Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 220601
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
201 AM EDT FRI AUG 22 2014

.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO PROVIDE
VERY WARM TEMPERATURES ACROSS THE REGION INTO SATURDAY. A BACK DOOR
COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST USHERING IN
COOLER TEMPERATURES STARTING SUNDAY.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 130 AM...NOT MUCH HAPPENING ACROSS THE WESTERN CAROLINAS AND
NE GEORGIA. WATCHING SOME CONVECTIVE DEBRIS CLOUDS OVER KY MOVING IN
THIS DIRECTION...AS WELL AS A WEAKENING MCS OVER OH. DOUBTFUL THAT
WILL MAKE IT HERE BEFORE SUNRISE IN ANY FORM THAT WOULD BE
THREATENING. WILL START TO TRIM BACK POP AROUND DAYBREAK ALONG THE
TN BORDER.

REMAINDER OF PREVIOUS DISCUSSION...
CONVECTIVE DEBRIS IS MUCH THINNER AND LESS COVERAGE THAN LAST NITE.
THIS COULD ALLOW MORE FOG TO FORM IN THE NORMALLY MORE FOGGY AREAS.
HAVE UPDATED FOR THESE FEATURES...AND LEFT LOWS AS IS.

AS OF 215 PM EDT...A PROMINENT 500 MB RIDGE AXIS WILL PERSIST OVER
THE LENGTH OF THE MS RIVER VALLEY TONIGHT THROUGH FRI. MAINLY MID
AND HIGH DEBRIS CLOUDS SHOULD LINGER THROUGH THE NIGHTTIME
HOURS...WITH ANY FOG AND LOW CLOUD ISSUES CONFINED TO THE SW MTN
VALLEYS. EXPECT ANOTHER NIGHT OF MILD MINS...WITH MAINLY LOW TO MID
60S IN THE MTNS AND AROUND 70 ELSEWHERE.

THE FLOW PATTERN BETWEEN THE RIDGE AND A NEW ENGLAND LOW PRES SYSTEM
WILL AMPLIFY ON FRI...WITH MORE NNW FLOW DEVELOPING ALONG THE
APPALACHIANS BETWEEN THESE FEATURES. THIS SHOULD BRING THE NRN TIER
OF THE FORECAST AREA A BIT MORE INTO THE PATH OF ANY UPSTREAM MCS
ACTIVITY FROM THE OH VALLEY LATE FRI. IN ADDITION...SFC BASED
INSTABILITY AND LAPSE RATES LOOK JUST A TOUCH MORE ROBUST FOR FRI
AFTN...BUT STILL RELATIVELY UNIMPRESSIVE FOR SEVERE WX COMPARED TO
UPSTREAM AREAS. OTHERWISE...WESTERLY DOWNSLOPING 850 MB FLOW THROUGH
THE PERIOD WILL MAKE IT A STRUGGLE TO GET MUCH CONVECTION GOING FROM
OTHER SOURCES...AND MAX TEMPS WILL LIKELY GAIN A DEGREE OR SO OVER
THU VALUES. SRN PIEDMONT HEAT INDEX VALUES COULD SURPASS 100 FRI
AFTN IF WE SEE SLIGHTLY LESS DEWPOINT MIXING.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 210 PM THURSDAY...STRONG UPPER RIDGE WILL PERSIST OVER THE
MISS VALLEY THROUGH THE PERIOD...PLACING MUCH OF THE SOUTHEAST AND
MID-ATLANTIC WITHIN MODERATE N/NW UPPER FLOW. OUR AREA WILL
THEREFORE REMAIN SUSCEPTIBLE TO /RING OF FIRE/ CONVECTION DEVELOPING
NEAR QUASI-STATIONARY FRONTAL ZONE ACROSS THE OHIO VALLEY/CTRL
APPALACHIANS REGION...WHICH COULD DROP INTO THE CAROLINAS IN
SOMEWHAT ORGANIZED FASHION DURING THE AFTERNOON AND EVENING.
THERMODYNAMIC PROFILES WILL REMAIN SUFFICIENT TO SUPPORT ISOLATED
SEVERE WEATHER SATURDAY AFTERNOON/EVENING.

