512
FXUS62 KRAH 170540
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1240 AM EST TUE DEC 17 2024
SYNOPSIS
HIGH PRESSURE AND ASSOCIATED COLD AIR DAMMING WILL EXTEND ACROSS THE
PIEDMONT OF THE CAROLINAS, WHILE GRADUALLY WEAKENING, THROUGH
TUESDAY. A SERIES OF COLD FRONTS WILL PROGRESS ACROSS THE REGION
WEDNESDAY NIGHT THROUGH SATURDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 923 PM MONDAY...
DENSE FOG HAS LARGELY REMAINED WEST AND SOUTHEAST OF CENTRAL NC THIS
EVENING. A FEW SITES ACROSS THE NORTHERN PIEDMONT HAVE DEVELOPED
SOME REDUCED VISIBILITY, BUT NOTHING NEAR DFA CRITERIA AT THIS
POINT. LATEST HRRR RUNS HAVE TRENDED A BIT MORE TOWARDS PERHAPS
KEEPING THE MOST DENSE FOG MOSTLY OUT OF OUR AREA TONIGHT. BEST
CHANCES FOR AREAS OF DENSE FOG WOULD REMAIN ACROSS THE WESTERN
PIEDMONT AND ALSO DOWN IN THE FAR SOUTHEASTERN COASTAL PLAIN.
REGARDLESS, PATCHY FOG IS POSSIBLE ANYWHERE TONIGHT. MAKE SURE TO
PRACTICE FOG SAFETY IF ENCOUNTERING ANY FOG TONIGHT/EARLY TUESDAY
MORNING.
PREVIOUS DISCUSSION AS OF 220 PM:
* THREAT FOR DENSE FOG WILL BE MOST PROBABLE ACROSS THE SOUTHERN
PIEDMONT AND SANDHILLS TONIGHT INTO EARLY TUESDAY MORNING.
REGIONAL SATELLITE IMAGERY ALONG WITH 19Z SURFACE OBSERVATIONS SHOW
THE CAD WEDGE BOUNDARY HAS LIFTING THROUGH THE SANDHILLS AND THE
CENTRAL/SOUTHERN COASTAL PLAIN WITH POCKETS OF THINNING/CLEARING
FORMING BETWEEN THE TRIAD AND THE TRIANGLE. THIS BOUNDARY WILL HAVE
A FEW MORE HOURS OF POLEWARD MIXING BEFORE IT IS STUNTED BY BOUNDARY
LAYER STABILITY FROM NOCTURNAL COOLING. OPTICAL DEPTH SATELLITE
IMAGERY FROM GOES16 AND PERIODIC PILOT REPORTS SUGGEST THE THICKEST
CLOUD LAYER STILL REMAINS OVER THE HEART OF THE HYBRID CAD REGIME
ACROSS THE NC FOOTHILLS INTO PORTIONS OF THE NORTHWEST PIEDMONT.
THIS SUGGESTS INT/GSO WILL LIKELY REMAIN LOCKED INTO THE LOW
OVERCAST THROUGH THE REMAINDER OF THE DAYLIGHT HOURS WITH GRADUAL RE-
THICKENING AND LOWERING THROUGH THE OVERNIGHT PERIOD.
A LOBE OF THE CAD SURFACE HIGH ANALYZED AT 15Z OVER THE CHARLOTTE
AREA WILL SETTLE SOUTH OVER CENTRAL SC AND ELONGATE ACROSS THE
SOUTHERN PIEDMONT AND SANDHILLS THROUGH TONIGHT. CALM WINDS WITHIN
THE HIGH AND RESIDUAL HIGH BOUNDARY LAYER MOISTURE WILL BE THE
FAVORED REGION FOR FOG, POTENTIALLY DENSE. ELSEWHERE, LIGHT
STIRRING ON THE NORTHERN PERIPHERY OF THE SURFACE HIGH WILL LIKELY
KEEP THE LOW OVERCAST THAT REDEVELOPS FROM REACHING THE SURFACE AND
PRODUCING ANY VISIBILITY CONCERNS, ALTHOUGH VISIBILITY OF 1 TO 2
MILES WILL CERTAINLY BE POSSIBLE. OVERNIGHT LOWS WILL BE MILD AND
SETTLE IN THE MID/UPPER 40S TO LOW 50S.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
AS OF 240 PM MONDAY...
