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000
FXUS61 KPHI 201629
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1229 PM EDT Tue Jun 20 2017

.SYNOPSIS...
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A frontal boundary will stall off the mid- Atlantic coast this
afternoon. Weak high pressure will gradually build into the
region through Thursday. Summertime southwest flow around the
Bermuda High looks to be re- establish by the end of the week.
Another frontal system may bring showers to the forecast area
over the weekend.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

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Partly sunny skies expected this afternoon as some cumulus
clouds develop in the westerly flow over the region in the wake
of the cold frontal passage early this morning. Wind gusts in
the 15 to 25 mph range can also be expected through the
afternoon hours...decreasing late. Maximum temperatures will
still favor the 80s today.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
High and mid level clouds over the ocean may build back over
parts of northeastern Maryland, Delaware and southern New Jersey
tonight. Also, light showers may brush southern Delaware and
the adjacent coastal waters late tonight. The sky is forecast to
be mostly clear over eastern Pennsylvania and central and
northern New Jersey.

Another mid level short wave trough is forecast to approach our
region from the west late tonight. A associated surface trough
is expected to arrive around daybreak.

A light southwest wind is anticipated for most of tonight. Low
temperatures should be in the middle and upper 50s in the
Poconos and far northern New Jersey, and in the 60s elsewhere in
our forecast area.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The overall pattern through the extended period will remain
rather summerlike with temperatures at or a few degrees above
normal. With this pattern it is difficult to completely rule out
precip on any given day, but as of now it appears lower mid-
week PoPs will increase towards the weekend as a frontal system
approaches.

An upper trof axis over the eastern US at mid-week will move
offshore but will be followed by a couple of additional
shortwave trofs over the weekend and perhaps early next week.
There is disagreement in the models timing of these features and
associated surface frontal systems, but a blend of models was
used for the gridded forecasts.

For Wednesday the forecast has low chance PoPs for southern DE
and vicinity in the morning due to proximity with a lingering
q-stationary frontal boundary. Then a weak upper impulse is fcst
to move through the upper trof in the aftn which could trigger
a few showers/t-storms in the afternoon, north/west of PHL.
Otherwise most areas should remain dry.

Thursday also looks dry with some weak ridging aloft. Lower
level warm advection and warmer 850 mb temp should result in
afternoon max temps in the mid to upper 80s. The forecast for
Friday and Saturday includes a good chance for showers and
t-storms. Higher PoPs will shift from N/W of PHL on Friday to
S/E on Saturday as a frontal boundary slowly works its way south
across the forecast area. If moisture from the tropical system
now over the GlfMex becomes entrained into the frontal zone
there could be some heavy rainfall, but this is very uncertain
at this time.

The forecast beyond Saturday depends on whether one or more
frontal boundaries can push past the mid-Atlantic region or
whether they stall out nearby.

&&

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

Expect VFR conditions today with a westerly wind with speeds
increasing to 10 to 15 knots along with gusts near 20 knots. The
wind is expected to diminish back below 10 knots for tonight
and the direction is forecast to change gradually to the
southwest.

OUTLOOK...

Wednesday and Thursday...VFR conditions expected. Southwest to
west winds 10 kt or less.

Friday and Saturday...mostly VFR conditions but occasional MVFR
or lower in scattered mainly afternoon showers and
thunderstorms. South to southwest winds 10 to 15 kt.

&&

.MARINE...
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The wind is forecast to favor the southwest for today and
tonight around 10 to 15 knots as the cold front inches further
eastward before stalling.

Wave heights have fallen below 5 feet south of Cape May, so the
SCA from Cape May through Fenwick Island has been cancelled. The
SCA along the NJ coast will continue for a few more hours, but
will probably be cancelled with the mid-afternoon update.

OUTLOOK...

Wednesday and Thursday... Winds and seas should remain below
SCA criteria.

Friday and Saturday...Winds and/or seas could approach SCA
thresholds in stronger southwest flow.

RIP CURRENTS...

We will continue with the moderate risk for the development of
dangerous rip currents for today along the coast of Delaware and
New Jersey. We are expecting a 7 second southerly wind swell on
top of a long period (around 13 to 15 second) southeasterly
ground swell.

Similar conditions are anticipated for Wednesday and perhaps
into Thursday when we should begin to lose the long period
southeasterly swell.
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&&

.EQUIPMENT...
NWS NWR broadcast of the surf zone forecast problems continue
here at NWS PHI. Hope to resolve today.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ450>453.
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&&

$$
Synopsis...AMC
Near Term...Iovino/Miketta
Short Term...Iovino
Long Term...AMC
Aviation...AMC/Iovino/Miketta
Marine...AMC/Iovino/Miketta
Equipment...