Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 072337
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
637 PM EST Thu Dec 7 2017

.SYNOPSIS...
A weak ridge of high pressure over the area tonight will weaken
Friday. Low pressure will strengthen and move along a front across
the offshore waters Friday night through Saturday. The low will then
move up into New England Sunday while a ridge of high pressure
builds back over the Middle Atlantic. A cold front will cross the
area Monday night. Another system may affect the area later Tuesday
and Wednesday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
An update to the forecast was sent out just after 6 PM with the
focus on hourly weather and temperatures. Snow showers/flurries
were added to the forecast for NE PA and NW NJ this evening.
This activity was associated with a residual cold front and
upper shortwave trough that is currently moving thru the region.
With surface temperatures at or below freezing in the higher
elevations, a quick dusting is possible on untreated/elevated
surfaces in the southern Poconos. Outside of these higher
elevations, no accumulation is expected with these showers.
Accordingly, no impact on travel is expected. These snow showers
should move quickly to the east and dissipate by 9 PM.

Previous Discussion...
A fairly nice night is in store across the region with mainly
cirrus overspreading the region from the south. A mid- level
trough will cross the region tonight bringing just some clouds
with it as it moves through. Winds will lose their gustiness
this evening and become fairly light through the overnight
period.

A cold night with temperatures dropping into the 20s across much do
the region. Some lower 30s can be expected along the coast and
across central and southern Delmarva and in the immediate Philly
metro area.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Clouds will continue to fill in on Friday in advance of a developing
system to our south. For the most part, we should remain mostly dry
through the morning but a few light snow/rain showers may start to
creep into southern Delaware during the morning. Rain will gradually
lift into Delaware and southern New Jersey through the mid/late
afternoon. Rainfall totals are not expected to be very much through
Friday.

Temperatures will remain cold as highs struggle to break out of the
30s in areas to the north and west of the I-95 corridor. Along the I-
95 corridor and to the south and east temperatures will rise into
the lower 40s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
The system that we have been watching for Friday night and Saturday
is showing better organization today and also a track closer to the
coast. All of the operational models are now showing a good chance
for some accumulating snow across parts of Delmarva and southern /
central NJ for the early part of the weekend. We have adjusted
pops/qpf/snowfall fcsts accordingly. Much of the show will occur during
the 4th period of the fcst, so we`ll hold for any winter weather
headlines for now. Our fcst would align with advisory criteria
snowfall, but with trends continuing to develop, we`ll see the
next set of model runs before deciding which flags are needed
and where. Our snowfall fcst may be conservative considering the
QPF amts being forecasted by some of the models at 12Z.
Temperatures will continue below normal through the weekend.
Snow will taper off Saturday evening, but a few snow showers
will occur up across the southern Poconos.

Much of Sunday through Monday will be dry as a ridge of high pressure
extends across the region. We have kept the chc for snow showers
across the highest elevations of the southern Poconos. Temperatures
will remain 5 to 10 degrees below normal thru this period.

Later next week, the upper trough that is setting up across the
east this weekend will be progressing across the Middle Atlantic
and Northeast. More cyclogenesis is possible with this and its
possible that more precip could be across the area Tuesday night
and Wednesday. The models vary with regards to how cold it will
be then, but its possible that we could have more snow across
the area then. We`ll fcst temperatures back close to normal Tue,
but then it appears that a cold front will bring back below
normal readings for Wed and perhaps lasting into Thu.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Tonight...VFR conditions will continue. Mainly cirrus across the
region through tonight. Some scattered to broken mid-level stratocu
will move through tonight, generally around 5000-6000 ft, with no
restrictions expected. Winds will diminish through this evening,
losing the gustiness by 00Z. Winds will become light out of the west
through the overnight period, generally around 8 knots or less.
Confidence: Moderate to High

Friday...VFR conditions continue through much of the day. Thickening
cirrus shield will overspread the region with lowering expected
towards the afternoon. Light rain may move into KACY/KMIV by early
afternoon with MVFR conditions possible. Did not include in TAF at
this time as best timing for rain falls outside of the TAF period.
Winds will remain out of the west, around 10 knots or less.
Confidence: Moderate

OUTLOOK...
Friday night thru Sat night...Lower CIGS/VSBYS in snows.
    Conditions will be better further W (KRDG-KABE).
Sunday thru Monday...Mostly VFR. Few snow showers far N/W.
Monday night and Tue...Restrictions psbl with rain/snow. High
 uncertainty in this period attm.

&&

.MARINE...
The Small Craft Advisory for the southern NJ waters, DE waters, and
lower DE bay has been taken down as winds have subsided and fallen
below 25 knots.

The Small Craft Advisory remains in effect for the northern NJ coast
waters along Monmouth and Ocean Counties. Winds have started to
subside a bit on the ocean waters but occasional gusts around 25
knots continue. Wind gusts are expected to briefly increase again
overnight with gusts around 25 knots. Therefore, the advisory was
left in place.

Conditions improve early Friday and a sub-advisory day is expected.
Winds will be out of the west around 10 to 15 knots. Seas will
be around 1 to 3 feet.

Outlook...
Friday night thru Saturday evening...Rain/Snows with sub-SCA
    conditions. Winds/seas beginning to build late.

Sat night thru Monday...SCA conditions expected much of the
    time. Winds and seas diminish on Delaware Bay Monday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EST Friday for ANZ450-451.

&&

$$
Synopsis...O`Hara
Near Term...Klein/Meola
Short Term...Meola
Long Term...O`Hara
Aviation...Meola/O`Hara
Marine...Meola/O`Hara



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