UPPER LEVEL DEEPENING TROUGH MOVING ACROSS CONUS TUESDAY AND
WEDNESDAY WITH THE AXIS OVER THE MID-ATLANTIC REGION LATE WEDNESDAY
NIGHT EARLY THURSDAY. AT THE SURFACE, A COLD FRONT EXTENDING FROM NY
DOWN ACROSS THE OH AND TN VALLEY INTO THE SOUTHERN PLAINS WILL
CONTINUE TO SLOWLY SHIFT SOUTH AND EAST THROUGH THE DAY. WHILE
TUESDAY IS EXPECTED TO BE MOSTLY DRY ACROSS THE REGION, CALM TO
LIGHT SW WINDS IN THE MORNING ON TUESDAY WILL RESULT IN PATCHY DENSE
FOG ACROSS THE WESTERN PIEDMONT AND PORTIONS OF THE SANDHILLS
REGION. MOST THE OF THE REGION WILL BE BLANKETED WITH CLOUDS DURING
THE DAY, EXCEPT SOME CLEARING IN THE AFTERNOON ACROSS THE SOUTHERN
COASTAL PLAIN AND PORTIONS OF THE SANDHILLS COULD RESULT IN
TEMPERATURES REACHING THE LOW TO MID 70S IN THOSE AREAS. OTHERWISE,
ELSEWHERE TEMPS ARE ONLY EXPECTED TO REACH THE MID/UPPER 60S. LATE
TUESDAY NIGHT THE FRONTAL BOUNDARY IS EXPECTED TO MOVE EAST OF THE
MOUNTAINS WITH INCREASING RAIN CHANCES FROM WEST TO EAST. ISOLATED
TO SCATTERED SHOWERS ARE EXPECTED EARLY WEDNESDAY MORNING ALONG WITH
ANOTHER ROUND OF PATCHY DENSE FOG AND LOW STRATUS EARLY WEDNESDAY.
THE BEST CHANCE FOR RAIN WILL BE IN THE AFTERNOON AND OVERNIGHT
HOURS. LATEST MODEL DATA HAS SHOWN AN UPTICK IN THUNDER POTENTIAL
ACROSS THE SOUTHEASTERN PORTION OF THE CWA. THE POTENTIAL IS LOW
HOWEVER, WITH ONLY 300-500 J/KG OF SBCAPE, BUT CANT RULE OUT A
COUPLE OF ISOLATED THUNDERSTORMS ESPECIALLY IN AREAS ACROSS THE
SOUTH WHERE TEMPERATURES ARE EXPECTED TO BE IN THE LOW 70S AND DEW
POINTS IN THE MID/UPPER 60S. SPC DOES NOT HAVE OUR AREA IN ANY KIND
OF SEVERE THREAT FOR NOW, BUT WOULDN'T BE SURPRISED IF THEY
INTRODUCED AT LEAST GENERAL THUNDER ACROSS OUR AREA FOR LATE
WEDNESDAY. THE FRONT IS ANTICIPATED TO MOVE ACROSS THE REGION PRE-
SUNRISE THURSDAY MORNING WITH COOL DRY AIR MOVING IN QUICKLY BEHIND
IT. TEMPERATURES WILL PROMPTLY DROP EARLY THURSDAY MORNING AFTER THE
FRONT MOVES THROUGH WITH LOWS RANGING FROM THE LOW 40S NORTH TO LOW
50S SOUTHEAST.
LONG TERM /THURSDAY THROUGH MONDAY/
AS OF 232 PM MONDAY...
