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 302135
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
535 PM EDT SAT MAY 30 2015

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL PERSIST ACROSS THE REGION INTO EARLY NEXT
WEEK...WITH MOIST SOUTHERLY FLOW SUPPORTING SCATTERED AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS. A COLD FRONT APPROACHES THE AREA
ON TUESDAY AND IS EXPECTED TO BECOME STATIONARY THROUGH THE MIDDLE
OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 530 PM...SEEING A BIT MORE ENHANCED CU OVER PARTS OF THE
PIEDMONT...WITH SOME SHOWERY ELEMENTS APPEARING ON RADAR...MAINLY S
OF I-85. THUS...KEEPING A SLIGHT CHC OF PRECIP EVERYWHERE LOOKS LIKE
A GOOD IDEA...AT LEAST UNTIL SUNSET. AIR MASS IS A BIT DRIER THAN
FCST AND THAT COULD BE WHY SOME TEMPS ARE ALREADY COOLING JUST A
BIT. WILL ADJUST THE TEMP TREND.

PREVIOUS DISCUSSION...

A FAIRLY HEALTHY CU FIELD IS OCCASIONALLY POPPING A STRAY/
SHORT-LIVED SHOWER OR TWO ACROSS THE AREA THIS AFTERNOON. WITH CAPE
VALUES OF LESS THAN 1000 J/KG EXPECTED TO PERSIST...AND RATHER WARM
MID-LEVELS CONCENTRATING WHAT CAPE THERE IS IN THE LOW
LEVELS...EXPECT THE CHARACTER OF DEEP CONVECTION TO REMAIN SHOWERY
THROUGH THE EVENING HOURS.

ANY CONVECTION WILL DIMINISH BY SUNSET OR SHORTLY THEREAFTER. LATE
TONIGHT...SHORT TERM NUMERICAL GUIDANCE INDICATES ANOTHER SURGE OF
LOW LEVEL ATLANTIC MOISTURE WILL PUSH INTO THE AREA. SOME OF THE
CONVECTION ALLOWING MODELS ARE SUGGESTING SHOWERS WILL REDEVELOP IN
ASSOCIATION WITH THIS IN RESPONSE TO WEAK UPGLIDE/UPSLOPE FLOW.
HOWEVER...THE HIRES MODELS WERE ALSO ADVERTISING SOMETHING SIMILAR
FOR LAST NIGHT...AND THIS DIDN/T HAPPEN. NEVERTHELESS...THERE/S
ENOUGH OF A SIGNAL TO ADVERTISE SLIGHT CHANCE POPS TOWARD
DAYBREAK...PRIMARILY FOCUSED ON THE ESCARPMENT.

HEIGHTS WILL BEGIN SLOWLY FALLING ACROSS THE AREA ON SUNDAY...
RESULTING IN NOMINAL COOLING OF THE MID-LEVELS. MOISTURE PROFILES
WILL ALSO BE A BIT IMPROVED OVER TODAY...ESP ACROSS THE WESTERN HALF
OF THE AREA. THE RESULTANT INCREASE IN BUOYANCY...AND A SYNOPTIC
PATTERN THAT WILL BE A BIT MORE CONDUCIVE TO UVV...SHOULD BE
SUFFICIENT TO RESULT IN AT LEAST SCATTERED CONVECTION ACROSS THE
WESTERN HALF OF THE AREA...WHERE POPS WILL RANGE FROM 40-60 PERCENT.
POPS TAPER TO 20-30 PERCENT ACROSS THE EASTERN ZONES DURING THE
AFTERNOON. MODEST WIND PROFILES DOWNSTREAM OF UPPER TROUGH WILL
RESULT IN SLIGHTLY ENHANCED CHANCES FOR ORGANIZED CONVECTION AND
POSSIBLY AN ISOLATED SEVERE STORM.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AT 2 PM EDT SATURDAY...ON SUNDAY EVENING THE NORTHERN AND SOUTHERN
STREAMS WILL BE OUT OF PHASE. AN UPPER TROUGH WILL BE OVER ATLANTIC
CANADA...WHILE A WEAK UPPER RIDGE WILL BE OFF THE EAST COAST OF THE
USA. AN LOW AMPLITUDE UPPER RIDGE WILL BE OVER CENTRAL CANADA...
WHILE A LOW AMPLITUDE UPPER TROUGH WILL BE OVER THE CENTRAL AND LOWER
MS RIVER VALLEY. THE SOUTHERN STREAM REMAINS LESS PROGRESSIVE THAN
THE NORTHERN STREAM IN THE GFS...WHICH CLOSES OFF AN UPPER LOW IN
THE LOWER MS RIVER VALLEY BY WEDNESDAY. MEANWHILE...THE ECMWF TROUGH
MOVES SLOWLY ACROSS THE GULF STATES TOWARD THE SOUTHERN APPALACHIANS.

AT THE SURFACE...ON SUNDAY EVENING A SLOW MOVING COLD FRONT WILL BE
APPROACHING THE SOUTHERN APPALACHIANS FROM THE NW. WEAK MOIST INFLOW
AHEAD OF THE FRONT WILL BACK UP AGAINST THE BLUE RIDGE..BUT LOW
LEVEL FLOW WILL VEER FROM S TO SW...REDUCING THE UPSLOPE FLOW
COMPONENT. ALTHOUGH WEAK ELEVATED INSTABILITY WILL BE PRESENT...NAM
MODEL SOUNDINGS SHOW A WEAK WARN NOSE ALOFT DEVELOPING AT AROUND 650
MB THAT WOULD PARTIALLY CAPPING LIFT.

