Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 012349
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
749 PM EDT MON JUN 1 2015

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL PERSIST ACROSS THE REGION EARLY THIS
WEEK. AN UPPER LOW IS EXPECTED TO FORM OVER THE TENNESSEE VALLEY BY
TUESDAY...REMAINING JUST WEST OF OUR REGION FOR MUCH OF THE
WEEK...WHILE COOL CANADIAN HIGH PRESSURE WILL BUILD DOWN FROM THE
NORTH. THIS PATTERN WILL HELP ENHANCE LIFT AND MOISTURE RETURN INTO
THE AREA...CREATING ELEVATED CHANCES FOR SHOWERS AND
THUNDERSTORMS...AND KEEPING TEMPERATURES SLIGHTLY BELOW NORMAL.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 745 PM EDT MONDAY...TWEAKED POPS/SKY TO ACCOUNT FOR CONVECTION
FIRING ALONG OLD STATIONARY OUTFLOW BOUNDARY ALONG/SOUTH OF
INTERSTATE 85 IN THE SC UPSTATE.  AMPLE INSTABILITY ALONG WITH THE
BOUNDARY BEING A FOCUS....WITH LEAD TO CONTINUED SHRA/TSRA IN THIS
REGION FOR A FEW MORE HOURS BEFORE INSTABILITY WAINS.
OTHERWISE...ONLY ISOLATED/SCATTERED CONVECTION PREVAILS OVER WESTERN
NC AND NORTHEAST GA WITH THE STRONGEST OF WHICH NOW BEING THE BROKEN
CLUSTER OF CELLS MOVING INTO NE GA FROM THE WEST.
OTHERWISE...TWEAKED TEMPS/DEWS TO BETTER REFLECT RECENT OBS.

PREVIOUS DISCUSSION...

AS OF 150 PM...AREA TEMPS REACHING THE UPR 70S TO MID 80S ARE
RESULTING IN CONVECTIVE INITIATION...WITH RADAR RETURNS BLOSSOMING
ACRS THE CWFA. A SHARP UPPER TROF WILL BEGIN TO CLOSE OFF INTO A
COMPACT UPPER LOW OVER THE TN VALLEY...ENHANCING THE LIFT ACRS THE
AREA. POPS RAMP UP TO THE HIGH-END CHC IN THE SOUTHEAST TO
CATEGORICAL ALONG THE TN BORDER BY LATE AFTN. THE 12Z GSO/FFC
SOUNDINGS SHOWED A LOT OF MID LVL MOISTURE...WITH WEAK SHEAR AND
MODERATE LAPSE RATES. SO EXPECTING MAINLY GARDEN VARIETY
CONVECTION...WITH A COUPLE OF MARGINAL PULSE SEVERE STORMS
POSSIBLE...WITH WIND BEING THE MAIN THREAT.

CONVECTION SHUD DIMINISH TO JUST ISOLD BY THE OVERNIGHT HOURS...WITH
PLENTY OF DEBRIS CLOUDINESS PERSISTING. THE MOIST GROUND FROM THE
EXPECTED CONVECTION WILL SUPPORT PATCHY FOG AND LOW STRATUS AGAIN
TUESDAY MORNING. MIN TEMPS WILL BE A COUPLE CATEGORIES ABOVE NORMAL.

