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fxus61 kphi 221445 

Area forecast discussion
National Weather Service Mount Holly New Jersey
945 am EST Fri Nov 22 2019

low pressure will move from Quebec toward the Canadian Maritimes
through today pushing a cold front across our region. The next low
pressure system will then develop across the southern Appalachians
and pass just to the south of the forecast area and offshore late
Saturday into early Sunday. High pressure then returns into early
next week before another system may potentially impact the region by
the middle of next week.


Near term /until 6 PM this evening/...
930 am update: rain showers currently across central PA and Maryland
will continue spreading eastward and into our forecast area
through the day. Bumped pops up a bit making everyone at least
likely late morning or early afternoon. Much of the precip and
the cold front will be offshore by about 4-5 PM. Skies are
forecast to clear quickly as precip ends from northwest to
southeast and winds will briefly pick up behind the front from
the northwest.

Previous discussion...
surface low entering Quebec early this morning will race east-
northeast today, reaching the Canadian Maritimes by Saturday
morning. A cold front will extend south-southwest from the low
and should move rapidly through the area this afternoon into
early this evening. As it does so, a weak southern-stream
perturbation will race into the mid-Atlantic, providing
increased lift near the frontal zone. The timing of this will be
critical, because rainfall accumulations will be heavier should
this stronger ascent outrun the front. Generally, this is
expected to occur in the southern cwa, where the front will be
slowest to pass through. However, the increased ascent looks to
be strong enough across the area to justify increasing pops to
likely from around midday through the afternoon. The highest
pops are generally along/southeast of the urban corridor, where
the added lift from the southern-stream system will be
strongest. Think precipitation will likely be done (or nearly
so) for the area by 4 PM, with quick clearing thereafter as
cold/dry advection set(s) in.

Quantitative precipitation forecast should be fairly light with this system, generally under a
quarter inch. Locally higher totals may occur in Delmarva and
southern New Jersey, depending on the extent of the southern-stream
perturbation's influence on the generation of precipitation.
Temperatures will be much too warm for anything other than liquid

In advance of the front, strong warm advection should keep
temperatures mild, likely 5-10 degrees above seasonal averages
today. This will be mitigated to some degree by the overall
cloudiness, but enhanced by fairly strong mixing as surface winds
increase and gust to around 20-25 mph this afternoon. After frontal
passage, winds will switch to northwest and increase, with gusts
approaching/exceeding 30 mph in many locations.


Short term /6 PM this evening through 6 am Saturday/...
with the rapid exit of today's system offshore, a brief period of
high pressure will begin tonight. The high should be centered near
or just southwest of the area by 12z Saturday, which should aid in
the rapid decrease of winds this evening. With clearing skies and a
colder source region of the upstream environment, think tonight will
be rather chilly. Have generally kept temperatures on the cold side
of guidance, though possibly not cold enough (yet) in the more
sheltered Rural/Valley locations in eastern PA, northern NJ, and The
Pine Barrens. Specifically, expecting lows near 20 in the Poconos,
near freezing in the urban corridor and along the coast, and in the
mid to upper 20s in most other locations.


Long term /Saturday through Thursday/...
the main story early in this period continues to be the low
pressure system still progged to affect the region late
Saturday into Sunday. To start the period early Saturday, a
ridge of high pressure will be located along the East Coast with
an area of low pressure associated with the southern stream
over Tennessee. The day will get off to a mostly clear and
chilly start however through the course of the day the high will
move off the coast while low pressure approaches as it moves NE
into the Ohio Valley. This will lead to skies becoming mostly
cloudy through the afternoon however the timing of the system
has slowed somewhat so precip looks to most likely hold off
until the early evening time frame. Highs Saturday generally
range from around 40 over the southern Poconos to the upper 40s
over the Delmarva.

For Saturday night, aformentioned low moves NE with the primary
low weakening and a secondary low eventually developing off the
Virginia coast. Rain will quickly overspread the area from SW
to NE through the evening and may fall moderate to occasionally
heavy at times. Also, as the precip moves in low level
temperatures still look to cool enough for some freezing rain to
be an issue across the southern Poconos and northwest New Jersey as
temperatures aloft will be above freezing. Best chances for ice
accretion look to be elevations above 1500 feet or so but
amounts should be limited to around a tenth of an inch or less.

