335
FXUS62 KCAE 152301
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
601 PM EST SUN DEC 15 2024
SYNOPSIS
WEAK COLD AIR DAMMING WILL LINGER INTO MONDAY MORNING, WITH
BELOW AVERAGE TEMPS EXPECTED. WELL ABOVE NORMAL TEMPS ARE
EXPECTED MONDAY THROUGH WEDNESDAY, WITH RAIN CHANCES INCREASING
BY MID- WEEK AS WELL. COLDER AIR RETURNS BY NEXT WEEKEND WITH A
DEEP TROUGH DIGGING INTO THE EASTERN US.
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
KEY MESSAGE(S):
- LIGHT SHOWERS ACROSS THE SC PIEDMONT, CLEARING OVERNIGHT
A STRONG SURFACE RIDGE OVER THE NORTHEAST IS PUSHING COLD, DRY
AIR INTO THE FORECAST AREA AT THE LOW LEVELS. WEAK MID-LEVEL
MOISTURE ADVECTION OVER THE RIDGING IS LEADING TO LIGHT SHOWERS
PRODUCING LIGHT RAINFALL ACROSS THE UPSTATE AND SC PIEDMONT.
WHILE THE STRONGER SUPPORT FOR SHOWERS WILL REMAIN NORTH OF THE
AREA, WE SHOULD SEE A COUPLE OF SHOWERS MOVE ACROSS THE VERY
EXTREME WESTERN PORTIONS OF THE FORECAST AREA. ANY AMOUNTS WILL
BE LIGHT, A FEW HUNDREDTHS OR LESS. CAMS ARE IN GOOD AGREEMENTS
THAT THESE SHOWERS WILL DIMINISH THROUGH THE NEAR TERM AS THE
SUPPORT FROM THE SHORTWAVE LIFTS OUT OF THE AREA. MOST AREAS
WILL SEE OVERCAST OR MOSTLY CLOUDY SKIES OVERNIGHT HELPING TO
KEEP TEMPS IN THE 40S.
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
KEY MESSAGE(S):
- IMPROVING CONDITIONS FOR MONDAY.
- WELL ABOVE NORMAL TEMPS EXPECTED MONDAY AND ESPECIALLY TUESDAY.
THE PATTERN WILL BE PROGRESSIVE MUCH OF THIS WEEK WITH A SERIES OF
SYSTEMS PASSING NEAR BUT MAINLY NORTH OF THE REGION. SHORTWAVE
RIDGING IS EXPECTED TO PUSH INTO THE REGION ON MONDAY WITH HIGH
PRESSURE CONTINUING AT THE SURFACE. THERE IS SOME INDICATION THAT
WEAK CAD MAY REDEVELOP OVERNIGHT AND PERSIST FOR THE FIRST PORTION
OF THE DAY. AS HIGH PRESSURE BREAKS DOWN AND MOVES OFFSHORE
SLIGHTLY, THERE SHOULD BE A GRADUAL WIND SHIFT FROM NORTHEASTERLY TO
EASTERLY TO SOUTHEASTERLY THROUGH THE DAY, WHICH WOULD GRADUALLY MIX
OUT THE WEDGE. EXPECT THAT THE NORTHERN AND WESTERN PORTIONS OF THE
FORECAST AREA WILL BE THE LAST TO BREAK OUT, SO THERE IS LIKELY TO
BE A TIGHT TEMPERATURE GRADIENT FROM NORTHWEST TO SOUTHEAST. IN
GENERAL, HIGHS MONDAY SHOULD BE AROUND 60 TOWARD THE UPSTATE TO
AROUND 70 CLOSER TO THE COASTAL PLAIN. NO RAIN IS EXPECTED. AS THE
LOW CLOUDS SCOUR OUT, EXPECT HIGH CLOUDS TO MOVE BACK IN AHEAD OF
ANOTHER QUICK-HITTING SHORTWAVE TROUGH. THIS WILL KEEP OVERNIGHT
LOWS IN THE UPPER 40S TO AROUND 50. THE TROUGH SKIRTS OUR NORTHERN
COUNTIES ON TUESDAY, WITH NOT MUCH IMPACT OUTSIDE OF SOME MID TO
HIGH LEVEL CLOUDS. INCREASING HEIGHTS WILL PUSH TEMPERATURES TO WELL
ABOVE NORMAL LEVELS, PEAKING IN THE LOW TO MID 70S FOR MOST.
