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fxus61 kphi 190231 

Area forecast discussion
National Weather Service Mount Holly New Jersey
931 PM EST Mon Nov 18 2019

a coastal low pressure system will continue to move off the
middle Atlantic coast this evening and head towards the Canadian
Maritimes. A weak wave of low pressure will cross the region Wednesday
before moving offshore Thursday with high pressure building in behind
it. Heading into the end of the work week another low pressure system
will begin to move through the region.


Near term /through Tuesday/...
with the evening update, the main changes were to the pops to
reflect current radar trends).

Two areas of precipitation (at this point all rain) we continue
to watch this evening. The first is an area of rain over
northern New Jersey and east central PA. This is associated with a low
level short wave trough which has been a bit faster to lift
northward than previously expected. Consequently, the risk for
snow has decreased as this precipitation may be completely clear
of our area before temperatures decrease enough (even in the
higher elevations) to see a change over to snow. Only higher
elevations in Monroe and Sussex (nj) counties look to have any
chance of seeing snow at this point, and even at that
accumulation appears unlikely.

The second area of rain we are watching is currently over
northern Virginia and Maryland associated with a mid level trough. This rain
is expected to break up as it reaches northern Delmarva (thanks
to the mid level ridge building in quickly behind the trough).
Consequently, I increased pops across Delmarva, but not
confident enough to include a mention of likely. This round of
precipitation should be all rain.


Short term /Tuesday night through 6 PM Tuesday/...
Tuesday should be much quieter weather-wise in the wake of the first
mid-lvl wave. A relatively dry westerly flow will prevail over the
area, and although a secondary/weaker low will pass offshore it
should not impact the area. Cloud cover will generally be less than
the last couple days although there may be some residual low clouds
in the morning, and then in the afternoon some high clouds should
spread from S-north ahead of the next shortwave. High temperatures will
generally be in the low-mid 50s and this combined with weaker winds
should make it feel more pleasant than the brisk NE flow of the past


Long term /Tuesday night through Monday/...
progressive is the name of the game in the extended forecast into
this weekend.

Summary...a weak disturbance will cross the region Wednesday as the
coastal storm complex continues to exit the region and enters the
Canadian Maritimes. Meanwhile into Thursday, a stronger storm system
will begin to evolve as cyclogenesis takes place across the Great
Plains, developing a mature Colorado low. This storm system will be
the next feature to watch by the end of the workweek as it pushes
across the Great Lakes and drags a cold front toward the mid-
Atlantic and northeast Friday into Saturday. High pressure will
begin to build eastward in its wake, leading to a quiet start to the
workweek next week.

A weak disturbance will skirt out of the Great Lakes and into the
mid-Atlantic Wednesday as an upper-level jet digs southward.
Moisture will be limited through the region, thus only a few clouds
are expected, save for a snow shower or two in the Poconos and
points north. Highs will be just a tad below average in the 40s to
low 50s for this time of year.

Quiet weather Thursday through early Friday as high pressure builds
across the region. A warm front will transition northward through
the region Thursday ahead of the developing extratropical cyclone
across the plains. Therefore, highs will moderate a few degrees each
day reaching the upper 50s to near 60 across Delmarva by Friday.

There is still some disagreement over the evolution of said system,
but at the very least, global model guidance appears to agree that
the primary low will move out of Ontario and Quebec and into the
Canadian maritime provinces into Saturday morning, drawing a cold
front through the Great Lakes and into the region sometime Friday
night and into Saturday morning. The tail end of this system still
remains somewhat of a mystery as both the GFS and ec form a
stretched pv feature from the Southern Plains into the northeast,
then developing another surface low as this energy ejects into the
southeast Saturday into Sunday. The big question is how far north
and fast does this system evolve? If it develops more quickly, as
the ec solution suggests, another widespread precip event may be in
store for Saturday night and Sunday. On the other hand, the GFS
suppresses the southern fringe of this pv feature and keeps the
evolving feature south of the mid-Atlantic and into the Carolinas. A
clipper-like feature, as noted in yesterday's discussion, is also of
interest in case these features emerge. This appears less likely
given this morning's model runs. Cooler weather returns behind the
main cold front with highs generally in the 40s across the County Warning Area
Saturday and Sunday.

