OVER THE NEXT FEW HOURS...AS COLD FRONT/ASSOCIATED UPPER
LEVEL VORT MAX INTERACTS WITH A LOW LEVEL JET/INCR WAA AND AN AXIS
OF INSTABILITY EXTENDING E/NE FROM THE ARKLATEX. CLOSER TO HOME...
THE NEXT SHIFT WILL NEED TO WATCH FOR THE POTENTIAL FOR SOME ISLD
ELEVATED CONVECTION TO SNEAK INTO THE AREA AS THE FRONT PUSHES IN
TOWARD DAYBREAK...AS THE 00Z NAM DEPICTS SOME WEAK MUCAPE OVER THE
AREA. HOWEVER...IT HAS A HABIT OF OVERDOING THIS...SO WILL MAINTAIN
PRECIP CHARACTER AS SHOWERS FOR NOW. IN THE INTERIM...A CONSENSUS OF
MODEL GUIDANCE HAS AN OK HANDLE ON THE VERY DRY NATURE OF THE AIR
MASS OVER THE AREA THIS EVENING. AS OF 02Z...SURFACE WET BULBS WERE
AT OR BELOW ZERO ACROSS A GOOD CHUNK OF THE MTNS. THIS IS A BIT
LOWER THAN DEPICTED BY THE SHORT TERM MODELS...BUT NOT EGREGIOUSLY
SO. A SLIGHT WARMING HAS ALSO BEEN NOTED IN THE HIGH ELEVATIONS OVER
THE PAST COUPLE OF HOURS...AND THIS TREND WILL CONTINUE AS WARM
ADVECTION GRADUALLY INCREASES. THEREFORE...IT APPEARS THAT SEVERAL
HOURS OF SLOW WARMING IS IN STORE FOR THE MTNS BEFORE PRECIP
ARRIVES...AND THE OVERWHELMING PREPONDERANCE OF EVIDENCE INDICATES
PRECIP SHOULD REMAIN IN THE FORM OF LIQUID MONDAY MORNING.

PEAK FORCING APPEARS TO OCCUR OVER THE PIEDMONT AROUND 12-14Z...AND
POPS SHOULD QUICKLY TRAIL OFF AS THE FRONT DEPARTS THRU THE REST OF
THE MRNG. WEAK UPSLOPE FORCING WILL PROLONG THE PRECIP CHANCES ALONG
THE TENN BORDER...BUT BY MID AFTN ALL PRECIP SHOULD HAVE COME TO AN
END. WINDS FLIPPING TO NWLY...AND THUS DOWNSLOPE...AS WELL AS
CLEARING SKIES SHOULD ALLOW TEMPS TO RISE TO NEAR NORMAL FOR AFTN
MAXES.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
AS OF 230 PM EDT SUNDAY...SFC HIGH PRESSURE WILL BUILD BRIEFLY OVER
THE SRN APPALACHIANS MON NIGHT BEFORE MOVING OFF THE SE COAST
THROUGH TUE. RADIATIONAL COOLING CONDITIONS WILL LIKELY BECOME
FAVORABLE ENOUGH FOR NEAR FREEZING TEMPERATURES IN PARTS OF THE
CENTRAL AND SRN MOUNTAINS...WHERE THE FROST/FREEZE SEASON IS NOW
ACTIVE. AN HWO MENTION OF POTENTIAL FREEZING TEMPERATURES WILL BE
ADDED FOR TUESDAY MORNING IN THIS AREA. OTHERWISE...DEEP LAYER NW
FLOW WILL SET UP OVER THE REGION ON TUESDAY. MAX TEMPS WILL REBOUND
TO ABOUT A CATEGORY ABOVE CLIMO TUE AFTN.

A BACKDOOR COLD FRONT WILL PUSH SWD THROUGH THE VIRGINIAS TUESDAY
NIGHT AND ENTER THE NRN TIER OF THE FORECAST AREA ON WED. WEAK
UPGLIDE MOISTURE MAY SET UP FROM THE SW ON WED...BUT WILL PROBABLY
NOT PROVIDE ENOUGH QPF TO ALLOW ANY SHALLOW COLD AIR DAMMING TO GET
ESTABLISHED. ANY INSTABILITY WED AFTN SHOULD BE LIMITED TO THE SW
HALF IN THE BETTER DEWPOINT AIR...BUT NO THUNDER WILL BE FEATURED AT
THIS POINT. TEMPS WILL LIKELY RECOVER ANOTHER DEGREE ON TWO OVER TUE
VALUES...BUT THE NRN TIER COULD BE COOLER IF ANY CAD FORMS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EDT SUNDAY...ON WEDNESDAY EVENING A LOW AMPLITUDE UPPER
RIDGE WILL BE OVER THE GREAT LAKES...WITH TROUGHS OVER THE WESTERN
ATLANTIC AND WESTERN USA. NEARLY ZONAL FLOW WILL EXIST OVER THE
SOUTHERN TIER OF STATES...WITH A SHORTWAVE CROSSING THE SOUTHERN MS
RIVER VALLEY. THE UPPER RIDGE MOVES TO THE EAST COAST LATE
THURSDAY...WHILE THE SOUTHERN STREAM SHORTWAVE CROSSES THE SOUTHERN
APPALACHIANS. ON FRIDAY THE TROUGH UPSTREAM MOVES TO THE CENTER OF
THE NATION...BUT UPPER FLOW REMAINS ZONAL ACROSS THE SOUTHERN TIER
OF STATES. THE NORTHERN STREAM TROUGH AMPLIFIES ALONG THE EAST COAST
ON SATURDAY...THEN MOVES OFF THE COAST ON SUNDAY WHILE A LOW
AMPLITUDE RIDGE CROSSES THE PLAINS.