OVERNIGHT, LOOK FOR TEMPS TO CONTINUE TO BE ABOVE NORMAL WITH LOWS
IN THE LOW TO MID 50S.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
KEY MESSAGE(S):
- ABOVE NORMAL TEMPERATURES CONTINUE WEDNESDAY AND THURSDAY.
- ACTIVE PATTERN CONTINUES TO BRING PERIODIC RAIN CHANCES.
MUCH OF THE EXTENDED IS DEFINED BY LONGWAVE TROUGHING OVER THE
EASTERN CONUS AS A SERIES OF WAVES ROTATE THROUGH THE MEAN FLOW.
WEDNESDAY STILL LOOKS QUITE WARM, WITH A DEEP UPPER TROUGH AND
ATTENDANT COLD FRONT BECOMING BETTER ORGANIZED ACROSS THE MIDDLE OF
THE COUNTRY. THE FRONT RACES THROUGH THE SOUTHEAST, BRINGING AN
INCREASED CHANCE OF RAIN AND POTENTIALLY A FEW RUMBLES OF THUNDER AS
A FEW MODELS INDICATE UP TO A COUPLE HUNDRED JOULES OF CAPE,
DEPENDING ON THE EXACT TIMING OF THE FRONT. BUT FOR NOW, HAVE
LEFT THUNDER OUT OF THE OFFICIAL FORECAST. TEMPERATURES COOL
DOWN A FEW DEGREES ON THURSDAY, BUT A MUCH COLDER AIRMASS AND
ASSOCIATED STRONGER UPPER LEVEL LOW AREN'T EXPECTED TO ARRIVE
UNTIL THE WEEKEND.
ENSEMBLES AND OPERATIONAL MODELS HAVE GENERALLY BEEN BACKING OFF ON
RAIN CHANCES FOR THIS LATE WEEK SYSTEM SO THERE REMAINS LIMITED
CONFIDENCE IN THE AMOUNT OF ANY RAIN AND HOW HEAVY OR LIGHT IT MAY
END UP BEING. THERE IS MORE CONFIDENCE THAT AFTER THE WARM
TEMPERATURES MID-WEEK, A MUCH COOLER AIRMASS WILL ARRIVE FOR THE
WEEKEND INTO EARLY NEXT WEEK.
AVIATION /00Z MONDAY THROUGH FRIDAY/
VFR CONDITIONS EXPECTED SUNDAY AFTERNOON. CIG RESTRICTIONS
LIKELY AGAIN SUNDAY NIGHT INTO MONDAY MORNING.
WEAK COLD AIR DAMMING CONDITIONS CONTINUE ACROSS THE REGION, BUT
ALL SITES ARE NOW SITTING WITH VFR CIGS BETWEEN 4K AND 8K FEET.
THIS IS EXPECTED TO HOLD IN PLACE THE REST OF SUNDAY AFTERNOON
BEFORE LOWERING CIGS ARE LIKELY LATER SUNDAY EVENING INTO MONDAY
MORNING. CURRENTLY, IT LOOKS LIKE CIGS SHOULD GENERALLY FALL TO
MVFR AFTER ~0800Z FOR ALL SITES WITH SOME PERIODIC DROPS TO IFR
CLOSER TO SUNRISE; CONFIDENCE IS TOO LOW IN TIMING HOWEVER FOR
TAF MENTION YET FOR IFR, SO RAN WITH MVFR MENTION THROUGH 15Z
MONDAY. THE SETUP AND SOME GUIDANCE DOES SUGGEST SOME LIFR CIGS
ARE POSSIBLE BETWEEN 1100-1300Z, BUT AGAIN CONFIDENCE IS TOO
LOW CURRENTLY BUT THE POSSIBILITY SHOULD BE MONITORED AS THE
FORECAST CONFIDENCE IMPROVES. WINDS THROUGHOUT SUNDAY AFTERNOON
WILL REMAIN OUT THE NORTHEAST, AROUND 5-10 KNOTS, BEFORE GOING
CALM OVERNIGHT.
EXTENDED AVIATION OUTLOOK...INCREASING POTENTIAL FOR SHOWERS AND
ASSOCIATED RESTRICTIONS WEDNESDAY INTO THURSDAY.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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