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Area Forecast Discussion

730
FXUS62 KGSP 221037
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
637 AM EDT FRI MAY 22 2015

.SYNOPSIS...
DRY CANADIAN HIGH PRESSURE WILL BUILD OVER THE CAROLINAS AND
NORTHEAST GEORGIA TODAY AND REMAIN THROUGH THE HOLIDAY WEEKEND. A
SOUTHERLY FLOW OF MOISTURE AROUND A BERMUDA HIGH PRESSURE WILL
GRADUALLY RETURN NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM...UPDATED THE SKY GRIDS AND TEMPS TO MATCH UP WITH
TRENDS. CLOUDS HAVE BEEN A LITTLE SLOWER TO CLEAR OUT THAN WHAT THE
GUIDANCE WAS INDICATING EARLIER. TEMPS WERE RUNNING WARMER THAN
EXPECTED WHERE THE CLOUDS HAVE PERSISTED. STILL...OVERALL TRENDS ARE
ON TRACK...SO NO MAJOR CHANGES WITH THIS UPDATE.

AS OF 230 AM...A BROAD UPPER LEVEL TROF AXIS WILL BEGIN TO SHIFT
EAST...WITH THE AXIS FROM THE APPALACHIANS TODAY TO THE EAST COAST
TONIGHT. THIS WILL ALLOW HEIGHTS TO START RISING ATOP THE CWFA...AND
MAKE FOR MOSTLY CLEAR SKIES. AT THE SFC...A LARGE AREA OF DRY HIGH
PRES WILL CONTINUE TO BUILD IN ACRS A HUGE PORTION OF THE EASTERN
CONUS. LLVL THICKNESSES WILL SUPPORT TEMPS A CATEGORY OR TWO BELOW
NORMAL WITH LOW HUMIDITY AND LIGHT WINDS...MAKING FOR A VERY
PLEASANT DAY. MIN TEMPS TONIGHT WILL BE ABOUT A CATEGORY BELOW
NORMAL.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 150 AM FRIDAY...AN UPPER LEVEL RIDGE BUILDS ACROSS THE SERN US
THRU THE PERIOD. AT THE SFC...THE CENTER OF HIGH PRESSURE MOVES FROM
THE MID ATLANTIC STATES OFF SHORE DURING THE DAY SAT...BUT REMAINS
RIDGED ACROSS THE AREA. THE CENTER SLOWLY MOVES EAST INTO THE
ATLANTIC THRU THE REST OF THE PERIOD...BUT REMAINS RIDGED INTO THE
AREA DURING THIS TIME. THERE IS NO INSTABILITY ACROSS THE AREA
DURING THE PERIOD AND DEEP MOISTURE REMAINS OFF TO THE WEST.
THEREFORE...THE DRY FCST WILL CONTINUE. HOWEVER...THERE COULD BE
SOME CLOUDS EARLY SAT AND SUN AS WEAK UPSLOPE FLOW INTERACTS WITH
SOME LINGERING LOW LEVEL MOISTURE. BETTER CHC OF CLOUDS SUN
AFTERNOON AND NITE AS LOW LEVEL MOISTURE AND UPSLOPE FLOW INCREASE.
HIGHS NEAR TO A LITTLE ABOVE NORMAL SAT RISE A COUPLE OF DEGREES ON
SUNDAY. LOWS A FEW DEGREES ABOVE NORMAL SAT NITE RISE A FEW DEGREES
ON SUN NITE.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 325 AM FRI...THE PATTERN TAKES ON A DEFINITE SUMMER FEEL THRU
MUCH OF THE MEDIUM RANGE WITH RIDGING SFC AND ALOFT. THE RIDGE AXIS
IS FAR ENUF EAST AND THE SFC RIDGE AXIS IS FAR ENUF SOUTH FOR A
MOIST SWLY FLOW TO DEVELOP ACROSS THE AREA MON THRU WED. INSTABILITY
AND MOISTURE INCREASE EACH DAY BRINGING AN INCREASE IN DIURNAL
CONVECTIVE COVERAGE EACH DAY. STILL...BEST PRECIP CHC EACH DAY WILL
BE OVER THE MTNS FARTHER FROM THE RIDGE AXES CREATING BETTER
MOISTURE AND HIGHER INSTABILITY. SOME DIFFERENCES CREEP IN ON THU.
THE ECMWF KEEPS THE UPPER RIDGE STRONGER DAMPENING THE APPROACHING
SHORT WAVE AND MOVING IT FARTHER NORTH. THE GFS HAS A STRONGER SHORT
WAVE WHICH KNOCKS DOWN THE RIDGE AND MOVES ACROSS THE AREA.
THEREFORE...THE ECMWF HAS LESS CONVECTIVE COVERAGE WHILE THE GFS IS
HIGHER. HAVE GONE WITH A BLEND WHICH KEEPS COVERAGE SIMILAR TO WED.
TEMPS START OUT ABOVE NORMAL AND RISE A COUPLE OF DEGREES EACH DAY.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...STRATOCU IS A BIT SLOWER TO DISSIPATE THAN
THE GUIDANCE HAD INDICATED...BUT IS STILL EXPECTED TO CLEAR OUT BY
AROUND 13-14Z...AS DRY AIR FILTERS IN FROM THE NORTH. A FEW WISPS OF
CIRRUS WILL STREAM BY FROM TIME TO TIME...BUT OTHERWISE...SKIES
SHOULD BE CLEAR. NORTH TO NORTHEAST WINDS WILL CONTINUE TO WEAKEN
THRU THE DAY...BECOMING CALM OR LIGHT AND VARIABLE AFTER SUNSET THIS
EVENING.

OUTLOOK...DEEP HIGH PRESSURE WILL SETTLE OVER THE REGION OVER THE
WEEKEND...THEN SHIFT EAST EARLY NEXT WEEK...ALLOWING MOISTURE TO
GRADUALLY RETURN OUT OF THE SOUTH. CONDITIONS SHOULD REMAIN
GENERALLY FAIR THROUGH THE PERIOD.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  80%     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...RWH
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK



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