988
FXUS61 KPHI 230904
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
404 AM EST SAT JAN 23 2021
SYNOPSIS
HIGH PRESSURE CENTERED IN NORTHERN ILLINOIS THIS MORNING WILL
DRIFT SOUTHEASTWARD AND IT SHOULD PASS OFF THE NORTH CAROLINA
COAST ON SUNDAY EVENING. WEAKENING LOW PRESSURE IS FORECAST TO
MOVE FROM MISSOURI ON MONDAY TO THE UPPER OHIO RIVER VALLEY ON
TUESDAY, AS A SECONDARY LOW SLIDES OFF THE MIDDLE ATLANTIC
COAST. HIGH PRESSURE IS EXPECTED TO NUDGE INTO OUR REGION FROM
THE NORTH ON WEDNESDAY. ANOTHER LOW IS ANTICIPATED TO PASS OFF
THE NORTH CAROLINA COAST ON THURSDAY BEFORE MOVING FARTHER OUT
TO SEA. HIGH PRESSURE APPROACHING FROM THE WEST IS EXPECTED TO
BUILD ACROSS OUR REGION ON FRIDAY AND SATURDAY.
NEAR TERM /THROUGH TONIGHT/
A COLD DAY IS IN STORE ALONG WITH A GUSTY WIND. A NORTHWESTERLY
FLOW REGIME FROM THE MIDWEST TO THE NORTHEAST AND MID-ATLANTIC
REGIONS IS FORECAST TO AMPLIFY SOME IN THE EAST TODAY. THIS IS
DUE TO STRONG SHORT WAVE ENERGY CARVING OUT MORE OF A TROUGH
TODAY IN THE NORTHEAST TO MID-ATLANTIC. MEANWHILE, SURFACE LOW
PRESSURE IS FORECAST TO BE CENTERED IN THE CANADIAN MARITIMES
WITH SURFACE HIGH PRESSURE BUILDING EAST FROM THE MIDWEST AND
OHIO VALLEY.
OUR REGION WILL BE BETWEEN THE TWO AFOREMENTIONED SURFACE
SYSTEMS RESULTING IN A TIGHT PRESSURE GRADIENT. COLD AIR
ADVECTION INCREASED LAST NIGHT AND THAT CONTINUES FOR MUCH OF
TODAY, RESULTING IN HIGH TEMPERATURES IN THE 20'S AND 30'S.
THERE WILL BE A NOTABLE BREEZE MAKING IT FEEL EVEN COLDER, WITH
WIND CHILL VALUES IN THE TEENS TO LOWER 20S FOR THE BALANCE OF
THE DAY (0-5F IN THE HIGHER TERRAIN OF THE POCONOS). THE
FORECAST SOUNDINGS INDICATE A FAVORABLE SETUP FOR DEEPER MIXING
ESPECIALLY BY MIDDAY WITH WINDS OF 30-40 MPH AVAILABLE TO MIX
DOWN. THE STRONGEST WINDS MAY OCCUR FROM MID-MORNING THROUGH
MID-AFTERNOON, THEN SOME RELAXING OF THE PRESSURE GRADIENT AND
THE COLD AIR ADVECTION WEAKENING SOME WILL RESULT IN LESS MIXING
LATE IN THE AFTERNOON AND EARLY EVENING. AS A RESULT, THE WINDS
SHOULD SETTLE AS WE START THIS EVENING.
NORTHWEST FLOW TODAY WILL DIRECT LAKE EFFECT SNOW BANDS TOWARD
ESPECIALLY NORTHEASTERN PENNSYLVANIA, HOWEVER THE ADVECTION OF
MUCH DRIER AIR AND A GRADUAL LOWERING INVERSION SHOULD LIMIT THE
SOUTHEASTWARD EXTENT OF THE BANDS (A FEW FLURRIES STILL AROUND
VERY EARLY THIS MORNING IN PARTS OF THE AREA). ANY SNOW SHOWERS
OR FLURRIES PARTICULARLY IN THE POCONO REGION MAY END UP BEING
CONFINED TO THIS MORNING AS A RESULT.
