Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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366
FXUS61 KPHI 191036
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
636 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/...
Low pressure was centered off Delaware and southern New Jersey
around 6:30 AM. It is forecast to strengthen today as it moves
northeastward and out to sea. An area of light rain showers
associated with the low was passing across eastern Pennsylvania,
and northern and central New Jersey early this morning. Some
snow flakes and isolated sleet will mix with the rain in the
elevated terrain of the Poconos and far northern New Jersey.
However, little or no snow and sleet accumulation is
anticipated.

There will be a break in the precipitation around mid morning.

A mid level trough located over the eastern Great Lakes and the
Ohio River Valley early this morning will progress eastward.
The feature is expected to pass overhead this afternoon.
Additional rain showers are forecast to accompany the mid level
trough and they will likely affect all of eastern Pennsylvania,
New Jersey and much of the upper Delmarva.

As the surface low moves out to sea, a light north wind is
expected to become northwest. Wind speeds are forecast to
increase around 15 to 20 mph with gusts approaching 30 mph for
this afternoon in much of our region.

High temperatures should range from around 40 in the elevated
terrain of the Poconos to near 60 in southern Delaware.

&&

.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 /12Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR conditions lowering to MVFR this morning at KRDG,
KABE, KTTN and KPNE. Ceilings lowering to MVFR this afternoon at
KPHL and KILG. Ceilings varying between MVFR and VFR at KMIV
and KACY. An area of light showers will move northeast and away
from KRDG, KABE and KTTN early this morning. Another area of
light showers is expected to impact all eight of our TAF sites
this afternoon. A light north wind early this morning, becoming
northwest and 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.

&&

.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
Short Term...Iovino
Long Term...Fitzsimmons
Aviation...Fitzsimmons/Iovino
Marine...Fitzsimmons/Iovino



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