989
FXUS62 KCAE 200054
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
754 PM EST THU DEC 19 2024
SYNOPSIS
THE END OF THIS WEEK LOOKS MOSTLY CLOUDY AND COOLER. A COLD
FRONT CLEARS SKIES OUT FRIDAY INTO FRIDAY NIGHT, WITH BREEZY
CONDITIONS POSSIBLE LATER IN THE DAY. THIS WILL BE FOLLOWED BY
SEVERAL DAYS OF COLD WEATHER WITH SUBFREEZING TEMPERATURES AT
NIGHT. A WARMING TREND IS EXPECTED TOWARDS CHRISTMAS ALONG WITH
THE NEXT CHANCE OF RAIN.
NEAR TERM /UNTIL 7 AM FRIDAY MORNING/
KEY MESSAGE(S):
- CONSIDERABLE CLOUDS AND COOLER TONIGHT.
SURFACE COLD FRONT HAS PUSHED OFFSHORE WITH UPPER TROUGHING
MOVING OVER THE FORECAST AREA, USHERING IN A COLDER AIR MASS
TONIGHT WITH COLD ADVECTION AT THE SURFACE. LOW LEVEL MOISTURE
TRAPPED BENEATH DEEP LAYER DRY AIR WILL CONTINUE TO SUPPORT LOW
LEVEL CLOUDS ACROSS THE AREA WHICH WILL LIMIT THE DEGREE OF
COOLING OVERNIGHT. TEMPERATURES EXPECTED TO DROP INTO THE MID TO
UPPER 40S. SOME HIRES GUIDANCE IS INDICATING THE POTENTIAL FOR
LIGHT SHOWERS NEAR DAYBREAK WITH WARM ADVECTION AROUND 850MB
PROVIDING SOME LIMITED LIFTING. WITH PWATS AROUND OR BELOW 0.6
INCHES ACROSS THE AREA, HOWEVER, IT WILL BE TOUGH FOR ANY LIGHT
SHOWERS TO PRODUCE MEASURABLE RAINFALL THROUGH TONIGHT.
SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/
KEY MESSAGE(S):
- DECREASING CLOUDINESS BEHIND A COLD FRONT ON FRIDAY WITH
SIMILAR DAYTIME TEMPERATURES TO TODAY.
- BREEZY CONDITIONS POSSIBLE BEHIND THE FRONT. A LAKE WIND
ADVISORY MAY BE NEEDED IF TRENDS CONTINUE.
- NOTICEABLY COLDER ON SATURDAY WITH SUBFREEZING TEMPERATURES
AT NIGHT.
A SERIES OF SHORTWAVE TROUGHS WILL BE MOVING THROUGH THE REGION
DURING THE PERIOD. AT THE SURFACE, A CLIPPER SYSTEM WILL MOVE
FROM INDIANA SOUTHEAST INTO NORTH CAROLINA ON FRIDAY, WITH A
COLD FRONT CLEARING OUT THE PERSISTENT CLOUD COVER OVER THE FA
FROM SOUTHWEST TO NORTHEAST. THE PASSAGE OF THE FIRST SHORTWAVE
ON FRIDAY COULD TRIGGER ISOLATED SHOWERS BUT WITH LIMITED
MOISTURE CONFIDENCE IS LOW, LESS THAN 20 PERCENT, WITH THE
HIGHEST PROBABILITIES ACROSS OUR NORTHERNMOST COUNTIES. GIVEN
THE STRONGER WINDS ALOFT, BREEZY CONDITIONS MAY DEVELOP BEHIND
THE COLD FRONT AND COULD REQUIRE A LAKE WIND ADVISORY FOR AT
LEAST THE CSRA WITH THE NEXT FORECAST PACKAGE. DAYTIME
TEMPERATURES WILL BE SIMILAR ACROSS THE NORTHERN MIDLANDS AND
5-10 DEGREES COOLER IN THE SOUTHERN MIDLANDS AND CSRA. WITH
CLEAR SKIES AND COLD AIR ADVECTION, TEMPERATURES WILL FALL INTO
THE UPPER 20S TO LOWER 30S BY DAYBREAK ON SATURDAY.
THE COOLING TREND CONTINUES INTO SATURDAY AS HIGH PRESSURE
BUILDS IN FROM THE WEST, WEAKENING THE PRESSURE GRADIENT.