FOR TONIGHT, SURFACE HIGH PRESSURE BUILDS CLOSER HOWEVER IT IS
NOT FORECAST TO SETTLE RIGHT OVER OUR REGION AND THEREFORE WE
REMAIN IN AN AREA OF AN ESTABLISHED PRESSURE GRADIENT. DESPITE
THIS, AT LEAST SOME DECOUPLE OF THE WINDS SHOULD OCCUR TONIGHT
ESPECIALLY OUTSIDE OF THE HIGHER TERRAIN AS AN INVERSION
STRENGTHENS SOME. THE EXTENT OF THE WINDS WILL HAVE AN IMPACT ON
TEMPERATURE TRENDS TONIGHT, BUT EITHER WAY MANY AREAS ARE
FORECAST TO DROP INTO THE TEENS TONIGHT (WIND CHILLS STILL IN
PLAY WITH SOME WIND CONTINUING).
SHORT TERM /SUNDAY THROUGH TUESDAY/
SURFACE HIGH PRESSURE SLIDING TO OUR SOUTHWEST AND SOUTH WILL
LIKELY BRING COLD DRY WEATHER TO OUR REGION FOR SUNDAY AND
SUNDAY NIGHT. DEVELOPING WARM ADVECTION ALOFT IS EXPECTED TO
BRING AND INCREASE IN MID AND HIGH LEVEL CLOUDS FROM SUNDAY
AFTERNOON INTO SUNDAY EVENING.
AN INITIAL MID LEVEL SHORT WAVE IS FORECAST TO BE EJECTED OUT
OF THE SOUTHWESTERN STATES OVER THE WEEKEND. IT SHOULD REACH THE
CENTRAL GREAT PLAINS ON MONDAY AND THE EASTERN GREAT LAKES LATE
ON TUESDAY. A WEAKENING SURFACE LOW IS EXPECTED TO PRECEDE THE
FEATURE WITH A SECONDARY LOW DEVELOPING IN THE VIRGINIA AND
NORTH CAROLINA VICINITY BEFORE SLIDING OFF THE COAST AND OUT TO
SEA ON MONDAY NIGHT AND TUESDAY.
PRECIPITATION IN ADVANCE OF THE COMPLEX SYSTEM SHOULD BEGIN TO
SPREAD INTO OUR REGION FROM THE SOUTHWEST ON MONDAY AFTERNOON.
THE PRECIPITATION WILL LIKELY CONTINUE INTO MONDAY NIGHT BEFORE
GRADUALLY LOSING SUPPORT ALOFT ON TUESDAY AND AND SLOWLY
DISSIPATING.
THE FORECAST TEMPERATURE PROFILES CONTINUE TO SUGGEST MOSTLY
SNOW FROM THE INTERSTATE 78 CORRIDOR NORTHWARD, MAINLY RAIN FOR
THE DELMARVA SOUTH OF THE CANAL AND FAR SOUTHERN NEW JERSEY, AND
A WINTRY MIX FOR AREAS BETWEEN THE TWO.
THE SYSTEM IS NOT ANTICIPATED TO HAVE A GREAT DEAL OF MOISTURE
ASSOCIATED WITH IT, LIMITING THE SNOW AND SLEET ACCUMULATIONS.
IT APPEARS AS THOUGH MOST LOCATIONS IN EASTERN PENNSYLVANIA, NEW
JERSEY AND NORTHERN DELAWARE THAT RECEIVE SNOW WILL FALL IN THE
1 TO 3 INCH RANGE.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
A NORTHERLY WIND IS EXPECTED TO BRING AN END TO ANY LINGERING
PRECIPITATION ON TUESDAY NIGHT, WITH DRY WEATHER AND SEASONABLE
TEMPERATURES FOR WEDNESDAY.
