Area Forecast Discussion
Issued by NWS Greer, SC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KGSP 301037 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 637 AM EDT SAT AUG 30 2014 .SYNOPSIS... A WEAK NEARLY STATIONARY FRONT NORTH CAROLINA WILL DISSIPATE TODAY. A BERMUDA HIGH WILL THEN DEVELOP AND LINGER INTO EARLY NEXT WEEK... BRINGING TYPICAL SUMMERTIME HEAT AND HUMIDITY...WITH SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM EDT SATURDAY...EARLIER 2KFT STRATUS CLOUD DECK OVER WESTERN NC HAS RECEDED TO THE NORTH ALLOWING FOR JUST ENOUGH COOLING TO YIELD PATCHY FOG DEVELOPMENT/EXPANSION. LATEST OBSERVATIONS ALONG WITH SATELLITE IMAGERY INDICATE LIGHT PATCHY FOG ACROSS PORTIONS OF THE NC PIEDMONT WHILE PATCHY DENSE FOG HAS DEVELOPED IN THE MOUNTAIN VALLEYS AS EXPECTED. CONDITIONS WILL IMPROVE ACROSS THE PIEDMONT SHORTLY AFTER SUNRISE WITH THE MOUNTAIN VALLEY FOG PERSISTING FOR AN HOUR OR SO. OTHERWISE....TWEAKED TEMPERATURES AND DEWPOINTS TO REFLECT LATEST OBSERVATIONS AND LEFT THE REMAINDER OF THE FORECAST AS IT WAS. PREVIOUS DISCUSSION... AS OF 300 AM EDT SATURDAY...RATHER NICE DAY IN STORE ACROSS NORTHEAST GA AND THE WESTERN CAROLINAS AS DEEP LAYER RIDGING PREVAILS. MEANWHILE...UPPER SHORT WAVE ENERGY TO THE WEST CONTINUES TO PROGRESS EAST ALONG THE MEAN FLOW PROMOTING DEVELOPMENT OF SURFACE TROF BENEATH AND SUSTAINED SOUTHERLY MOISTURE ADVECTION REGIME. CLOSER TO HOME...REMNANT LOW LEVEL MOISTURE AXIS FROM OLD STATIONARY BOUNDARY CONTINUES TO PROVIDE A FOCUS FOR EXPANDING STRATUS CLOUD DECK. LATEST MOS GUIDANCE CONTINUES TO SUPPORT PATCHY FOG DEVELOPMENT THIS MORNING ACROSS THE NC PIEDMONT WITH SOME AREAS OF DENSE FOG POSSIBLE IN AND AROUND THE MOUNTAIN VALLEYS. THAT SAID...ABOVE MENTIONED STRATUS DECK WILL INHIBIT COOLING SOMEWHAT THEREBY DELAYING/PREVENTING FOG DEVELOPMENT FOR AREAS OF THE NC PIEDMONT. CONDITIONS WILL IMPROVE BEYOND DAYBREAK AS HEATING WORKS TO ERODE LOW STRATUS/FOG PRESENT ACROSS THE REGION. LIGHT/CALM SURFACE FLOW WILL GRADUALLY INCREASE OUT OF THE SOUTHEAST TO AROUND 5-10MPH BY MID/LATE AFTERNOON. SOUNDINGS CONTINUE TO INDICATE JUST ENOUGH LOW LEVEL MOISTURE TO SUPPORT MINIMAL COVERAGE OF FAIR WX CU AS LAPSE RATES STEEPEN WITH HEATING THIS AFTERNOON. CONVECTION TO THE WEST ASSOCIATED WITH WAA CONVEYOR BELT AND SURFACE TROFFING WILL ALSO LIKELY PROMOTE SOME MID/HIGH LEVEL CIRRUS STREAMING ALOFT. SPEAKING OF MOISTURE ADVECTION PATTERN...POPS WILL REMAIN NON MENTIONABLE THROUGH MUCH OF THE MORNING BEFORE GRADUALLY INCREASING TO NEAR LIKELY LEVELS ACROSS THE WESTERN MOST ZONES...TAPERING TO SLIGHT CHANCE LEVELS FOR PORTIONS OF THE WESTERN UPSTATE AND NC FOOTHILLS BY LATE EVENING. THIS IS IN RESPONSE TO BOTH THE MOISTURE AXIS APPROACHING AND ALSO PROXIMITY OF SOUTHEAST RIDGE LEADING TO WEAKER INHIBITION