HAVING SAID THAT, WINDS MAY START OFF ON THE BREEZY SIDE MAKING
TEMPERATURES FEEL EVEN COLDER. THIS WILL BE THE FIRST OF SEVERAL
DAYS OF BELOW NORMAL TEMPERATURES. CONDITIONS WILL BE MORE
FAVORABLE FOR RADIATIONAL COOLING SATURDAY NIGHT, ALLOWING
TEMPERATURES TO FALL INTO THE 20S. EVEN COLDER TEMPERATURES ARE
EXPECTED THE FOLLOWING NIGHT.
LONG TERM /SUNDAY THROUGH THURSDAY/
KEY MESSAGE(S):
- SUNDAY AND MONDAY ARE THE COLDEST DAYS OF THE PERIOD, FOLLOWED
BY A WARMING TREND.
- THE NEXT STORM SYSTEM ARRIVES AROUND CHRISTMAS DAY.
SURFACE HIGH PRESSURE WILL PASS TO OUR NORTH ON SUNDAY AND
MONDAY, MAINTAINING A COLD, DRY AIR MASS OVER THE REGION.
TEMPERATURE AND MOISTURE ADVECTION OCCURS TUESDAY AND WEDNESDAY
AS THE HIGH MOVES OFFSHORE AND THE NEXT STORM SYSTEM APPROACHES.
CONFIDENCE REMAINS HIGH THAT THERE WILL BE SEVERAL DAYS OF BELOW
NORMAL TEMPERATURES, FALLING BELOW FREEZING EACH NIGHT. THE
PERIOD OF GREATEST CONCERN REMAINS SUNDAY NIGHT WHEN WIND CHILL
VALUES COULD APPROACH COLD WEATHER ADVISORY CRITERIA ACROSS
PORTIONS OF THE CWA. REGARDLESS OF WHETHER ADVISORY CRITERIA IS
MET, IT IS IMPORTANT THAT COLD WEATHER PREPARATIONS ARE MADE
AHEAD OF TIME, ESPECIALLY FOR THOSE WHO WILL NOT BE HOME DURING
THIS PERIOD. TEMPERATURES AND PWATS INCREASE DURING THE MIDDLE
OF NEXT WEEK, BUT AN APPROACHING STORM SYSTEM WILL BRING THE
CHANCE FOR RAIN AROUND CHRISTMAS DAY. TIMING OF THIS SYSTEM IS
LOW SO IT IS NOT A GUARANTEE THAT CHRISTMAS WILL BE WET.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
MVFR CEILINGS EXPECTED TO DETERIORATE TO IFR POSSIBLE OVERNIGHT.
WIDESPREAD LOW CLOUDS CONTINUE ACROSS THE AREA WITH MVFR CIGS AT
ALL TERMINALS, ALTHOUGH CIGS HAVE BEEN BOUNCING AROUND BETWEEN
MVFR/VFR AT AGS/DNL WHICH IS ON THE EDGE OF THE CLOUD FIELD.
HOWEVER, LATEST TRENDS IN SATELLITE ARE SHOWING REFORMATION IN
THE CSRA SO EXPECT MVFR CIGS ALL TERMINALS THROUGH THE EVENING
HOURS. CIGS ARE EXPECTED TO LOWER THROUGH THE NIGHT AND COULD
LOWER INTO THE IFR RANGE AS HRRR AND SOME MOS GUIDANCE SUGGESTS,
ALTHOUGH SOME GUIDANCE KEEPS CIGS IN THE MVFR RANGE SO LOWER
CONFIDENCE IN THE IFR CIGS AT AGS/DNL.
AN APPROACHING UPPER TROUGH WILL INCREASE LOW LEVEL FLOW FROM
THE SOUTH DURING THE PREDAWN HOURS AND LOWER CLOUDS SHOULD BEGIN
TO ERODE FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY FRIDAY.
EXPECT VFR CIGS TO RETURN AT AGS/DNL BY 12Z AND AT CAE/CUB/OGB
BY 16Z. WINDS SHOULD BE LIGHT FROM THE NORTH TO NORTHEAST
OVERNIGHT BEFORE SHIFTING TO THE SOUTHWEST AROUND 12Z-13Z THEN
AS A COLD FRONT CROSSES THE REGION BY LATE MORNING WINDS SHIFT
TO THE WEST AND INCREASE TO AROUND 10 TO 15 KNOTS WITH GUSTS
OVER 20 KNOTS THROUGH THE AFTERNOON.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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