Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 290753
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
353 AM EDT TUE JUL 29 2014

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO PUSH OFFSHORE AND WILL BECOME STATIONARY
SOUTH AND SOUTHEAST OF THE AREA THROUGH THE MIDDLE OF THE WEEK. THE FRONT
WILL THEN SLOWLY MOVE BACK TOWARDS THE SOUTHEAST COAST LATE IN THE WEEK
THROUGH EARLY NEXT WEEK...BRINGING THE POSSIBILITY OF SOME UNSETTLED
WEATHER TO THE LOCAL AREA.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TODAY...THE DEEP MID/UPPER LEVEL TROUGH ALOFT WILL CONTINUE TO TAKE
HOLD ACROSS THE EASTERN CONUS. AS IT DOES...THE TROUGH WILL REMAIN
ANOMALOUSLY STRONG WITH 500 MB HEIGHTS BECOMING 2 TO 3 STANDARD
DEVIATIONS BELOW NORMAL. MEANWHILE AT THE SURFACE...THE COLD FRONT
WILL PUSH A BIT FURTHER OFFSHORE AS MUCH DRIER AIR WORKS INTO THE
FORECAST AREA. IN FACT...PWATS WILL DROP TO AROUND AN INCH THIS
AFTERNOON. THE DRY MOISTURE PROFILES AND A STRONG CAP AROUND 700 MB
WILL KEEP THE FORECAST DRY TODAY. FURTHERMORE...THE LOW HEIGHTS
ALOFT MEAN WE WILL SEE MUCH MORE COMFORTABLE TEMPERATURES TODAY.
LOOK FOR HIGHS IN THE UPPER 80S TO LOW 90S WHICH IS A COUPLE OF
DEGREES BELOW CLIMATOLOGY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...THE FORECAST WILL REMAIN VERY QUIET WITH THE COLD FRONT
WELL OFFSHORE AND VERY DRY MID/UPPER LEVELS. THE PRESSURE FIELD WILL
BECOME A BIT NEBULOUS AND WEAK...RESULTING IN NEAR CALM CONDITIONS
IN MANY AREAS. MUCH COOLER LOWS ARE ON TAP AS WELL...WITH VALUES
EXPECTED TO FALL INTO THE UPPER 60S AWAY FROM THE IMMEDIATE COAST.

A DEEP LAYERED GYRE WILL REMAIN SPINNING NEAR JAMES BAY IN CANADA
DURING THE MIDDLE AND LATTER PARTS OF THE WEEK...WITH AN ANOMALOUS
TROUGH TO REMAIN ANCHORED OVER THE EASTERN UNITED STATES.
SIMULTANEOUSLY AT THE SURFACE WE/LL FIND A STATIONARY FRONT
STRETCHING FROM OFF NEW ENGLAND TO SOUTHERN FLORIDA WEDNESDAY AND
THURSDAY...BEFORE THE FRONT BEGINS TO TREK BACK TOWARD THE SE COAST
ON FRIDAY. THERE COULD EVEN BE A WEAK WEDGE THAT ATTEMPTS TO FORM
WELL INLAND AS THE FRONT APPROACHES FROM THE SE LATE IN THE WEEK.

MOISTURE WILL GRADUALLY BEGIN ITS RETURN WEDNESDAY AS THE SYNOPTIC
FLOW VEERS AROUND TO THE EAST AND SE. FORCING FROM THE SEA BREEZE
LOOKS TO BE THE ONLY MECHANISM FOR A FEW SHOWERS OR T-STORMS TO POP.
BUT A STRONG CAP REMAINS IN PLACE...SO WE HAVE HELD OFF ON ANY
MENTIONABLE PRECIPITATION PROBABILITIES IN THE FORECAST AT THIS TIME.

THERE IS SLIGHTLY BETTER RAIN CHANCES TO OCCUR THURSDAY AS THE
INFLUX OF MARITIME AIR CONTINUES TO INCREASE AND OUR CAP IS WEAKER.
WE/LL SHOW NO HIGHER THAN 20 POPS ACROSS THE BOARD...ALTHOUGH THERE
ARE HINTS OF SOME MID LEVEL FORCING THAT COULD RESULT IN SLIGHTLY
GREATER COVERAGE.

OUR BEST CHANCE OF RAINFALL FOR THE SHORT TERM PERIOD WILL COME
FRIDAY...AS THE CAP HAS ERODED AND THERE IS A CONTINUED FEED OF
MOISTURE FROM THE ATLANTIC IN THE LOW LEVELS. ADDITIONALLY THE FLOW
ALOFT BACKS MORE TO THE SW WITH SOME RETROGRESSION TO THE LONG WAVE
TROUGH IN THE EAST. THIS PROVIDES FOR A FEED OF GULF MOISTURE...AND
ALSO ALLOWS THE STATIONARY FRONT TO LIFT BACK CLOSER TO THE SE
COAST. WE/LL BUMP POPS INTO THE SOLID CHANCE RANGE AS A RESULT.

