653
FXUS61 KPHI 202017
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
317 PM EST MON JAN 20 2025
SYNOPSIS
ARCTIC HIGH PRESSURE BUILDS INTO THE OHIO VALLEY, THEN EXTENDS
INTO OUR AREA TUESDAY BEFORE SETTLING OVERHEAD LATER WEDNESDAY.
THIS WILL KEEP WELL BELOW NORMAL TEMPERATURES IN PLACE ACROSS
THE REGION THROUGH MUCH OF THIS WEEK. A SYSTEM TRACKS TO OUR
SOUTH AND EAST TUESDAY NIGHT AND WEDNESDAY WITH ANOTHER ONE
THURSDAY NIGHT AND FRIDAY. HIGH PRESSURE SLIDES ACROSS OUR AREA
SATURDAY, THEN A COLD FRONT SHOULD ARRIVE LATER SUNDAY.
NEAR TERM /THROUGH TUESDAY/
BITTER COLD AND WINDY AFTERNOON CONTINUES WITH WIND CHILLS IN
THE TEENS AND SINGLE DIGITS. A FEW LIGHT SNOW SHOWERS CONTINUE
TO FILTER IN ACROSS THE DELMARVA THROUGH THE AFTERNOON, TAPERING
OFF EARLY THIS EVENING. ONLY MINIMAL ACCUMULATIONS ARE EXPECTED
FROM THESE SNOW SHOWERS.
DANGEROUS COLD SETTLES IN TONIGHT WITH TEMPERATURES TAKING A
DIVE INTO THE SINGLE DIGITS FOR MOST. LOWS NEAR OR EVEN BELOW 0
ARE FORECASTED IN LOCATIONS WITH A DECENT SNOWPACK IN PLACE,
MAINLY NORTHWEST NJ, THE POCONO PLATEAU, LEHIGH VALLEY, AND
HIGHER ELEVATIONS ON SOUTHEAST PA. AREAS ALONG THE SOUTHERN
DELMARVA AND COASTAL STRIP WILL "ONLY" GET INTO THE LOW-TEENS
TONIGHT; CERTAINLY NOT MUCH BETTER BY ANY STRETCH OF THE
IMAGINATION. WHILE HIGH PRESSURE DOES BUILD IN FROM THE WSW
HELPING DIMINISH WINDS, A STEADY BREEZE AROUND 5-10 MPH IS STILL
EXPECTED WITH SOME GUSTS AROUND 15 MPH, ESPECIALLY ACROSS THE
HIGHER ELEVATIONS INCLUDING THE POCONO PLATEAU. THIS MAY HELP
KEEP RADIATIONAL COOLING FROM GETTING TOO OUT OF HAND, ALLOWING
SOME MIXING TO TAKE PLACE. BUT IT WILL CERTAINLY MAKE THE WIND
CHILLS OVERNIGHT MUCH WORSE. SOUTH JERSEY AND THE DELMARVA WILL
SEE MINIMUM WIND CHILL VALUES AROUND 0 WHILE AREAS NORTH AND
WEST OF THE I-95 CORRIDOR WILL BE BELOW ZERO. THE POCONO PLATEAU
WILL SEE THE WORST OF IT WITH WIND CHILLS GETTING AS LOW AS -
20 DEGREES. AS A RESULT, CARBON AND MONROE COUNTIES HAVE BEEN
UPGRADED TO AN EXTREME COLD WARNING. A COLD WEATHER ADVISORY
REMAINS IN EFFECT FOR THE REST OF THE REGION.
THE DAYTIME TUESDAY WILL BRING LITTLE RELIEF WITH HIGHS ONLY
REACHING THE TEENS AND LOW-20S, EVEN COLDER THAN MONDAY. A MIX
OF SUN AND CLOUDS TO START, BUT INCREASING HIGH CLOUDS SOUTH TO
NORTH WILL FILTER MUCH OF THE SUN WE MAY SEE IN THE AFTERNOON.
