805
FXUS62 KCHS 250053
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
853 PM EDT SUN MAY 24 2020
SYNOPSIS
A WEAK COLD FRONT WILL PUSH INTO THE AREA LATER TONIGHT AND
MONDAY, AND HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE
NORTH. A COASTAL TROUGH SHOULD DEVELOP AROUND MID WEEK, AND LOW
PRESSURE COULD TRACK OVER OR NEAR THE SOUTHEAST COAST MID TO
LATE WEEK. A COLD FRONT COULD APPROACH THE REGION NEXT WEEKEND.
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
ONE LAST CONVECTIVE CLUSTER WILL WORK WEST ACROSS NORTHERN
JENKINS COUNTY OVER THE NEXT HOURS, THEN DRY WEATHER WILL
PREVAIL. ADJUSTED POPS BASED ON SHORT TERM RADAR TRENDS.
EXPECT LOW STRATUS AND POSSIBLE SOME FOG TO FILL IN ALONG/AHEAD
OF THE BACKDOOR FRONT EARLY MONDAY. THE FOG IS NOT EXPECTED TO
HAVE MUCH IMPACT, BUT SOME AREAS OF REDUCED VISIBILITIES COULD
OCCUR. DENSE FOG IS NOT EXPECTED AT THIS TIME.
WARM AND HUMID CONDITIONS WILL PERSIST WITH LOWS RANGING FROM
THE UPPER 60S/NEAR 70 INLAND, LOWER 70S AT THE COAST, WITH MID
70S AT THE BEACHES AND DOWNTOWN CHARLESTON.
SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/
MONDAY: HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH AND
WILL PUSH A WEAKENING COLD FRONT TOWARD THE SOUTH. AT LEAST
SCATTERED SHOWERS AND THUNDERSTORMS COULD DEVELOP NEAR THIS
BOUNDARY, WITH HIGHER POPS ACROSS NORTHERN COUNTIES DURING THE
MORNING FOLLOWED BY HIGH POPS SHIFTING INTO SOUTHERN/WESTERN
SECTIONS DURING THE AFTERNOON. FORECAST INSTABILITY SUGGESTS ONLY A
LOW CHANCE FOR A BRIEF/ISOLATED PULSE SEVERE THUNDERSTORM OR TWO.
MONDAY NIGHT: DUE TO DIURNAL STABILIZATION, ISOLATED/SCATTERED
SHOWERS AND PERHAPS ISOLATED THUNDERSTORMS NEAR THE STALLING COLD
FRONT ACROSS SOUTHERN/WESTERN COUNTIES SHOULD DIMINISH IN COVERAGE
THROUGH AT LEAST THE FIRST HALF OF THE NIGHT. THEN, GUIDANCE DEPICTS
A BAND OF DEEPER MOISTURE TO SPREADING FROM THE SOUTH IN AT LEAST
SOUTHERN COUNTIES LATER ON.
TUESDAY AND WEDNESDAY: GUIDANCE INDICATES A WET PERIOD AS A POOL OF
PWAT VALUES AROUND 2 INCHES SETTLES OVER THE REGION. HOWEVER,
TIMING/COVERAGE OF SHOWERS/THUNDERSTORMS WILL BE LINKED WITH
STRENGTH OF THE SURFACE HIGH N/NE OF THE REGION AND TO THE UNCERTAIN
EVOLUTION OF A SURFACE TROUGH/SURFACE LOW S/SE OF THE AREA. THE
LATEST FORECAST RAMPS POPS UP TO LIKELY ALL BUT FAR NORTHERN/INLAND
COUNTIES TUESDAY. THEN, POPS VARY FROM LIKELY ALONG THE SC COAST TO
CHANCE ELSEWHERE TUESDAY NIGHT. WEDNESDAY, POPS RANGE FROM LIKELY
NORTH TO CHANCE SOUTH. HOWEVER, FORECAST CONFIDENCE DECREASES
TUESDAY NIGHT AND REMAINS RATHER LOW THROUGH WEDNESDAY.
THE POTENTIAL FOR LOCALLY HEAVY RAIN WILL INCREASE TUESDAY THROUGH
WEDNESDAY, ESPECIALLY NEAR THE COAST WHERE TIDES WILL BE ELEVATED
DUE TO PERSISTENT E/NE FLOW. IF STRONGER LOW PRESSURE TRACKS OVER OR
INLAND FROM THE COAST TUESDAY NIGHT THROUGH WEDNESDAY, THE POTENTIAL
FOR SEVERE WEATHER COULD INCREASE.
