552
FXUS62 KCAE 171813
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
113 PM EST TUE DEC 17 2024
SYNOPSIS
WARM AND DRY CONDITIONS ARE EXPECTED AS MID-LEVEL RIDGING
DEVELOPS ACROSS THE SOUTHEASTERN US TODAY. A FRONT WITH SOME
SCATTERED SHOWERS IS EXPECTED ON WEDNESDAY, WITH A STEADY COOL
DOWN EXPECTED FOLLOWING THIS FRONT INTO THE WEEKEND. WELL BELOW
AVERAGE TEMPS ARE LIKELY SUNDAY AND INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- PATCHY DENSE FOG POSSIBLE LATE TONIGHT.
UPPER RIDGE HAS SHIFTED OFF THE COAST. UPPER TROUGH OVER THE
MIDWEST WITH SOUTHWEST FLOW ALOFT ACROSS THE AREA. AS THE UPPER
TROUGH TO THE WEST AMPLIFIES, A FRONTAL BOUNDARY IN EASTERN
TENNESSEE THIS AFTERNOON WILL SLIDE A LITTLE EAST BUT LIKELY
REMAIN NORTH AND WEST OF THE REGION. MOISTURE/CLOUDS WILL
SPREAD EAST FROM THE UPSTATE AS SEVERAL WEAK SHORT WAVE TROUGHS
MOVE TO THE NORTHEAST ACROSS NORTH CAROLINA. AT THE SURFACE,
RIDGE OFFSHORE WITH WEAK SOUTHWEST FLOW. WARM ADVECTION APPEARS
TO BE FOCUSED IN THE SOUTHEAST MIDLANDS, WHERE CLOUDINESS IS A
LITTLE MORE AGITATED. CAN'T RULE OUT A BRIEF LIGHT SHOWERS
MAINLY EAST OF I-95 THIS AFTERNOON. SO GENERALLY CLEAR EARLY
THIS EVENING ALTHOUGH AN INCREASE IN MID LEVEL CLOUDS POSSIBLE
OVERNIGHT ESPECIALLY IN THE PIEDMONT AND NORTH MIDLANDS.
GUIDANCE IS SUGGESTING AT LEAST PATCHY FOG OVERNIGHT, ESPECIALLY
IN THE CENTRAL AND SOUTHEAST MIDLANDS/CSRA WHERE UPPER LEVELS
REMAIN MAINLY CLEAR. OVERNIGHT LOWS A LITTLE WARMER THAN
PREVIOUS NIGHT, LOW TO MID 50S.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
KEY MESSAGE(S):
- AN APPROACHING FRONT WILL DEVELOP SOME SHOWERS AND
THUNDERSTORMS FOR WEDNESDAY. AN ISOLATED STRONG STORM CANNOT
BE RULED OUT.
- FIRST FRONT PASSES WEDNESDAY NIGHT, WITH A SECOND QUICKLY ON
ITS HEELS THURSDAY NIGHT.
REALLY INTERESTING FORECAST HAS DEVELOPED ON WEDNESDAY AS GUIDANCE
HAS TRENDED SLOWER AND DEEPER WITH THE APPROACHING TROUGH. THE
SLOWER TIMING AND DEPTH OF THE TROUGH OVERALL LOOKS POISED TO ALLOW
GREATER MOISTURE RETURN IN ADVANCE OF THE SURFACE LOW PRESSURE
SYSTEM AND FRONT ITSELF. SOUTH AND SOUTH-SOUTHWESTERLY FLOW AT THE
SURFACE AND 850 HPA SHOULD YIELD DEWPOINTS BACK UP INTO THE LOW 60S
BY WEDNESDAY AFTERNOON. LOW CLOUDS OR FOG EARLY ON WEDNESDAY SHOULD
GIVE WAY TO CUMULUS DURING THE AFTERNOON, WITH BREAKS IN THE CLOUDS
LIKELY RESULTING IN MORE SIGNIFICANT DESTABILIZATION THAT WAS
PREVIOUSLY ANTICIPATED. BOTH OPERATIONAL AND ENSEMBLE GUIDANCE HAVE
TRENDED TOWARDS SBCAPE IN THE 500-1000 J/KG RANGE BY WEDNESDAY
AFTERNOON AND EVENING. WARM AIR ADVECTION SHOWERS MAY BE SOMETHING
THAT LIMITS OVERALL DESTABILIZATION BUT THE GENERAL TREND IS TOWARDS
GREATER INSTABILITY WITHIN GUIDANCE. AND MODELS ARE SHOWING
CONVECTION DEVELOPING ALONG, AND IN ADVANCE OF, THE APPROACHING COLD
FRONT WEDNESDAY EVENING. SHEAR PROFILES ARE SUPPORTIVE OF ORGANIZED
CONVECTION, WITH 6KM BULK SHEAR FORECAST TO BE 30-40 KNOTS BY THE
TIME OF PEAK HEATING. SO THIS PAINTS THE PICTURE OF POTENTIAL STRONG
CONVECTION DURING THE AFTERNOON HOURS. NOT SURE THAT THE COVERAGE
WILL BE GREAT, BUT THE TREND DEFINITELY SUPPORTS ISOLATED STRONG TO
MARGINALLY SEVERE STORMS AHEAD OF THE FRONT. HIGHS WEDNESDAY LIKELY
WILL BE IN THE 70-75F RANGE FOR MOST. RAIN SHOWERS OR THUNDERSTORMS
ARE LIKELY TO HANG AROUND UNTIL THE FINAL PUSH OF THE FRONT
WEDNESDAY NIGHT. LOWS SHOULD BE ELEVATED DESPITE THE FRONT PASSING
THROUGH WITH LOWS IN THE UPPER 40S AND LOW 50S. ANOTHER TROUGH IS
FORECAST TO QUICKLY APPROACH ON THURSDAY, WITH SHORTWAVE RIDGING
DEVELOPING AND PASSING THROUGH THE DAY. TEMPS SHOULD BE NICE, ALBEIT
A BIT COOLER, WITH HIGHS IN THE UPPER 50S AND LOW 60S EXPECTED.
