352
FXUS61 KPHI 162100
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
400 PM EST MON DEC 16 2024
SYNOPSIS
THE NEXT LOW PRESSURE SYSTEM MOVES IN LATER THIS EVENING AND
CONTINUES INTO EARLY TUESDAY. HIGH PRESSURE LOOKS TO BUILD IN
BRIEFLY LATER TUESDAY BEFORE ANOTHER LOW PRESSURE SYSTEM AFFECTS
OUR REGION LATER WEDNESDAY. HIGH PRESSURE MOVES IN ON THURSDAY,
WITH A CLIPPER SYSTEM POTENTIALLY MOVING INTO THE AREA TO CLOSE
OUT THE WEEK. MUCH COLDER WEATHER ARRIVES BY THE END OF THE
WEEKEND, POTENTIALLY CONTINUING INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TUESDAY/
A DREARY AND DRIZZLY START TO THE WEEK IS ONGOING. A WARM FRONT IS
TRYING TO PUSH NORTHWARD, BUT STRUGGLING WITH SOME PESKY COLD AIR
VIA COLD AIR DAMMING REMAINING IN PLACE. SOUTHWESTERLY FLOW WILL
STRENGTHEN THOUGH, PUSHING THE WARM FRONT THROUGH THE NORTHERN AREAS
AS THE EVENING GOES ON. UNTIL THAT HAPPENS THOUGH, PATCHY FOG, SOME
OF WHICH COULD BE DENSE, REMAINS POSSIBLE NORTH AND WEST OF THE
PHILADELPHIA METRO. ISSUED A SPECIAL WEATHER STATEMENT THROUGH THIS
EVENING FOR CARBON AND MONROE COUNTY AS DENSE FOG WILL MAINLY BE AT
HIGHER ELEVATIONS.
FOR TONIGHT, A WEAK AREA OF LOW PRESSURE MOVES BY TO THE NORTH.
PRECIPITATION BEGINS TO OVERSPREAD THE AREA THIS EVENING AS
ISENTROPIC FORCING INCREASES. A SOUTHWESTERLY LOW-LEVEL JET WILL
ALSO ENHANCE RAINFALL, WITH PERIODS OF RAIN EXPECTED THROUGH THE
OVERNIGHT HOURS. THE INCOMING SYSTEM WILL BE ON THE FASTER SIDE,
WITH RAINFALL AMOUNTS ONLY GETTING INTO THE 0.1"-0.3" INCH RANGE.
LOCALLY HIGHER AMOUNTS ARE POSSIBLE, BUT NOTHING MORE THAN A HALF
INCH. WITH THE WARM FRONT MOVING THROUGH THIS EVENING, AND WARM AIR
ADVECTION STRENGTHENING, TEMPERATURES WILL ACTUALLY RISE OVERNIGHT,
GETTING INTO THE UPPER 40S/LOW 50S.
RAIN MOVES OUT BY DAYBREAK, THOUGH THE COLD FRONT AND ENSUING COLD-
AIR ADVECTION WILL LAG BEHIND. THIS WILL RESULT IN A PRETTY NICE DAY
OVERALL. TEMPERATURES WILL CLIMB INTO THE MID TO UPPER 50S/LOW 60S
WITH SKIES CLEARING OUT AS THE DAY GOES ON.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
A MORE SEASONABLE AND CERTAINLY DRY NIGHT IS ON TAP FOR TUESDAY
NIGHT WITH WEAK HIGH PRESSURE IN CONTROL. LOWS WILL BE ABOUT 10
DEGREES BELOW THOSE EXPECTED TONIGHT, MOSTLY IN THE 30S, WHICH
IS STILL A LITTLE ON THE PLUS SIDE OF NORMAL, BUT NOT NEARLY AS
MUCH AS IT WILL BE TONIGHT.
NEXT LOW PRESSURE APPROACHES FROM THE SOUTHWEST ON WEDNESDAY, SO
WHILE IT SHOULD START OUT DRY WITH A BIT OF SUN, CLOUDS INCREASE
AS THE DAY WEARS ON WITH RAIN LIKELY ARRIVING IN THE AFTERNOON.
