048
FXUS62 KRAH 170801
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
300 AM EST TUE DEC 17 2024
SYNOPSIS
A FRONT WILL REMAIN TO THE WEST OF CENTRAL NORTH CAROLINA TODAY AND
TOMORROW, FINALLY MOVING ACROSS THE AREA WEDNESDAY NIGHT. ANOTHER
FRONT MOVING THROUGH FRIDAY WILL BRING SHARPLY COLDER WEATHER FOR
THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 300 AM TUESDAY...
LOW CLOUDS AND FOG ARE IMPACTING THE WESTERN AND EASTERN EDGES OF
THE FORECAST AREA, LEAVING JUST HIGH CLOUDS ACROSS MUCH OF THE
REGION. LOW PRESSURE CENTERED OVER HUDSON BAY HAS A FRONT EXTENDING
SOUTHEAST INTO NEW YORK, THEN ARCING BACK TO THE SOUTHWEST ALONG THE
APPALACHIAN MOUNTAINS. ALTHOUGH THE LOW WILL CONTINUE MOVING
NORTHEAST ACROSS CANADA, THE COLD FRONT IS EXPECTED TO MOVE LITTLE
LOCALLY ALONG THE APPALACHIANS. AS A RESULT, IT DOESN'T APPEAR THAT
THE CHANCE OF RAIN ALONG THE MOUNTAINS SHOULD MOVE TO THE EAST,
LEAVING DRY CONDITIONS TODAY. WHAT WILL CHANGE TONIGHT IS A WAVE OF
LOW PRESSURE DEVELOPING ALONG THE FRONT OVER TEXAS THAT WILL MOVE
NORTHEAST INTO KENTUCKY BY WEDNESDAY MORNING. THE ECMWF/EPS HAS
CONSISTENTLY BEEN FARTHER SOUTHEAST WITH THIS NEW WAVE OF LOW
PRESSURE THAN THE GFS/GEFS, BUT THE MODELS ARE IN BETTER AGREEMENT
WITH THE 00Z RUNS. THE ECMWF HAS SHIFTED A BIT FARTHER NORTHWEST,
AND HAVE RESTRICTED POPS AFTER MIDNIGHT TO AN AREA NORTHWEST OF
RALEIGH. SOME PARTIAL CLEARING OF CLOUDS IS FORECAST TODAY,
ESPECIALLY ACROSS THE SOUTHEAST. HIGH TEMPERATURES COULD BE TRICKY -
WHILE HIGH PRESSURE HAS MOVED OFF TO THE EAST, THE AIR MASS OVER THE
REGION HASN'T CHANGED WITH THE COLD FRONT REMAINING TO THE WEST.
HAVE UNDERCUT NBM GUIDANCE SLIGHTLY, WITH MOST LOCATIONS IN THE 60S
AND SOME LOWER 70S ACROSS THE SOUTH. LOWS WILL RANGE FROM THE MID
40S TO THE MID 50S.
SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/
AS OF 300 AM TUESDAY...
THE KENTUCKY LOW WILL BECOME THE PRIMARY LOW PRESSURE CENTER
AFFECTING THE REGION, MOVING UP TO NEW JERSEY BY WEDNESDAY EVENING
AND OFF THE NEW ENGLAND COAST BY THURSDAY MORNING. DURING THE
DAYTIME, THE CHANCE OF SHOWERS SHOULD SPREAD ACROSS THE WHOLE
FORECAST AREA, BUT THE BULK OF THE RAIN IS FORECAST TO REMAIN ALONG
THE MOUNTAINS. AS THE LOW MOVES OFFSHORE, THE GREATEST FORCING WILL
BE WELL TO THE NORTH OF NORTH CAROLINA, AND WHILE MOST OF THE
FORECAST AREA STILL HAS LIKELY POPS WEDNESDAY EVENING, OVERALL
RAINFALLS AMOUNTS SHOULD BE LIGHT - LESS THAN A QUARTER INCH.
