Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 171354
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
954 AM EDT Wed Oct 17 2018

.SYNOPSIS...
A cold front will cross the Mid-Atlantic region this afternoon. It
will be followed by high pressure from the Ohio Valley which will be
across the area through Friday. Low pressure and a cold front will
affect our area Friday night and Saturday. High pressure will
then move in for the end of the weekend into early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The mid and high level clouds associated with an upper-level jet
continues to progress eastward this morning, allowing for increasing
sunshine across the far southern areas. Elsewhere, plenty of
sunshine is ongoing although some clouds will develop from the
northwest as the next cold front arrives this afternoon.

The pressure gradient is forecast to tighten today especially behind
the front. This along with some increase in the cold air advection
aloft this afternoon will result in a significant increase in the
surface winds. Given the 925 mb and 850 mb flow coupled with deeper
mixing this afternoon, peak wind gusts are anticipated to be between
30-40 mph. As a result, the wind and wind gusts have been increased
some this afternoon across much of the area.

The front is moisture starved however there looks to be a few light
rain showers across the northwest zones by later this afternoon
especially as the cold air advection aloft strengthens. The surface
dew points are anticipated to drop this afternoon especially due to
mixing, and therefore any rain showers will be light. Have kept
slight chance PoPs across the southern Pocono region and northwest
New Jersey.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
Behind the front, expect continued dry and cold air advection
overnight. Consequently, we could see the first freeze of the season
for some of our area. There are however a few unknowns that could
have an impact on how widespread the freeze will be. First of all,
winds are not expected to decouple much overnight, but rather should
remain near or above 10 mph. As a result, we likely won`t see much
in the way of a frost. However, this could also limit radiational
cooling. Secondly, if mid level clouds that are expected this
afternoon with the front are slower to clear out, that could also
limit radiational cooling.

Freezing conditions look to be most likely in the southern Poconos
where we have issued a freeze warning. For far NW NJ, confidence is
lower, so have issued a freeze watch for Sussex County. For the rest
of NW NJ, Lehigh Valley, and Berks County, we will likely see lows
in the mid 30s, but are not planning any frost advisory at this time
as the winds should preclude the development of frost.

For areas along and southeast of the I95 corridor, expect lows from
the mid 30s to lower 40s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Thursday thru Friday...Mostly fair this period with a ridge of
high pressure affecting the region. Some gusty winds early
Thursday will diminish by afternoon. Temperatures well below
normal Thu then a little below normal for Friday. Increasing
clouds are expected later Friday.

Friday night and Saturday...The wettest part of the long term
with a low pressure system moving north of the area and a cold
front expected to cross the region. Pops were raised from the
earlier fcst with high chc/low likely pops now in the grids.
Temperatures will be close to normal Sat with higher humidity
levels too. The cold front will cross the area during the
afternoon, so showers are possible until after the front passes.
Gusty winds are possible Sat, but nothing too serious.

Sunday thru Tuesday...Mostly fair weather is expected this
period, however a couple showers may occur across the northern
counties Mon night and Tuesday. High pressure from the west will
build in Mon and the move offshore Tue. Temperatures will be
mostly below normal Sun/Mon then rebound back to near normal for
Tue.

Normal Highs: PHL/MPO/GED : 64/55/66
Normal Lows : PHL/MPO/GED : 46/34/43

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of today...VFR. West to southwest winds near 10 knots,
increasing to 15-20 knots around midday and shift from the west and
northwest. Wind gusts to around 30 knots are expected especially
this afternoon.

Tonight...VFR. Northwest winds 10-15 knots with gusts to 25 knots,
gradually diminish to near 10 knots overnight.

Outlook...
Thu thru Fri...VFR expected. Gusty NW winds Thu morning.
Fri night/Sat...Sub-VFR possible with showers. Gusty winds Sat.
Sat night/Sunday...VFR expected. Gusty winds again Sunday.

&&

.MARINE...
Small craft advisory in effect for the northern and central NJ
coastal waters as winds are already gusting to 25 KT at buoy 44065.

Winds will be increasing, especially through the afternoon with
gale force gusts expected to develop by early this evening on
all waters except the upper Delaware Bay. There is a chance that
gale force gusts could develop a few hours earlier, but don`t
have enough confidence at this time to move up the start time of
the gale warning. Gale force gusts should continue for most, if
not all of the overnight hours. On the upper Delaware Bay,
expect small craft advisory conditions through out the period.

Outlook...
Thu: Early Gales will settle to SCA conditions then drop below SCA later
    Thursday. Fair weather.
Thu night thru Fri: Sub-SCA, but winds increase Fri late
    afternoon. Fair.
Fri night thru Sat. Showers. SCA conditions expected.
Sat night into Sunday..A continuation of SCA conditions with
    some low-end Gales possible. Fair weather.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Warning from midnight tonight to 9 AM EDT Thursday for
     PAZ054-055.
NJ...Freeze Watch from late tonight through Thursday morning for
     NJZ001.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ431-
     452>455.
     Gale Warning from 6 PM this evening to 9 AM EDT Thursday for
     ANZ452>455.
     Small Craft Advisory until 6 PM EDT this evening for ANZ450-
     451.
     Gale Warning from 6 PM this evening to 6 AM EDT Thursday for
     ANZ431-450-451.
     Small Craft Advisory until 6 PM EDT Thursday for ANZ430.

&&

$$
Synopsis...O`Hara
Near Term...Gorse
Short Term...Johnson
Long Term...O`Hara
Aviation...Gorse/O`Hara
Marine...Johnson/O`Hara


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