Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 201331
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
931 AM EDT Sun May 20 2018

.SYNOPSIS...
A warm front will lift across northern New Jersey and the Poconos
this morning. It will be followed by a cold front for the region
this afternoon. Weak high pressure will overspread the area tonight
and lat into Monday. Another slow moving disturbance will move in
Monday night and linger across the area into Wednesday. High
pressure will return to the scene for Thursday and remain into the
beginning of next weekend.
&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
930 AM Update...Very muggy morning as the area is in the warm
sector of a low passing through eastern Canada. Only a few very
isolated showers on radar at the moment across the north,
otherwise not too much happening. Still expect scattered
showers and storms to redevelop by this afternoon as a cold
front moves south across the area so no major changes to the
forecast other than mostly minor changes to Temp, POP, sky, and
weather grids based on latest obs and trends. Of note,
temperatures rising a little faster than expected with breaks in
the cloud cover so temps were adjusted upward.

Previous Discussion...The warm front has lifted across the area
this morning as an area of low pressure continues to move
across eastern Canada. Behind the front, winds have shifted to
the south, and the dense fog has dissipated. Therefore the Dense
Fog Advisory was allowed to expire. There will still remain
some areas of light fog and drizzle for a couple of hours, along
with low clouds and isolated showers.

The low clouds, fog, and drizzle will continue to lift and dissipate
through the morning hours, and later this morning the clouds are
expected to break and some sunshine will likely return across the
area. As the sunshine returns, temperatures will warm across the
area, with everyone reaching several degrees above normal.

With the warming temperatures, instability will develop across the
area. Meanwhile, a cold front will be approaching the area later
this afternoon. A weak short wave/vorticity impulse will slide
across the area later today in conjuction with the cold front. This
will likely lead to a broken line of showers, with a few
thunderstorms possible. While severe weather is not expected with
only marginal instability and shear, some gusty winds and heavy rain
could be possible if any thunderstorms do develop. Even outside of
any convection, winds will likely still gust 15-20 mph today.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
The cold front will be crossing the area early in the evening, with
any showers or thunderstorms weakening and likely dissipating as
they move eastward and offshore. Once the front moves offshore, dry
weather will prevail for the remainder of the night and skies will
begin to clear out some. Winds will become lighter overnight, but
may not go completely calm everywhere. Where winds do lighten up the
most and skies clear out the most, there could be some patchy areas
of fog, especially where any rain falls during the day.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Good weather to begin the long term as weak high pressure will
settle across the region. Skies on Monday will be partly to mostly
sunny and seasonable temperatures are expected with highs mostly
mid/upper 70s.

Another period of unsettled and showery conditions is expected
beginning Monday night and it will likely carry on into the middle
of the week as another upper short wave and a weak surface feature
will affect the area. The arrival of the system will feature showers
moving in from the west overnight Monday and into Tuesday with a few
tstms possible as a warm front brings more moist and milder air to
the region. The chances for showers and afternoon tstms continue
Tuesday and also Wednesday as the system will be slow to move
through the area. A cold front on Wednesday will sweep the system
away allowing more high pressure to arrive for late week.

This late week period should be dry for the most part and the good
weather should carry into Saturday as well. Temperatures will mild
though the period with highs in the upper 70s to low 80s in many
areas. Cooler temps expected close to the shore and over the
southern Poconos. Some of the models are showing another wet pattern
possibly beginning as early as Sunday and into Monday. Too early to
be certain about this though, keep the forecast in mind when making
your Memorial Day plans.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Today...Conditions will vary between VFR, MVFR, and IFR early
this morning now that the warm front has lifted across the
area. Later this morning, low level mixing will continue to
help scour out the low clouds. All TAF sites should make a
return to VFR by late this morning into this afternoon. A cold
front will move across the area later this afternoon, bringing
the chance for scattered showers or an isolated thunderstorm. We
have inserted SHRA into the TAFS, but have kept reduction to
visibilities out at this time as we are not confident on any
reductions to take place. Also, we have left out thunderstorms
from the TAFS as the chance is small for thunder to occur at
this time.

Winds have switched or will switch to the south to southwest behind
the warm front. Winds will be 5-10 knots through today, with gusts
of 15-20 knots likely to develop by this afternoon as daytime mixing
begins to take place. Winds will begin to turn more southwest or
westerly late in the afternoon as the front and showers move across
the area.

Tonight...The cold front will continue to move offshore and any
showers will move offshore as well. Behind the cold front, winds
will become west to northwest. Any locations that have their winds
become light overnight and have clear skies develop could have some
patchy fog develop. This may be more likely for RDG, MIV, and ACY,
especially if any showers move across the area.


Outlook...

Monday...VFR expected.
Monday night thru Tuesday night...Sct showers and tstms with
   sub-VFR conditions possible.
Wednesday...VFR with slgt chc for a shower or tstm.
Wednesday night thru Thursday...VFR expected.

&&

.MARINE...
The Small Craft Advisory on the Atlantic Ocean remain in place
as seas could build back to 5 feet as the southerly flow could
help build seas back to 5 feet. Winds on the ocean could gust
near 25 knots during the day as well as southerly flow increases
ahead of an approaching cold front.

Seas should lower back below 5 feet later this evening and winds
should fall below 25 knots as a cold front moves across the area, so
the advisory will not be extended at this time.

The Dense Fog Advisory on the waters will remain in place at this
time, although with the southerly flow and showers across the
waters, visibilities may improve through the morning into this
afternoon.

Outlook...
Monday...Sub-SCA with fair weather.
Monday night thru Tuesday night...Sub-SCA with scattered
   showers and tstms
Wednesday thru Thursday night...Sub-SCA with fair weather.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until noon EDT today for ANZ450>453.
     Small Craft Advisory until 10 PM EDT this evening for
     ANZ450>455.

&&

$$
Synopsis...O`Hara
Near Term...Fitzsimmons/Robertson
Short Term...Robertson
Long Term...O`Hara
Aviation...Robertson/O`Hara
Marine...Robertson/O`Hara



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