SLIGHTLY EXPANDED THE AREA WITH A SLIGHT CHANCE OF THUNDERSTORMS
WEDNESDAY AFTERNOON AND EVENING WITH PRIMARILY ELEVATED
THUNDERSTORMS POSSIBLE - LOCATIONS SOUTHEAST OF US-1 MAY HAVE A
RUMBLE OF THUNDER. WEDNESDAY'S HIGHS SHOULD BE SIMILAR TO TODAY'S
HIGHS, CONSIDERING THERE WILL STILL NOT HAVE BEEN ANY APPRECIABLE
CHANGE IN AIR MASS OVER THE AREA. AS THE COLD FRONT PASSES THROUGH
WEDNESDAY NIGHT, LOWS WILL FALL INTO THE UPPER 30S IN THE NORTHWEST,
YET ONLY DROP INTO THE LOWER 50S ACROSS THE SOUTHEAST.
LONG TERM /THURSDAY THROUGH MONDAY/
AS OF 204 AM TUESDAY...
NEAR TO SLIGHTLY BELOW NORMAL HIGHS ARE EXPECTED TO TREND WELL BELOW
NORMAL FOR THE WEEKEND AND INTO EARLY NEXT WEEK. PRECIPITATION
CHANCES APPEAR MINIMAL, WITH ANY CHANCES HIGHEST ON FRI.
QUASI-ZONAL FLOW WILL BE IN PLACE THU, WITH A TROUGH AXIS SLIDING
THROUGH DURING THE DAY. WHILE THE SURFACE COLD FRONT WILL CONTINUE
TO MOVE THROUGH DURING THE DAY, IN A BACKDOOR FASHION, MODELS SEEM
TO BE SLOWING OR HOLDING UP THE 850-700 MB FRONT, NOT MOVING IT
THROUGH UNTIL LATER FRI AS ANOTHER TROUGH MOVES THROUGH. MODELS SHOW
A SURFACE LOW FORMING OFFSHORE ALONG THE STALLED FRONT FRI, WHICH
COULD FAVOR SOME LIGHT RAIN OVER OUR COASTAL PLAIN. MOST ENSEMBLE
GUIDANCE, HOWEVER, SHOWS THAT THIS STAYS OFFSHORE. AS A RESULT, HAVE
KEPT THE FORECAST DRY FOR THE MOMENT. THE TROUGH MOVING OVERHEAD FRI
COULD ALSO WARRANT A LOW-END RAIN CHANCE, BUT MOST ENSEMBLE CLUSTERS
TAKE THE MAIN ENERGY ACROSS VA. AN OUTLIER CLUSTER, MAINLY FROM THE
GEFS, SHOWS A FURTHER SOUTH TRACK, WHICH WOULD WARRANT HIGHER RAIN
CHANCES. WE SUSPECT MODELS WILL HAVE A BETTER HANDLE ON THIS FEATURE
AFTER IT MOVES ONSHORE ACROSS THE PACIFIC NW WED MORNING. HAVE KEPT
THE FORECAST DRY FOR THE MOMENT, BUT IT MAY NEED TO BE REVISITED IF
TRENDS CHANGE. HIGHS THU/FRI WILL BE NOTICEABLY COOLER FROM WED IN
THE LOW TO MID/UPPER 50S.
THE WEEKEND FORECAST WILL LARGELY BE FOCUSED ON WELL BELOW NORMAL
TEMPERATURES, ESPECIALLY SUN AND MON. NW FLOW WILL PERSIST AS
TROUGHING RESIDES OVER THE FAR EASTERN US AND MID-ATLANTIC REGION. A
REINFORCING SHOT OF COLD AIR MOVES IN SAT WITH HIGHS IN THE LOW TO
MID/UPPER 40S. MUCH COLDER AIR ARRIVES SUN INTO MON AS COLD 1040 MB
HIGH PRESSURE SETTLES INTO THE NORTHERN MID-ATLANTIC. LOW-LEVEL
THICKNESSES ARE FORECAST TO BE SOME 40-45 M BELOW AVERAGE, FAVORING
HIGHS IN THE UPPER 30S TO MID 40S. LOWS WILL ALSO BE QUITE COLD,
LOWEST EARLY MON AS RIDGING BUILDS IN ALOFT, WITH UPPER TEENS TO
LOWER 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...GREEN
NEAR TERM...GREEN
SHORT TERM...GREEN
LONG TERM...KREN
AVIATION...GREEN
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