TUESDAY...THE UPPER LOW WILL SLOW DOWN OVER THE TN VALLEY...KEEPING
OUR AREA UNDER THE Q-VECTOR CONVERGENCE SIDE OF THE CIRCULATION.
MEANWHILE...A SFC FRONT WILL SAG SOUTHEAST INTO THE AREA...WITH AXIS
OF DEEP MOISTURE STILL IN PLACE. SO ANOTHER ROUND OF NUMEROUS TO
WIDESPREAD SHOWERS AND TSTMS IS EXPECTED WITH DAYTIME HEATING. THE
SEVERE THREAT LOOKS EVEN MORE MARGINAL THAN MONDAY...WITH LOW DCAPE
AND WEAK SHEAR. TEMPS WILL ALSO BE HELD IN CHECK BY PLENTY OF CLOUD
COVER AND RELATIVELY EARLY CONVECTIVE INITIATION...GENERALLY A
CATEGORY OR SO BELOW NORMAL.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM MON...CLOSED UPPER LOW REMAINS NEARLY STATIONARY OVER
THE SRN APPALACHIANS WED THEN WEAKENS ON THU AS IT MOVES SLOWLY EAST
INTO THE CWFA. AT THE SFC...A WEAK SFC BOUNDARY MOVES EAST OF THE
AREA AS HIGH PRESSURE BUILDS IN FROM THE NE IN A CAD LIKE
CONFIGURATION. THIS SHOULD LEAD TO QUITE A BIT OF CONVECTIVE
COVERAGE EACH DAY...WITH A DIURNAL TREND. HOWEVER...COPIOUS LOW
LEVEL MOISTURE AND A SELY LOW LEVEL FLOW...ALONG WITH WEAK ELEVATED
INSTABILITY...WILL HELP KEEP CONVECTION AROUND DURING THE OVERNIGHTS
AND THE MORNINGS. THERE WILL BE A CHC OF ISOLATED SVR STORMS EACH
DAY WITH DAMAGING WINDS THE MAIN THREATS. HOWEVER...THE CHANCE OF
FLOODING WILL BE ON THE INCREASE GIVEN THE HIGH PW VALUES AND
POSSIBLE TRAINING OR BACK BUILDING OF CELLS. HIGHS WILL BE A LITTLE
BELOW NORMAL EACH DAY WHILE LOWS WILL BE A LITTLE ABOVE NORMAL.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 2 PM MON...SMALL DIFFERENCES IN SYNOPTIC FEATURES OF
THE GFS AND ECMWF FOR THE MEDIUM RANGE AT LEAST ON FRIDAY AND
SATURDAY. UPPER LOW OPENS INTO THE GENERAL TROFINESS THURSDAY NIGHT
INTO FRIDAY WITH THE AFTERNOON WARMTH HELPING TO FUEL THE MORE
CONVECTIVE ACTIVITY.  THE FORECAST THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK WILL DEPEND ON THE TIMING OF SHORTWAVES AND THE
BRIEF CALM OF HIGH PRESSURE RIDGING DOWN FROM THE NORTH.  THE GFS
AND ECMWF DIFFER THE MOST IN THE DAY 6 AND 7 PORTION OF THE
FORECAST WHERE THE GFS CONTINUES ALMOST NONSTOP ACTIVITY AND THE EC
HAS SUNDAY AND MONDAY UNDER HIGH PRESSURE. BEST NOT TO MAKE MUCH
CHANGE IN THE PRIOR FORECAST TO SEE MORE CONSISTENCY TOWARD THE
LATER PERIODS. PM INSTABILITY FORECASTS HAVE TRENDED LOWER SO
PERHAPS LESS THUNDER AROUND NEXT WEEKEND. TEMPERATURES REMAIN TO BE
A LITTLE BELOW NORMAL.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AT KCLT...VFR THROUGH THE PERIOD WITH THE EXCEPTION OF MID EVENING
SHRA/TSRA THAT IS CURRENTLY FIRING ALONG AN OLD OUTFLOW BOUNDARY
ACROSS THE I85 CORRIDOR IN THE UPSTATE OF SC.  THIS BOUNDARY EXTENDS
NORTHWARD ALONG THE INTERSTATE INTO THE SOUTHERN NC PIEDMONT.
HOWEVER...CONFIDENCE THAT IT WILL ADVECT EASTWARD BEFORE DEPLETING
IS ONLY MARGINAL AT BEST...THUS OPTED TO CARRY MVFR TEMPO FROM
02-04Z.  OTHERWISE...GUIDANCE VARIES AS TO MVFR CIGS OVERNIGHT
ACROSS WESTERN NC THEREFORE OPTED TO GO WITH THE CONSENSUS WHICH
FEATURED LOW/MID VFR STRATUS WITH A MENTION OF SCT MVFR CLOUDS
AROUND DAYBREAK.  THE POSSIBILITY OF MVFR CIGS AT THIS TIME
REMAINS.  BEYOND THAT...PRETTY MUCH A CARBON COPY OF TODAY FOR
TUESDAY AS UPPER LOW CONTINUES TO ROTATE OVERHEAD AND THE BOUNDARY
LAYER DESTABILIZES.  THUS...WITH HEFTY POPS IN THE FCST OPTED TO
PREVAIL TSRA AT 19Z THROUGH THE PERIOD HOWEVER LEFT RESTRICTIONS OUT
DO TO TIMING UNCERTAINTY.  WINDS THROUGH THE TAF CYCLE WILL REMAIN
GENERALLY LIGHT/SOUTHERLY...EXCEPT ADJACENT TO ANY STRONG CONVECTION
WHERE G20-G30 GUSTS ARE POSSIBLE.

ELSEWHERE...ONGOING CONVECTION ACROSS THE REGION CONTINUES TO
WARRANT TEMPOS FOR SUCH AT THE SC SITES WHERE OLD OUTFLOW BOUNDARY
IS PROVIDING FOCUS FOR TSRA.  FURTHER NORTH INTO WESTERN
NC...CONVECTION IS LESS DENSE WITH THE MOST ORGANIZED STORMS
KNOCKING ON KHKY DOORSTEP...THEREFORE PREVAILED TSRA FOR 1HR...WITH
VCTS AT KAVL.  BEYOND THAT THE TAFS ARE FAIRLY SIMILAR TO THAT OF
KCLT ABOVE WITH LOW STRATUS AND OR FOG TONIGHT WITH THE MOST LIKELY
RESTRICTIONS TO OCCUR AT KAVL/KAND...AND POSSIBLY KHKY WHERE
CONVECTION THIS EVENING MOISTENS THE BL.  THAT SAID...CANT RULE SUCH
OUT AT KGSP/KGMU.  THEREFORE THE TAF FEATURES MVFR RESTRICTIONS AT
KAVL/KAND/KHKY...WITH A SCT IFR DECK FCST AT KAVL...WHICH COULD FILL
IN LEADING TO IFR CIGS.  FINALLY...SOUTHERLY FLOW AND INCREASING CU
WILL HIGHLIGHT THE DAY ON TUESDAY WITH EARLY AFTERNOON CONVECTION
EXPECTED...HENCE ALL SITES CARRY VCTS FOR SUCH.

OUTLOOK...A MID LEVEL LOW IS FORECAST TO REMAIN ACROSS THE DEEP
SOUTH THROUGH THE WORK WEEK. DEEP MOISTURE WILL LINGER ACROSS
THE SOUTHEAST CONUS THROUGH THE WEEK. SHOWERS AND THUNDERSTORMS MAY
DEVELOP EACH AFTERNOON AND EVENING. MORNING STRATUS AND FOG WILL
REMAIN A POSSIBILITY...ESPECIALLY OVER WET GROUND.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH  94%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH  94%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     LOW   55%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     MED   67%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH  94%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  94%     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...DEO
NEAR TERM...ARK/CDG
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...CDG


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