BY MONDAY MORNING THE ECMWF FRONT WILL HAVE MOVED TO THE WESTERN
PIEDMONT...WHILE THE GFS FRONT REMAINS WEST OF THE MOUNTAINS. CAPE
AND SHEAR VARY BETWEEN THE NAM AND GFS...BUT EVENT THE WEAKER GFS
VALUES APPROACH THOSE NEEDED FOR ORGANIZED CONVECTION. THE MODELS
VARY ON AVAILABLE DRY AIR ALOFT FOR DOWNBURST ENHANCEMENT.

BY MONDAY EVENING THE GFS COLD FRONT APPEARS TO CATCH UP TO THE
SLOWING ECMWF FRONT OVER THE CENTRAL CAROLINAS AND GA...WHILE
MOISTURE LINGERS BEHIND THE BOUNDARY INTO E TN. MODEL SOUNDINGS SHOW
ELEVATED CAPE PERSISTING IN THE WAKE OF THE FRONT MONDAY MONDAY
NIGHT...THOUGH WITH A DIMINISHING TREND.

THE FRONT WEAKENS OVER THE CENTRAL CAROLINAS AND GA ON TUESDAY...
WHILE ASSOCIATED MOISTURE AND VERTICAL SHEAR REMAIN...AND
INSTABILITY INCREASES WITH DAYTIME HEATING. THE MODELS AGAIN VARY ON
HOW MUCH DRY AIR ALOFT WILL BE AVAILABLE FOR EVAPORATIVE COOLING
AND DOWNBURST POTENTIAL.

TEMPERATURES WILL EXHIBIT A REDUCED DIURNAL TEMPERATURE RANGE DUE TO
CLOUDS AND MOISTURE...WITH MAXIMUMS NEAR TO SLIGHTLY BELOW
NORMAL...AND MINIMUMS ABOVE NORMAL.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 100 PM SATURDAY...THERE IS SOME DEGREE OF BAGGINESS AND/OR
UPPER LEVEL TROUGHING IN THE PATTERN ATOP THE SE CONUS PROGGED TO
START OFF THE PERIOD. ACCOMPANIED BY WEAK RIDGING NOSING SWWD INTO
THE SOUTHERN APPALACHIANS...SENSIBLE WX WILL CONTINUE TO FEATURE
SOLID CHANCE POPS AND MAX TEMPERATURES A FEW DEG F BELOW CLIMO FOR
WEDNESDAY. THE PATTERN IS SHAPING UP TO EVOLVE ONLY SLOWLY THROUGH
THURSDAY...FEATURING LINGERING UPPER LEVEL TROUGHING AND SOME DEGREE
OF WEAK LLVL RIDGING. PROBABLY BEST TO KEEP THE ABOVE CLIMO POP GOING
THROUGH THE NEW DAY 5 WITH NEAR NORMAL TEMPERATURES.

FOR THE LATTER HALF OF THE PERIOD...IF THE 30/12 UTC ECMWF IS
CORRECT...UPPER LEVEL RIDGING WILL BUILD BACK ATOP THE REGION. THE
WPC EXTENDED RANGE GUIDANCE SEEMS TO FAVOR THIS...FEATURING A WARMING
TREND FRIDAY AND SATURDAY...WITH DAILY TSTM CHANCES RETREATING BACK
TO CLIMO VALUES.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...SCT/BKN CUMULUS IN THE 035-050 RANGE AND SE
WINDS AT 5-10 KTS WILL CONTINUE THROUGH THE AFTERNOON. VERY SPOTTY/
MAINLY SHORT LIVED RAIN SHOWERS WILL CONTINUE TO DEVELOP ACROSS THE
AREA THIS AFTERNOON...BUT COVERAGE IS EXPECTED TO BE TOO SPARSE TO
WARRANT ANY TAF MENTION ATTM. OTHERWISE...THE MAIN CONCERN WILL BE
THE POTENTIAL FOR RESTRICTIONS LATE TONIGHT...AS MODEL GUIDANCE
SUGGESTS ANOTHER SURGE OF LOW LEVEL ATLANTIC MOISTURE WILL PUSH INTO
THE AREA BY DAYBREAK. THERE IS A STRONG CONSENSUS IN THE GUIDANCE
THAT THIS SURGE WILL RESULT IN IFR CIGS DEVELOPING AROUND 12Z AT
MOST TERMINALS. HOWEVER...IN LIGHT OF THE FACT THAT THIS WAS ALSO
MORE OR LESS ADVERTISED FOR THIS MORNING...BUT DIDN/T PAN OUT TOO
WELL...OPTED TO GENERALLY KEEP CONDITIONS AT THE LOW MVFR
LEVELS...EXCEPT AT THE CLIMATOLOGICALLY FAVORED LOCATIONS OF KAVL
AND KHKY.

OUTLOOK...THE PATTERN IS EXPECTED TO BECOME MORE UNSETTLED/ACTIVE
FROM SUNDAY AFTERNOON INTO AT LEAST MID-WEEK...AS A COLD FRONT
STALLS OVER THE REGION. EXPECT AT LEAST LOCALIZED AREAS OF MORNING
FOG AND/OR STRATUS MOST DAYS...WITH GOOD CHANCES FOR AFTN/EVENING
SHRA/TSRA EACH DAY.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-18Z
KCLT       HIGH 100%     HIGH 100%     MED   78%     HIGH  90%
KGSP       HIGH 100%     HIGH 100%     HIGH  86%     HIGH  92%
KAVL       HIGH 100%     HIGH 100%     MED   72%     MED   78%
KHKY       HIGH 100%     HIGH 100%     HIGH  80%     HIGH  92%
KGMU       HIGH 100%     HIGH 100%     HIGH  86%     MED   78%
KAND       HIGH 100%     HIGH 100%     HIGH  84%     HIGH  97%

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...JDL/PM
SHORT TERM...JAT
LONG TERM...CSH
AVIATION...JDL



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