« Back
NWS Peachtree City, Ga » Text Product » CHS Area Forecast Discussion


Printer-friendly Version
Current Version              Previous Versions:   1  2  3  4  5  6  7  8  9  

Area Forecast Discussion

811
FXUS62 KCHS 231809
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
209 PM EDT TUE SEP 23 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD FROM THE NORTH THROUGH MID WEEK...WHILE
A COASTAL TROUGH REMAINS OFFSHORE INTO LATE WEEK. HIGH PRESSURE
WILL LINGER TO THE NORTH INTO THIS WEEKEND AND MAINTAIN PERSISTENT
NORTHEAST FLOW.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY....LATEST WATER VAPOR IMAGERY AND UPPER LEVEL ANALYSIS
SHOWS AN ANOMALOUS LOW LOCATED ACROSS CENTRAL GEORGIA AND CENTRAL
SOUTH CAROLINA. SIGNIFICANTLY DRIER AIR ALOFT IS PUSHING INTO THE
SOUTHWEST PERIPHERY OF THE UPPER LOW...WHILE DEEP LAYER MOISTURE
CURRENTLY WRAPS AROUND THE EASTERN AND NORTHERN PERIPHERIES. THE
NEARLY STATIONARY UPPER LOW IS EXPECTED TO GRADUALLY FILL AND
EXPAND ACROSS MUCH OF THE SOUTHEAST AND MID ATLANTIC REGION AS THE
DAY PROGRESSES. THE SURFACE FEATURES WILL BECOME MORE
AMPLIFIED...WITH AN INLAND WEDGE OF HIGH PRESSURE PRESSING DOWN
TOWARD SOUTHERN GEORGIA AND A TROUGH ALONG ITS PERIPHERY
SHARPENING OFFSHORE. THE PRESSURE GRADIENT WILL STEADILY TIGHTEN
BETWEEN THE INLAND RIDGE AND OFFSHORE TROUGH...AND EXPECT
NORTHEAST FLOW TO INCREASE THROUGH THE AFTERNOON AND EVENING HOURS
ACCORDINGLY.

PERSISTENT SHOWER ACTIVITY IS EXPECTED TO FAVOR THE MARINE
ZONES...COASTAL AREAS...AND CHARLESTON TRI COUNTY REGION TODAY.
HAVE INDICATED A RATHER NOTABLE GRADIENT IN PRECIPITATION
POTENTIAL...WITH SCATTERED TO NUMEROUS SHOWERS IMPACTING EASTERN
AND NORTHERN ZONES CLOSER TO DEEP MOISTURE/FORCING...WHILE MORE
ISOLATED ACTIVITY WILL OCCUR FARTHER TO THE WEST. THICK CLOUD
COVER...PERIODS OF RAIN AND COOLER NORTHEAST FLOW WILL SUPPRESS
TEMPERATURES AROUND 10 DEGREES BELOW SEASONAL NORMALS. HAVE
ADVERTISED HIGH TEMPERATURES RANGING FROM ONLY THE LOWER 70S
SOUTH CAROLINA ZONES TO THE UPPER 70S CLOSER TO THE ALTAMAHA RIVER
IN SOUTHEAST GEORGIA.

