Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 050229
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1029 PM EDT MON MAY 4 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL TONIGHT INTO WEDNESDAY. AN
AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP OFF THE EAST COAST OF
FLORIDA ON WEDNESDAY...AND LIFT NORTHWARD OFF THE SOUTHEAST COAST
THROUGH THURSDAY. THE LOW COULD THEN MEANDER BACK TOWARD THE COAST
THROUGH FRIDAY...AND LINGER NEARBY THROUGH THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SURFACE HIGH PRESSURE WILL REMAIN CENTERED OFF THE MID-ATLANTIC
COAST TONIGHT...AS UPPER LEVEL RIDGING GRADUALLY STRENGTHENS
ALOFT. STRONG SUBSIDENCE COMBINED WITH A LACK OF MOISTURE WILL
MAINTAIN RAIN-FREE CONDITIONS ACROSS THE AREA. THERE COULD BE SOME
THIN HIGH CLOUDS STREAMING IN FROM OFF THE ATLANTIC...BUT SKIES
SHOULD GENERALLY BE MOSTLY CLEAR. A MODERATING AIR MASS WILL KEEP
LOW TEMPERATURES A BIT MORE MILD THAN PREVIOUS NIGHTS DESPITE
FAVORABLE RADIATIONAL COOLING CONDITIONS. LOW TEMPERATURES WILL
RANGE FROM THE MID 50S INLAND...TO LOW/MID 60S AT THE COAST WHERE
LIGHT ONSHORE FLOW WILL PREVAIL.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
TUESDAY...EXPECT A SUMMERTIME LIKE PATTERN WITH AN ATLANTIC RIDGE OF
HIGH PRESSURE EXTENDING OVER THE SOUTHEASTERN UNITED STATES. MOST
AREAS ARE ANTICIPATED TO REMAIN DRY THROUGHOUT THE DAY...BUT A
PREVAILING EASTERLY FLOW SHOULD INCREASE MOISTURE LEVELS OVER THE
REGION AND RESULT IN A SLIGHT CHANCE OF SHOWERS DRIFTING ONSHORE
LATE TUESDAY NIGHT. LATEST 1000-850 MB THICKNESS VALUES SUPPORT
OVERALL HIGH TEMPS IN THE LOWER 80S INLAND TO MID/UPPER 70S NEAR THE
COAST. OVERNIGHT LOWS SHOULD RANGE IN THE UPPER 50S INLAND TO MID
60S ALONG THE COAST.

WEDNESDAY AND THURSDAY...THE MAIN CONCERN FOR THE MIDWEEK TIME FRAME
WILL DEAL WITH THE TRACK AND INTENSITY OF A SFC LOW THAT DEVELOPS
OFF THE EAST FLORIDA COAST/NORTHERN BAHAMAS. OVERALL MODEL CONSENSUS
CONTINUES TO IMPROVE...BUT NOTABLE DIFFERENCES REMAIN IN REGARDS TO
THE ACTUAL TRACK AND STRENGTH OF THE LOW THAT DEVELOPS ON
WEDNESDAY...THEN SHIFTS NORTH OFF THE SOUTHEAST COAST THROUGH
THURSDAY.

