Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | 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

000
FXUS62 KGSP 231819
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
219 PM EDT SAT MAY 23 2015

.SYNOPSIS...
DRY CANADIAN HIGH PRESSURE WILL LINGER ATOP THE REGION THROUGH THE
HOLIDAY WEEKEND. MOIST SOUTHERLY FLOW AROUND THE BERMUDA HIGH WILL
GRADUALLY RETURN TO THE AREA BY TUESDAY WITH INCREASED CHANCES FOR
WIDESPREAD CONVECTION FOR THE LATER PORTION OF THE WORKWEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 200 PM EDT SATURDAY...RISING HEIGHTS ALOFT AHEAD OF AN
APPROACHING RIDGE AXIS...ALONG WITH BROAD/DRY HIGH PRESSURE AT THE
SURFACE CONTINUE TO YIELD PLEASANT WX ACROSS NORTHEAST GA AND THE
WESTERN CAROLINAS.  ASIDE FOR FURTHER EASTWARD MIGRATION OF THE
SURFACE RIDGE...LITTLE PATTERN CHANGE IS EXPECTED THROUGH THE NEAR
TERM LEADING TO A DRY AND MOSTLY SUNNY/CLEAR FCST.  LOW LEVEL FLOW
WILL GRADUALLY VEER ESE THIS AFTERNOON BEFORE CALMING FOR THE
OVERNIGHT.  WINDS WILL INCREASE YET AGAIN AS SOME MIXING OCCURS ON
SUNDAY...WITH WEAK MOISTURE RETURN EXPECTED OFF THE WESTERN
ATLANTIC.  THEREFORE DEWPOINTS AND TEMPERATURES ARE FCST TO
GRADUALLY RISE THROUGH THE PERIOD.  HIGHS ON SUNDAY WILL TOP OUT A
FEW DEGREES BELOW NORMAL AMIDST DEWPOINTS IN THE LOWER 50S UNDER
MID/HIGH LEVEL CIRRUS...WITH PERHAPS SOME AFTERNOON CU OVER THE
EASTERN THIRD OF THE CWFA WHERE MOISTURE ADVECTION IS BEST.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM SATURDAY...EARLY NEXT WEEK LOOKS LIKE A TRANSITION INTO A
MORE SUMMER-LIKE WEATHER REGIME. THE CULPRIT WILL BE THE SLOW
EVOLUTION OF THE UPPER PATTERN THAT WILL SEE THE AXIS OF AN UPPER
RIDGE MOVE EAST OF THE FCST AREA BY MONDAY MORNING. AS THAT
HAPPENS...A GULF MOISTURE PLUME WILL MIGRATE EASTWARD RIGHT BEHIND
IT. THE RETURN FLOW OF MOISTURE FROM THE GULF/ATLANTIC WILL COMMENCE
TO THE WEST EARLY MONDAY MORNING...AND AN UPSLOPE COMPONENT AT LOW
LEVELS COULD FORCE SOME SHOWER ACTIVITY OVER THE NE GEORGIA/UPSTATE
SC BLUE RIDGE BY SUNRISE. FROM THERE...MOISTURE WILL CONTINUE TO
INCREASE OVER THE WESTERN HALF OF THE FCST AREA. THE MODEL TREND
SEEMS TO BE TO CREEP THE MOISTURE A BIT FARTHER E WITH EACH RUN...
SO THE SHOWER/TSTM CHANCE OVER THE NC MTNS/WRN UPSTATE/NE GEORGIA IS
LOOKING BETTER AND BETTER. TEMPS MIGHT BE A FEW DEGREES WARMER ON
MONDAY COMPARED TO SUNDAY. MONDAY NIGHT IS KIND OF INTERESTING IN
THAT WE MIGHT NOT SEE MUCH OF THE USUAL DIURNAL DROP IN CONVECTIVE
ACTIVITY. THE MODELS SHOW A WEAKENING BAND OF UPPER DIVERGENCE
MOVING IN FROM THE W/SW AFTER 00Z TUESDAY AS A JET STREAK LIFTS NWD
OVER THE MS VALLEY/MIDWEST...AND A WEAK VORT MAX ALSO LIFTS NE FROM
THE GULF COAST. THIS SUBTLE FORCING...ALONG WITH SOME STRENGTHENING
OF THE FLOW OUT OF THE GULF...SHOULD BE FAVORABLE FOR CONVECTION
OVERNIGHT...ESPECIALLY NEAR THE BLUE RIDGE. TUESDAY LOOKS LIKE A
DECENT CONVECTIVE PRECIP DAY AND A CHANCE WAS KEPT IN THE FCST. THE
THREAT OF SEVERE WEATHER WILL BE MITIGATED BY POOR LAPSE RATES AND
RELATIVELY WEAK INSTABILITY. TEMPS WILL CREEP ANOTHER DEGREE OR TWO
HIGHER...BUT THE INCREASE IN HUMIDITY MIGHT BE MORE NOTICEABLE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM EDT SATURDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
WEDNESDAY WITH A STEEP UPPER RIDGE AXIS CENTERED OVER THE EAST COAST
AND MULTIPLE UPPER SHORTWAVES MOVING ACROSS THE GREAT LAKES REGION.
OVER THE NEXT 24 TO 48 HOURS...THE RIDGE AXIS MOVES FARTHER EAST AND
OFFSHORE WHILE MULTIPLE UPPER SHORTWAVES PASS JUST TO OUR NORTH. THE
LONG RANGE MODELS ALSO MOVE A CLOSED UPPER LOW NW AND TOWARDS
BERMUDA ON FRI AND SAT...BUT THIS SYSTEM SHOULD NOT HAVE ANY SIG
IMPACT ON OUR FCST. ON SAT...HEIGHTS RECOVER TO SOME DEGREE AS THE
UPPER RIDGE APPEARS TO RESTRENGTHEN.

