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075
FXUS61 KPHI 161848
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
248 PM EDT Mon Jun 16 2025

.SYNOPSIS...
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A nearly stationary frontal boundary will hover just south of the
area through tonight. By later Tuesday into Tuesday night the front
will lift northward as a warm front. Bermuda high pressure sets up
offshore Wednesday and Thursday. A regime change occurs towards the
end of the week as a cold front passes through the region Thursday
afternoon and night. High pressure should then generally dominate
for the end of the week through the weekend into early next week
with a building ridge aloft over the east coast through this
period.
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&&

.NEAR TERM /THROUGH TUESDAY/...
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Static and dreary weather pattern persists as rounds of showers,
mist, and drizzle continue this afternoon with the stalled frontal
boundary remaining located over Virginia. RH values in the 0-2 km
layer remain above 90% with PWATs ranging between 1.50-1.75" with
deep warm cloud depths. This will support periods of heavy rainfall
with efficient rain rates despite overall minor accumulation totals.

This will be the story through this evening and Tuesday as well as
an area of low pressure approaches from the west tonight causing the
stalled boundary to lift north as a warm front on Tuesday. The
location of the front will remain nearly stationary tonight however,
but will begin making steady progress on Tuesday, likely reaching
the southernmost portions of our area by Tuesday evening. With this
in mind, we`ll continue to experience several rounds of showers and
mist/drizzle through tonight and perhaps some fog developing as
well, especially near the coast. Lows tonight will range from the
upper 50s to mid 60s areawide.

Tuesday will feature much of the same through the morning hours,
however we should begin to see at least improvement in the afternoon
as the warm front approaches. Skies may feature some brightening
with potentially a few brief breaks of sun. There will be some
energy aloft passing through during the afternoon coinciding
with the approaching warm front so another round of showers and
possibly isolated thunder should occur ahead of the front. Highs
will vary across the region with upper 60s to mid 70s across
northern areas with upper 70s to mid 80s across southern areas.
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&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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The pattern finally starts to shift as we go through the short term
period. For Tuesday night, a warm front lifts through the area along
with a disturbance aloft. This will bring some showers and
thunderstorms by later in the evening into the overnight. Some of
these could produce heavy downpours as PWAT values rise to around 2
inches. Best chances for showers/storms appears to be for areas near
and N/W of the urban corridor. It will be a warm and muggy night
with lows generally in the middle to upper 60s and dew points not
much below these values.

Wednesday we really get into the heat and humidity as the SW flow
kicks in. Mainly cloudy skies to start the day should give way to
some sunshine by afternoon, especially over central and southern
parts of the CWA. Expect highs for most areas getting into the
mid/upper 80s to low 90s with dew points into the 70s. As a result
of this, heat indicies over SE PA, interior southern NJ, and
Delmarva could reach as high as the mid to high 90s. As we get into
Wednesday afternoon, there looks to be a surface trough setting up
over the area and this should help trigger some showers and
potentially severe thunderstorms. In fact Wednesday`s threat for
severe weather appears to be increasing relative to previous
forecasts as ML CAPES look to reach 1500-2500 j/kg with modest
shear. Damaging winds look to be the biggest threat.

Storms diminish Wednesday evening with an even warmer, muggier night
on tap for Wednesday night compared to Tuesday night. By Thursday
morning, lows will only be down into the mid upper 60s north and low
to mid 70s over SE PA, central/southern NJ, and Delmarva.

Thursday still looks to be the day featuring an even greater severe
weather threat. As we go through the Wednesday night and Thursday
timeframe, low pressure will be tracking eastward through Ontario
and Quebec and this will help continue to pump in hot, humid air
into the area with a continuing SW flow. This SW flow and associated
heat will also be aided by the Bermuda high setting up over the
western Atlantic. Highs Thursday look to be similar to if not a
couple degrees warmer than Wednesday so heat impacts could start to
build, especially since there will be so little relief at night.
Once again, max heat indicies should be in the mid to upper 90s over
portions of SE PA, central/southern NJ and Delmarva. Regarding the
severe weather threat, a cold front will be approaching in the
afternoon and then moving through in the evening. ML CAPE values
look to top out around 2000+ j/kg with deep layer shear of 30-40+
knots. While this is still a few days out this set up could favor a
potentially higher end severe weather event with numerous instances
of damaging winds. Again confidence regarding these details is still
not high as it will depend on the timing of the front and the
strength of a disturbance aloft, etc. Right now, timing for storms
and associated severe weather looks to be afternoon / evening.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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For Thursday night, showers/storms diminish by the overnight period
as the cold front moves offshore and this will be followed by high
pressure building in to our south on Friday. Friday will be cooler
and less humid with highs generally in the 80s under partly to
mostly sunny skies. An upper level disturbance moving through late
day could trigger a few storms in the Poconos but otherwise it
should be dry.

As we head into the weekend and early next week, it should be
rainfree much of this time as an upper level ridge builds over the
east. Saturday will still feature highs in the 80s and humidity
levels that are not too high but by Sunday and Monday high heat and
humidity looks to really build as the upper level ridge strengthens.
By next Monday, highs could be into the mid 90s for many areas with
heat indicies over 100! While most of the Saturday through Monday
period should be rain free, there may be a weak impulse that moves
through along a warm front bringing a few showers/storms Saturday
night into early Sunday. We have POPs generally around 20 to 30
percent for this time period but otherwise POPs are below 15
percent.
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&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of Today...IFR conditions to continue with little improvements.
Periods of rain showers, mist and drizzle expected. East-northeast
winds around 7-12 kt. Moderate confidence.

Tonight...IFR conditions expected early with LIFR conditions
developing at all terminals generally between 03-05Z. In addition to
mist, patchy fog is possible as well, but confidence is lower in
this occurrence, so left out of the TAFs for now. East-northeast
winds around 5 kt becoming LGT/VRB at times. Low-moderate confidence
overall.

Tuesday...LIFR/IFR conditions expected through the morning,
potentially lifting to IFR/MVFR in the afternoon. Periods of mist
expected early, with a slight chance of showers during the
afternoon. Northeast winds will gradually become south-southeast
around 3-8 kt. Low-moderate confidence.

Outlook...

Tuesday night...Sub-VFR CIGs/VSBYs in fog, stratus, and scattered
SHRA.

Wednesday through Wednesday night...Becoming mainly VFR by midday
Wednesday. Scattered TSRA possible with brief sub-VFR conditions,
mainly in the afternoon and evening.

Thursday through Thursday night...VFR in the morning. Scattered
afternoon and evening SHRA/TSRA with relatively brief sub-VFR
conditions.

Friday through Saturday...VFR.
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&&

.MARINE...
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No marine headlines are in effect through Tuesday. East-northeast
winds around 12-17 kt with gusts up to 20 kt today will diminish
to around 10-15 kt tonight. Winds will gradually turn from northeast
to southeast on Tuesday around 5-10 kt. Seas of 3-4 feet. Periods
of showers, drizzle, and mist to continue through tonight.

Outlook...

Tuesday night through Saturday...Sub-SCA conditions expected through
the week with max wind gusts below 20 kt and seas in the 2 to 4 ft
range. VSBY restrictions in showers and fog through Tuesday night.
Afternoon and evening showers and thunderstorms possible on
Wednesday and Thursday with locally stronger winds and higher
waves.
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&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Deal/Fitzsimmons/MPS
NEAR TERM...DeSilva
SHORT TERM...Fitzsimmons
LONG TERM...Fitzsimmons
AVIATION...DeSilva/Fitzsimmons
MARINE...DeSilva/Fitzsimmons