FURTHER WEST. THAT SAID...PROFILES SUPPORT ONLY MINIMAL CAPE AND WOULD LIKELY NOT YIELD ROBUST UPDRAFTS LEADING TO SUSTAINED CONVECTION. THUS...ONLY EXPECTING GENERAL THUNDERSTORMS AT BEST WITH CLOUD TO GROUND LIGHTNING BEING A PRIMARY THREAT WHICH WILL BE MENTIONED IN THE HWO. POPS WILL REMAIN AT SOLID CHANCE LEVELS ACROSS THE HIGH TERRAIN THROUGH THE OVERNIGHT HOURS TO ACCOUNT FOR CONTINUED SOUTHERLY UPSLOPE ENHANCED SHOWERS. TEMPERATURES ON SATURDAY WILL WARM TO ABOVE NORMAL LEVELS ACROSS THE MAJORITY OF THE FORECAST AREA AS STRONG UPPER RIDGE PREVAILS. ALTHOUGH STILL ABOVE NORMAL...TEMPERATURES COULD BE SLIGHTLY COOLER ACROSS THE MOUNTAINS AS BETTER SKY COVER LIMITS HEATING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 215 AM SATURDAY...A WEAKENING SHORT WAVE TROUGH EJECTING FROM THE GREAT PLAINS WILL PHASE WITH A SHORT WAVE CROSSING THE GREAT LAKES AND NUDGE THE SERN CONUS ANTICYCLONE OFF THE SE COAST EARLY IN THE SHORT TERM. A SECONDARY WEAK WAVE MOVES ACROSS THE AREA MONDAY AS THE ANTICYCLONE DROPS TO THE GA COAST AND RETROGRADES INTO GA MON NITE. AT THE SFC...A WEAKENING FRONTAL ZONE MOVES ACROSS THE AREA SUNDAY IN ASSOCIATION WITH THE SHORT WAVE. THERE WILL ALSO BE SOME UPPER DIVERGENCE AS THE RIGHT ENTRANCE REGION OF A JET STREAK MOVES THRU. HOWEVER...ALL GUIDANCE HAS BACKED OFF ON THE AMOUNT OF INSTABILITY DEVELOPING SUNDAY...AT LEAST OUTSIDE OF THE MTNS. CAP DOES ERODE DURING THE DAY...SO EXPECT CONVECTION TO DEVELOP. HOWEVER...POP HAS BEEN LOWERED OUTSIDE OF THE MTNS IN LINE WITH GUIDANCE CONSENSUS...BUT KEPT IN THE SCT RANGE AS THERE WILL BE SOME FORCING ALONG WITH WEAK INSTABILITY. WITH THE CONTINUED MODERATE INSTABILITY EXPECTED OVER THE MTNS...LIKELY POP IS RETAINED THERE. GUIDANCE ALSO IN AGREEMENT SHOWING LOWER PW VALUES THAN PREVIOUSLY FCST...LEADING TO ONLY ISOLATED POTENTIAL FOR HEAVY RAINFALL. ANY SVR STORMS SHUD BE ISOLATED AS WELL WITH WEAK SHEAR. TEMPS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. ONLY WEAK INSTABILITY IS FORECAST ON MONDAY WITH LITTLE IN THE WAY OF FORCING. HAVE DROPPED POP ACROSS THE BOARD...BUT KEPT IN THE SCATTERED RANGE. STILL...THE BEST MOISTURE AND INSTABILITY WILL BE OVER THE MTNS...SO POP SLIGHTLY HIGHER THERE. TEMPS WILL WARM A FEW DEGREES MONDAY AND MONDAY NITE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 335 AM SATURDAY...A LOW AMPLITUDE TROF MOVES EAST ACROSS THE ERN CONUS TUE KEEPING THE UPPER ANTICYCLONE SUPPRESSED ACROSS THE GULF COAST STATES. AS THE TROF MOVES EAST OFF SHORE WED...RIDGING DEVELOPS OVER THE SERN CONUS. THIS RIDGING REMAINS IN PLACE THU AND FRI. AT THE SFC...A WEAK COLD FRONT DROPS SOUTH TOWARD THE AREA AS THE TROF MOVES EAST TUE. THE FRONT STALLS NORTH OF THE AREA WED... BUT A LEE TROF DEVELOPS OVER THE CWFA. THE FRONT DISSIPATES THU BUT LEAVES