Monday looks fairy quiet as high pressure begins to build across the
southeast. A weak mid-level wave looks to travel through the long-
wave trough as the aforementioned evolving low shifts offshore, but
this is not expected to noticeable affect the weather at this point.
Highs should reach into the mid to upper 40s across the region,
maybe reaching 50 across Delaware and Maryland.


Aviation /02z Tuesday through Saturday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Tonight through Tuesday morning... mostly MVFR, with rain expected
roughly Acy-phl-Abe and northward. Some periods of VFR possible at
ridge/ilg with IFR cigs possible generally north of phl. Winds
generally 5 kts or less and favoring a westerly component if not

Tuesday... some initial MVFR cigs/vsbys may linger into Tuesday
morning although expect recovery to VFR by 15z at all sites. Winds
generally west/west-northwest around 5-10 kts. High confidence.


Wednesday...generally VFR with northwest winds from 5 to 10 knots
and gusts up to 20 knots.

Thursday...VFR with westerly winds around 5 knots with gusts
to 10 knots turning southerly in the evening.

Friday...restrictions possible as rain showers enter the region
ahead of a cold front. Westerly winds from 10 to 15 knots and gusts
to 20 knots.

Saturday...restrictions possible in the morning as a cold front
exits the region and moves offshore, bringing rain showers with it.
West-northwesterly winds from 5 to 10 knots and gusts to 15


Delaware bay: winds and waves are expected to stay below Small Craft
Advisory conditions tonight and Tuesday.

Delaware bay: winds and waves are expected to stay below Small Craft
Advisory conditions tonight and Tuesday.

New Jersey and Delaware Atlantic coastal waters: winds and seas will
continue to gradually diminish. However, seas will stay elevated
above 5 feet through Tuesday morning, before finally dropping below
Small Craft Advisory criteria Tuesday afternoon.


Wednesday...sub-sca conditions in the morning will give way to
possible advisory-level gusts past 25 knots out of the northwest in
the afternoon and evening. Seas building from 2 to 4 feet.

Thursday...sub-sca conditions expected with westerly winds around 10
knots and gusts to 15 knots. Seas from 1 to 3 feet.

Friday...sub-sca conditions in the morning may give way to advisory-
level southerly winds as gust may approach 25 to 30 knots in the
afternoon and evening ahead of a cold front. Seas building to 3 to 5

Saturday...Small Craft Advisory conditions possible in the morning with northwesterly
winds gusting from 25 to 30 knots. Winds should die off behind the
cold front and drop below advisory criteria to 10 to 15 knots with
gusts from 15 to 20 knots in the afternoon. Seas ranging from 4 to 6
feet in the morning to 2 to 4 feet in the afternoon.


Tides/coastal flooding...
now that winds are shifting offshore, tidal departures should
continue lower, and the high tide cycle that just passed should
be the last of concern as tidal levels are lowering back below
minor flood levels. The next astronomical high tide is lower
than the previous cycles, and by the next cycle, departures will
be even lower. The are two exceptions where levels remain above
the advisory-minor flood level. This is Barnegat Bay, to the
north of Barnegat Inlet, and its tidal tributaries as well as
Little Assawoman Bay. We will have a coastal flood statement for
these areas until tidal levels lower.

For Chesapeake Bay, Claiborne may get close to or just barely reach
minor flood levels, but they are not expected to reach advisory-
minor levels.

For the tidal Delaware River, points should either remain just below
or just barely reach minor flood levels, but they are not expected
to reach advisory-minor levels.


Phi watches/warnings/advisories...
New Jersey...none.
Marine...Small Craft Advisory until 2 PM EST Tuesday for anz450>455.


near term...Carr/Johnson
short term...Carr

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