000
FXUS62 KCHS 211123
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
623 AM EST FRI FEB 21 2025
SYNOPSIS
COLD HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH THE START
OF THE WEEKEND. A WEAK DISTURBANCE WILL PASS TO OUR SOUTH ON
MONDAY, FOLLOWED BY MORE HIGH PRESSURE INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
DRY SURFACE HIGH PRESSURE WILL BUILD ACROSS SE GA/SC THROUGH THE
DAY. THE PRESSURE GRADIENT SHOULD SUPPORT NORTH-NORTHEAST BETWEEN 5
TO 10 MPH THIS MORNING. WIND CHILL VALUES SHOULD REMAIN BELOW 20
DEGREES EARLY THIS MORNING. A WIND CHILL ADVISORY HAS BEEN ISSUED
FOR THE ENTIRE FORECAST AREA UNTIL 10 AM THIS MORNING. THE REST OF
THE DAY SHOULD FEATURE SUNNY CONDITIONS WITH STEADY NORTH WINDS.
RAGGED THIN CIRRUS COULD ARRIVE OVER SE GA LATE THIS AFTERNOON, BUT
SHOULD NOT LIMIT INSOLATION NOTABLY. COLD LLVL THICKNESSES SHOULD
KEEP TEMPERATURES AROUND 15 DEGREES BELOW NORMAL, RANGING FROM THE
UPPER 40S TO LOW 50S. IN FACT, IT IS POSSIBLE THAT KCHS MAY TIE THE
RECORD LOW MAXIMUM OF 47 SET IN 2020.
TONIGHT, THE PATTERN WILL FEATURE ZONAL H5 FLOW AS THE CENTER OF THE
SFC HIGH BUILDS EAST OF THE APPALACHIANS ACROSS VA/NC. MID AND HIGH
CLOUDS SHOULD STREAM WEST TO EAST ACROSS THE FORECAST AREA, KEEPING
CONDITIONS MOSTLY CLEAR TO PARTLY CLOUDY. LOW TEMPERATURES ARE
EXPECTED TO RANGE FROM THE MID 20S INLAND TO THE MID TO UPPER 30S
ACROSS THE COASTAL COUNTIES. GIVEN LIGHT TO CALM WINDS TONIGHT, NO
COLD WEATHER ADVISORY IS ANTICIPATED FOR TONIGHT.
SHORT TERM /SATURDAY THROUGH MONDAY/
SATURDAY: THE MID-LEVELS WILL CONSIST OF A SHORTWAVE OVER THE MID-MS
VALLEY IN THE MORNING. IT'LL SHIFT EAST AS TIME PROGRESSES, PASSING
JUST TO OUR NORTH IN THE EVENING, THEN OFFSHORE OVERNIGHT. THERE
WILL BE SOME LIFT ASSOCIATED WITH THIS DISTURBANCE, BUT NOT A
SIGNIFICANT AMOUNT. AT THE SURFACE, HIGH PRESSURE WILL BE CENTERED
JUST TO OUR NORTH IN THE MORNING. IT'LL SHIFT OFFSHORE INTO THE
AFTERNOON. AT THAT TIME, WEAK TROUGHING IS EXPECTED TO FORM OFF OUR
COAST, THEN PREVAIL INTO THE EVENING AND OVERNIGHT. A SECOND AREA OF
HIGH PRESSURE WILL THEN APPROACH FROM THE WEST LATE AT NIGHT.
MOISTURE IS EXPECTED TO INCREASE WITH THE TROUGH, WITH THE HIGHEST
VALUES REMAINING JUST OFF OUR COAST. LIKEWISE, BOTH THE SYNOPTIC
MODELS AND LONG-RANGE CAMS POINT TOWARDS SOME SHOWERS OFFSHORE,
MAINLY IN THE LATE AFTERNOON INTO THE FIRST PART OF THE NIGHT. LAND
AREAS ARE EXPECTED TO REMAIN DRY, AS THE HIGHS WIN OUT.
LOW-LEVEL THICKNESS VALUES AND COLD 850 MB TEMPERATURES SUPPORT HIGH
TEMPERATURES IN THE MID TO MAYBE UPPER 50S. THOUGH, THIS MAY BE
LOWER AS CLOUDS INCREASE DURING THE DAY. MOSTLY CLOUDY SKIES IN THE
EVENING WILL CLEAR OVERNIGHT, LEADING TO A LARGE TEMPERATURE SPREAD.
TEMPERATURES FAR INLAND SHOULD BOTTOM OUT NEAR FREEZING, WHILE NEAR
THE IMMEDIATE COAST THEY SHOULD BE IN THE MID TO UPPER 30S, AND THE
LOW TO MID 40S AT THE BEACHES.
SUNDAY: WEAK MID-LEVEL TROUGHING WILL BE LOCATED OFF THE EAST COAST
IN THE MORNING, LEADING TO NW FLOW OVERHEAD. ADDITIONALLY, A
SHORTWAVE WILL BE LOCATED OVER THE SOUTHERN PLAINS. IT'LL SHIFT EAST
AS TIME PROGRESSES, BECOMING LOCATED OVER THE SOUTHEAST U.S. LATE AT
NIGHT. WEAK SURFACE TROUGHING LOCATED JUST OFF OUR COAST IN THE
MORNING WILL BE PUSHED AWAY BY HIGH PRESSURE BUILDING IN FROM THE
WEST. THE HIGH SHOULD PASS TO OUR NORTH LATE IN THE DAY, THEN WEAKEN
AS IT MOVES OFFSHORE OVERNIGHT. MEANWHILE, A STORM SYSTEM WILL BE
IMPACTING THE NORTHERN GULF STATES DURING THE DAY, SHIFTING EASTWARD
WITH TIME. IT SHOULD START IMPACTING THE SOUTHEAST LATE AT NIGHT.