BY THE END OF THE PERIOD...THE FRONTAL ZONE MAY BEGIN TO BACK DOOR
ITS WAY INTO THE AREA BY EARLY SUNDAY...AS THE STILL-BUILDING UPPER
RIDGE BEGINS TO SQUEEZE THE DOWNSTREAM UPPER LOW OFF THE EAST
COAST...ALLOWING WEAK SURFACE RIDGING TO BUILD DOWN THE EASTERN
SEABOARD. THEREFORE...IN ADDITION TO THE CONTINUED THREAT OF
MIGRATION OF UPSTREAM CONVECTION INTO THE AREA...THE BACKDOOR FRONT
MAY PROVIDE AN ADDITIONAL FOCUS FOR CONVECTION ON SUNDAY. HOWEVER...
EXACTLY WHERE THE BEST CHANCES WILL OCCUR IS STILL SUBJECT OF
DEBATE...AS THE AIR NORTH OF THE BOUNDARY MAY BE TOO STABLE TO
SUPPORT MUCH IN THE WAY OF PRECIP CHANCES. THE HIGHEST POPS WILL BE
FAVORED ACROSS THE SOUTHWEST ZONES...WHERE CONFIDENCE IN ADEQUATE
INSTABILITY IS HIGHEST...AND A WEAK EASTERLY FLOW MAY PROVIDE AN
ADDITIONAL SOURCE OF LIFT NEAR THE BLUE RIDGE. TEMPS WILL REMAIN
ABOVE NORMAL UNTIL SUNDAY...WHEN MAXES WILL LIKELY BE BELOW NORMAL
UNDER MORE EXTENSIVE CLOUD COVER AND E/NE FLOW.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...THE MEDIUM RANGE MODEL CONSENSUS PROVIDES
GOOD CONTINUITY FROM INHERITED FCST TO START OFF THE WORKWEEK. STILL
EXPECTING SFC RIDGING TO BE NOSED SSWD INTO THE CWFA WHILE UPPER
RIDGE AXIS BUILDS INTO THE EASTERN CONUS. SENSIBLE WX WILL FEATURE
MAX TEMPERATURES ABOUT 5 DEG F BELOW CLIMO WITH POSSIBLY A FEW
SHOWERS FORCED BY THE EASTERLY LLVL FLOW. SUPPRESSED ORIENTATION TO
AMOPSHERE LOOKS TO CONTINUE INTO TUESDAY WITH EFFECTIVELY MINIMAL
SHOWER CHANCES AND TEMPERATURES PERHAPS WARMING A FEW DEG F.
DEEPER LAYERED RIDGING IS PROGGED TO BREAK DOWN DURING THE LATTER
HALF OF THE PERIOD...ALLOWING TEMPERATURES TO CLIMB BACK TO NORMAL
AND PERHAPS THUNDERSTORM CHANCES RETURNING BY THURSDAY.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR THROUGH THE PERIOD. MID/HIGH LEVEL CONVECTIVE DEBRIS
EXPECTED THROUGH MOST OF FRIDAY MORNING...WITH A LIGHT WNW WIND.
EXPECT WIND TO COME AROUND TO SOMETHING EVEN MORE NW FRIDAY
AFTERNOON WITH A FEW HIGH BASED CU DEVELOPING. THERE SHOULD BE A FEW
TSRA AROUND...BUT THE BETTER CHANCES WILL BE OVER THE HIGHER
TERRAIN.

ELSEWHERE...THE GUIDANCE ONCE AGAIN HITS THE FOG HARD OVER THE NC
MOUNTAINS. PREFER TO TAKE MORE OF A WAIT AND SEE APPROACH BECAUSE
THIS LOOKS LIKE ANOTHER OVERFORECAST AT THIS TIME. WILL KEEP AN MVFR
AT KAVL FOR FOG...BUT THAT IS NOT CERTAIN. WIND SHOULD BE W OR NW
THROUGH THE PERIOD. THE MTNS AND FOOTHILLS HAVE THE BEST CHC FOR
PRECIP...SO THE PROB30 WILL BE KEPT AT KAND/KHKY.

OUTLOOK...A SIMILAR PATTERN IS EXPECTED FRI NIGHT...WITH MAINLY FAR
NRN TIER SCT CONVECTION POSSIBLE. A BACKDOOR COLD FRONT WILL SAG
INTO THE REGION THROUGH THE WEEKEND...WITH CHANCES OF RESTRICTIONS
INCREASING AT KHKY AND KAVL. A MORE DIURNAL PATTERN OF EARLY MORNING
LOW CLOUDS/FOG AND SCATTERED AFTN TSTMS MAY RETURN EARLY NEXT WEEK.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-05Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  91%     HIGH  93%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH  88%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH  91%     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...HG/PM/RWH
SHORT TERM...JDL
LONG TERM...CSH
AVIATION...PM





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