ALSO OF NOTE, GREATER THAN EXPECTED COVERAGE/PERSISTENCE OF
CLOUDS/PRECIPITATION COULD TRANSLATE TO COOLER DAYTIME TEMPERATURES
THAN INDICATED WITHIN THE LATEST FORECASTS.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
THE START OF THIS PERIOD REMAINS UNCERTAIN AND WILL DEPEND ON
WHETHER SURFACE LOW PRESSURE REMAINS IN THE VICINITY INTO THURSDAY.
OTHERWISE, ON THE WESTERN PERIPHERY OF ATLANTIC SURFACE HIGH
PRESSURE/BENEATH A WEAK RIDGE OF HIGH PRESSURE ALOFT, A SURFACE
TROUGH SHOULD LINGER OVER THE REGION WITH ABOVE NORMAL PRECIPITATION
AND TEMPS INTO THIS WEEKEND. A COLD FRONT COULD APPROACH OR MOVE
INTO THE AREA BY LATE NEXT WEEKEND.
AVIATION /01Z MONDAY THROUGH FRIDAY/
THE MAIN CONCERN CENTERS ON THE FOG/STRATUS POTENTIAL EARLY
MONDAY AT BOTH KCHS AND KSAV. LOW CLOUDS AND POSSIBLY SOME FOG
ARE EXPECTED TO FILL IN AFTER MIDNIGHT AS A WEAK, BACKDOOR COLD
FRONT APPROACHES. THE STRONGEST LOW CLOUD SIGNAL LOOKS TO SETUP
AT KCHS WHERE CIGS AS LOW AS 400-600 FT COULD OCCUR. OPTED TO
HOLD CIGS RIGHT AT ALTERNATE MINIMUMS FOR NOW, BUT CIGS COULD
DROP BELOW THIS JUST BEFORE DAYBREAK. CIGS WILL LIFT TO MVFR BY
14-15Z WITH VFR PREVAILING BY EARLY AFTERNOON. RIGHT NOW, IT
APPEARS THE RISK FOR IFR CIGS WILL REMAIN JUST WEST OF KSAV, BUT
MVFR CIGS LOOK LIKELY. LIMITED CIGS TO 1200 FT AFTER 09Z FOR
NOW WITH A TEMPO 10-12Z FOR BRIEF IFR RIGHT AT ALTERNATE
MINIMUMS TO TREND. VFR WILL RETURN BY LATE MORNING OR EARLY
AFTERNOON. SCATTERED SHOWERS/TSTMS LOOK TO SETUP WEST OF BOTH
TERMINALS TOMORROW AFTERNOON.
EXTENDED AVIATION OUTLOOK: PERIODS OF FLIGHT RESTRICTIONS, ESPECIALLY
RELATED TO SHOWERS/THUNDERSTORMS IN THE AREA, SHOULD PERSIST INTO
LATE WEEK.
MARINE
TONIGHT: SOUTH TO SOUTHEAST WINDS WILL GRADUALLY BACK AS A WEAK
COLD FRONT APPROACHES. SPEEDS WILL REMAIN <10KT WITH SEAS 1-2 FT
NEARSHORE WATERS AND 2-3 FT OFFSHORE WATERS.
MONDAY THROUGH FRIDAY: ON MONDAY, AS A HIGH PRESSURE SYSTEM BUILDS
OVER THE AREA THROUGHOUT THE DAY, WINDS WILL INCREASE AS THE
PRESSURE GRADIENT TIGHTENS. THEN, AS A LOW PRESSURE SYSTEM LINGERS
OFF THE EAST COAST OF FLORIDA, THE PRESSURE GRADIENT WILL TIGHTEN
MORE, CAUSING WINDS AND SEAS TO GRADUALLY INCREASE. SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED STARTING TUESDAY AFTERNOON INTO AT
LEAST WEDNESDAY MORNING. WHILE THERE IS STILL SOME UNCERTAINTY ABOUT
THE TRACK OF THE LOW OVER OR CLOSE TO THE SOUTHEAST COAST MID TO
LATE WEEK. SOME GUIDANCE SUGGESTS THAT THE PRESSURE GRADIENT STARTS
TO RELAX MID TO LATE WEEK, BUT THE LOW PRESSURE COULD MAINTAIN
ELEVATED WINDS AND SEAS THROUGH FRIDAY.
TIDES/COASTAL FLOODING
PERSISTENT E/NE FLOW WILL SUPPORT ELEVATED TIDES THIS WEEK. MID TO
LATE WEEK, THERE EXISTS A LOW PROBABILITY FOR MINOR SALT WATER
FLOODING AROUND THE TIMES OF THE OVERNIGHT HIGH TIDES. ALSO, WE'LL
CONTINUE TO ASSESS THE POTENTIAL FOR HEAVY RAINFALL TO COINCIDE WITH
HIGH TIDES AT THE COAST, ESPECIALLY DURING THE TUESDAY-THURSDAY
PERIOD.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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