AFTER THE FRONT EXITS THE REGION ON THURSDAY, TEMPERATURES WILL
START TO COOL, WITH MAXIMUM TEMPERATURES IN THE MID TO UPPER 50S AND
LOWS IN THE MID TO UPPER 30S THURSDAY NIGHT. FRIDAY, AN UPPER LEVEL
TROUGH WILL PASS THROUGH THE AREA WHICH WILL BRING A LOW-END CHANCE
OF A FEW VERY ISOLATED SHOWERS IN THE COASTAL PLAIN IN THE
AFTERNOON, HOWEVER, POPS ARE LIMITED DUE TO A LACK OF MOISTURE AND
INSTABILITY ACROSS THE AREA. THIS SYSTEM WILL FURTHER COOL
TEMPERATURES THROUGH THE WEEKEND AS COOL HIGH PRESSURE BUILDS IN.
MAXIMUM TEMPERATURES ON FRIDAY WILL BE IN THE LOW TO UPPER 50S
BEFORE COOLING TO THE 40S ON SATURDAY AND COOLING FURTHER TO UPPER
30S ON SUNDAY. MINIMUM TEMPERATURES FOLLOW A SIMILAR COOLING TREND
WITH TEMPERATURES ON THURSDAY NIGHT IN THE 30S, COOLING TO UPPER 20S
TO LOW 30S ON FRIDAY NIGHT, LOW TO MID 20S ON SATURDAY NIGHT, AND
UPPER TEENS TO LOW 20S ON SUNDAY NIGHT. TEMPERATURES WILL BEGIN TO
MODERATE MONDAY, WITH HIGHS IN THE 40S AND LOWS IN THE LOW TO MID
20S.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
AS OF 1240 AM TUESDAY...
TAF PERIOD: HIGH CONFIDENCE IN LIFR CONDITIONS AT INT/GSO AND RWI,
LESS CONFIDENCE IN THE CONDITIONS THROUGH THE NEXT 6-12 HOURS IN
BETWEEN AT RDU AND FAY. LIFR CEILINGS ARE ALREADY OBSERVED AT
INT/GSO, AND IT APPEARS LIKELY THAT DENSE FOG WILL DEVELOP FOR A FEW
HOURS AROUND SUNRISE. SIMILARLY, A FOG BANK IS SPREADING TOWARDS RWI
AND IS EXPECTED TO BRING SEVERAL HOURS OF LIFR CONDITIONS THERE.
THERE IS LESS CERTAINTY AS TO WHAT CONDITIONS WILL BE OBSERVED IN
FAY/RDU. BACKED OFF SLIGHTLY ON RESTRICTIONS AT RDU, AND SOME FOG
APPEARS IMMINENT AT FAY. INT/GSO WILL LIKELY CARRY RESTRICTIONS INTO
THE AFTERNOON, THEN HAVE MVFR CEILINGS MOVE BACK IN FROM THE WEST BY
THE END OF THE TAF PERIOD. MEANWHILE, RDU/FAY/RWI SHOULD RETURN TO
VFR CONDITIONS BY LATE MORNING, THEN REMAIN VFR THROUGH THE REST OF
THE PERIOD.
OUTLOOK: IFR/LIFR CEILINGS ARE LIKELY AT ALL SITES LATE TUESDAY
NIGHT, WITH IFR/MVFR CEILINGS PERSISTING THROUGH WEDNESDAY NIGHT. A
CHANCE OF SHOWERS WILL BE POSSIBLE EVERYWHERE LATE TUESDAY NIGHT
THROUGH WEDNESDAY NIGHT, WITH THE MOST LIKELY PERIOD WEDNESDAY
EVENING. DRY VFR CONDITIONS SHOULD RETURN BY THURSDAY MORNING AND
CONTINUE THROUGH THE REST OF THE OUTLOOK PERIOD.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...LUCHETTI/SWIGGETT
SHORT TERM...CA
LONG TERM...HELOCK
AVIATION...GREEN
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