« Back
NWS Peachtree City, Ga » Text Product » GSP Area Forecast Discussion


Printer-friendly Version
Current Version              Previous Versions:   1  2  3  4  5  6  7  8  9  

Area Forecast Discussion

885
FXUS62 KGSP 011759
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
159 PM EDT MON SEP 1 2014

.SYNOPSIS...
SOUTHERLY FLOW INDUCED BY A PERSISTENT BERMUDA HIGH WILL CONTINUE TO
PROMOTE DIURNAL SHOWERS AND THUNDERSTORMS THROUGH MUCH OF THE
WEEK.  A FRONTAL PASSAGE WILL OCCUR ON TUESDAY EVENING INTO
WEDNESDAY MORNING WITH ANOTHER FRONT PASSING THROUGH OVER THE
WEEKEND LEADING TO ENHANCED SHOWER AND THUNDERSTORM CHANCES FOR
THOSE PERIODS.  HIGH PRESSURE WILL ONCE AGAIN REGAIN CONTROL BY
EARLY NEXT WEEK BEHIND THE ABOVE MENTIONED FRONT LEADING TO SLIGHTLY
COOLER TEMPERATURES AND MORE SETTLED WEATHER.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 200 PM...A FEW SHOWERS WERE DEVELOPING OVER THE HIGHER
TERRAIN...MAINLY OVER THE SMOKIES AND SRN MOUNTAINS OF NC AND N
GEORGIA...AS ANTICIPATED BY THE CONSENSUS OF THE CONVECTION ALLOWING
MODELS. THE CONSENSUS GENERALLY FAVORS THE SMOKIES AND BALSAMS...AND
DOWNPLAYS THE CHANCES OVER THE NC PIEDMONT...SO THAT TREND WILL BE
KEPT THROUGH THE AFTERNOON. SKY COVER ALSO NEEDS TO BE ADJUSTED TO
TAKE INTO ACCT THE THICKER AREA OF HIGH CLOUDS E OF THE MTNS. NO
OTHER BIG CHANGES AS TEMPS STILL LOOK GOOD.

OVER THE NEXT 24 HOURS...THE UPPER RIDGE ACROSS THE SOUTHEAST WILL
BE FLATTENED FURTHER BY THE PASSAGE OF A SHORT WAVE UP THE OH VALLEY
LATE TONIGHT AND EARLY TUESDAY. HOWEVER...THE CLOSEST THIS FEATURE
WILL COME IS A CHUNK OF ENERGY BRUSHING PAST THE NRN MOUNTAINS THIS
EVENING. AT THAT EARLY TIME...THERE WILL BE LITTLE FOR THIS WAVE TO
WORK WITH. ALTHO IT MAY ENHANCE THE CHANCE OF CONVECTION A BIT... IT
DOES NOT LOOK LIKE WE WILL HAVE ANYTHING MORE THAN SCT/WIDELY SCT
SHOWERS AND STORMS MAINLY OVER THE HIGHER TERRAIN. THE WAVE PASSES
EARLY ENOUGH THAT ANY STORMS SHOULD DIE OFF WITH LOSS OF HEATING.
THEREAFTER...PERHAPS SOME DENSE FOG AGAIN IN SOME OF THE MOUNTAIN
VALLEYS. LOWS SHOULD BE SEASONALLY MILD AGAIN.

