Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 190126

Area Forecast Discussion
National Weather Service Mount Holly NJ
926 PM EDT Tue Oct 18 2016

High pressure will remain over the Southeast coast before moving
into the western Atlantic waters into the end of the week.
Meanwhile, a weak cold front will approach the region on
Wednesday, pass through on Wednesday night, and then will return
to the north as a warm front on Thursday. Low pressure developing
over the Ohio Valley will pass to the north on Friday, dragging a
strong cold front through the region. High pressure then builds in
from the south as low pressure deepens to the north over the


Initial bank of mid level clouds tried to move into the region,
but have been dissipating as they move further east into our
region. However, as the upper level short wave ridge shifts
further off shore later tonight, expect mid level clouds to
increase. The question is though, will we see the mid level clouds
move in before dew point depressions drop to near zero. If not, we
could have another night of patchy fog, possibly dense in a few
locations. For now, given the uncertainty with the low clouds,
mention general patchy fog across the region.

Temperature wise, it will be another unseasonably warm night,
with lows higher than the normal highs in many areas.

The front will still stay far enough west that we should see dry
weather through the overnight hours.


Another very warm day is in store, possibly the warmest yet. The
aforementioned cold front will be making its way from w to e from
morning through the afternoon. The only caveat on temps is if
there are too many clouds to suppress temps.

The frontal passage looks to be dry with any precip holding off
until after the end of the period, despite lowering and
thickening clouds.

Temps should make it into the 80s in most areas.


A prolonged period of unsettled weather on tap for the middle to
the end of the week.

Cold front works its way through the region Wednesday night. Not
sure how far south that front will actually go, as it may get hung
up across central NJ and southern PA before stalling out. That
front then returns to the north as a warm front on Thursday.
Meanwhile, a deepening upper level trough will dig into the
central U.S. on Thursday, and primary low pressure will develop
over the Ohio Valley during that time. That low will track to the
north and east, passing through western NY/PA as it lifts into
eastern Canada on Friday.

As that trough approaches, it will become negatively tilted, and
models indicating the potential for secondary low pressure
development off the Mid-Atlantic coast. In addition, a weak
tropical low currently east of the Caribbean Islands will track to
the north, and that aforementioned secondary low may tap into and
merge with the tropical low. Models keep this system over the
western Atlantic waters

As the primary low lifts into Canada, it will drag a strong cold
front through the region Friday and Friday night.

As a result, scattered showers will develop Wednesday night with
the approach of the initial cold front, and then showers will
increase and become more widespread on Thursday and Friday. Cannot
rule out a rumble of thunder, especially on Friday, but it is too
soon to include in the forecast at this time.

Over the weekend, low pressure over eastern Canada will intensify
as high pressure strengthens over the Southeast U.S. The pressure
gradient will tighten between those 2 systems over the Northeast
and Mid-Atlantic, and can expect gusty W-NW winds for the region.
Upper trough remains over the area, and with several shortwaves
diving into the base of the trough, some showers are possible, but
no strong signal for showers yet.

Trough continues to depart for the start of the new week as high
pressure builds in from the west.

Well above normal temps on tap to close out the work week, and
then temps fall below normal for the weekend and new week.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

VFR conditions should continue through at least 06Z. After 06Z,
there remains a chance for low clouds and fog. Exact timing and
lowest conditions are uncertain as guidance has done poorly the
last several nights with the fog, and we remain in the same air
mass. A complication tonight is that a cold front will inch
closer to the region last tonight (but still stay west of the
region through at least 12Z). Even with it remaining just west of
the region, leading mid level clouds associated with the trough
could move into our region (ceilings around 5000 ft AGL). If this
happens early enough, this could limit fog development especially
from the Delaware Valley and west.

Any low clouds and fog should dissipate no later than 15Z.

Wind speeds through 18Z will be light, generally below 10kt.
However, wind direction will be shifting from southerly to
southwesterly, to westerly. Once the front arrives, expect winds
to shift to northwesterly and be near 10kt.


Wednesday night...Mainly VFR, but some showers possible, which
could lower conditions to MVFR at least.

Thursday through Friday night...Showers developing on Thursday,
becoming more widespread into Friday, tapering off Friday night.
MVFR conditions likely, with the chance for IFR and lower.

Saturday through Sunday...Mainly VFR. NW winds with 25-35 KT
gusts possible.


Along the northern coastal waters, wind gusts at or above 25 kt
will be possible through the overnight hours. In addition, waves
have already started to increase and may go above 5 ft for several
hours tonight. Thus, the small craft advisory remains in effect
through 7 AM EDT.

For the southern coastal waters and the Delaware Bay, a few gusts
near 20 kt will be possible overnight, but winds and seas should
remain below SCA criteria.

Through the day time hours tomorrow, winds and seas should stay
below SCA criteria.


Wednesday through Friday afternoon...Forecast winds and seas
below SCA criteria.

Friday night through Sunday...A strong cold front passes across
the waters Friday night. Tight pressure gradient develops over the
weekend with winds gusting to at least 30 KT with the potential
for gale force wind gusts.


The following sites tied or set record highs for Tuesday, 10/18

New RecordOld Record
Allentown, PA8581 (1963)
Reading, PA8585 (1908) *record tied
Georgetown, DE8481 (1996)
Wilmington, DE8381 (1938)
Trenton, NJ8382 (1908)

Here are the record high temperatures for Wednesday (10/19)...and
across southern portions of the area on Thursday (10/20).

                   WED OCT 19     THU OCT 20

Mount Pocono, PA   80 in 1963     75 in 1963

Reading, PA        84 in 1963     80 in 1947/1953/1969

Allentown, PA      82 in 1963     78 in 1936

Trenton, NJ        83 in 1963     80 in 1969

Philadelphia, PA   80 in 1947     80 in 1916/1938

Atlantic City, NJ  80 in 1991     85 in 1987

Wilmington, DE     81 in 1963     82 in 1969

Georgetown, DE     81 in 1953     83 in 1953

Thursday is dependent on sunshine. For now, no records but this
could change in future forecasts. We`ve left the records in this
section since it could be near record in a few locations,
especially south of Philly.

Monthly averages are projecting 3 degrees or so above normal, ranking
a top 15 warmest October for PHL/ABE. This is stated with the usual
mid month uncertainty. What we do know is that the warmth of this
week will virtually lock in an above normal month, especially
since the pattern for the last week of October does not indicate
any lengthy period of below normal temperatures.


MARINE...Small Craft Advisory until 7 AM EDT Wednesday for ANZ450>452.


Near Term...Johnson/Nierenberg
Short Term...Nierenberg
Long Term...MPS
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