638
FXUS62 KILM 201520
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1020 AM EST FRI DEC 20 2024
SYNOPSIS
A DEVELOPING LOW-PRESSURE CENTER OFF OF CAPE HATTERAS WILL MOVE TO
THE NORTHEAST AWAY FROM THE REGION TODAY. A COLD FRONT WILL CROSS
THE REGION TONIGHT, AND COLD HIGH PRESSURE WILL BUILD INTO THE AREA
SATURDAY THROUGH MONDAY. AS HIGH PRESSURE MOVES OFF THE NEW ENGLAND
COAST, WARMER WEATHER WILL MOVE INTO THE REGION, WITH INCREASING
CHANCES OF RAIN TUESDAY THROUGH THURSDAY.
UPDATE
HAVE REMOVED POPS THROUGH EARLY AFTERNOON AS RADAR IS PRESENTLY
QUIET OVER OUR AREA AND UPSTREAM. OTHERWISE, EXPECTATIONS FOR
THE DAY REMAIN UNCHANGED.
NEAR TERM /THROUGH TONIGHT/
WV IMAGERY SHOWS MID LEVEL TROUGH OVER OH VALLEY. LEAD
SHORTWAVE CROSSING WESTERN TN/KY BUT THIS FEATURE IS PROGGED TO
WEAKEN AS THE DOMINANT FEATURE OF THE TROUGH BECOMES THE JET
DIVING ACROSS MN WHILE THE ENTIRE SETUP DRIVES A SURFACE COLD
FRONT TOWARDS AND EVENTUALLY THROUGH THE CAROLINAS. AND ALTHOUGH
ANY RAINFALL THAT OCCURS WILL BE INSIGNIFICANT THIS PERIOD,
MODELS HAVE CONSIDERABLY DIFFERING IDEAS AS TO WHERE THE LIGHT
RAIN FALLS, IF ANY. THE HRRR, FOR EXAMPLE BRINGS A SMALL BATCH
OF WHAT LOOKS LIKE A BIT OF PREFRONTAL WAA IN FROM THE SW
WHEREAS THE MAIN OP MODELS LIKE THE WRF AND GFS HAVE AN AREA OF
DYNAMICALLY FORCED SHOWERS THAT COME IN FROM THE WNW, AND LATER.
LEANED A BIT ON THE NBM WHICH ACTUALLY SHOWS BOTH, BUT GIVEN
THE VERY DRY AIR IN FORECAST SOUNDINGS ABOVE 10KFT CAPPED ITS
POPS AT 30 PERCENT. THE AFOREMENTIONED WAA WILL ALLOW ROUGHLY
THE SOUTHERN HALF OF THE CWA TO TOP 60 DEGREES ESPECIALLY WITH
SOME BREAKS IN THE CLOUDS. COLD ADVECTION TONIGHT DRIVES LOWS
INTO THE MID 30S.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
A 500 MILLIBAR TROUGH CENTERED OVER THE EAST COAST WILL MOVE TO THE
EAST WITH NORTHWEST FLOW OVER THE CAROLINAS ESTABLISHED ALOFT. AT
THE SURFACE, A 1038 MILLIBAR HIGH-PRESSURE AREA CENTERED NORTH OF
LAKE SUPERIOR WILL SHIFT TO WESTERN QUEBEC. THIS COLD HIGH PRESSURE
WILL BUILD INTO THE CAROLINAS THIS WEEKEND, WITH THE LOWS DROPPING
INTO THE MID-20S ON SATURDAY AND LOWER 20S (TEENS IN THE COLDER
LOCATIONS) ON SUNDAY NIGHT.
LONG TERM /MONDAY THROUGH THURSDAY/
ON MONDAY, WESTERLY FLOW WILL BE OVERHEAD IN THE MID-LEVELS, AND A
CUTOFF LOW WILL DEVELOP OVER THE PLAINS ON TUESDAY. THIS CUTOFF LOW
WILL BE NEGATIVELY TILTED OVER ARKANSAS ON WEDNESDAY BEFORE LIFTING
INTO THE OHIO VALLEY. THIS WILL PROVIDE SHARP RIDGING OF HEIGHTS
FROM OFF THE SOUTHEAST U.S. COAST INTO THE GREAT LAKES. THE 00 UTC
DETERMINISTIC RUNS OF THE GFS AND ECMWF AGREE WITH THIS EVOLUTION.