ON TUESDAY...STILL NOT MUCH HAPPENING AT MID LEVELS...BUT THERE
COULD BE SOME WEAK UPPER DIVERGENCE AS THE JET STREAK PASSES WELL TO
THE NORTH. THE MODELS ARE A BIT MORE ROBUST WITH CONVECTIVE PRECIP
COVERAGE OWING TO SOME IMPROVED SURFACE BASED INSTABILITY BY THE
AFTERNOON. SO...THE TREND OF HAVING A HIGHER POP FOR TUESDAY
AFTERNOON STILL LOOKS LIKE A GOOD ONE...AS DOES REACHING A FEW
DEGREES HIGHER FOR THE HIGH TEMP.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 305 AM EDT SUNDAY...NOT A LOT OF CHANGE REGARDING THE SHORT
TERM FORECAST PERIOD WHICH INITIALIZES TUESDAY MORNING AMIDST BROAD
SUBTROPICAL DEEP LAYER RIDGING.  AMPLIFYING UPPER TROF PUSHING
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY WILL BE MOVING EAST WITH
AN ASSOCIATED COLD FRONT DRAPED ALONG OR JUST NORTH OF THE OHIO
RIVER VALLEY.  CONTINUED SOUTHERLY FLOW OVER THE SOUTHEAST AHEAD OF
APPROACHING FRONTAL BOUNDARY WILL WARRANT NEAR CLIMO POPS FOR MUCH
OF THE REGION ON A DIURNAL TREND.  ABOVE MENTIONED RIDING WILL
PROVIDE SOME INHIBITION TO CONVECTION ON TUESDAY...ESPECIALLY ACROSS
THE EAST.  WEAK LEE TROF PRESENT ACROSS CENTRAL NC/SC COULD BE A
FOCUS FOR CONVECTION PROVIDING ENOUGH LOW LEVEL CONVERGENCE TO
SUPPORT INITIATION DESPITE ABOVE MENTIONED CAP.  LAPSE RATES ACROSS
THE REGION WILL BE RATHER STEEP LATER IN THE DAY AS TEMPS SURGE TO
ABOVE NORMAL LEVELS...THEREFORE MODERATE INSTABILITY COULD ALLOW FOR
ENHANCED/STRONG CONVECTION ACROSS THE WESTERN MOST ZONES WHERE
UPDRAFTS WILL BE LESS INHIBITED.  OTHERWISE...EXPECTING GENERAL
SHOWERS AND THUNDERSTORMS ON TUESDAY AFTERNOON/EVENING AHEAD OF
APPROACHING FRONT.

