Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 191714

Area Forecast Discussion
National Weather Service Mount Holly NJ
114 PM EDT Wed Oct 19 2016

High pressure will remain over the Southeast coast before moving
into the western Atlantic waters by the end of the week. Meanwhile,
a weak cold front will move southward through the region today and
tonight, before returning 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 our north over the weekend.


Cold front continues to slowly work its way through eastern PA,
and is just pushing into NW NJ. Not sure how much forward progress
it will make during the day, but there is not precip with it, so
the forecast remains dry.

Most of the SCT-BKN mid and high clouds are across S NJ and into
DE, with some SCT lower clouds moving into E PA and NW NJ. As a
result, temps are warming up quite nicely across the region with
temps generally running in the upper 70s to low 80s for much of
the CWA, and in the low 70s in the Pocono Mountains.

Think highs may end up a couple of degrees warmer than forecast,
so will go ahead and bump up highs, and daily record high
temperatures will likely be tied or broken at many of our climate
sites this afternoon.


The west-east oriented cold front will drift southward through the
Delaware Bay and lower Delmarva regions this evening. The surface
boundary may then stall or even start to return back northward late
tonight. Meanwhile, a wave of low pressure is forecast to organize
over Mid South and Ohio River Valley tonight. Isentropic lift in the
H9-H7 layer will ensue as the flow to the east of this developing
wave backs out of the south. There is still some discrepancies
between models regarding how quickly overrunning precipitation
develops in the vicinity of the front. We anticipate at a band of
light rain to develop by early Thursday morning somewhere between
ILG and ABE but PoPs were kept low due to  forecast uncertainty.

Forecast low temperatures range from the lower 50s in northeastern
PA-northwestern NJ (since cloud cover will arrive late in the
period) to the mid 60s from about the Philly metro southward (where
clouds will arrive much earlier in the night).

Surface winds will veer from north to northeast tonight as high
pressure builds southward from New England. Wind speeds will be 10
mph or less.


A cold front and low pressure across the Ohio Valley and a storm
offshore will eventually merge and become a strong system north of
our area this weekend. Clouds and shower chcs will increase from
Thu thru friday night. A strong cold front will cross the area Fri
night with showers likely. Above normal temperatures will continue
Thu and (to a lesser extent) Fri. Once the cold front crosses the
area, readings will turn sharply colder.

Showery weather with cool temperatures is expected Sat with
decreasing chc for showers Sat night and Sunday. The models are at
odds with how much moisture circulates across our region. The
ECMWF has more showers Sat across our area than its previous runs
while the GFS is notably drier. We will continue with mostly chc
or slgt chc for showers attm. Highs Sat and Sun will be in the
upper 50s north and low 60s elsewhere. These temperatures will be
several degrees below normal.

Mon and Tue will feature dry weather with cooler than normal temperatures
as high pressure builds across the area. Highs will again be mostly
in the 50s up north and low/mid 60s over srn NJ and Delmarva.


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

Cold front continues to slowly work its way south through the
region, and then will return north as a warm front on Thursday as
low pressure passes to the north and west.

VFR forecast for the rest of the afternoon and through tonight.
Not expecting much, if any, rain until after 12Z Thursday. CIGs
gradually lower to MVFR over KABE/KRDG by 12Z, and then MVFR CIGs
will continue to spread east through 18Z Thursday. Rain will
develop first over western terminals, and will spread east
Thursday morning. Possible that KMIV/KACY/KILG will remain dry
through the TAF period, and conditions at those terminals my
remain VFR through 18Z.

NW winds less than 10 KT, veering to the NE 5 KT or less through
this evening. Winds become E-SE 5-10 KT Thursday morning.


Thursday night through Friday night...Showers developing Thursday
night, 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.


Sub-SCA conditions on tap for the rest of the day.

A cold front will move southward through the waters tonight. SW
winds ahead of the front will become NW and then NE with speeds
under 20 kt.


Wednesday through Friday afternoon...Forecast winds and seas
below SCA criteria. Scattered showers Thu thru Friday.

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.

Sunday night...Winds and seas will drop back below SCA criteria.


Observed tidal anomalies are around two-thirds of foot above
astronomical normal early this morning. The ETSS guidance predicts
Cape May to reach minor tidal flooding threshold of 6.7 ft with
the upcoming morning high tide. Although this is below our
threshold to issue a Coastal Flood Advisory, spotty minor tidal
flooding may occur later this morning.

The same ETSS guidance indicates the potential for several of the
forecast sites along the oceanfront and lower Delaware Bay to
come within a tenth of a foot of minor Thursday morning.


The following sites tied or set daily record high temperatures
yesterday (Tuesday, 10/18)

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

Warmth of this magnitude seen yesterday (and potentially again
today) was/is a rare occurrence for this late in the year:

For Allentown, the only other year that recorded a high
temperature of at least 85 degrees this late in the calendar year
was 1947. In 1947, the high was 85 degrees on the 21st and 23rd of
October. Climate records at Allentown go back to 1922.

For Philadelphia, yesterday (10/18) marked the latest occurrence
in a calendar year with a high of 84 degrees or warmer since 1950
(it was 84 degrees on November 11, 1950).

Here are the record high temperatures for today (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

Monthly average temperatures are projecting 3 degrees or so above
normal, which would rank in the top 15 warmest Octobers at
Philadelphia and Allentown. 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.




Near Term...Klein/MPS
Short Term...Klein
Long Term...O`Hara
Tides/Coastal Flooding...
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