AT THIS TIME...THE NATIONAL HURRICANE CENTER HAS INDICATED A 30
PERCENT CHANCE OF CYCLONE FORMATION OFF THE SOUTHEAST COAST THURSDAY
OR FRIDAY. FORECAST CONFIDENCE REMAINS LOW UNTIL THE SYSTEM DEVELOPS
SOMETIME ON WEDNESDAY. REGARDLESS OF A TROPICAL VS SUBTROPICAL
STORM...THE POTENTIAL IMPACTS FROM SUCH SYSTEM WILL REMAIN HIGHLY
DEPENDENT ON THE EXACT TRACK AND STRENGTH OF THE SYSTEM AS IT
APPROACHES THE AREA LATE THURSDAY. SHOULD THE TRACK BE MORE
EAST...HAZARDOUS CONDITIONS WILL LIKELY REMAIN CONFINED TO COASTAL
WATERS AND THE IMMEDIATE COASTLINE. AT THE VERY LEAST...IT APPEARS
WE WILL BE DEALING WITH AN INCREASED RISK OF RIP CURRENTS AND THE
POTENTIAL FOR SOME BEACH EROSION WITH THE PERSISTENT NORTHEAST TO
NORTHERLY WINDS AROUND THE LOW AS IT TRACKS NORTH. SHOULD THE TRACK
OF THE LOW BE MORE WEST...THE THREAT FOR HEAVY RAINFALL AND
INCREASED WINDS WILL EXIST. GIVEN A SLIGHTLY MORE WESTWARD CONSENSUS
FOR THE TRACK OF THE LOW...HAVE INCREASED CHANCES OF SHOWERS OVER
MOST AREAS ON THURSDAY AND MAINTAINED SLIGHTLY COOLER TEMPS...AROUND
80 INLAND AND MID/UPPER 70S ALONG THE COAST.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THERE CONTINUES TO BE MUCH UNCERTAINTY IN THE LONG TERM PERIOD DUE
TO THE PRESENCE OF THE AFOREMENTIONED SFC LOW NEAR THE COAST. THOUGH
THE MODELS HAVE COME INTO BETTER AGREEMENT THERE ARE STILL
SIGNIFICANT DIFFERENCES THAT HAVE A SIGNIFICANT IMPACT ON THE
FORECAST. DUE TO A SLIGHTLY WESTWARD TREND IN THE MODEL
GUIDANCE...POPS HAVE BEEN INCREASED BUT CONFIDENCE IS STILL LOW
ENOUGH TO KEEP POPS IN THE CHANCE RANGE AT BEST. OTHER THAN THE
GFS...THE CONSENSUS IS FOR THE LOW TO PULL AWAY TO THE EAST AND
NORTHEAST THROUGH THE WEEKEND AND EARLY NEXT WEEK. THIS WOULD ALLOW
FOR A WARMING TREND IN TEMPERATURES WITH THE POSSIBILITY FOR DIURNAL
CONVECTION.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 00Z
WEDNESDAY. A FEW PATCHES OF STRATUS AND SHALLOW GROUND FOG WILL BE
POSSIBLE TOWARD DAYBREAK...ESPECIALLY AT KSAV...BUT NO FLIGHT
RESTRICTIONS ARE ANTICIPATED. GUSTY E-SE WINDS SHOULD DEVELOP AT
THE TERMINALS TUESDAY AFTERNOON.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH
WEDNESDAY. CHANCES FOR FLIGHT RESTRICTIONS WILL INCREASE AS AN AREA
OF LOW PRESSURE TRACKS NEAR THE COAST THURSDAY AND FRIDAY.

&&

.MARINE...
TONIGHT...RATHER BENIGN MARINE CONDITIONS EXPECTED TONIGHT AS
SURFACE HIGH PRESSURE REMAINS CENTERED OFF THE MID-ATLANTIC COAST.
WEAK PRESSURE GRADIENT WILL KEEP EASTERLY FLOW 15 KT OR LESS. SEAS
WILL BE 2-4 FEET ON AVERAGE...HIGHEST IN THE OUTER WATERS.

TUESDAY THROUGH FRIDAY...THE MAIN FORECAST ISSUE WILL REVOLVE AROUND
AN AREA OF LOW PRESSURE EXPECTED TO DEVELOP OFF THE EAST COAST OF
FLORIDA ON WEDNESDAY AND TRACK NORTH THROUGH THE END OF THE
WEEK...EVENTUALLY DRAWING CLOSER TO THE COAST. MARINE IMPACTS WILL
ULTIMATELY BE DETERMINED BY THE PROXIMITY AND STRENGTH OF THE SYSTEM
NEAR THE COAST. ALSO...THE NATIONAL HURRICANE CENTER CONTINUES TO
ADVERTISE A 30 PERCENT CHANCE THAT THE SYSTEM COULD ACQUIRE
SUBTROPICAL CHARACTERISTICS LATE IN THE WEEK. REGARDLESS...BEGINNING
WEDNESDAY NIGHT AND CONTINUING THROUGH FRIDAY...THE GRADIENT WILL
TIGHTEN ACROSS THE COASTAL WATERS LEADING TO AT LEAST LIKELY SMALL
CRAFT ADVISORY WINDS. GALES WILL BE POSSIBLE AS WELL...DEPENDING ON
THE PROXIMITY OF THE LOW. SEAS WILL BUILD DURING THE LATTER PART OF
THE WEEK DUE TO STRENGTHENING WINDS AND SWELL ENERGY ASSOCIATED WITH
THE LOW. MODELS HAVE TRENDED SLIGHTLY WEST...AND FURTHER TRENDS WILL
HAVE TO BE MONITORED IN THE COMING DAYS.

RIP CURRENTS...AN ELEVATED RISK FOR RIP CURRENTS IS EXPECTED LATER
THIS WEEK AND THIS WEEKEND AS A SURFACE LOW MOVES NEAR THE COAST.
INCREASING SWELL ENERGY AND COASTAL WINDS ASSOCIATED WITH THE LOW
WILL BE THE MAIN CAUSES FOR THE INCREASED RIP CURRENT RISK.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...JAQ/ECT
SHORT TERM...DPB
LONG TERM...BSH
AVIATION...JAQ/DPB
MARINE...ECT/DPB


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