WINDS, AT LEAST, WILL BE A BIT LIGHTER AROUND 5-10 MPH FROM THE
WEST.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
BITTERLY COLD CONDITIONS CONTINUING ACROSS THE REGION. COLD
WEATHER HAZARDS REMAIN IN EFFECT THROUGH WEDNESDAY MORNING.
ARCTIC AIR FIRMLY ENTRECHED ACROSS THE REGION THROUGH WEDNESDAY
NIGHT. WHILE THE WIND WILL DIMINISH SOME TUESDAY NIGHT, A
BREEZE IS EXPECTED TO CONTINUE WITH BITTER COLD CONTINUING AS
LOWS RANGE FROM NEAR TO BELOW ZERO DEGREES NEAR AND NORTH OF
I-78 AND IN THE SINGLE DIGITS ELSEWHERE (WIND CHILLS DROPPING TO
ZERO AND BELOW ZERO). FOR WEDNESDAY, HIGHS REACH THE TEENS TO
NEAR 20 DEGREES FOR MOST AND WINDS ARE GENERALLY AROUND 10 MPH
WHICH LEADS TO WIND CHILLS BELOW ZERO FOR ALL AREAS TO START
WEDNESDAY MORNING. GIVEN THE EXTENDED STRETCH OF BITTERLY COLD
CONDITIONS (CUMULATIVE IMPACTS) AND THAT TUESDAY MORNING,
TUESDAY NIGHT AND WEDNESDAY MORNING HIT THE CRITERIA FOR MANY
AREAS, THE COLD WEATHER ADVISORY WILL REMAIN IN EFFECT FOR THE
ENTIRE AREA THROUGH NOON ON WEDNESDAY (WARNING FOR THE SOUTHERN
POCONOS).
AS FOR THE WEATHER FEATURES DURING THIS TIME PERIOD, WE HAVE AN
ARCTIC HIGH PRESSURE SYSTEM BUILDING IN THROUGH TUESDAY.
MEANWHILE, AT THE UPPER-LEVELS, A TROUGH MOVES INTO THE REGION
FROM TUESDAY INTO WEDNESDAY MORNING. NOW THIS TROUGH WILL MAKE
THINGS A LITTLE INTERESTING BECAUSE THERE IS A PIECE OF ENERGY
ROTATING THROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING. AT THE
SURFACE, THERE IS A LOW PRESSURE SYSTEM WHICH MOST MODELS KEEP
OFFSHORE WITH NO PRECIPITATION REACHING OUR AREA. INCREASED POPS
SLIGHTLY UP INTO THE I-95 CORRIDOR, AS THIS SYSTEM COULD YIELD
SOME FLURRIES ACROSS THE COASTAL PLAIN, ALTHOUGH NO
ACCUMULATIONS ARE ANTICIPATED. HIGH PRESSURE IS THE MAIN WEATHER
FEATURE FOR WEDNESDAY AND KEEPS THINGS QUIET BUT VERY COLD WITH
WEAK UPPER- LEVEL RIDGING.
LONG TERM /THURSDAY THROUGH MONDAY/
TEMPERATURES START TO IMPROVE THURSDAY AND THE WARMING TREND
CONTINUES INTO THE WEEKEND.
AFTER A VERY COLD FIRST HALF OF THE WEEK, TEMPERATURES START TO
IMPROVE IN THE LONG TERM. HIGHS ON THURSDAY ARE IN THE UPPER
TEENS TO UPPER 20S ACROSS THE AREA. FOLLOWING THURSDAY, EACH DAY
BUILDS UPON THE PREVIOUS DAY IN TERMS OF HIGH TEMPERATURES.