TONIGHT...THE POTENTIAL FOR AT LEAST ISOLATED TO SCATTERED RAIN WILL
LINGER WITHIN THIS SYNOPTIC PATTERN...AND EXPECT CLOUDY AND COOL
WEATHER TO PERSIST. BREEZY TO WINDY CONDITIONS ARE ALSO POSSIBLE
ALONG COASTAL AREAS AS THE SURFACE TROUGH TIGHTENS JUST OFFSHORE.
TEMPERATURES WILL FALL INTO THE UPPER 50S WELL INLAND TO LOWER 60S
ALONG THE COAST.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
THERE HAS BEEN A RATHER REMARKABLE SHIFT IN THE MODELS FOR THE
MEDIUM RANGE PERIOD COMPARED TO 24 HR PRIOR. BOTH THE GFS AND
ECMWF NOW LIFT THE UPPER LOW OUT OF THE SOUTHEAST UNITED STATES BY
WEDNESDAY NIGHT. THIS WOULD PUSH THE COASTAL TROUGH FARTHER
OFFSHORE BY THURSDAY AND FRIDAY WHILE THE SURFACE HIGH OVERSPREADS
FROM THE NORTHWEST. THE OVERALL EFFECT IS LOWER POPS ACROSS THE
BOARD... ESPECIALLY INLAND. SINCE THERE HAS BEEN SOME RUN TO RUN
INCONSISTENCY WE DID NOT COMPLETELY ERADICATE POPS DURING THIS
PERIOD. WE SHOW CHANCE POPS OVER THE WATERS AND COASTAL AREAS WITH
SLIGHT CHANCE INLAND. THUNDERSTORM POTENTIAL LOOKS TO BE CONFINED
TO THE MARINE AREAS SINCE THE COOL STABLE WEDGE OF HIGH PRESSURE
WILL MAKE CONDITIONS UNFAVORABLE FOR THUNDER ELSEWHERE.
CONSIDERABLE CLOUDINESS AND COLD ADVECTION WILL KEEP HIGH TEMPS IN
THE UPPER 70S MOST AREAS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
CONSIDERABLE DISAGREEMENT BETWEEN MODELS IN THE LONG TERM THOUGH IT
LOOKS AS THOUGH THE EXPANSIVE HIGH WILL REMAIN NORTH OF THE AREA
THROUGH SUNDAY. ENOUGH MOISTURE AND LIFT WILL EXIST FOR ISOLATED TO
SCATTERED SHOWERS ACROSS THE AREA. POTENTIAL FOR INCREASING RAIN
CHANCES EARLY NEXT WEEK IF A FRONT LIFTS NORTH OUT OF THE GULF PER
THE 00Z ECMWF. TEMPS RETURN TO NEAR NORMAL FOR LATE SEPT BY THE
WEEKEND.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
LATEST RADAR IMAGERY SHOWS AREAS OF RAIN CONTINUE TO STREAM ACROSS
THE CHARLESTON TRI COUNTY REGION AND SC/GA COASTAL WATERS THIS
AFTERNOON. HAVE INITIALIZED THE KSAV TAF WITH DRY WEATHER...AS THE
MAJORITY OF ACTIVITY WILL LIKELY REMAIN TO THE EAST AND NORTH.
DETERMINING TIMING AND DURATION OF LIGHT RAIN AT KCHS WILL BE MORE
DIFFICULT DUE TO ITS CLOSER PROXIMITY TO THE FLUX OF MOISTURE FROM
THE MARINE ZONES...AND PREFER TO INITIALIZE WITH VCSH THROUGH THE
NIGHTTIME PERIOD. HOWEVER...WILL CONSIDER ADDING A TEMPO GROUP FOR
-RA AND BROKEN MVFR CONDITIONS AT KCHS IF LATEST TRENDS CONTINUE.

THE PRESSURE GRADIENT WILL BEGIN TO TIGHTEN BETWEEN AN INLAND
WEDGE OF HIGH PRESSURE AND A TROUGH OFFSHORE...SUPPORTING AN
INCREASE IN NORTHEAST WINDS THIS AFTERNOON. STRONGEST WINDS COULD
ACTUALLY OCCUR OVERNIGHT...WHEN THE GRADIENT IS THE TIGHTEST.
BROKEN TO OVERCAST SKY COVER WILL LIKELY VARY BETWEEN LOW VFR AND
MVFR THROUGH THE PERIOD. 18Z TAF ISSUANCE IS OPTIMISTIC WITH
PREVAILING VFR OVERNIGHT...ESPECIALLY IF STRONGER WINDS PROVIDE
ENOUGH MIXING TO KEEP CLOUD BASES HIGHER. HOWEVER ADJUSTMENTS
WILL LIKELY BE NEEDED AS THE AFTERNOON/EVENING PROGRESSES. WILL
RETURN CONDITIONS TO PREVAILING MVFR BY DAYBREAK WEDNESDAY...AS
WIND SPEEDS DIMINISH SLIGHTLY AND THE INLAND WEDGE INVERSION HOLDS
IN PLACE.

EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS POSSIBLE
AT TIMES INTO THE END OF THE WEEK WITH A LINGERING WEDGE PATTERN
AND AMPLE LOW LEVEL MOISTURE.

&&

.MARINE...
A STRONG COOL SEASON STYLE WEDGING/PINCHING PATTERN WILL EVOLVE
TODAY...CHARACTERIZED BY A TIGHTENING GRADIENT AS HIGH PRESSURE
BUILDS IN FROM THE NORTH. HAVE INITIALIZED SMALL CRAFT ADVISORIES
FOR ALL COASTAL WATERS AS CONDITIONS STEADILY DETERIORATE. SOLID
ADVISORY CONDITIONS ARE EXPECTED ACROSS ALL WATERS BY
TONIGHT...WITH SEAS BUILDING TO 6 TO 8 FT...HIGHEST OFFSHORE.
THERE COULD BE SOME LOCAL PINCHING AND A FEW GUSTS NEARING GALES
AT TIMES...BUT HAVE CAPPED ALL WINDS AT 30 KT FOR NOW.

HIGH PRESSURE TO THE NORTH WITH A PROLONGED NORTHEAST GRADIENT
EXPECTED OVER THE WATERS DURING THE PERIOD. THE BEST SURGE WILL
PERSIST FROM TUESDAY THROUGH WEDNESDAY EVENING WITH SMALL CRAFT
ADVISORIES FOR ALL WATERS. LATE WEEK INTO THE WEEKEND THE GRADIENT
LOOKS TO WEAKEN SOMEWHAT...HOWEVER WE COULD AT TIMES FLIRT WITH
ADVISORY CRITERIA.

RIP CURRENTS...LOCAL GUIDANCE YIELDED A MODERATE RISK FOR RIP
CURRENTS ON AREA BEACHES TODAY...MAINLY DUE TO STRONG ONSHORE
WINDS. AN ELEVATED RISK FOR RIP CURRENTS WILL CONTINUE THROUGH AT
LEAST LATE THIS WEEK...AND PERHAPS EVEN INTO THE WEEKEND.

&&

.TIDES/COASTAL FLOODING...
A PROLONGED NORTHEAST FLOW WITH MODERATE WIND SPEEDS WILL RESULT IN
ABOVE PREDICTED TIDE LEVELS THROUGH THE UPCOMING WEEKEND. ALTHOUGH
THE POSITIVE ANOMALY WOULD NEED TO BE A LITTLE MORE THAN 1.0
FEET...THERE IS A MODERATE CHANCE OF THE TIDE REACHING 7 FT MLLW
ALONG THE SOUTH CAROLINA COAST THAT WOULD NECESSITATE COASTAL
FLOOD ADVISORIES DURING THE EVENING HIGH TIDES.

&&

.EQUIPMENT...
THE DOWNTOWN CHARLESTON WEATHER SENSOR AT WATERFRONT PARK /KCXM/
IS INOPERABLE. IT IS UNKNOWN AT THIS TIME WHEN THE SENSOR WILL BE
RETURNED TO SERVICE. HOURLY OBSERVATIONS AND DAILY CLIMATE
INFORMATION WILL NOT BE AVAILABLE UNTIL FURTHER NOTICE.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT WEDNESDAY FOR AMZ330.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT WEDNESDAY NIGHT FOR
     AMZ350-352-354-374.

&&

$$

NEAR TERM...WMS
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...WMS/
MARINE...JRL
TIDES/COASTAL FLOODING...
EQUIPMENT...






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