008
FXUS62 KRAH 171544
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1044 AM EST TUE DEC 17 2024
SYNOPSIS
A BACK DOOR COLD FRONT WILL EDGE INTO THE NORTHERN PIEDMONT TONIGHT
BEFORE LIFTING BACK NORTH IN VIRGINIA WEDNESDAY MORNING. A SERIES OF
COLD FRONTS WILL MOVE ACROSS THE REGION FROM WEDNESDAY NIGHT THROUGH
SATURDAY MORNING.
NEAR TERM /THROUGH TONIGHT/
AS OF 1040 AM TUESDAY...
* NOTICEABLY WARMER TODAY COMPARED TO MONDAY.
* PATCHY DENSE FOG POSSIBLE AGAIN TONIGHT WITH FAVORED LOCATIONS
ACROSS THE SOUTHERN PIEDMONT, SANDHILLS, AND INTO THE COASTAL
PLAIN.
REGIONAL SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOWS AN EROSION
OF BOTH THE HYBRID CAD REGIME OVER THE NORTHWEST PIEDMONT AS WELL AS
THE WIDESPREAD AREA OF FOG, DENSE IS ISOLATED LOCATIONS, OVER
EASTERN NC INTO THE EASTERN SANDHILLS. REGIONAL RADAR IMAGERY SHOWS
A REMNANT MCV ORIGINATING FROM UPSTREAM CONVECTION OVER NORTHERN
AL/GA LATE LAST NIGHT INTO THIS MORNING. RAP ANALYSIS SUGGESTS THIS
MCV WILL TRACK GENERALLY ENE AND MAY PRODUCE SOME ISOLATED SPRINKLES
OR PERHAPS A PASSING SHOWER INTO THE WESTERN PIEDMONT INTO THE
AFTERNOON. OTHERWISE, DRY WEATHER WITH MULTI-LAYERED CLOUDINESS IS
EXPECTED FOR MUCH OF TODAY ACROSS CENTRAL NC. LOW-LEVEL THICKNESSES
HAVE RISEN 10 TO 20M FROM MON MORNING, AND WITH THE LACK OF LOW
OVERCAST IN THE RESIDUAL CAD AIRMASS, EXPECT A NOTICEABLE RISE IN
TEMPERATURES TODAY (5-10 DEGREES WARMER IN THE SANDHILLS AND COASTAL
PLAIN AND 10-15 DEGREES WARMER ACROSS THE PIEDMONT). HIGHS RANGE
FROM MID/UPPER 60S (NW) TO LOW/MID 70S (SE).
TONIGHT, A SURFACE COLD FRONT ANALYZED AT 12Z REMAINS PINNED UP
AGAINST THE WESTERN SLOPES OF THE APPALACHIAN MOUNTAINS THIS MORNING.
AS THE 1027MB SURFACE HIGH PRESSURE OVER THE SOUTHERN OHIO VALLEY
TRACKS GENERALLY EASTWARD TODAY, THIS WILL ALLOW THE FRONT TO SPILL
ACROSS THE VA MOUNTAINS AND DIP INTO THE NORTHERN NC PIEDMONT LATE
TONIGHT INTO EARLY TUES MORNING. SOUTH OF THIS BACKDOOR FRONT, A
LINGERING RESIDUAL CAD AIRMASS REMAINS IN PLACE, ALTHOUGH MODERATED
BY CONSIDERABLE SOLAR HEATING TODAY. THIS CONTINUED MOIST AIRMASS
WILL SUPPORT THE REDEVELOPMENT OF LOW OVERCAST AND PERHAPS SOME
PATCHY/AREAS OF FOG. THE REMNANT CAD HIGH WILL BECOME MORE DIFFUSE
THROUGHOUT THE DAY, BUT CONTINUE TO RIDGE ACROSS SOUTHERN NC INTO SC
AND GA THROUGH TONIGHT AND BE THE FAVORED AREA FOR POTENTIALLY DENSE
FOG. LIGHTS SHOWERS WILL ALSO BE POSSIBLE, MAINLY ALONG AND NORTH OF
THE I-85 CORRIDOR, AS MOIST ISENTROPIC ASCENT ALONG THE 290K
STRENGTHENS ATOP OF THE BACKDOOR COLD FRONT SPILLING INTO THE AREA
FROM THE NORTH. MILD OVERNIGHT LOWS WILL CONTINUE FOR AT LEAST ONE
MORE NIGHT WITH LOWS SETTLING IN THE MID/UPPER 40S TO LOW 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 /12Z TUESDAY THROUGH SATURDAY/
AS OF 630 AM TUESDAY...
TAF PERIOD: LIFR CEILINGS HAVE BEEN OBSERVED AT ALL TERMINALS EXCEPT
RDU. ALL SITES SHOULD RETURN TO VFR CONDITIONS BY EARLY AFTERNOON.
NO RESTRICTIONS ARE FORECAST FOR MUCH OF THE AFTERNOON AND THE
EVENING BEFORE CEILINGS WITH RESTRICTIONS DEVELOP AFTER MIDNIGHT,
WITH THE LOWEST CEILINGS ONCE AGAIN AT INT/GSO. THE WIND WILL BE OUT
OF THE SOUTHWEST AROUND 5 KT, AND WILL THEN BE CALM TONIGHT.
OUTLOOK: IFR/MVFR CEILINGS WILL PERSIST 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...SWIGGETT
NEAR TERM...SWIGGETT
SHORT TERM...GREEN
LONG TERM...KREN
AVIATION...GREEN
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