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000
FXUS62 KCHS 150221
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1021 PM EDT TUE MAY 14 2013

.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION THIS WEEK. A WARMING
TREND WILL BEGIN MID WEEK WITH RAIN CHANCES INCREASING SLIGHTLY
BY LATE WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
PER TUESDAY EVENING TRENDS...ADJUSTED HOURLY/LOW TEMPERATURES DOWN
A COUPLE OF DEGREES MOST AREAS...AND ADJUSTED RELATIVE HUMIDITY
VALUES UPWARD. IF THE TIGHTENING SURFACE PRESSURE GRADIENT
EVIDENT N/W OF THE FORECAST SETTLES INTO THE REGION OVERNIGHT...
HOURLY TEMPERATURE TRENDS COULD BECOME UNEVEN OR TEMPERATURES
COULD EVEN RISE A FEW DEGREES LATER TONIGHT.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
WEDNESDAY...ANOTHER BEAUTIFUL DAY EXPECTED WITH FEW CLOUDS AND
WARMING TEMPERATURES. UPPER LEVEL RIDGE WILL BECOME CENTERED OVER
THE SOUTHEAST COAST...WHILE SURFACE HIGH PRESSURE SHIFTS EAST OVER
THE ATLANTIC. AT THE SAME TIME...A SURFACE TROUGH WILL SET UP
INLAND EAST OF THE APPALACHIANS. THIS WILL RESULT IN A SLIGHTLY
TIGHTENED PRESSURE GRADIENT...BEST ACROSS THE NORTHERN HALF OF THE
FORECAST AREA. LITTLE MOISTURE THROUGH THE COLUMN AND SUBSIDENCE
UNDERNEATH THE UPPER RIDGE WILL ALLOW FOR A POP-FREE DAY.
SOUTHERLY RETURN FLOW WILL HELP BOOST TEMPERATURES INTO THE MIDDLE
AND UPPER 80S...WITH LOWS CLOSER TO NORMAL IN THE LOWER AND MIDDLE
60S.

THURSDAY...UPPER LEVEL RIDGE WILL BREAK DOWN A BIT AND SHIFT
EASTWARD WHILE A WEAK TROUGH BEGINS TO APPROACH FROM THE WEST.
ASSOCIATED SHORTWAVE ENERGY IS FORECAST TO CROSS THROUGH THE AREA IN
THE AFTERNOON AND EVENING...MAINLY RESULTING IN AN INCREASE IN CLOUD
COVER. MODELS ARE FAIRLY CONSISTENT IN KEEPING THE FORECAST AREA
DRY...HOWEVER GFS DOES HINT AT SOME PRECIP. CONTINUED WITH SILENT
POPS AT THIS TIME. HIGHS AGAIN WILL BE A FEW DEGREES ABOVE NORMAL IN
THE MIDDLE AND UPPER 80S. LOWS WILL BE IN THE LOWER AND MIDDLE 60S.

FRIDAY...WEAK UPPER TROUGH WILL CONTINUE TO MOVE EAST THROUGH THE
DAY AND PUSH OFF THE COAST BY LATE. AT THE SURFACE...THE FORECAST
AREA WILL REMAIN UNDER THE INFLUENCE OF HIGH PRESSURE CENTERED OFF
THE SOUTHEAST COAST. ALTHOUGH THERE IS NO HUGE SYNOPTIC FORCING
FEATURES...MODELS ARE HINTING AT CONVECTION FIRING OFF THE INLAND
PENETRATING SEA BREEZE. WILL MAINTAIN SLIGHT CHANCES IN THE
AFTERNOON AS COVERAGE WILL BE FAIRLY ISOLATED.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE UPPER LEVEL PATTERN WILL REMAIN RATHER WEAK AND ILL-DEFINED
THROUGH MUCH OF THE EXTENDED PERIOD...WHILE ATLANTIC HIGH PRESSURE
PREVAILS AS THE MAIN FEATURE AT THE SURFACE. WITH LITTLE CHANGE IN
THE PATTERN UNTIL AS LATE AS TUESDAY...EXPECT SHOWER/THUNDERSTORM
POTENTIAL TO MAINLY BE DRIVEN BY TYPICAL DIURNAL HEATING/INSTABILITY
AND SEABREEZE FORCING. HAVE THUS INDICATED A SLIGHT CHANCE FOR
THUNDERSTORMS DURING THE CLIMATOLOGICALLY FAVORED AFTERNOON AND
EARLY EVENING HOURS SATURDAY THROUGH AT LEAST MONDAY. HIGH
TEMPERATURES EACH AFTERNOON WILL RANGE FROM THE MID TO UPPER 80S
INLAND...TO THE LOW 80S RIGHT ALONG THE COAST BEHIND THE
SEABREEZE. MEDIUM RANGE MODEL SOLUTIONS INDICATE AN UPPER TROUGH
SWINGING EAST/SOUTHEAST FROM THE GREAT LAKES REGION...PUSHING A
COLD FRONT INTO THE TENNESSEE VALLEY REGION. THIS FEATURE WILL
LIKELY REMAIN WEST OF THE FORECAST AREA UNTIL MID WEEK.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
VFR THROUGH WEDNESDAY.

EXTENDED AVIATION OUTLOOK...VFR.

&&

.MARINE...
OVERNIGHT...A WEAK PRESSURE GRADIENT SUPPORTING SOUTHERLY WINDS 10
KT OR LESS WILL GIVE WAY TO A TIGHTENING GRADIENT...AND S/SW
WINDS ARE EXPECTED TO INCREASE 10-15 KTS...PERHAPS ACCOMPANIED BY
A FEW GUSTS TO 20 KT ESPECIALLY ACROSS AMZ3650 AND AMZ374.
SEAS WILL REMAIN 2 TO 3 FT NEARSHORE AND 3-4 FT BEYOND 20 NM.

WEDNESDAY THROUGH SUNDAY...WEATHER WILL REMAIN QUIET THROUGH THE
PERIOD...WITH SUB-SCA CRITERIA EXPECTED. THERE WILL BE A BIT OF A
SURGE ON WEDNESDAY...AS SURFACE HIGH PRESSURE SHIFTS EAST OF THE
WATERS AND AN INLAND TROUGH SETS UP. SOUTHERLY FLOW BETWEEN THE
TWO WILL BE A SOLID 15-20 KTS WEDNESDAY AFTERNOON INTO THURSDAY...
HIGHEST OVER THE SC WATERS. SEAS WILL BE 3-4 FEET OVER SC
WATERS...AND 2-3 FEET FURTHER SOUTH. BY FRIDAY...THE GRADIENT WILL
SLACKEN AND WINDS WILL REMAIN 10-15 KTS THROUGH WEEKEND. WAVE
HEIGHTS WILL GENERALLY RANGE FROM 2 TO 4 FT...HIGHEST IN THE OUTER
WATERS.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...ECT
LONG TERM...WMS
AVIATION...SPR
MARINE...ECT/SPR