AT THE SFC...WE WILL BE UNDER THE INFLUENCE OF A TYPICAL SUMMERTIME
BERMUDA HIGH AT THE START OF THE PERIOD. THIS WILL KEEP MOIST SLY
LOW LVL FLOW OVER THE REGION THRU PRETTY MUCH THE ENTIRE PERIOD. THE
GUIDANCE INDICATES THAT SOME MINOR LOW TO MID LVL DRYING IS POSSIBLE
ON FRI AND SAT...YET IT DOES NOT APPEAR SUBSTANTIAL. THE MODELS ALSO
GENERATE AN ELONGATED COLD FRONT TO OUR NW BY THE END OF THE PERIOD.
THIS FRONT IS ASSOCIATED WITH A SFC LOW THAT DEEPENS AS IT MOVES NE
OF THE GREAT LAKES...HOWEVER IT PROBABLY WONT HAVE MUCH IMPACT ON
THE CAROLINAS UNTIL BEYOND DAY 7 IF AT ALL. AS FOR THE SENSIBLE
FCST...WE CAN EXPECT A TYPICAL WARM SUMMERTIME PATTERN WITH GOOD
CHANCES FOR WIDESPREAD SHOWERS AND TS ON WED AND THURS WITH SOMEWHAT
REDUCED CHANCES ON FRI AND SAT AS PROFILES SHOULD BE DRIER
OVERALL...BUT WITH GOOD AMOUNTS OF INSTABILITY STILL PRESENT.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD.  PRIMARILY A WIND
FCST AS SKIES WILL REMAIN SKC...OR POSSIBLY FEW 150-250 TO ACCOUNT
FOR MID/HIGH LEVEL CIRRUS STREAMING IN ALOFT.  AS FOR WINDS...OPTED
TO GO AHEAD AND PREVAIL ESE FLOW IN THE 6-10KTS RANGE AT ALL SITES
AS PARENT HIGH PRESSURE ADVECTS BY TO THE NORTHEAST.  WINDS WILL
CALM OVERNIGHT BEFORE INCREASING TO APPROX 7-10KTS BY LATE MORNING
AND WILL BE PRIMARILY OUT OF THE SOUTH.

OUTLOOK...HIGH PRESSURE WILL SHIFT EAST OFF THE EAST COAST EARLY
NEXT WEEK...ALLOWING MOISTURE TO GRADUALLY RETURN OUT OF THE SOUTH.
CONDITIONS SHOULD REMAIN GENERALLY FAIR THROUGH THE PERIOD.

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 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     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...JPT
NEAR TERM...CDG
SHORT TERM...PM
LONG TERM...JPT
AVIATION...CDG



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