419
FXUS62 KCHS 192304
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
704 PM EDT MON APR 19 2021
SYNOPSIS
WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION EARLY THIS WEEK.
THEN, A COLD FRONT WILL SWEEP ACROSS THE REGION ON WEDNESDAY.
HIGH PRESSURE WILL THEN RETURN FOR LATE WEEK. LOW PRESSURE WILL
IMPACT THE AREA OVER THE WEEKEND.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
THERE HAS BEEN A LITTLE RECOVERY IN DEW POINTS, WHICH IS
COINCIDING WITH WINDS DIMINISHING. THESE CHANGES HAVE BEEN
INCORPORATED INTO THE GRIDS, BUT THE FORECAST IS ESSENTIALLY
UNCHANGED FROM EARLIER.
PREVIOUS DISCUSSION...
AS OF 330 PM: THE CENTER OF DRY HIGH PRESSURE WILL PUSH OVER THE
REGION TONIGHT. SFC WINDS SHOULD VEER FROM NW LATE THIS AFTERNOON TO
NE AROUND MIDNIGHT, THE SE BY DAYBREAK TUESDAY. A WEAK LOW IS
FORECAST TO TRACK OVER THE FL PENINSULA LATE TONIGHT, RESULTING IN
SCATTERED HIGH CLOUDS TO ARRIVE FROM THE SOUTH. THE COMBINATION
OF DRY BOUNDARY LAYER CONDITIONS, LIGHT WINDS, AND LATE ARRIVAL
OF HIGH CLOUDS SHOULD YIELD NEAR NORMAL LOWS TONIGHT. MIN
TEMPERATURES ARE FORECAST TO RANGE FROM THE LOW 50S INLAND TO
NEAR 60 ALONG THE COAST.
SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/
AS HIGH PRESSURE MOVES AWAY FROM THE AREA AND INTO THE ATLANTIC ON
TUESDAY, LOW PRESSURE WILL MOVE OFF THE COAST OF FLORIDA IN AN
EASTWARD DIRECTION ACROSS THE ATLANTIC. WHILE THERE WILL BE
INCREASED ISENTROPIC LIFT AND PWATS WILL BE AROUND AN INCH, ANY
SHOWER ACTIVITY WILL LIKELY REMAIN JUST ALONG THE COAST AND ACROSS
THE COASTAL WATERS. MOST INLAND AREAS SHOULD REMAIN RAIN-FREE. HIGH
TEMPERATURES WILL BE IN THE 70S. THEREAFTER, A SURFACE LOW WILL MAKE
ITS WAY ACROSS THE OHIO RIVER VALLEY OVERNIGHT TUESDAY. LOW
TEMPERATURES WILL BE IN THE MID TO UPPER 50S INLAND AND LOW 60S JUST
ALONG THE COAST. THEN ON WEDNESDAY, A DRY COLD FRONT ASSOCIATED WITH
THE LOW WILL THEN MOVE THROUGH THE AREA AND AS THE PRESSURE GRADIENT
TIGHTENS, WINDS WILL BECOME GUSTY. THOUGH, THE DAY SHOULD BE MOSTLY
SUNNY WITH HIGH TEMPERATURES IN THE UPPER 70S TO LOW 80S. LOWS WILL
BE IN LOW TO UPPER 40S INLAND WITH LOW 50S JUST ALONG THE COAST DUE
TO COLD AIR ADVECTION. FOR THURSDAY, HIGH PRESSURE WILL GENERALLY
PREVAIL AND IT WILL BE A NICE, SUNNY DAY. HIGH TEMPERATURES WILL BE
IN THE MID 60S TO LOW 70S INLAND AND LOW 60S JUST ALONG THE COAST.
LAKE WINDS: WINDS AHEAD AND BEHIND A COLD FRONT WILL BECOME QUITE
GUSTY DUE TO A TIGHTENING PRESSURE GRADIENT. A LAKE WIND ADVISORY
COULD BE NEEDED FOR LAKE MOULTRIE.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
OVERNIGHT THURSDAY, HIGH PRESSURE WILL PREVAIL AND LOW TEMPERATURES
WILL BE IN THE MID 40S TO LOW 50S INLAND AND MID 50S JUST ALONG THE
COAST. THEN ON FRIDAY, ANOTHER DRY DAY AND MOSTLY SUNNY SKIES IS
EXPECTED. THOUGH, AS A DEEP-LAYERED TROUGH MOVES CLOSER TO THE AREA
FROM THE WEST, CLOUD COVER WILL SLIGHTLY INCREASE. HIGH TEMPERATURES
WILL BE IN THE 70S WITH LOWS IN THE MID TO UPPER 50S INLAND AND LOW
TO MID 60S JUST ALONG THE COAST.