THE HIGH WILL BRING DRY CONDITIONS DURING THE DAY AND INTO THE
EVENING. MOISTURE WILL INCREASE FROM THE SOUTH AFTER MIDNIGHT.
LIKEWISE, MOST OF THE MODELS HAVE ISOLATED SHOWERS SOUTH OF I-16
DURING THAT TIME PERIOD. HENCE, WE WENT WITH SLIGHT CHANCE POPS.
WITH A DECENT AMOUNT OF SUN, HIGH TEMPERATURES SHOULD RANGE FROM
AROUND 60 DEGREES TO MAYBE THE MIDDLE 60S, EXCEPT COOLER AT THE
BEACHES. INCREASING CLOUDS LATE AT NIGHT SHOULD LIMIT LOW
TEMPERATURES TO THE MID 30S INLAND TO THE MID 40S ALONG THE BEACHES.
MONDAY: THE MID-LEVELS WILL CONSIST OF A SHORTWAVE OVER THE
SOUTHEAST U.S. IN THE MORNING. IT'LL SLOWLY SHIFT OFFSHORE BY LATE
IN THE DAY. AT THE SURFACE, A STORM SYSTEM WILL BE IMPACTING THE
SOUTHEAST U.S. IN THE MORNING. THOUGH, MOST OF IT'S ENERGY SHOULD
PASS JUST TO OUR SOUTH. LIKEWISE, MODELS HAVE MOST OF THE MOISTURE
AND SHOWER ACTIVITY IN THIS LOCATION. THE NBM KEEPS OUR AREA FAIRLY
DRY, BUT THIS MAY BE UNDERDONE BASED ON SOME OF THE SYNOPTIC MODELS.
THIS PORTION OF THE FORECAST WILL NEED TO BE ADJUSTED. HIGHS MAY
RISE TO NEAR NORMAL.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
HIGH PRESSURE WILL BRING DRY CONDITIONS THROUGH WEDNESDAY. A COLD
FRONT SHOULD BRING A ROUND OF SHOWERS ON THURSDAY. TEMPERATURES
SHOULD BE ABOVE NORMAL THROUGHOUT THE LONG TERM.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
12Z TAFS: VFR CONDITIONS EXPECTED ACROSS THE TERMINALS THROUGH
THE TAF PERIOD.
EXTENDED AVIATION OUTLOOK: A WEAK DISTURBANCE WILL PASS TO OUR SOUTH
ON MONDAY, BRINGING LOW PROBABILITIES OF FLIGHT RESTRICTIONS, MAINLY
TO OUR GA COUNTIES. OTHERWISE, VFR SHOULD PREVAIL THE REST OF THE
TIME.
MARINE
TODAY, THE PRESSURE GRADIENT ACROSS THE MARINE ZONE WILL SUPPORT
NORTHEAST WINDS GUSTING TO 25 KTS OUTSIDE THE CHS HARBOR. SMALL
CRAFT ADVISORIES WILL REMAIN IN EFFECT FOR THE NEARSHORE WATERS
UNTIL 10 AM THIS MORNING. WINDS SHOULD DECREASE THROUGH THE REST OF
THE DAY, GENERALLY REMAINING FROM THE NORTHEAST BETWEEN 10-15 KTS.
SEAS ARE FORECAST TO RANGE BETWEEN 3-6 FT, THEN SUBSIDING LATE THIS
AFTERNOON TO 2-5 FT. A SMALL CRAFT ADVISORY WILL HIGHLIGHT LINGERING
WAVE HEIGHTS AROUND 6 FT UNTIL 5 PM THIS AFTERNOON.
A SFC RIDGE WILL DEVELOP OVER THE MARINE ZONES TONIGHT, SUPPORTING
NORTHEAST AROUND 10 KTS. SEAS SHOULD GENERALLY RANGE BETWEEN 2 TO 3
FT.
EXTENDED MARINE: LOTS OF SYNOPTIC CHANGES WILL OCCUR. HIGH PRESSURE
WILL BE CENTERED JUST TO OUR NORTH SATURDAY MORNING. IT'LL SHIFT
OFFSHORE SATURDAY AFTERNOON. AT THAT TIME, WEAK TROUGHING IS
EXPECTED TO FORM OVER THE COASTAL WATERS, THEN PREVAIL SATURDAY
EVENING AND OVERNIGHT. A SECOND AREA OF HIGH PRESSURE WILL THEN
APPROACH FROM THE WEST LATE SATURDAY NIGHT. THE TROUGH WILL BE
PUSHED AWAY BY THIS HIGH ON SUNDAY. THE HIGH SHOULD PASS TO OUR
NORTH LATE SUNDAY, THEN WEAKEN AS IT MOVES OFFSHORE SUNDAY NIGHT. A
STORM SYSTEM SHOULD START IMPACTING THE SOUTHEAST U.S. LATE SUNDAY
NIGHT. THOUGH, MOST OF IT'S ENERGY SHOULD PASS JUST TO OUR SOUTH ON
MONDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST LATER MONDAY
AND PREVAIL THROUGH THE MIDDLE OF THE WEEK. EVEN WITH ALL OF THESE
CHANGES, NO MARINE HEADLINES ARE EXPECTED.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
FEBRUARY 21:
KCHS: 47/2020
RECORD LOW TEMPERATURES:
FEBRUARY 21:
KCHS: 22/1958
CHS WATCHES/WARNINGS/ADVISORIES
GA...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ087-
088-099>101-114>119-137>141.
SC...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ040-
042>045-047>052.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ350-
352-354.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ374.
NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...NED
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