GUIDANCE HAS WAVERED ON THIS A BIT, WITH SOME GUIDANCE LIKE THE
LATEST GFS HOLDING OFF ON THE RAIN FOR THE I-95 CORRIDOR ON
SOUTH AND EAST UNTIL EVENING, BUT IT STILL LOOKS LIKELY TO RAIN
AT SOME POINT LATER WEDNESDAY INTO WEDNESDAY NIGHT. HIGHS WILL
BE ABOUT 10 DEGREES BELOW TUESDAY'S HIGHS, UPPER 40S TO LOW 50S
FOR THE MOST PART, WHICH IS STILL ABOVE NORMAL, BUT NEARLY AS
FAR ABOVE AS TUESDAY.
THE LOW PRESSURE PULLS EAST OF THE REGION OVERNIGHT WEDNESDAY,
WITH PERHAPS A LITTLE SNOW IN THE POCONOS ON THE TAIL END, BUT
OVERALL, A MOSTLY NON-WINTRY SYSTEM. IN FACT, THERE ISN'T AN
IMMEDIATE COLD PUSH BEHIND IT, SO LOWS MOSTLY STAY ABOVE
FREEZING EXCEPT IN THE POCONOS. BY DAYBREAK THURSDAY, THE AREA
SHOULD BE DRY ONCE AGAIN AS HIGH PRESSURE BEGINS TO BUILD IN
WITH COLDER AIR FOLLOWING BEHIND THE DEPARTING LOW. HIGHS MAINLY
IN THE 40S ARE EXPECTED.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
COLDER AIR CONTINUES TO MOVE IN THROUGH THE LONG TERM AS HIGH
PRESSURE REMAINS LARGELY IN CONTROL.
THE EXCEPTION BEING A POTENTIAL CLIPPER SYSTEM SWINGING BY ON
FRIDAY INTO FRIDAY NIGHT. HAVE CONTINUED TO HOLD ONTO SLIGHT
CHANCE TO CHANCE POPS (MAINLY 20-30%) BUT THE LATEST
OPERATIONAL MODELS HAVE CONTINUED THE NOTABLY DRIER TREND AS
THE LOW PRESSURE MOSTLY FIZZLES AND STAYS A BIT FURTHER NORTH.
THUS, A CHANCE OF RAIN AND SNOW, BUT ODDS RIGHT NOW APPEAR TO
CONTINUE TO BE DIMINISHING THAT THERE WILL BE ANY IMPACT FROM
THIS SYSTEM. HIGHS WILL DROP A FEW DEGREES, BUT STILL NOT FAR
FROM NORMAL.
THAT PART CHANGES AS WE HEAD INTO THE WEEKEND, AND ANOTHER
STRONG CANADIAN HIGH PRESSURE BUILDS SOUTHWARD ACROSS OUR
REGION. THIS ONE MAY BE ACCOMPANIED BY THE COLDEST AIR SINCE
LAST JANUARY, RIVALING LAST WINTER'S COLDEST DAYS, WITH HIGHS BY
SUNDAY POTENTIALLY STAYING IN THE 20S AND LOWS IN THE SINGLE
DIGITS AND TEENS. THE LACK OF SNOW COVER LIKELY KEEPS THINGS A
LITTLE MORE MODERATE, BUT EITHER WAY, IT COULD BE QUITE A SHOCK
TO THE SYSTEM. SO, IF YOU LIKE REALLY COLD AND DRY WEATHER,
SUNDAY IS STARTING TO LOOK LIKE YOUR FAVORITE DAY OF THE
FORECAST. TEMPERATURES MAY BEGIN TO MODERATE SLIGHTLY INTO
MONDAY, AS THE CENTER OF THE HIGH SHIFTS EASTWARD, BUT DRY
CONDITIONS LOOK TO CONTINUE.