WHILE THERE IS STILL UNCERTAINTY WITHIN THE MODELS FOR TIMING AND
LOCATION OF THE APPROACHING LOW PRESSURE, RAIN CHANCES WILL INCREASE
ON SATURDAY INTO SUNDAY MORNING. THE BEST CHANCE OF RAIN LOOKS TO BE
DURING SATURDAY AFTERNOON INTO THE OVERNIGHT. BY DAYBREAK, THE LOW
PRESSURE SHOULD BE COMFORTABLY TO THE NORTHEAST AND THE COLD FRONT
SHOULD BE OFFSHORE. THOUGH, A SECONDARY COLD FRONT COULD THEN MOVE
THROUGH THE REGION. THE MAJORITY OF SUNDAY AND ALL OF MONDAY SHOULD
BE RAIN-FREE AS HIGH PRESSURE QUICKLY BUILDS INTO THE AREA. HIGH
TEMPERATURES WILL BE IN THE MID TO UPPER 70S TO LOW 80S EACH DAY.
LOW TEMPERATURES WILL BE IN THE 50S INLAND AND LOW 60S JUST ALONG
THE COAST.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
VFR THROUGH 00Z WEDNESDAY. SE WINDS WILL BECOME A LITTLE GUSTY
IN WAKE OF THE SEA BREEZE TUESDAY AFTERNOON.
EXTENDED AVIATION OUTLOOK: MAINLY VFR. GUSTY WINDS LIKELY ON
WEDNESDAY, THEN AGAIN ON SATURDAY. FLIGHT RESTRICTIONS WILL ALSO BE
POSSIBLE ON SATURDAY DUE TO SHOWERS/THUNDERSTORMS.
MARINE
HIGH PRESSURE WILL BUILD OVER THE REGION TONIGHT. AS PRESSURES RISE
FROM THE NE, A BIT OF WIND SURGE WILL PUSH FROM THE NE TO SW
ACROSS THE COASTAL WATERS TONIGHT. N AND NW WINDS WILL VEER
AROUND TO THE ENE, AND STRENGTHEN TO 10 TO 15 KTS WITH GUSTS TO
20 KTS AFTER MIDNIGHT OVER THE MARINE ZONES OUTSIDE THE CHS
HARBOR. SEAS WILL INCREASE SLIGHTLY FROM 1-2 FT THIS EVENING TO
2 FT ACROSS MOST AREAS BY DAYBREAK.
TRANQUIL MARINE CONDITIONS EXPECTED TO LAST THROUGH EARLY WEDNESDAY.
THEN, AHEAD OF AN APPROACHING COLD FRONT, WINDS WILL INCREASE BY
WEDNESDAY AFTERNOON TO 15-20 KNOTS AND SMALL CRAFT ADVISORIES COULD
BE NEEDED FOR WINDS AND SEAS THROUGH THURSDAY MORNING. HIGH PRESSURE
WILL THEN BUILD INTO THE AREA AND TRANQUIL MARINE CONDITIONS SHOULD
RETURN THROUGH LATE FRIDAY. ANOTHER ROUND OF SMALL CRAFT ADVISORIES
COULD BE NEEDED OVER THE WEEKEND DUE TO ANOTHER APPROACHING COLD
FRONT.
FIRE WEATHER
A COMBINATION OF GUSTY WINDS, LOW RELATIVE HUMIDITY, AND DRY FUELS
COULD PRODUCE HAZARDOUS FIRE CONDITIONS WEDNESDAY AFTERNOON/EARLY
EVENING. NEAR CRITICAL RELATIVE HUMIDITY VALUES WILL PERSIST
THURSDAY AND FRIDAY AFTERNOONS, ALTHOUGH WINDS WILL REMAIN LESS THAN
15 MPH.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...
SHORT TERM...RAD
LONG TERM...RAD
AVIATION...
MARINE...
FIRE WEATHER...
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