417
FXUS62 KCAE 161817
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
117 PM EST MON DEC 16 2024
SYNOPSIS
COLD AIR DAMMING WILL EXIT THE AREA WITH TEMPERATURES
REBOUNDING TO ABOVE NORMAL THROUGH WEDNESDAY. RAIN CHANCES
INCREASING DURING THE MIDDLE OF THE WEEK AS WELL. COLDER AIR
RETURNS BY NEXT WEEKEND WITH A DEEP TROUGH DIGGING INTO THE
EASTERN US.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- DENSE FOG POSSIBLE TONIGHT.
FLAT UPPER RIDGE CENTERED OVER FLORIDA. LOW AMPLITUDE UPPER
TROUGH OVER THE UPPER MIDWEST MOVING TOWARD THE GREAT LAKES/OHIO
VALLEY THIS EVENING AND NORTHEAST BY MORNING. GENERALLY
SOUTHWEST FLOW ALOFT AS RIDGE AXIS MOVES OFF THE COAST. SURFACE
RIDGE CENTERED ACROSS THE WESTERN CAROLINAS. LOW CLOUDINESS THIS
MORNING HAS ERODED ACROSS MUCH OF THE AREA. EXPECT MAINLY CLEAR
SKIES EARLY THIS EVENING. TEMPERATURES ARE RISING INTO 60S
ACROSS CENTRAL AND EASTERN AREAS WITH 50S IN THE PIEDMONT. A FEW
AREAS WILL RISE TO NEAR 70, WELL ABOVE NORMAL FOR THIS TIME OF
YEAR, MAINLY IN THE SOUTHEAST MIDLANDS DUE TO WARM ADVECTION.
CLEAR SKIES AND NEAR CALM WINDS THIS EVENING LEADING TO STRONG
NOCTURNAL COOLING EARLY. GUIDANCE IS FAIRLY CONSISTENT TONIGHT
WITH WIDESPREAD FOG DEVELOPMENT BY AROUND MIDNIGHT WITH SUPPORT
FROM THE NBM, LAMP AND HRRR. FOG MAY BE DENSE. STAYED CLOSE TO
THE NBM FOR OVERNIGHT LOWS WITH UPPER 40S TO LOW 50S.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
KEY MESSAGE(S):
- WELL ABOVE NORMAL TEMPS EXPECTED TUESDAY AND WEDNESDAY.
- RAIN CHANCES EXPECTED ON WEDNESDAY ESPECIALLY ACROSS THE
EASTERN HALF OF THE FORECAST AREA
FOG IS EXPECTED TO FORM LATE TONIGHT AS THE SURFACE HIGH PRESSURE
REMAINS ACROSS THE FORECAST AREA. THIS WILL PROBABLY TAKE A BIT TO
BURN OFF ON TUESDAY MORNING BUT IT IS UNLIKELY IT DOES MUCH TO
HAMPER TEMPERATURE RECOVERY THROUGH THE DAY. THE TEMPERATURES ARE
FORECAST TO BE WARMEST THIS WEEK ON TUESDAY. A WEAK FRONT IS FORECAST
TO APPROACH THE AREA FROM THE NORTH, WITH SOUTHWESTERLY FLOW AND
MID/UPPER LEVEL RIDGING SETTING UP AS WELL. SO WHILE SOME CLOUDS MAY
HANG AROUND IN THE AFTERNOON AS THE WEAKENING FRONT APPROACHES,
TEMPS ARE EXPECTED TO GET INTO THE LOW AND MID 70S ACROSS THE
SOUTHERN HALF OF THE AREA. UPPER 60S ARE MORE LIKELY IN OUR NORTHERN
COUNTIES WHERE LOW CLOUDS EARLY IN THE DAY ARE MORE LIKELY TO HANG
AROUND. MOISTURE IS GRADUALLY EXPECTED TO INCREASE ACROSS THE AREA
ON TUESDAY NIGHT, WITH CLOUDS REDEVELOPING SPECIFICALLY ACROSS THE
EASTERN HALF OF THE FORECAST AREA. THIS SHOULD HOLD TEMPS DOWN INTO
THE LOW OR MID 50S FOR MOST.
AS WE GET INTO WEDNESDAY, OUR FIRST BIG TROUGH OF THE WEEK IS
EXPECTED TO DEEPEN AND APPROACH THE AREA. GUIDANCE IS SLIGHTLY
SLOWER AND DEEPER WITH THIS FEATURE THAN IT WAS 24 HOURS AGO. THIS
DOESN'T CHANGE THE FORECAST TOO MUCH; HOWEVER, IT DOES GIVE THE
ABILITY FOR MOISTURE TO ADVECT FURTHER NORTH AND THAN WAS SHOWN BY
OPERATIONAL AND ENSEMBLE GUIDANCE. WHAT THIS DOES IS RAISE THE
CONFIDENCE IN RAINFALL EVER SO SLIGHT, ESPECIALLY ACROSS THE EASTERN
FORECAST AREA WHERE MOISTURE ADVECTION AND PLACING WITHIN SYNOPTIC
FEATURES MAY BE MOST FAVORABLE FOR RAINFALL LATER IN THE DAY ON
WEDNESDAY. IT IS IMPORTANT TO NOTE THAT THERE IS STILL SOME
UNCERTAINTY DESPITE THIS BEING FAIRLY CLOSE IN TIME. MODELS ARE
STILL CHANGING RUN-TO-RUN AND ARE SLIGHTLY DIFFERENT FROM ONE
ANOTHER, WHICH DOES MODULATE THE POTENTIAL FOR PRECIP. REGARDLESS,
IT DOES LOOK LIKE CLOUD COVER WILL BE A FEATURE ON WEDNESDAY. TEMPS
ARE FORECAST TO BE WELL ABOVE NORMAL, WITH HIGHS IN THE LOW TO MID
70S AGAIN. THE FRONT IS FORECAST TO MOVE THROUGH ON WEDNESDAY NIGHT,
WITH LITTLE TO NO PRECIP EXPECTED ALONG IT. LOWS SHOULD FALL INTO
THE MID 40S TO LOW 50S.