AT THE SURFACE...ON THURSDAY HIGH PRESSURE WILL BE OFF THE EAST
COAST...WHILE A COLD FRONT MOVES ACROSS THE MS RIVER VALLEY. ROBUST
GULF INFLOW WILL SPREAD MOISTURE FROM THE GULF STATES TO THE OH
RIVER VALLEY...REACHING AS FAR EAST AS THE SOUTHERN APPALACHIANS. ON
FRIDAY...THE PROGRESSION OF THE NORTHERN STREAM TROUGH WILL LEAD TO
THE SURFACE FRONT BECOMING MORE NE TO SW ORIENTED...AND TO LESS OF A
PRESSURE GRADIENT OVER THE GULF. THIS MAY REDUCE GULF INFLOW
SOMEWHAT...BUT THE PROGRESSION OF THE SURFACE RIDGE OFF THE EAST
COAST WILL ALLOW MORE MOISTURE TO SPREAD INTO GA AND THE CAROLINAS.
THE RESULT IS THAT PRECIPITATION CHANCES ARE EXPECTED TO INCREASE
AHEAD OF THE FRONT. THE COLD FRONT WILL CROSS OUR AREA EARLY
SATURDAY...FOLLOWED BY SOME BRIEF NW FLOW SHOWERS IN THE NC
MOUNTAINS WHERE THICKNESS VALUES SUPPORT AN ALL RAIN EVENT. DRY HIGH
PRESSURE SPREAD OVER THE AREA FROM THE WEST ON SUNDAY. TEMPERATURES
WILL RUN ABOVE NORMAL AHEAD OF THE FRONT...AND SLIGHTLY BELOW NORMAL
IN ITS WAKE.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS THRU THE EARLY MORNING HOURS
AS A PATCH OF LOW CLOUDS WITH A BASE OF 050-060 MOVES EAST ACROSS
THE PIEDMONT OF THE CAROLINAS. CONDITIONS SHOULD DETERIORATE TOWARD
DAYBREAK AS A BAND OF PRECIP AHEAD OF A COLD FRONT MOVES IN FROM THE
WEST. THE PRECIP IS FCST TO FILL IN ALONG THE FRONT AND BRING AT
LEAST A TEMPORARY MVFR CEILING/VIS RESTRICTION TO ALL TAF SITES
VARIOUSLY IN THE 09Z TO 15Z TIME FRAME FROM W TO E. UNFORTUNATELY...
SKEPTICISM REMAINS. UNTIL THE PRECIP ACTUALLY DEVELOPS AND FILLS
IN...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE THE SHOWERS AS MORE
THAN A TEMPO GROUP. WILL ALSO NOT INCLUDE ANY IFR RESTRICTIONS FOR
THE SAME REASON. THE FRONTAL ZONE WILL MOVE ACROSS THE REGION DURING
THE LATE MORNING AND EARLY AFTERNOON AND WILL BRING A WIND SHIFT TO
W AND THEN WNW BY MID AFTERNOON...WITH CONDITIONS BECOMING VFR ONCE
AGAIN. ALL SITES SHOULD HAVE ONLY SCATTERED CIRRUS FOR THE REST OF
THE PERIOD WITH WIND REMAINING NW THRU THE EVENING. WIND MAY GO
LIGHT NW OR PERHAPS CALM TOWARD THE END OF THE PERIOD...BUT THOSE
DETAILS WERE OMITTED FOR BREVITY.

OUTLOOK...VFR FROM EARLY TUESDAY MORNING THROUGH WEDNESDAY. AN
APPROACHING WARM FRONT AND RESULTANT MOISTURE RETURN WILL BRING
BETTER CHANCES FOR PRECIP/RESTRICTIONS ACROSS THE AREA LATER IN THE
WEEK...PERHAPS STARTING THURSDAY MORNING. EVENTUALLY...A SLOW MOVING
COLD FRONT WILL AFFECT THE AREA FRIDAY OR SATURDAY WITH MORE
RESTRICTIONS.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH  85%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     MED   73%     HIGH 100%     HIGH 100%
KAVL       HIGH  93%     MED   74%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH  81%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     MED   72%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     MED   77%     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...JPT
NEAR TERM...JDL/PM/WIMBERLEY
SHORT TERM...HG
LONG TERM...JAT
AVIATION...PM


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