THE BROAD CYCLONIC FLOW ALOFT COMBINED WITH A FETCH OFF THE ATLANTIC
AND INCREASING RAIN CHANCES WILL HOLD DAYTIME TEMPS DOWN A BIT BELOW
LATE JULY/EARLY AUGUST NORMS. NIGHT TIME LOWS WILL AVERAGE NEAR OR
SLIGHTLY BELOW NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE LATTER PORTION OF THE FORECAST PERIOD LOOKS TO BE RATHER
UNSETTLED WITH THE MEAN LONG WAVE TROUGH POSITION ALOFT TO SHIFT A
HAIR FURTHER WEST...ALLOWING FOR THE STATIONARY FRONT AT THE
SURFACE TO SET UP OVER OR NEAR THE FORECAST AREA THIS WEEKEND AND
EARLY NEXT WEEK. MOISTURE WILL CONTINUE TO STREAM IN COURTESY OF A
SE AND SOUTH FLOW IN THE LOW LEVELS AND A RICH SW FEED IN THE MID
AND UPPER REACHES OF THE TROPOSPHERE. FORCING DUE TO THE PROXIMITY
OF THE STATIONARY FRONT WILL PROVIDE THE NECESSARY LIFT TO GENERATE
AT LEAST A SOLID CHANCE OF PRECIPITATION COVERAGE THROUGHOUT. TEMPS
WILL BE HELD IN CHECK DUE TO PLENTY OF CLOUDS AND THE HIGHER RAIN
CHANCES.

THERE ARE FORTUNATELY STILL NO INDICATIONS THAT ANY SORT OF TROPICAL
OR SUB-TROPICAL LOW WILL FORM ON THE FRONT...ESPECIALLY SINCE IT
LOOKS TO HAVE TOO MUCH INTERACTION WITH THE NEARBY LAND MASS OF THE
SE. HOWEVER...THE TROPICAL WAVE IN THE EASTERN ATLANTIC HAS A HIGH
PROBABILITY OF DEVELOPING INTO A TROPICAL CYCLONE. BUT THIS FEATURE
LOOKS TO CURVE OUT IN THE ATLANTIC...TURNING AWAY FROM CONUS BEFORE
IT GETS MUCH FURTHER WEST THAN ABOUT 70-75 DEGREES AND TO THE NE OF
THE BAHAMAS. SHOULD IT BECOME A NAMED SYSTEM IT WOULD BE BERTHA. IN
2008 BERTHA WAS BOTH THE LONGEST LIVED AND EASTERNMOST DEVELOPING
JULY TROPICAL CYCLONE ON RECORD.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH 06Z WEDNESDAY.

EXTENDED AVIATION OUTLOOK...VFR INTO WEDNESDAY...AND POSSIBLE EVEN
INTO THURSDAY. THEN OCCASIONAL FLIGHT RESTRICTIONS ARE POSSIBLE
LATE IN THE WEEK AS A STATIONARY FRONT BEGINS TO LIFT CLOSER TO THE
SE COAST.

&&

.MARINE...
TODAY AND TONIGHT...A VERY QUIET PERIOD IS ON TAP AS A COLD FRONT
PUSHES EAST OF THE WATERS. IN THE WAKE OF THE FRONT TODAY...THE
PRESSURE FIELD WILL BECOME QUITE WEAK. WINDS WILL LIKELY BECOME
LIGHT AND VARIABLE AT TIMES. THIS WILL CONTINUE THROUGH THE
OVERNIGHT PERIOD AS WELL...THOUGH THE PREVAILING DIRECTION WILL
INCREASINGLY BECOME NORTHEASTERLY WITH TIME. SEAS WILL DIMINISH WITH
TIME...STARTING OFF THE DAY 2-3 FT AND BECOMING 1-2 FT BY LATE
TONIGHT.

WEDNESDAY...CONDITIONS ACROSS THE COASTAL WATERS WILL BE FAIRLY
BENIGN WITH A LAX NE TO EAST PRESSURE PATTERN. WE LOOK FOR WINDS
HELD UNDER 10 OR 12 KT AND SEAS MAINLY AROUND 2 FT.

THURSDAY THROUGH FRIDAY...HIGH PRESSURE TO THE NORTH AND THE
STATIONARY FRONT TO THE SE LIFTING SLOWLY BACK TOWARD THE AREA WILL
ALLOW FOR A SMALL INCREASE IN THE LOCAL GRADIENT. WINDS AND SEAS
WILL CLIMB A TAD...BUT REMAINING WELL BELOW ANY SMALL CRAFT ADVISORY
CRITERIA.

SATURDAY THROUGH SUNDAY...THE STATIONARY FRONT LOOKS TO SLIDE INTO
THE WATERS...PERHAPS EVEN MOVING ONSHORE OF THE SE. WINDS WILL VEER
IN RESPONSE...BUT STILL NOTHING MORE THAN ABOUT 12-18 KT AND 3 OR 4
FT SEAS.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.

&&

$$

NEAR TERM...BSH
SHORT TERM...33
LONG TERM...33
AVIATION...BSH
MARINE...BSH/33




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