LONG TERM /THURSDAY THROUGH MONDAY/
KEY MESSAGE(S):
- MUCH COOLER AND DRIER WEATHER EXPECTED THROUGH THE PERIOD
WHILE THE WEATHER LOOKS INCREASINGLY COLD, DRY, AND BENIGN, THE
SYNOPTIC PATTERN DRIVING IT SHOULD BE PROGRESSIVE AND MERIDIONAL.
GUIDANCE CONTINUES TO POINT TO AN ANOMALOUSLY STRONG ZONAL UPPER
LEVEL JET STREAK ACROSS THE NORTH PACIFIC DURING THIS PERIOD. THIS
WILL BE THE MODULATING FEATURE FOR THIS PERIOD, WITH SEVERAL
SHORTWAVES DEVELOPING AS IT BREAKS DOWN OVER THE NORTHWESTERN CONUS.
SUCH AN INTENSE FEATURE INTRODUCES SOME UNCERTAINTY THAT NEEDS TO BE
BAKED INTO THE FORECAST, ESPECIALLY BECAUSE IT IS NOT ABLE TO BE
SAMPLED BY UPPER AIR SOUNDINGS. KEEPING THAT IN MIND, GUIDANCE
MAINTAINS RELATIVELY GOOD CONSISTENCY REGARDING THE DRY AND COOL
PATTERN EXPECTED THROUGH THE LONG TERM. THURSDAY AND FRIDAY
SHOULD SEE TRANSIENT SURFACE HIGH PRESSURE PASS THROUGH BEHIND
WEDNESDAY'S FRONT. THE AIRMASS LOOKS VERY DRY, WITH PWS FALLING
BELOW NORMAL DURING THE PERIOD. HIGHS AND LOWS WILL LIKELY BE
NEAR TO SLIGHTLY ABOVE NORMAL BOTH DAYS.
A SHARP SHORTWAVE TROUGH IS EXPECTED TO RACE SOUTHEASTWARD &
DIG THE LARGE SCALE TROUGH DEEPER ALONG THE EAST COAST FRIDAY
AND INTO THE WEEKEND. A DRY FRONT SHOULD PUSH THROUGH ON FRIDAY,
WITH ANOTHER ARCTIC HIGH PRESSURE PUSHING IN OVER THE WEEKEND.
CONFIDENCE IS HIGH ON THIS, AS MODELS HAVE BEEN FAIRLY
CONSISTENT RUN TO RUN OVER THE LAST COUPLE OF DAYS. MINOR
CHANGES ARE POSSIBLE BUT SHOULDN'T HAVE SIGNIFICANT IMPACTS ON
THE DETAILS OF THE FORECAST. ECM EFI IS SIGNALING THAT THIS
PERIOD (SAT/SUN/MON) SHOULD FEATURE WELL BELOW NORMAL TEMPS,
ADDING TO OVERALL CONFIDENCE IN THIS FORECAST. THE WEATHER
SHOULD REMAIN DRY WITH GEFS AND EC ENS MEAN PWS 30-40% OF NORMAL
BENEATH STRONG SUBSIDENCE ON THE BACK SIDE OF A LONGWAVE
TROUGH.
AVIATION /18Z MONDAY THROUGH SATURDAY/
VFR CONDITIONS THROUGH THE EARLY EVENING. LIFR RESTRICTIONS
EXPECTED AFTER 05Z DUE TO DENSE FOG DEVELOPMENT.
HIGH PRESSURE ACROSS THE AREA. LOW CLOUDS FROM THE MORNING HAVE
ERODED. EXPECT AT MOST A FEW STRATO-CU CLOUDS THIS AFTERNOON BUT
MAINLY CLEAR THROUGH AT LEAST 00Z. WINDS LIGHT AND VARIABLE.
GUIDANCE IS CONSISTENT WITH DEVELOPING FOG AFTER 05Z WITH CLEAR
SKIES ALOFT, SHALLOW LOW-LEVEL MOISTURE AND NEAR CALM WINDS.
THE CONFIDENCE IS RELATIVELY HIGH FOR DENSE FOG. WENT WITH LIFR
AT ALL TERMINALS AFTER 05Z THROUGH 12Z TUESDAY, THEN SLOW
IMPROVEMENT WITH VFR BY 15Z.
EXTENDED AVIATION OUTLOOK...POTENTIAL FOR SHOWERS AND ASSOCIATED
RESTRICTIONS WEDNESDAY INTO THURSDAY.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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