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000
FXUS61 KPHI 241029
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
629 AM EDT Sat Oct 24 2020

.SYNOPSIS...
A cold front extended southwestward from Quebec, across western
Pennsylvania and West Virginia to the lower Mississippi River
Valley early this morning. The front will move to the east and
it is forecast to pass through our region this afternoon and
evening. High pressure is expected to build across New York and
New England on Sunday. A warm front is anticipated to lift
through our area on Monday, followed by a cold front from the
northwest late on Monday night. Weak high pressure should
influence our weather from Tuesday into Wednesday. Another cold
front is expected to move slowly through our region late in the
week as low pressure passes to our south.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Once more, we are dealing with a murky morning across the
region. Fog has been much less prevalent tonight versus prior
nights, but low stratus has been abundant and most of the area
is cloaked in the low cloud deck. Light but steady southwesterly
flow will continue to develop this morning and will help to
gradually erode the low clouds. Skies won`t go clear, but some
breaks are expected by later this morning and into the
afternoon.

Once low clouds begin to lift and erode, the next forecast
challenge will be a cold frontal passage this afternoon and
evening. Seasonally strong low pressure tracks well to our north
into Quebec today, and its trailing cold front will sweep
through later on in the day. A respectable thermal gradient with
this front, as will be evidenced by much cooler temperatures
tonight and Sunday. However, with its parent low tracking so far
away and with weak ridging present over the East Coast, there
will not be much forcing for ascent this afternoon. As has been
the case for several days, have maintained mostly slgt chc PoPs
for most of the area for the possibility of some spotty light
showers along the front, but a mainly dry day is expected.

The expected timing of the frontal passage has slowed slightly
over the past couple of days. Because of this, we will remain in
the warm sector for most of today, and another warm day is
likely. Temperatures will be somewhat dependent on the degree of
clearing this morning and early afternoon. They could also
begin to slide backwards a bit later this afternoon behind the
front, especially to the west. Generally raised the max values
slightly over the previous forecast but did not go too far from
consensus. This brings most areas into the low to mid 70s today.
If we do clear out a little more and sooner than expected, some
values in the upper 70s to near 80 will be possible especially
over southern NJ and Delmarva. Either way, a warm day for late
October, with highs running about 10 degrees above average.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
For tonight, the cold front settles to our south. A mainly dry
night is expected. There could be a lingering spotty shower in
southeastern areas during the early part of the night along the
front. In addition, an upper level disturbance will approach
from the west-southwest during the second half of the night and
will start to interact with the frontal boundary. The front may
make it far enough south to keep the entire area dry, but at
worst the approach of this disturbance would mean a renewed
chance for some light showers later tonight, again mainly on
Delmarva.

The low temperature forecast tonight will be tricky with
multiple factors in play. A colder air mass will be advecting in
behind the front, but a steady 5 to 10 mph northerly breeze
will keep values from falling off too much at least initially.
However, as building high pressure to the north begins to
encroach further, winds may let up during the second half of the
night especially to the northwest. This should support lows
falling into the mid to upper 30s over the Lehigh Valley,
northern NJ, and the Poconos. Further south and east, winds are
less likely to go calm, and there is also the chance of more
cloudiness associated with the approaching disturbance mentioned
above. So values along and southeast of I-95 will be mainly in
the 40s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
A fairly progress weather pattern is expected during the period
from Sunday through Friday.

Surface high pressure in the Saint Lawrence River Valley on
Sunday will try to push down into our region. However, the
return flow aloft is expected to result in a mostly cloudy day
along with a chance of rain in northeastern Maryland, Delaware,
southeastern Pennsylvania and southern New Jersey. Increasing
cloudiness is anticipated for the Lehigh Valley, the Poconos and
northern New Jersey. The air mass centered to our north will be
quite chilly. Highs on Sunday are forecast to be mainly in the
50s.

Mostly cloudy conditions with a chance of rain will continue
for Sunday night and Monday as a warm front lifts toward and
through our region. Some improvement is expected across our
southern counties on Monday afternoon as the front progresses
farther to their north and that area gets more solidly into the
warm sector.

A cold front is expected to pass through our region late on
Monday night. The boundary should be slow moving so the chance
of showers will continue on Tuesday.

It appears as though Wednesday will be the driest day of the
week as high pressure drifts across our area.

Clouds and the potential for rain are forecast to return late
in the week. A mid level low is expected to be over west Texas
on Wednesday, The feature will likely progress to the east
northeast and it should pass off the Middle Atlantic coast on
either Friday or Friday night. It may become an open wave by
that time. Another cold front is anticipated to drop into our
region on Thursday. Surface low pressure associated with the mid
level feature is expected to pass to our south in the Thursday
night into Friday time frame.

Temperatures are forecast to be seasonable from Monday through
Thursday, with readings falling below normal on Friday.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today... Lingering restrictions to MVFR or localized IFR this
morning, with gradually improving CIGs through the morning hours. By
late morning and especially this afternoon, mainly VFR conditions
will develop, though localized MVFR will remain possible. An
isolated shower is also possible but coverage is expected to be too
low to include in TAFs. Southwest wind 5 to 10 kt this morning.
Winds will shift to west then northwest through the afternoon and
evening due to a cold frontal passage, with speeds remaining 5 to 10
kt. Moderate confidence.

Tonight... Mainly VFR, though CIGs will begin to lower late tonight
near and south of MIV and ACY. Winds becoming north then north-
northeast at 5 to 10 kt, with some higher gusts possible near the
coast. Moderate confidence.

Outlook...

Sunday...VFR ceilings with a chance of rain. Lowering
conditions at night. North to northeast wind around 10 knots.
Medium confidence.

Monday...Generally IFR/MVFR in the morning with some
improvement possible in the afternoon. A chance of rain. East
wind 5 to 10 knots, becoming south to southwest. Low to medium
confidence.

Tuesday...VFR/MVFR with a chance of showers. Northwest to north
wind 5 to 10 knots. Medium confidence.

Wednesday...Mainly VFR. Northwest wind 5 to 10 knots, becoming
southwest. Medium to high confidence.

&&

.MARINE...
A Small Craft Advisory (SCA) remains in effect on the Atlantic
coastal waters due to continued 5 to 7 ft seas associated with
Hurricane Epsilon well offshore. On Delaware Bay, sub-SCA
conditions will continue through today and tonight.
Southwesterly winds of 10 to 15 kt are expected for most of
today, becoming westerly then northwesterly this evening.
Overnight, winds will veer from northwest to north or northeast
with some 20 kt gusts possible.

Outlook...

Sunday and Sunday night...A Small Craft Advisory is in effect
on our ocean waters for wave heights of 5 to 6 feet.

Monday...Wave heights on our ocean waters may remain around 5
to 6 feet, especially in the morning.

Monday night through Wednesday...No marine headlines are
anticipated.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>455.

&&

$$
Synopsis...Iovino
Near Term...O`Brien
Short Term...O`Brien
Long Term...Iovino
Aviation...Iovino/O`Brien
Marine...Iovino/O`Brien