AVIATION /20Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
REST OF TODAY...PRIMARILY IFR/LIFR CIGS, THOUGH BRIEF IMPROVEMENTS
TO MVFR POSSIBLE, MAINLY AT THE SOUTH JERSEY TERMINALS. IMPROVEMENTS
TO VFR VSBYS LIKELY AS A WARM FRONT MOVES THROUGH FOR
KPHL/KILG/KMIV/KPNE/KACY. WINDS SOUTHERLY AROUND 5-10 KT. MODERATE
CONFIDENCE IN TIMING AND EXTENT OF RESTRICTIONS.
TONIGHT... ANOTHER QUICK MOVING SYSTEM WITH RAINS AND LOW CIGS/VSBYS
EXPECTED. PRIMARILY LIFR/IFR WITH AN IMPROVEMENT TO IFR AT SOME
POINT FOR THE REMAINING SITES WITH LIFR CIGS, PERHAPS AFTER
MIDNIGHT. SOUTHWEST WINDS AROUND 10 KNOTS. LOW-LEVEL WIND SHEAR
ANTICIPATED AT KRDG/KMIV/KACY, WITH SOME BRIEF PERIODS OF LLWS
POSSIBLE AT KTTN AND KABE. HIGH CONFIDENCE IN PREVAILING LIFR/IFR,
LOW CONFIDENCE ON TIMING OF IMPROVEMENT.
TUESDAY...PRIMARILY IFR TO START, BUT CONDITIONS IMPROVING TO VFR BY
THE LATE MORNING/EARLY AFTERNOON. WINDS OUT OF THE SOUTHWEST AROUND
10 KT. MODERATE CONFIDENCE IN TIMING OF IMPROVEMENT.
OUTLOOK...
TUESDAY NIGHT...VFR WITH NO SIGNIFICANT WEATHER.
WEDNESDAY...MAINLY VFR CONDITIONS TO START. INCREASING
RESTRICTIONS, LIKELY TO IFR, BY LATE WEDNESDAY INTO WEDNESDAY
NIGHT AS WIDESPREAD RAIN MOVES INTO THE REGION, CONTINUING
THROUGH MUCH OF WEDNESDAY NIGHT. CONDITIONS BEGIN TO IMPROVE
BACK TOWARDS VFR LATE WEDNESDAY NIGHT AS RAIN CLEARS OUT OF THE
REGION.
THURSDAY...VFR CONDITIONS EXPECTED.
FRIDAY...SUB-VFR CONDITIONS POSSIBLE WITH A CHANCE FOR
RAIN AND/OR SNOW.
SATURDAY...VFR CONDITIONS EXPECTED.
MARINE
A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL OCEAN ZONES UNTIL 1 PM
TOMORROW. THE SCA CONTINUES THROUGH THE REMAINDER OF TUESDAY FOR
COASTAL ZONES NORTH OF GREAT EGG INLET. SEAS OF 4 TO 6 FEET ARE
EXPECTED THOUGH WIND GUSTS OUT OF THE SOUTHWEST COULD GET NEAR 25 KT
AT TIMES TONIGHT.
ON DELAWARE BAY, NO MARINE HEADLINES EXPECTED AS WINDS WILL BE MUCH
LIGHTER, GENERALLY AROUND 10-20 KT OUT OF THE SOUTH/SOUTHWEST
THROUGH TOMORROW MORNING, BECOMING WESTERLY FOR THE AFTERNOON.
OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY...MAINLY SUB-SMALL CRAFT
ADVISORY CONDITIONS BUT WIND GUSTS AROUND 20 KNOTS POSSIBLE
WEDNESDAY.
WEDNESDAY NIGHT THROUGH THURSDAY...SCA CONDITIONS POSSIBLE AS
WINDS INCREASE TO AROUND 25 KNOTS WITH AROUND 5 FOOT SEAS.
THURSDAY NIGHT THROUGH FRIDAY...SUB-SCA CONDITIONS EXPECTED.
SATURDAY...SCA CONDITIONS POSSIBLE.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST TUESDAY FOR ANZ450-451.
SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR ANZ452>455.
SYNOPSIS...AKL/RCM
NEAR TERM...HOEFLICH
SHORT TERM...AKL/RCM
LONG TERM...AKL/RCM
AVIATION...AKL/HOEFLICH
MARINE...AKL/HOEFLICH
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