607
FXUS61 KPHI 172335
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
735 PM EDT Fri May 17 2024

.SYNOPSIS...
As low pressure continues to move farther away from our area through
tonight, another area of low pressure slides to our south over the
weekend. High pressure then builds across our area early next week
before shifting to our south. A cold front then moves through
Thursday into Friday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Increasing high/mid clouds overnight as the next system
approaches. Scattered showers are possible for the western areas
overnight. Many of the models have the rains decreasing
overnight. Patchy fog is possible overnight. Lows will drop into
the low/mid 50s for most spots with some upper 50s for metro
Philadelphia. Winds will be light tonight.

On Saturday, a disorganized short wave will move from the upper Ohio
Valley across the Middle Atlantic region. A weak surface low will
accompany the feature. Clouds will have the upper hand much of the
day and scattered to numerous showers will be across the area.
Better chances for rains will be across Delmarva, south NJ and up
into Berks County PA. These areas will be close to the better lift
associated with the low/short wave. It`ll remain cool with the
clouds and rains, so high temperatures will likely only climb into
the low/mid 60s. Winds will be light from the East or Southeast much
of the time.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Surface high pressure extends southward into our area later Saturday
night and Sunday, with most of the energy now confined to the south
of the area which will help to completely end the shower chances
after Saturday evening. Some lingering low-level moisture though and
especially if the clouds clear enough may result in patchy fog
Saturday night into early Sunday. By Sunday afternoon, expect at
least some sunshine to make a return. High temperatures top out into
the 70s for many inland areas, although a lingering onshore flow
will keep it much cooler closer to the coast.

As an upper-level ridge starts to build over the area Monday,
surface high pressure becomes more centered across our region. The
increasing subsidence and drier air should assist in less cloud
cover for much if not all of the region. The air mass will continue
to modify and therefore afternoon high temperatures are forecast into
the 70s again for much of the area. A northeast wind though should
turn east to southeast as a sea breeze becomes more established and
this will yet again keep it much cooler closer to the coast
Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Summary...Above average temperatures and dry to start, followed by
some chances for showers/thunderstorms with a cold front. Some
cooling then possible Friday.

Synoptic Overview...An upper-level ridge is forecast to be across
much of the East Tuesday before it shifts offshore Wednesday. An
upper-level trough tracking eastward from south-central Canada to
the mid-Mississippi Valley will drive surface low pressure well to
our north. A cold front however is forecast to arrive across our
area Thursday into Friday as the upper-level trough mostly glances
the Northeast. The flow aloft then may turn more zonal into Friday,
although a shortwave trough in the Tennessee Valley may make a run
at our area later Friday. The latter is much more uncertain at this
time range.

For Tuesday and Wednesday...Given the presence of upper-level
ridging overhead Tuesday along with high pressure at the surface, a
warmer air mass will be in place. The light winds however should
result in a sea breeze Tuesday afternoon which will then make a run
inland keeping it cooler closer to the coast. This setup is expected
to result in no precipitation and a decent amount of sunshine given
the subsidence. As we go through Wednesday, more of a return flow
should become established as the ridge aloft and also the surface
high shifts offshore. Low-level warm air advection should increase
some with this southerly flow ahead of an upper-level trough which
drives surface low pressure and a cold front. The forward
motion/timing of the cold front is less certain especially as the
main upper-level trough may just glance the Northeast and the
surface low tracks well to our north. It is possible a band or
broken band of showers and thunder makes it into our far western
zones late Wednesday tied to a surface trough. Given the initial
subsidence and favorable setup, temperatures were bumped up some
especially away from the coast.

For Thursday and Friday...The aforementioned upper-level trough
glances our area Thursday however a cold front tied to low pressure
well to our north should move through sometime during this time
frame. There looks to be enough forcing to produce some showers and
instability should be sufficient during the afternoon and evening
Thursday for some possible thunderstorms. The warmth (and more
humid) may peak Thursday ahead of the cold front with widespread low
to mid 80s for highs, although probably cooler closest to the coast
due to a southerly wind. As of now, the cold front should be
offshore to start Friday with some cooling in its wake. The cooling
does not look all that significant at this time given the weakness
of the upper-level trough and it tending to just glance our
region.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Tonight...VFR to start in many areas. Later tonight, increasing
clouds will develop over the area with a lowering of CIGS into
lower-end MVFR probable after midnight and towards early
Saturday morning. Light E/NE winds early then mostly SE
overnight. Winds speeds mostly 5 knots or less overnight.
Low/medium confid.

Saturday...Solid MVFR, with moments of IFR possible, much of
the day with showers across most areas into the late afternoon.
Light SE winds. Low/medium confid.

Outlook...

Saturday night and Sunday...Areas of MVFR conditions possible with
lingering showers Saturday evening, then VFR overall.

Monday through Wednesday...VFR overall.

&&

.MARINE...
Fair tonight and then showers for Saturday. There is a better
chance for showers across the southern NJ and Delaware waters as
well as Delaware Bay. SCA is not expected through Saturday.

Outlook...

Saturday night through Wednesday...The conditions are anticipated to
be below Small Craft Advisory criteria.

.Rip Currents...

Winds are generally around 5 to 10 mph, and the rip current risk
is no longer HIGH. Will therefore cancel the HIGH risk for rip
currents that was set to expire at 8 pm.

A prolonged period of N to NE winds at 5 to 10 mph through the
weekend along with 3 to 4 ft seas will result in a MODERATE risk
for the development of dangerous and life threatening rip
currents on Saturday and Sunday.

&&

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

&&

$$

SYNOPSIS...Gorse
NEAR TERM...MJL/OHara
SHORT TERM...Gorse/RCM
LONG TERM...Gorse
AVIATION...Gorse/MJL/OHara
MARINE...Gorse/MPS/OHara