EXPECTING A NOCTURNAL FROPA OVERNIGHT INTO WEDNESDAY MORNING WITH
THE MORE ENHANCED UPPER LEVEL SUPPORT PASSING BY TO NORTH.
THUS...POPS WILL ACTUALLY TAPER WITH DIURNAL COOLING THROUGH THE
NIGHT WITH ONLY LOW END CHANCE LEVEL POPS RESIDING ACROSS THE HIGH
TERRAIN.  MODELS CONTINUE TO INDICATE THE FRONT SLOWING AND BECOMING
NEARLY STATIONARY THROUGH THE REMAINDER OF THE DAY ON WEDNESDAY AS
THE UPPER FLOW FLATTENS AND PARENT SURFACE TROF EJECTS TO THE
NORTHEAST.  THIS WILL BEGIN A RATHER NOCTURNALLY INDUCED UNSETTLED
WEATHER PERIOD ACROSS NORTHEAST GA AND THE WESTERN CAROLINAS.  DUE
TO THE SLOWER/STALLED PROGRESSION OF THE FRONT...EXPECTING ANY
SURFACE COOLING/DRYING TO BE MINIMAL.  HOWEVER...THE MID AND UPPER
LEVELS WILL EXPERIENCE MODERATE DRYING WHICH WILL ACTUALLY ALLOW FOR
RATHER STEEP LAPSE RATES WEDNESDAY AFTERNOON.  AS THE UPPER RIDGE
SLOWLY RETROGRADES WEST AND THE SURFACE HIGH WEAKENS...THE
ATMOSPHERE WILL LIKELY BE FREE FOR CONVECTION AMIDST PROFILES
SUPPORTING NEARLY 1500J/KG SBCAPE.  THUS...POPS WILL RAMP UP INTO
THE AFTERNOON TO LOW END LIKELY LEVELS OVER THE MORE CLIMO FAVORED
REGIONS OF THE UPPER FRENCH BROAD WHILE SOLID CHANCE POPS RESIDE
SOUTH OF INTERSTATE 40 WHERE FRONTAL BOUNDARY REMAINS.  WILL
CONTINUE TO EVALUATE STRONG/SEVERE THUNDERSTORM POTENTIAL ON
WEDNESDAY AS PROFILES WOULD SUPPORT DOWNBURST/HAIL THREATS.
TEMPERATURES THROUGH THE SHORT TERM PERIOD WILL REMAIN NEAR OR JUST
ABOVE NORMAL.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 330 AM EDT MONDAY...THE EXTENDED RANGE FORECAST PERIOD
INITIALIZES THURSDAY MORNING WITH DIFFUSE QUASI STATIONARY MOISTURE
AXIS FROM OLD FRONTAL BOUNDARY REMAINING OVER THE REGION.
MEANWHILE...UPPER RIDGE WILL REBUILD SOMEWHAT ACROSS THE SOUTHEAST
WITH REINFORCING SURFACE HIGH PRESSURE SLIDING EAST AND OUT TO SEA
OVER THE MID ATLANTIC.  THIS PATTERN WILL PERSIST THROUGH WEEKS END
WITH DIURNALLY INDUCED INSTABILITY WORKING TO OVERCOME CAPPING EACH
DAY WARRANTING AT LEAST CHANCE LEVEL POPS FOR THE AFTERNOON HOURS.
GLOBAL MODELS REMAIN IN CONSENSUS ON ANOTHER RATHER ROBUST FROPA
OVER THE WEEKEND WITH SOME DISCONTINUITY REGARDING TIMING AND
INTENSITY.  THE GFS SOLUTIONS ARE A FEW HOURS FASTER THAN THAT OF
THE ECWMF...NEVERTHELESS BOTH INDICATE FRONTAL PASSAGE LATE SATURDAY
EVENING INTO SUNDAY.  AS THE FRONT APPROACHES...ABOVE MENTIONED
SUBSIDENCE WILL WEAKEN AS UPPER HEIGHTS AND SURFACE PRESSURES FALL.
THEREFORE FAIRLY HEALTHY POPS ARE FORECAST OVER THE WEEKEND WITH MID
LEVEL CHANCE POPS FEATURED ACROSS THE LOWER TERRAIN WHILE NEAR
LIKELY LEVEL POPS ARE MENTIONED ACROSS THE NORTHERN
MOUNTAINS/FOOTHILLS.  HIGH PRESSURE LOOKS TO BUILD IN BEHIND THE
FRONT FOR THE START OF THE NEW WORK WEEK LEADING TO DECREASING
PRECIPITATION CHANCES AS DRIER AIR ADVECTS IN.  TEMPERATURES THROUGH
THE MAJORITY OF THE EXTENDED RANGE WILL BE ABOVE NORMAL WITH SLIGHT
COOLING FORECAST BEHIND THE LATE WEEKEND FROPA FOR THE NEW WEEK.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...A BAND OF CIRRUS WILL TRANSLATE EWD OVERHEAD THROUGH MID
AFTERNOON...BUT OTHER PATCHES OF THICKER CIRRUS REMAIN UPSTREAM AND
SHOULD MOVE THROUGH DURING THE LATE AFTERNOON. THIS WILL HELP TO
KEEP A LID ON THE DEEPER CONVECTION...SO NO VCSH IS INCLUDED. EXPECT
WIND TO REMAIN LIGHT FROM THE WSW. THE CLOUDS SHOULD THIN OUT A BIT
OVERNIGHT WITH A LIGHT SSW WIND. SOME POTENTIAL FOR FOG ACROSS THE
PIEDMONT...BUT TOO LOW TO MENTION IN THE TAF. ON TUESDAY...EXPECT A
SIMILAR SITUATION...WITH WIND COMING UP FROM THE SW AFTER THE
BOUNDARY LAYER WARMS AROUND 13Z-14Z.

ELSEWHERE...OUTSIDE OF THE MTNS WILL SEE SIMILAR CONDITIONS AS KCLT.
KAVL HAS THE ONLY OUTSIDE CHANCE OF SEEING A SHOWER OR STORM...IF
THE MODEL GUIDANCE IS CORRECT. NOT OVERLY EXCITED ABOUT THEIR
CHANCES...SO THIS IS LIMITED TO A VCTS. LATE TONIGHT...EXPECT
ANOTHER ROUND OF VALLEY FOG...AT LEAST DOWN INTO THE IFR RANGE...
AFTER 07Z. THIS COULD VERY WELL GO LIFR OR VLIFR...BUT THAT WILL NOT
BE USED IN THE FCST YET. THE FOG SHOULD BURN OFF AGAIN AROUND 13Z.

OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE
WEEK...BUT RESTRICTIONS ARE POSSIBLE EARLY EACH MORNING DUE TO LOW
CLOUDS AND FOG...PRIMARILY IN THE MOUNTAIN VALLEYS. DIURNALLY DRIVEN
SHRA/TSRA ARE EXPECTED EACH AFTERNOON WITH THE MOST COVERAGE OVER
THE MOUNTAINS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  97%     MED   65%     HIGH  86%
KHKY       HIGH 100%     HIGH 100%     HIGH  80%     HIGH  94%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  94%     HIGH  94%

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...CDG
NEAR TERM...PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...PM






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.