Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 270531
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
131 AM EDT WED MAY 27 2015

.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION THROUGH EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ISOLATED SHOWERS MAY PERSIST THROUGH THE NIGHT DUE TO A WEAK
SHORTWAVE IN PLACE AND FAIRLY DEEP MOISTURE OVER THE AREA. THE
WAVE WILL LIFT NORTHEAST OF THE AREA BY DAWN SO WE EXPECT A
DIMINISHING TREND IN RAIN SHOWER COVERAGE.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
WEDNESDAY...PART OF THE DEEP LAYERED MEAN ANTI-CYCLONE CENTERED OFF
THE SE COAST WILL GET NUDGED A BIT FURTHER INTO THE ATLANTIC IN
RESPONSE TO WEAK IMPULSES THAT IMPINGE ON THE WESTERN PERIPHERY OF
THIS LARGE SCALE FEATURE. UNDERNEATH AT THE SURFACE WE STILL FIND
SPRAWLING ATLANTIC HIGH PRESSURE ALIGNED ACROSS THE FORECAST
ZONES...BUT IN RESPONSE TO THE PERTURBATIONS ALOFT AND A SLIGHTLY
WEAKER RIDGE THERE IS ALSO A SUBTLE LEE SIDE TROUGH THAT IS ABLE TO
DEVELOP. OVERALL THERE IS STILL ENOUGH OF A CAP TO LIMIT HOW MUCH
CONVECTION IS ABLE TO DEVELOP...ESPECIALLY ACROSS OUR EASTERN
SECTIONS. BUT FURTHER INLAND THE MOISTURE PROFILES ARE A LITTLE
BETTER AND THE SUBSIDENCE IS LESS PRONOUNCED. WE HAVE OPTED FOR
SLIGHT CHANCE-CHANCE POPS MAINLY NEAR AND INLAND FROM I-95 FOR THE
LATE MORNING/AFTERNOON PERIOD WHERE WE FIND THE HIGHEST THETA-E AIR.
THE LACK OF SHEAR AND ONLY MODEST THERMODYNAMICS AT BEST WILL
SUPPORT LITTLE IF ANY RISK OF STRONG/SEVERE STORMS. WITHIN A SUB-
TROPICAL MARITIME AIR MASS OUR MAX TEMPS WILL PEAK IN THE MID-UPPER
80S AWAY FROM THE IMMEDIATE COAST. CONVECTION FAR INLAND WILL FADE
WITHIN THE NOCTURNAL STABILIZING INFLUENCES WEDNESDAY EVENING. WE/LL
MAINTAIN A WEATHER WATCH FOR POSSIBLE FOG NW TIER WHERE RAINS
OCCURRED EARLIER IN CONJUNCTION WITH LIGHT UPSLOPE FLOW. A LARGE
RANGE OF TEMPS FROM LOWER 60S NORMALLY COOL SPOTS TO 68-72 ON THE
BARRIER ISLANDS.

THURSDAY THROUGH FRIDAY...THE DEEP RIDGING GETS SHUNTED BACK A BIT
FURTHER WEST IN RESPONSE TO A DEEP CYCLONE AND IT/S ASSOCIATED
SURFACE WAVE CENTERED FAR EAST/NE OF THE BAHAMAS. INCREASING
SUBSIDENCE...THE LACK OF FORCING AND DIMINISHING MOISTURE SUGGESTS
THAT DIURNAL RAIN CHANCES WILL ONLY BE 20-30 PERCENT FAR INLAND
THURSDAY AND NO MORE THAN 10 PERCENT FRIDAY. VERY LITTLE
FLUCTUATIONS IN MAX/MIN TEMPS FROM RECENT DAYS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A BROAD UPPER RIDGE WILL EXIST FRIDAY NIGHT THROUGH SUNDAY BEFORE AN
UPPER TROUGH BEGINS TO PUSH INTO THE EASTERN UNITED STATES EARLY
NEXT WEEK. ALTHOUGH WEAK CAPPING WILL EXIST FOR THE BRUNT OF THE
PERIOD...ONSHORE MOISTURE FLUX WITH HIGH TEMPS IN THE UPPER 80S TO
NEAR 90 AND A DAILY SEA BREEZE WILL SUPPORT ISOLATED SHOWERS AND
TSTMS. A MORE PROMINENT UPPER TROUGH APPROACHING ON TUESDAY SHOULD
SUPPORT BETTER COVERAGE OF SHOWERS AND TSTMS.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
MOIST SOUTHERLY FLOW EXPECTED TO BRING MVFR CEILINGS FOR A FEW
HOURS AT KCHS PRIOR TO DAYBREAK. OTHERWISE WE SHOW VFR CONDITIONS
AT BOTH TERMINALS. BEST CONVECTION COVERAGE WILL BE INLAND FROM
THE TERMINALS TODAY THOUGH WE CANNOT RULE OUT SOMETHING MOVING
THROUGH EITHER TERMINAL LATE IN THE DAY.

EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE PERIOD.

&&

.MARINE...
TONIGHT...MARINE CONDITIONS WILL BE RATHER BENIGN TONIGHT AS
SURFACE HIGH PRESSURE REMAINS EAST OF THE WATERS. SOUTHEAST
ONSHORE FLOW OF 10-15 KT WILL DECREASE TO 5-10 KT LATE. SEAS WILL
BE 2-3 FT...EXCEPT IN THE OUTER GA WATERS WHERE 3-4 FT IS
EXPECTED.

WEDNESDAY THROUGH FRIDAY...A RATHER FLAT BUT ENORMOUS SUB-TROPICAL
RIDGE WILL MAINTAIN IT/S HOLD ACROSS THE COASTAL WATERS...GENERATING
A CONTINUOUS ONSHORE FLOW THROUGH THE PERIOD. EVEN WITH MINOR SEA
BREEZE INFLUENCES WINDS WILL HOLD UNDER 10 OR 15 KT. SEAS WILL BE A
MIX OF WIND-DRIVEN WAVES AND EVENTUALLY MORE SWELL ENERGY ARRIVING
DUE TO THE PERSISTENT EAST-SE FLOW. COMBINED SEAS WILL HOLD AT LESS
THAN OR EQUAL TO 3 OR 4 FT.

SATURDAY THROUGH MONDAY...SPRAWLING ATLANTIC HIGH PRESSURE WILL
CONTINUE TO CONTROL CONDITIONS LOCALLY AS IT LIES OVERHEAD INTO
EARLY NEXT WEEK. ONSHORE TRAJECTORIES WON/T OBTAIN ANYTHING MORE
THAN 10 OR 15 KT...AND WHILE SWELL ENERGY WILL BECOME MORE THE
DOMINANT FEATURE...SEAS ARE STILL MAINLY 4 FT OR LESS.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...JRL
MARINE...


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