FOR THE WEATHER FEATURES, THERE IS STILL HIGH PRESSURE HAVING
ITS INFLUENCE ON OUR REGION. UPPER-LEVEL TROUGHING IS MOVING
INTO THE REGION THURSDAY THROUGH FRIDAY NIGHT AND ANOTHER PIECE
OF ENERGY IS HINTED TO ROTATE THROUGH. ONCE AGAIN, THIS WOULD BE
IN THE FORM OF A LOW PRESSURE SYSTEM. THERE IS STILL A LARGE
AMOUNT OF UNCERTAINTY GIVEN THIS BEING IN THE LONG TERM. MODEL
GUIDANCE SHOWS THE POTENTIAL FOR SOME SNOW TO BRUSH PARTS OF OUR
AREA THURSDAY INTO FRIDAY MORNING. GIVEN THE UNCERTAINTY,
SLIGHT CHANCE TO CHANCE POPS WERE THE EXTENT FOR ANY
PRECIPITATION DURING THAT TIME PERIOD. FOR THE WEEKEND, SATURDAY
LOOKS DRY WITH SOME RAIN/SNOW SHOWERS BY LATER SUNDAY (KEPT ANY
POPS AT SLIGHT CHANCE THROUGH SUNDAY FOR NOW).
AVIATION /20Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
REST OF TODAY (THROUGH 00Z)...PRIMARILY VFR CONDITIONS.
HOWEVER, AREAS OF BLOWING SNOW ARE POSSIBLE NEAR KABE AND KRDG,
WHICH MAY RESULT IN PERIODS OF MVFR VISIBILITY. HAVE LOW
CONFIDENCE ON THE DURATION OR EXTENT OF BLSN, BUT THERE IS
ENOUGH OF A RISK TO INCLUDE A MENTION IN BOTH TAFS. WEST-
NORTHWEST WINDS 10-20 KNOTS WITH GUSTS 20-30 KNOTS. MODERATE
CONFIDENCE OVERALL.
TONIGHT...VFR. WEST/NORTHWEST WINDS GRADUALLY DIMINISHING TO
AROUND 5-10 KT. HIGH CONFIDENCE.
TUESDAY...VFR WITH INCREASING CLOUDS. WEST-NORTHWEST WINDS
10-15 KNOTS. HIGH CONFIDENCE.
OUTLOOK...
TUESDAY NIGHT...MAINLY VFR. LOW CHANCE (10-20%) OF SOME
FLURRIES OVERNIGHT. NORTHWEST WINDS NEAR 5 KNOTS.
WEDNESDAY THROUGH SATURDAY...VFR AND NO SIGNIFICANT WEATHER.
WINDS 10 KTS OR LESS.
MARINE
SMALL CRAFT ADVISORY FOR THE DELAWARE BAY WAS CANCELLED. SMALL
CRAFT ADVISORY REMAINS IN EFFECT FOR THE COASTAL WATERS UNTIL
LATE TONIGHT FOR WIND GUSTS UP TO 25 KTS AND SEAS 3-5 FEET.
A FREEZING SPRAY ADVISORY REMAINS IN EFFECT FOR ALL MARINE
ZONES THROUGH TUESDAY AFTERNOON.
OUTLOOK...
TUESDAY NIGHT AND WEDNESDAY...A PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS ARE POSSIBLE LATER TUESDAY NIGHT AND WEDNESDAY
MORNING. FREEZING SPRAY POSSIBLE AT TIMES.
THURSDAY THROUGH SATURDAY...THE CONDITIONS OVERALL SHOULD BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR PAZ070-071-
102-104-106.
COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR PAZ060>062-
101-103-105.
EXTREME COLD WARNING UNTIL NOON EST WEDNESDAY FOR PAZ054-055.
NJ...COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR NJZ010-
012>027.
COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR NJZ001-
007>009.
DE...COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR DEZ001>004.
MD...COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR MDZ012-015-
019-020.
MARINE...FREEZING SPRAY ADVISORY UNTIL 6 PM EST TUESDAY FOR ANZ430-431-
450>455.
SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ450>455.
SYNOPSIS...GORSE/STAARMANN
NEAR TERM...MJL
SHORT TERM...GORSE/GUZZO/STAARMANN
LONG TERM...GORSE/GUZZO/STAARMANN
AVIATION...MJL/STAARMANN
MARINE...MJL/STAARMANN
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