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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 191401
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1001 AM EDT Thu Apr 19 2018

.SYNOPSIS...
An area of low pressure will move out to sea this morning. This
low will then drift into the Canadian Maritimes through Friday,
which will keep northwest flow across the area with a couple of
dry surface troughs moving across the east coast. High pressure
will build into the Mid Atlantic and Northeast Saturday through
Sunday, before moving offshore Monday into Tuesday. A coastal
low may move north along the coast and affect the area during
the middle of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
The surface low pressure system located offshore of the Mid
Atlantic coast this morning will continue to lift to the
northeast through today away from our area. Meanwhile, a couple
of short wave/vorticity impulses will move across the area
as well. We had one round of showers early this morning
associated with the surface low pass through the area. A second
round of showers associated with the first short wave is moving
across Delaware, Maryland, and southern New Jersey now through
the late morning hours. Finally, another round of showers
ongoing to our west associated with the next short wave will
move across the area during the midday and afternoon hours.

Temperatures across most of the area will remain well above
freezing to keep precipitation rain for most places. The
exceptions would be across the higher elevations of the Poconos
of northeast Pennsylvania, as well as portions of extreme
northwest New Jersey. With temperatures in the low to mid 30s in
some places, some snow will likely mix in, or be the predominant
precipitation type. With temperatures being above freezing,
little accumulation is expected, although would not be
surprising to see up to an inch total snow through the day for
the coldest spots where it is mostly snow.

The wind is varying between northeast and northwest this morning
as slight ridging has build in from the north, and a weak trough
has developed in the backside of the low. As the surface low
continues to moves out to sea, the wind is expected to become
northwest everywhere. Wind speeds are forecast to increase
around 15 to 20 mph with gusts approaching 30 mph for this
afternoon in much of our region.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
The intensifying surface low is forecast to pass near Nova
Scotia tonight and high pressure will begin building into our
region from the west. The pressure gradient between the two
systems should maintain a northwest wind around 10 to 15 mph for
much of the night with gusts near 20 mph.

The cloud cover is expected to decrease from south to north
during the course of the night. Scattered light snow showers and
flurries may linger in the Poconos and far northern New Jersey.

Low temperatures are forecast to be mainly in the 30s in the
Lehigh Valley, southeastern Pennsylvania, New Jersey, Delaware
and northeastern Maryland. Readings should drop into the upper
20s in the elevated terrain up north.

The northwest wind is expected to preclude the development of
any frost tonight. However, temperatures may approach the
freezing mark in some location where we have started to issue
frost and freeze products for the season (generally from a
Reading to Trenton to New Brunswick line southward). We are
particularly concerned with parts of Berks County, Chester
County and lower Montgomery County in Pennsylvania. We will take
a look at the next full round of guidance before deciding
whether a Freeze Warning is necessary.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Friday Through Sunday...

High pressure will bring dry, quiet weather with sunshine for
the weekend. To start the period Friday morning, low pressure
will be over Atlantic Canada with an associated upper level
trough extending back into the northeast CONUS. Meanwhile a
broad high will be situated over the midwest. This will keep the
area in a relatively cool, breezy, NW flow for Friday with
highs generally in the low to mid 50s (40s across the southern
Poconos). Early in the day there could still be some lingering
snow/rain showers in the southern Poconos but otherwise
conditions will be dry with considerable cloud cover persisting
in the far north but otherwise partly to mostly sunny skies with
just some afternoon Cu farther south.

High pressure gradually builds eastward into the region through
the course of Friday night and Saturday. The result will be
lighter winds for Saturday and somewhat warmer temperatures as
the airmass modifies. Most area will see highs in the mid to
upper 50s Saturday under abundant sunshine with again, the
southern Poconos being cooler in the 40s. The high will remain
in place over the area right through Sunday bringing more
sunshine with the general moderation in temperatures continuing
as temperatures Sunday should be a few degrees warmer than
Saturday.

Sunday night through Wednesday...

High pressure maintains control over the region bringing
sunshine and seasonable temperatures through at least Monday. By
Tuesday, the GFS indicates that a coastal low over the
southeast US will begin to move north toward the
area...potentially bringing in some light rain to southern areas
by late day. However the ECMWF and GEM Global are slower to
bring this system up and based on the GFS tending to be a little
too progressive in these scenarios, we trimmed back POPs and
keep Tuesday dry at this point. However by Wednesday, system
looks to make its move up the coast as its associated upper
level low opens up at the same time another trough moves in from
the west. So we keep chances of rain in the forecast for
Wednesday. Temperatures look to generally remain around seasonal
through this period.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...TAFS are mostly VFR this morning, with ABE and RDG begin
the exception as they are MVFR. CIGS are expected to lower to
MVFR by this afternoon for the remaining TAF sites as lower
clouds and showers move in from the west. An area of light
showers will move across Maryland, Delaware, and southern New
Jersey this morning, before another area of light showers is
expected to impact all eight of our TAF sites this afternoon.

Winds are varying between northwest and northeast this morning,
but are expected to become northwest everywhere through the
morning hours while increasing to 10 to 20 knots with gusts of
25 to 30 knots this afternoon.

Tonight...VFR with decreasing cloud cover. Northwest wind 10 to
15 knots with gusts of 20 to 25 knots.

OUTLOOK...
Friday-Monday...VFR through the period. Gusty northwest winds
gusting 20-30 knots Friday; 15-20 knots Friday night; and 10-15
knots Saturday.
-- End Changed Discussion --

&&

.MARINE...
Low pressure off our coast early this morning will move farther
out to sea and strengthen. A northwest wind will develop today
and speeds should be on the increase. We continue to expect gale
force gusts on Delaware Bay and on our ocean waters from Great
Egg Inlet, New Jersey to Fenwick Island, Delaware. As a result,
the Gale Warning remains in effect for those areas.

We have a Small Craft Advisory for our waters off the coast
from Great Egg Inlet northward to Sandy Hook. Wind gusts should
be slightly lower there than in areas to the south. We are
anticipating wind gusts to peak around 30 to 32 knots in the
area covered by the Small Craft Advisory.

OUTLOOK...
Friday...Small Craft Advisory conditions likely in the morning
with winds diminishing below SCA levels by afternoon.

Friday night - Monday...Sub Small Craft Advisory conditions
exected.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 4 PM this afternoon to noon EDT
     Friday for ANZ450>452.
     Gale Warning from 2 PM this afternoon to 8 AM EDT Friday for
     ANZ430-431-453>455.

&&

$$
Synopsis...Fitzsimmons
Near Term...Iovino/Robertson
Short Term...Iovino
Long Term...Fitzsimmons
Aviation...Fitzsimmons/Iovino/Robertson
Marine...Fitzsimmons/Iovino