Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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823
FXUS61 KPHI 160214
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
914 PM EST Fri Dec 15 2017

.SYNOPSIS...
Surface low pressure, well off the Delmarva, will track
northeast into the open Atlantic overnight. High pressure,
centered over the southeastern United States, will nose into the
region early on Saturday. This will be short-lived as a cold
front, coming in from the north, will move into or through the
area on Saturday night and Sunday. This front will then stall
before lifting northward as a warm front Sunday night and
Monday. A cold front will progress through the region around the
middle of next week. Another system may affect the area near
the close of next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
The remainder of the Winter Weather Advisory has expired. The
back edge of the accumulating snow was off the coast at 9:00 PM.

Snowfall accumulations in the 1.5 to 3.5 inch range were
common, except in the Poconos and far northern New Jersey and in
parts of northeastern Maryland, central and southern Delaware,
and far southern New Jersey where totals were less than an inch.

Gradual clearing is anticipated for tonight as low pressure
moves farther out to sea.

A west wind should increase to 5 to 10 MPH. Minimum
temperatures are forecast to favor the teens in much of eastern
Pennsylvania and northern New Jersey, and the lower and middle
20s in southern New Jersey and on the upper Delmarva.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Shortwave energy rotating around the based of the large scale
trough is forecast to move across the Great Lakes and Northeast
states on Saturday. At the surface, a weak area of low pressure
will pass to our north but a northwest flow behind this
disturbance will help steer a cold front southward into the I-80
corridor by the late afternoon.

Even with the deepest, more organized synoptic lift staying to
our north, models show a ribbon of low-level
convergence/frontogenetical lift near the front that could
support some snow shower activity across the I-80 and I-78
corridor during the mid to late afternoon. We are currently only
expecting minor accumulations. Elsewhere, expect clouds to
increase as the day progresses.

Forecast high temperatures range from the lower 30s across the
I-80 corridor to the lower 40s in Delmarva and coastal NJ.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Overview...The period starts with a deepening surface low off
Delmarva. This low will track to the northeast overnight into
the open Atlantic. Surface high pressure, centered across the
deep south, will push up into the Mid-Atlantic by daybreak
Saturday. This high won`t hang around long. A cold front, coming
in from the north, will move into or through the forecast area
Saturday night into Sunday. This front will back up as a warm
front Sunday night into Monday. Another cold front will push
through the region in the Tuesday/Wednesday timeframe. Surface
high pressure is expected on Thursday. This will elide to a warm
front later on Thursday into Friday and a cold front very late
in the period. Both of these fronts are associated with low
pressure moving across the eastern Great Lakes.

Temperatures...For reference, normals for KPHL are around 30
and in the middle 40s. Sunday will be slightly below normal.
Monday and Tuesday will be above normal with some mid-50s
possible across portions of the coastal plain. Wednesday looks
to be about normal with Thursday slightly below. Friday will
rebound once again with above normal temperatures. Once again,
portions of the coastal plain could see temperatures top out in
the middle 50s.

Precipitation...Small PoPs have been inserted late Sunday and
maintained into Sunday night. This associated with the warm
front in the vicinity. Small PoPs will continue into Monday and
through Tuesday night. Wednesday and Thursday will be PoP free
behind the mid-week cold front. Some chance PoPs will be
inserted into the grids on Friday.

Winds...Fairly benign through the period. Moist noticeable
winds will be right ahead and behind the cold front Tuesday and
Wednesday.

Impacts...While the forecast will see a roller coaster week
with temperatures and multiple chances of precipitation, none
are expected to create widespread hazardous weather at this
time.

&&

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

Overnight...Improving to VFR. Clearing. West wind 4 to 8 knots.

Saturday...VFR. Mostly clear in the morning, then increasing
clouds. West to southwest wind 5 to 10 knots.

Outlook...
Saturday night...Generally VFR with light and variable winds.
Medium confidence.

Sunday...Generally VFR. Light northeast winds to start the day
and southeast to finish. Increasing clouds and a small chance of
precipitation later in the day. Medium confidence.

Sunday night and Monday...Generally VFR, though brief sub-VFR
conditions are possible with light rain or snow, especially
north of PHL. Light winds generally transitioning from southeast
to southwest during the period. Low confidence.

Monday night and Tuesday: Sub-VFR conditions possible, with
scattered showers during the period, especially on Tuesday.
Winds primarily southwest at 5 to 15 kts. Medium confidence.

Tuesday night and Wednesday...Generally VFR. Decreasing clouds
and showers on Tuesday night. No precipitation expected on
Wednesday. Winds west or northwest 10 to 20 mph. Medium
confidence.

&&

.MARINE...
NW winds expected to increase as low pressure intensifies while
tracking to our east overnight. Opted for a SCA instead of a
GLW for tonight and Saturday with winds generally in the 25-30
kt range. However, a brief ramp up in winds are expected late
tonight when pressure rises behind the offshore low are
greatest. Isolated gusts to near gale force at our offshore
buoys is certainly a possibility.

Outlook...
Saturday night: Residual advisory-level northwest winds in the
evening will diminish overnight. Gale force gusts during the
evening can`t be ruled out. Seas below criteria.

Sunday and Sunday night: Sub small craft advisory conditions.
No headlines anticipated. There may be some light rain in the
afternoon and overnight with potential for some visibility
restrictions.

Monday and Monday night: Sub small craft advisory conditions.
No headlines anticipated. Scattered showers, at times, could
create visibility restrictions.

Tuesday: Southwest winds increasing to near advisory levels by
afternoon with seas also building. A chance of showers and
visibility restrictions.

Tuesday night and Wednesday...Small craft advisory conditions
expected due to northwest winds behind the front and building
seas.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 1 AM EST Sunday for ANZ452>455.
     Small Craft Advisory until 1 AM EST Sunday for ANZ450-451.
     Small Craft Advisory from 1 AM to 6 PM EST Saturday for ANZ430-
     431.

&&

$$

Synopsis...Kruzdlo
Near Term...Iovino
Short Term...Klein
Long Term...Kruzdlo
Aviation...Iovino/Kruzdlo
Marine...Klein/Kruzdlo



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