A WEAK CONVERGENCE ZONE WHICH MOVES IN ON THU AND REMAINS IN PLACE FRI. THIS PATTERN WILL KEEP LOW LEVEL MOISTURE AND INSTABILITY ACROSS THE AREA. EVEN WITH THE RIDGE IN PLACE...THE SFC BOUNDARY WILL HELP PROVIDE ENOUGH FORCING TO TAP THE ELEVATED INSTABILITY ACROSS THE AREA. THIS WILL LEAD TO GENERALLY SCT DIURNAL CONVECTION EACH DAY...WITH COVERAGE SLIGHTLY FAVORING THE MTNS THRU THE PERIOD. TEMPERATURES WILL REMAIN ABOVE NORMAL UNTIL FRI WHEN THEY DROP TO NEAR NORMAL. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...VFR WILL PREVAIL THROUGH THE PERIOD AS DEEP LAYER RIDGING PREVAILS LEADING TO DRY WEATHER AND MOSTLY SUNNY SKIES. LIGHT WINDS INITIALLY WILL INCREASE OUT OF THE SOUTH BY MID/LATE MORNING WITH AFTERNOON FEW LOW VFR CU AND SCT HIGH LEVEL CIRRUS BEING THE DOMINATE SKY COVER. AS UPPER WAVE AND ASSOCIATED MOISTURE ADVECTION AXIS CONTINUES TO SLIDE EAST THROUGH THE DAY...SKIES WILL FILL IN FROM THE WEST. THUS...10Z FM GROUP CARRIES LIGHT SOUTHERLY WINDS UNDER LOW VFR CU AT BKN045. ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE MAJORITY OF THE FORECAST PERIOD WITH THE EXCEPTION OF IFR/MVFR LEVEL FOG/STRATUS THIS MORNING AT KHKY AND KAVL. EARLIER MVFR LEVEL STRATUS DECK HAS RECEDED SOMEWHAT GIVING WAY TO FOG DEVELOPMENT AS COOLING RESUMES. ALL SITES WILL RETURN TO VFR LEVELS BY MID MORNING WITH ABOVE MENTIONED DEEP LAYER RIDGING DOMINATING THE WEATHER FOR THE DAY. INITIAL LIGHT WINDS WILL INCREASE INTO THE 5-8KTS RANGE OUT OF THE SOUTH BY LATE MORNING TO EARLY AFTERNOON. LOW VFR CU WILL HIGHLIGHT THE SKIES BY LATE MORNING BENEATH OCCASIONAL HIGH LEVEL CIRRUS. EXPECTING OVERALL COVERAGE OF SKY COVER TO INCREASE LATE IN THE PERIOD AS DEEPER MOISTURE ADVECTS IN FROM THE WEST. AS THIS MOISTURE AXIS INTRUDES...SHRA/TSRA CHANCES WILL INCREASE BY LATE AFTERNOON LASTING INTO THE EARLY EVENING AT KAND AND KAVL. DUE TO LOW PROBABILITIES AND EFFECTS OF CAPPING CONTINUING TO PLAY A ROLE...OPTED FOR VCTS/VCSH MENTION INSTEAD OF PREVAILING WX. OUTLOOK...MOISTURE ADVECTION BEGINNING TONIGHT WILL LEAD TO INCREASING CHANCES FOR ISOLATED/SCATTERED DIURNAL SHRA/TSRA THROUGH MIDWEEK WITH THE GREATEST PROBABILITIES RESIDING ALONG THE HIGH TERRAIN. IN ADDITION...MORNING FOG/STRATUS WILL BE POSSIBLE WITH THE MOUNTAINS ONCE AGAIN HAVING THE GREATEST CHANCES AT RESTRICTIONS. CONFIDENCE TABLE... 10-16Z 16-22Z 22-04Z 04-10Z KCLT HIGH 93% HIGH 100% HIGH 100% MED 62% KGSP HIGH 100% HIGH 100% HIGH 100% MED 62% KAVL MED 60% HIGH 100% HIGH 97% MED 62% KHKY HIGH 85% HIGH 100% HIGH 100% MED 62% KGMU HIGH 91% HIGH 100% HIGH 100% MED 62% KAND HIGH 100% HIGH 100% HIGH 100% MED 62% 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...RWH NEAR TERM...CDG SHORT TERM...RWH LONG TERM...RWH AVIATION...CDG

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