AT THE SURFACE, THE HIGH-PRESSURE RIDGE ON THE LEE SIDE OF THE
APPALACHIAN MOUNTAINS WILL STUBBORNLY REMAIN. STILL, IT WILL SLOWLY
GIVE WAY TO THE LOW-PRESSURE AREA MOVING FROM NORTHERN TEXAS TOWARD
THE CAROLINAS. AS THE HIGH PRESSURE SHIFTS OFF THE COAST, THE
SOUTHERLY FLOW WILL DEVELOP TO THE WEST, WITH LOW-LEVEL MOISTURE
(MAINLY BELOW 850 MB) INCREASING THROUGH MID-WEEK. A 20-30% CHANCE
OF SHOWERING IS PROBABLE WITH A WEAK ISENTROPIC LIFT PRESENT.
HIGH TEMPERATURES WILL WARM FROM THE MID TO UPPER 40S ON MONDAY TO
THE UPPER 50S TO LOWER 60S BY THURSDAY. LOW TEMPERATURES SHOW A
SIMILAR TREND, WITH LOWS FROM THE UPPER 20S TO THE LOWER 30S ON
MONDAY NIGHT AND RISING TO THE LOWER TO MIDDLE 40S ON WEDNESDAY
NIGHT.
AVIATION /15Z FRIDAY THROUGH TUESDAY/
CEILINGS TO AVERAGE 1-2KFT EARLY TODAY WITH SOME SHORT-LIVED
VARIABILITY, FOLLOWED BY CLEARING SKIES FROM SW TO NE THIS
AFTERNOON. IN BETWEEN THERE IS A SMALL WINDOW OF OPPORTUNITY FOR
SOME SHOWER DEVELOPMENT AND WHILE THE EXACT LOCATION IS RATHER
UNCERTAIN THEY WILL BE SO LIGHT IN NATURE AS TO BE OF LITTLE
CONSEQUENCE TO AVIATORS.
EXTENDED OUTLOOK...VFR CONDITIONS EXPECTED LATE FRIDAY,
CONTINUING THROUGH THE WEEKEND.
MARINE
THROUGH TONIGHT, A FEW SUBTLE WIND SHIFTS TODAY AS NW FLOW
ASSOC WITH LOW PRESSURE OFF HSE GIVES WAY TO NW AND THEN W WINDS
AS THE LOW EXITS AND COLD FRONT APPROACHES FROM THE NW. THE
LATE AFTERNOON FROPA WILL BRING NW WINDS TONIGHT THAT WILL BE
GUSTING READILY TO 20KT BUT NO HEADLINES ANTICIPATED.
SATURDAY THROUGH TUESDAY NIGHT, A COLD FRONT/LEADING EDGE OF
ARCTIC AIR WILL BE WELL OFFSHORE AT THE START OF THIS FORECAST.
HIGH PRESSURE WILL BUILD TOWARD THE WATERS THROUGH MONDAY. A
COASTAL TROUGH IS EXPECTED TO DEVELOP ON TUESDAY. NORTH WINDS OF
15 TO 20 KNOTS WILL BLOW EARLY SATURDAY MORNING AND SLOWLY
DIMINISH TO THE NORTH-NORTHEAST AT 15 KNOTS BY SUNDAY EVENING.
ON MONDAY, NORTHEAST WINDS OF 15 KNOTS WILL WEAKEN TO 10 KNOTS
BY TUESDAY. SEAS OF 3 TO 5 FEET ON SATURDAY MORNING WILL LEVEL
OUT AT 3 TO 4 FEET THROUGH TUESDAY EVENING.
ILM WATCHES/WARNINGS/ADVISORIES
NC...NONE.
SC...NONE.
MARINE...NONE.
SYNOPSIS...ILM
UPDATE...31
NEAR TERM...MBB
SHORT TERM...RH
LONG TERM...RH
AVIATION...MBB
MARINE...ILM
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