599
FXUS62 KRAH 161926
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
226 PM EST MON DEC 16 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 220 PM MONDAY...
* 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 NIGHT THROUGH WEDNESDAY NIGHT/
AS OF 305 AM MONDAY...
BY TUESDAY NIGHT, LOW PRESSURE WILL BE ACROSS FAR EASTERN CANADA
WITH A COLD FRONT EXTENDING SOUTH INTO THE WESTERN ATLANTIC THEN
BACK TO THE SOUTHWEST ACROSS VIRGINIA AND TENNESSEE. ANOTHER WAVE OF
LOW PRESSURE WILL DEVELOP ALONG THE FRONT AND MOVE NORTHEAST. THE
ECMWF/EPS HAS REMAINED VERY CONSISTENT OVER THE LAST THREE DAYS
DEVELOPING THE SYSTEM SLIGHTLY FARTHER TO THE SOUTHEAST THAN THE
GFS/GEFS, WHICH BRINGS POPS INTO THE REGION MORE QUICKLY. DID DECIDE
TO SLIGHTLY BACK OFF THE ARRIVAL OF CHANCE POPS TUESDAY NIGHT, AND
MADE MINIMAL CHANGES TO POPS ON WEDNESDAY. MODELS ARE NOW BEGINNING
TO SHOW A SPLIT IN PRECIPITATION WEDNESDAY NIGHT, WITH ONE AREA
FOCUSED ALONG THE APPALACHIAN MOUNTAINS AND A SECOND AREA FOCUSED
ALONG THE GULF STREAM, POTENTIALLY SPLITTING THE CENTRAL PART OF THE
STATE. HAVE EXPANDED LIKELY POPS TO ALL LOCATIONS, BUT RIGHT NOW
THIS LOOKS LIKE A HIGH POP/LOW QPF SCENARIO, WHERE THERE IS A GOOD
CHANCE OF RAIN WITH LOW OVERALL RAINFALL AMOUNTS. LOWS TUESDAY NIGHT
WILL RANGE FROM THE MID 40S TO THE MID 50S. WEDNESDAY WILL BE
ANOTHER WARM DAY WITH SOUTHERLY FLOW, AND HIGHS WILL RANGE FROM THE
MID 60S TO THE MID 70S. AS THE COLD FRONT MOVES THROUGH WEDNESDAY
NIGHT, LOWS WILL FALL INTO THE 40S EVERYWHERE.
LONG TERM /THURSDAY THROUGH SUNDAY/
AS OF 305 AM MONDAY...
MODELS CONTINUE TO SPEED UP THE DEPARTURE OF THE COLD FRONT, AND
HAVE REMOVED ALL POPS ON THURSDAY. LOW PRESSURE ACROSS THE NORTHERN
PLAINS ON THURSDAY WILL REACH THE OHIO RIVER VALLEY BY FRIDAY
MORNING. THE OHIO RIVER VALLEY LOW WILL WEAKEN AS IT MOVES TO THE
SOUTHEAST, BRINGING LITTLE MORE THAN SKY COVER AND NO CHANCE OF
RAIN. HIGH PRESSURE WILL THEN DOMINATE THE FORECAST OVER THE
WEEKEND, WITH THE CENTER DROPPING FROM MANITOBA ON SATURDAY INTO THE
PLAINS ON SUNDAY. AFTER NEAR NORMAL HIGHS IN THE 50S THURSDAY AND
FRIDAY, NORTHERLY FLOW WILL PLUNGE HIGHS INTO THE 40S ON SATURDAY
AND INTO THE 30S/40S ON SUNDAY. LOWS WILL BE NEAR FREEZING THURSDAY
AND FRIDAY NIGHTS, THEN DROP INTO THE UPPER TEENS AND 20S SATURDAY
NIGHT.
AVIATION /18Z MONDAY THROUGH SATURDAY/
AS OF 110 PM MONDAY...
THE MORE SHALLOW CLOUD LAYER OVER FAY, RDU, AND RWI HAS STEADILY
BEEN ERODING ON THE SOUTHEAST EDGE AND LIFTING GENERALLY NORTHWARD
THROUGH THE LATE MORNING. A GENERAL IMPROVEMENT TO VFR IS EXPECTED
OVER THE NEXT SEVERAL HOURS, LATEST AT RDU. THE HEART OF THE HYBRID
CAD REGIME OVER THE NC FOOTHILLS INTO PORTIONS OF THE NORTHWEST
PIEDMONT MAY SCATTER, MORE LIKELY AT GSO, BUT SHOULD QUICKLY FILL
BACK IN WITH NOCTURNAL STABILIZATION AFTER SUNSET. IFR-LIFR
CONDITIONS ARE EXPECTED TO RAPIDLY BUILD BACK ACROSS THE AREA WITH
THE CONTINUED COOL AND MOIST CAD REGIME STILL LINGERING OVER THE
AREA. DENSE FOG, WITH VISIBILITY BELOW AIRPORT MINIMUMS, WILL BE
MOST PROBABLE IN THE VICINITY OF FAY INTO EARLY TUESDAY MORNING.
OUTLOOK: FLIGHT RESTRICTIONS AT INT/GSO WILL LIKELY FLUCTUATE
BETWEEN IFR-MVFR BY DAY AND LIFR-IFR BY NIGHT THROUGH WEDNESDAY
MORNING, AS COLD AIR DAMMING HOLDS OVER THE NW NC PIEDMONT.
MEANWHILE TO THE EAST, FLIGHT RESTRICTIONS ARE LIKELY TO BE CONFINED
MAINLY TO THE LATE NIGHT-MORNING HOURS THROUGH THE SAME TIME.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...MWS
NEAR TERM...SWIGGETT
SHORT TERM...GREEN
LONG TERM...GREEN
AVIATION...SWIGGETT/MWS
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