Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 230210
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
910 PM EST Wed Nov 22 2017

.SYNOPSIS...
High pressure will begin to build eastward into the region
tonight and move over the region Thursday and Friday. This will
be followed by a cold frontal passage on Saturday. Another area
of high pressure will build into the region for the early part
of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
High pressure will continue to build eastward from the Ohio
River Valley overnight. Meanwhile, the deck of stratocumulus
that extended over our northwestern counties will continue to
erode. As a result, we are anticipating a clearing trend.

A northwest wind around 10 to 15 MPH this evening should
diminish to 5 to 10 MPH overnight as the pressure gradient in
our region lessens.

Minimum temperatures are forecast to favor the 20s and lower
30s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Sunny with spotty high cloudiness early in the day and then a
general deck of waa mid or high clouds arriving from the west
northwest late in the day reaching to near I-95 around 6 PM.
Light northwest to west wind. Mixing doesn`t look too good so a
fairly chilly Thanksgiving day. Highs 6 to 9 degrees below
normal.

This forecast was a 50 50 blend of the 12z/22 GFS/NAM MOS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Thursday night through Friday night:

High pressure will be in place during this period with mostly
sunny skies. Temperatures will warm into the 50`s Friday after
starting out in the 20`s and 30`s. Friday night has trended
warmer with the past few model runs. Light winds will shift to
southerly and increase slightly ahead of an approaching cold
front with lows generally in the 30`s and low 40`s.

Saturday and Saturday night:

A cold frontal boundary will move through the area on Saturday.
Overall, timing has sped up a few hours on average with the
modeling and ensembles. Enough lift and moisture should be
present for a few spotty rain showers, primarily in the
afternoon hours. Temperatures Saturday morning may be close
enough to freezing in the southern Poconos and NW NJ for a
freezing rain concern. Right now any precipitation is expected
to hold off till mid-morning when it warms well above freezing.
Precipitation looks very light, only a few hundredths and this
forecast used a SREF/WPC blend. A few southerly wind gusts in
the afternoon around 15 mph are possible before the frontal
passage. Northwest flow on the backside of the front could also
kick off some sprinkles and flurries toward sunrise Sunday that
could be enhanced where the elevation is highest (southern
Poconos and NW NJ).

The 12z 11/22 NAM was discounted given a NW bias tendency in
the medium range with low pressure systems. Ensemble guidance
continues to show a low pressure will track from the Carolinas
northeast out to sea with little to no influence in our area.


Sunday through Wednesday:

A fairly strong push of cold air advection will occur behind
the front. This will lead to another period of more winter like
temperatures across the region with stronger northwest winds,
gusting perhaps to 25 mph on Sunday. The northwest flow may also
allow for some moisture to transport southeast off of the Great
Lakes. The moisture could be enhanced by the higher terrain.
Highs Sunday and Monday will generally be in the 40`s with
overnight lows will be in the 20`s and 30`s. Conditions are
expected to clear later Sunday and Monday as the northwest flow
weakens and high pressure builds into the region.

We should see a fairly quick rebound Tuesday and Wednesday with
temperatures into the 50`s as the high pressure system moves
offshore. Right now the forecast does hedge above the mean of
the ensemble guidance on Tuesday but is closer to the ensemble
mean on Wednesday. Some uncertainty is present with the speed of
a cold frontal boundary moving toward the area sometime
Wednesday or Thursday of next week. For now, we went middle of
the road between the GFS and ECMWF with a shower chance for next
Wednesday night.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Overnight...VFR with a clearing trend. Northwest wind 10 to 15
knots decreasing to 5 to 10 knots.

Thursday...VFR with a mainly clear sky. Northwest wind 5 to 10
knots gradually becoming west.

OUTLOOK...

Thursday night through Friday night: VFR, westerly winds
becoming southwesterly but staying at 10 knots or less. High
confidence.

Saturday and Saturday night: Sub-VFR possible with some
scattered showers primarily from 15 to 23Z. Southerly wind gusts
10-15 knots, becoming northwest Saturday night. Medium
confidence.

Sunday and Sunday night: VFR, a few sprinkles or flurries
possible. Northwest winds with gusts from 20-25 knots in the
afternoon. Medium confidence.

Monday and Monday night: VFR, West winds at or under 10 knots.
High confidence.

&&

.MARINE...
As high pressure builds toward our region from the west, wind
speeds will continue to diminish gradually. The Small Craft
Advisory for Delaware Bay remains in place until midnight. The
Small Craft Advisory on our ocean waters continues until 6:00 AM
Thursday.

OUTLOOK...

Thursday night through Friday night: Sub-SCA winds and seas.
West winds becoming south on Friday with any gusts under 15
knots. Seas lower for a time to around three feet. Medium to
high confidence.

Saturday and Saturday night: Seas building slightly but staying
under 5 feet. Southerly wind gusts 15-20 knots in the
afternoon. Winds becoming northwesterly Saturday night. Medium
confidence.

Sunday and Sunday night: Seas continue to to build slightly
close to 5 feet with a increase in northwest wind gusts around
25 knots in the afternoon. Low to medium confidence.

Monday and Monday night: West-southwest wind gusts around 15
knots Monday increasing Monday night to around 25 knots late.
Seas decrease to below SCA levels but should begin to build up
by Tuesday. Medium confidence.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EST Thursday for ANZ450>455.
     Small Craft Advisory until midnight EST tonight for ANZ430-431.

&&

$$

Synopsis...Gaines
Near Term...Iovino
Short Term...Drag
Long Term...Gaines
Aviation...Gaines/Iovino
Marine...Gaines/Iovino



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