By Sunday morning, low pressure will be located near or just
east of Cape May as it will be continuing to deepen and move NE
driven by a sharp upper level wave becoming negatively tilted.
With the slower speed of the system compared to previous
forecasts, rain may continue through a good part of the morning
for much of the forecast area before finally tapering off west
to east through the afternoon as the low finally pulls away. It
may also end as some wet snow or a mix of rain/snow over the
southern Poconos. Of note, some differences in the models on
how quickly low moves away with the Gem being the fastest while
the ec is the slowest. Total rain amounts by the time the rain
ends look to generally range from around a half an inch north to
around an inch near the coast so it shouldn't cause any Hydro

Heading into next week, the weather pattern looks to be overall
not too active for this region. High pressure moves in Monday
and should influence our weather right through Tuesday bringing
dry weather and a good deal of sunshine for both days and
temperatures returning to more seasonable levels. The next low
pressure system looks to affect the area around the middle of
next week as it tracks north of the region through the lower
Great Lakes towards New England. This will keep US on the warm
side of the system so highs Wednesday could be quite
mild...possibly around 60 in places. As the system's cold front
eventually moves through it may also bring some showers followed
by cooler, mainly dry weather for Thanksgiving day.


Aviation /15z Friday through Tuesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Today...initially, VFR conditions will prevail, but as a cold
front moves through the area around midday into the afternoon, a
period of sub-VFR conditions and showers is expected (generally
16z to 21z). Winds will switch from southwest (5 to 15 kt with
gusts to 20 kt) to west or northwest 10 to 15 kt with gusts
20-25 kt. Rapid clearing is expected after the frontal passage,
with VFR anticipated after 21z. Moderate confidence in winds;
low confidence with cigs/vsbys (especially with timing).

Friday night...VFR with northwest winds 10 to 15 kt with higher
gusts in the evening diminishing to below 10 kt overnight. High


Saturday and Saturday night...VFR initially with MVFR
restrictions developing Saturday evening as rain moves in.
Winds 5 kts or less initially west becoming variable. Low

Sunday...lingering sub-VFR restrictions likely much of the
morning as rain continues with some improvement occuring west to
east through the afternoon as rain ends. Winds becoming
northwest around 10 kts with gusts 15-20 kts. Moderate
confidence on overall evolution; low confidence on timing of
improving restrictions.

Sunday night through Monday...VFR expected. Westerly winds
around 5-10 kts. Moderate confidence.

Monday night through Tuesday...VFR expected with winds becoming
SW around 5 knots.


southwest winds have increased to marginal advisory levels early
this morning offshore. This is forecast to continue through the
early afternoon before a cold front sweeps through and switches
winds to west or northwest. At that point, the strongest gusts are
expected to occur, including on lower Delaware Bay, where an
advisory has been issued beginning at 1 PM. The stronger northwest
winds should continue on Delaware Bay through the evening before
diminishing (with the advisory expiring at 10 pm), but may take a
little longer on the Atlantic waters. Thus, the Small Craft Advisory
for the Atlantic waters continues through 6 am Saturday.

A period of showers is expected this afternoon, generally between
midday and 6 PM. The strongest gusts may occur with these showers.

Seas are expected to range from 3 to 5 feet through tonight.


Saturday...sub-sca conditions expected.

Saturday night...conditions nearing Small Craft Advisory criteria overnight along
with light to moderate rain.

Sunday...Small Craft Advisory conditions developing by the afternoon hours with
offshore winds gusting around 25-30 kts and waves 3-5 feet.
Rain tapering off west to east through the day.

Sunday night through Tuesday...lingering Small Craft Advisory conditions will
diminish by daybreak Monday, then sub-Small Craft Advisory conditions expected.


Phi watches/warnings/advisories...
New Jersey...none.
Marine...Small Craft Advisory until 6 am EST Saturday for anz450>455.
Small Craft Advisory from 1 PM this afternoon to 10 PM EST
this evening for anz431.



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