THERE REMAINS A FAIR AMOUNT OF VARIABILITY IN THE WAY THAT THE
DIFFERENT GUIDANCE SOLUTIONS ARE HANDLING THE MAIN MID LEVEL
TROUGH COMING OUT OF THE SOUTHWESTERN STATES ON TUESDAY. THIS
CONTINUES TO HAVE IMPLICATIONS ON THE EVENTUAL STRENGTH AND
TRACK OF ANOTHER SURFACE LOW THAT IS FORECAST TO PASS OFF THE
NORTH CAROLINA COAST ON THURSDAY. WE WILL KEEP THE MENTION OF A
CHANCE OF WINTRY PRECIPITATION FOR EASTERN MARYLAND, DELAWARE
AND SOUTHERN NEW JERSEY AT THAT TIME. DEPENDING ON MODEL TRENDS
OVER THE COMING DAYS, WE MAY NEED TO EXPAND THE FORECAST OF
PRECIPITATION A BIT FARTHER TO THE NORTH.
ONCE THURSDAY'S SYSTEM MOVES OUT TO SEA, IT APPEARS AS THOUGH
HIGH PRESSURE WILL BUILD INTO OUR REGION FROM THE WEST FOR
FRIDAY AND SATURDAY.
AVIATION /09Z SATURDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR WITH A CEILING BETWEEN 4000-6000 FEET THROUGH AT
LEAST THIS MORNING, THEN CLOUDS SHOULD DISSIPATE FROM SOUTHEAST
TO NORTHWEST. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS (STRONGEST WINDS SHOULD BE IN THE 14-21Z TIME FRAME).
MODERATE CONFIDENCE.
TONIGHT...VFR. NORTHWEST WINDS DIMINISHING TO AROUND 10 KNOTS
IN THE EVENING. HIGH CONFIDENCE.
OUTLOOK...
SUNDAY...VFR. NORTHWEST WIND 10 TO 15 KNOTS WITH GUSTS AROUND
20 KNOTS. HIGH CONFIDENCE.
MONDAY...MAINLY VFR. LIGHT WINTRY PRECIPITATION MAY SPREAD INTO
OUR REGION FROM THE SOUTHWEST DURING THE AFTERNOON. CONDITIONS
SHOULD DETERIORATE FOR MONDAY EVENING AND MONDAY NIGHT IN SNOW.
THE SNOW MAY MIX WITH SLEET AND RAIN AT KILG, KMIV AND KACY.
NORTH TO EAST WIND 5 TO 10 KNOTS. LOW TO MEDIUM CONFIDENCE.
TUESDAY...MVFR AND IFR CONDITIONS IN SNOW AROUND KRDG AND KABE,
A WINTRY MIX OF PRECIPITATION AT KTTN, KPNE AND KPHL, AND
MAINLY RAIN AROUND KILG, KMIV AND KACY. NORTHEAST WIND 5 TO 10
KNOTS. LOW TO MEDIUM CONFIDENCE.
WEDNESDAY...MAINLY VFR. NORTH WIND 5 TO 10 KNOTS. MEDIUM
CONFIDENCE.
MARINE
GALE WARNING INTO THIS EVENING FOR ALL ZONES. THROUGH TONIGHT,
STRONG NORTHWEST FLOW WILL RESULT IN SURFACE GUSTS TO GALE FORCE
BEFORE DIMINISHING SOME LATER THIS EVENING FROM SOUTH TO NORTH.
SOME LIGHT FREEZING SPRAY MAY DEVELOP TONIGHT GIVEN THE GUSTY
WINDS AND COLDER AIR TEMPERATURES, HOWEVER SINCE WATER
TEMPERATURES ARE STILL ON THE RELATIVELY MILDER SIDE KEPT ANY
MENTION AS CHANCE FOR NOW.
OUTLOOK...
SUNDAY...NORTHWEST WIND 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30
KNOTS.
MONDAY...NO MARINE HEADLINES ARE ANTICIPATED.
TUESDAY...NORTHEAST WIND 15 TO 20 KNOT WITH GUSTS AROUND 25
KNOTS.
WEDNESDAY...NORTH WIND 10 TO 15 KNOTS WITH GUSTS AROUND 20
KNOTS. WAVES ON OUR OCEAN WATERS MAY REMAIN AROUND 5 FEET.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ430-431-
450>455.
SYNOPSIS...IOVINO
NEAR TERM...GORSE
SHORT TERM...IOVINO
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...GORSE/IOVINO
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