OVERNIGHT, LOOK FOR LOWS TO REMAIN ELEVATED IN THE 40S AS CLOUDS AND
ISOLATED SHOWERS DEVELOP IN ADVANCE OF THE APPROACHING SHORTWAVE
TROUGH.
LONG TERM /FRIDAY THROUGH MONDAY/
KEY MESSAGE(S):
- A GENERAL COOL DOWN IS EXPECTED THROUGH THE WEEKEND. THE
COLDEST AIR OF THE SEASON WILL LIKELY PUSH IN FOR SUNDAY AND
INTO MONDAY.
CONFIDENCE IS FAIRLY HIGH DURING THE LONG TERM. SECOND SHORTWAVE IN
AS MANY DAYS IS FORECAST TO QUICKLY APPROACH AND PUSH THROUGH THE
REGION THURSDAY NIGHT AND FRIDAY. THIS SHOULD FORCE A SURFACE LOW
OFF THE CAROLINA COASTLINE, WITH SOME SHOWERS POTENTIALLY DEVELOPING
AS THE FORCING PUSHES THROUGH EARLY ON FRIDAY. CLOUDS ARE LIKELY TO
START THE DAY BUT WILL CLEAR QUICKLY AS DRY AIR PUSHES INTO THE
REGION BEHIND THE TROUGH AND ASSOCIATED FRONT. FROM THERE,
CONFIDENCE IS HIGH IN THE FORECAST THROUGH EARLY NEXT WEEK. STRONG,
COLD HIGH PRESSURE IS FORECAST TO SHIFT INTO THE EASTERN CONUS
UNDERNEATH STRONGLY CONVERGENT MID/UPPER LEVEL FLOW THROUGH
EARLY NEXT WEEK. THIS HIGH IS FORECAST TO BE ON THE ORDER OF
1038-1040 MB AT ITS CORE, WITH A SURFACE RIDGE AXIS EXTENDING
SOUTHWARD ALONG THE APPALACHIANS. WELL BELOW NORMAL TEMPS ARE
EXPECTED WITH THIS OVER THE WEEKEND, WITH HIGHS NOT GETTING OUT
OF THE UPPER 40S OR LOW 50S SATURDAY THROUGH TUESDAY. OVERNIGHT
LOWS ARE LIKELY TO BE COLDER AND IN THE 20S. NBM 50TH
PERCENTILE IS WELL BELOW THE OPERATIONAL NBM & DID A MUCH BETTER
JOB WITH THE LAST SHOT OF COLD AIR. HAVE ADDED A MIX OF
NBM50/NBM FOR LOWS IN THE LONG TERM. OVERALL, IT IS A BIT
UNCERTAIN JUST HOW COLD WE GET BECAUSE THE CENTER OF THE SURFACE
HIGH IS NOT EXPECTED TO BE DIRECTLY OVER THE AREA. THIS WILL
MAKE IT TOUGH TO GET IDEAL RADIATIONAL COOLING CONDITIONS.
REGARDLESS, THE AIRMASS IS FORECAST TO BE VERY COLD, SO BE SURE
TO TAKE EXTRA PRECAUTIONS TO PROTECT PIPES IF YOU ARE TRAVELING
IN ADVANCE OF THE CHRISTMAS HOLIDAY NEXT WEEK. ADDITIONALLY, IT
DOES LOOK LIKE WE COULD BE COLD ENOUGH TO APPROACH OUR CRITERIA
FOR NEW 2024 COLD WEATHER PRODUCTS, SO KEEP YOUR EYE ON THE
FORECAST FOR THE LATEST!
AVIATION /18Z TUESDAY THROUGH SUNDAY/
VFR CONDITIONS EXPECTED THROUGH THE EARLY EVENING. RESTRICTIONS
POSSIBLE LATE TONIGHT DUE TO POSSIBLE FOG DEVELOPMENT.
HIGH PRESSURE OFFSHORE WITH LIGHT SOUTHWEST FLOW ACROSS THE
AREA. STRATO-CUMULUS DECK MAINLY IN THE COASTAL PLAIN THIS
AFTERNOON WELL EAST OF THE TERMINALS. CLOUDS IN THE UPSTATE
SHOULD STAY MAINLY NORTHWEST OF THE AREA. SO A FEW CUMULUS
POSSIBLE THIS AFTERNOON THEN MAYBE SOME MID AND HIGH CLOUDS
OVERNIGHT. MODELS ARE SUGGESTING AT LEAST SOME PATCHY, POSSIBLY
DENSE FOG DEVELOPING LATE TONIGHT. WENT WITH IFR VISIBILITY
RESTRICTIONS AT THIS TIME DEVELOPING AFTER 09Z AT ALL TERMINALS.
VISIBILITY SHOULD IMPROVE AROUND 14Z-15Z WEDNESDAY WITH
SCATTERED TO BROKEN STRATO-CU.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AHEAD OF A COLD
FRONT WEDNESDAY AFTERNOON AND EVENING WITH BRIEF RESTRICTIONS
POSSIBLE. PATCHY FOG POSSIBLE THURSDAY MORNING.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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