Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 222358

Area Forecast Discussion
National Weather Service Mount Holly NJ
758 PM EDT Fri Sep 22 2017

Post-Tropical Cyclone Jose will continue to weaken and drift
southeast of New England  before dissipating late this weekend.
High pressure stretched from New England to the central Appalachians
will hold firm into early next week. Hurricane Maria will be moving
northward in the offshore Atlantic waters off the east coast next
week. A cold front passing through the mid Atlantic states should
turn Maria eastward and far out to sea later Thursday.


630 PM ESTF: adjusted some temps and dews. The respite from the
drier air that arrived earlier today may be short lived. Have
also added Maria to the synopsis as possible (for now small
chance) player in our weather...mainly via substantial se swell,
but possibly contributing moisture to a cold frontal passage
and need showers on Thu. Patchy fog is in a few countryside
locations between 9-11z/23,

Post-Tropical Cyclone Jose, which has been around a long time,
will finally drift to the southeast tonight and weaken as it
does so. TPC began issuing advisories on Jose on September 5, 18
days ago. The 70th advisory will be issued by the TPC this

The large mid-level ridge over the eastern half of the U.S. will
expand to the eastern seaboard tonight. H5 heights are an impressive
590 dm over the Ohio Valley.

Other than some wrap around moisture from Jose across our far outer
coastal waters into the early evening hours, the forecast area will
remain dry tonight under the influence of the summertime ridge. An
increase in clouds across the coastal plain this evening is expected
before Jose makes its move out to sea.

North winds will slacken and go calm in spots. Temperatures will
drop back to mid 50s north and west and into the lower to mid 60s
across the I-95 corridor and coastal plain. Overnight lows will run
above normal. Dewpoints are lower compared to 24 hours ago.


The mid-level ridge continues to drift eastward tomorrow. H5 heights
climb to at least 588 dm. H8 temps climb to about 30 deg C. As a
result, another warm day is in store for the Delaware valley and
adjacent locales. Just about everyone should hit at least 80. The
exceptions could be the higher terrain in the Poconos and NW NJ and
at the beaches.

No rain is forecast. Expect lots of blue sky, especially by late
morning. Winds will be out of the north and slacken during the
afternoon hours. With the gradient weakening, a seabreeze should


Sunday through Monday...Surface high settles in over the region. As
a result expect continued dry and very warm weather. We could get
close to record highs both days at inland locations (see climate
section for the current record highs for those days). A light
onshore flow could temper the warming trend at coastal locations.

Tuesday and Wednesday...Surface high weakens. As it does so, we
could have some showers develop, primarily diurnally driven (rain
associated with the low over eastern Canada will stay well to our
northwest, and at this point it doesn`t look like Maria will get
close enough that we will see any of the outer rain bands). As for
Maria, it is expected to stay well to our south (by a few hundred
miles) through this period. Please see the forecast discussion from
the National Hurricane Center for the latest information on the

Thursday...There are two things to watch through this period. First,
the cold front still looks on track to propagate through our region
late Wednesday night into Thursday. That will bring us back to near
normal temperatures (although depending on how quickly it moves
through, we may not notice it until Friday). The other thing we will
be watching is the eventual track of Maria. This is beyond the 5
days of the official hurricane track forecast, so there is
considerable uncertainty, but at this point, almost all guidance
shows the storm taking a right turn, further out to sea,
through this period. If this does occur, we will see very little
in the way of impacts aside from the swells and high surf.

Friday...Cooler and drier air should settle in over the region. It
will be quite a bit cooler than the early week periods, but only
near normal for late September.


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

Tonight...VFR with patches of cloud aoa 6000 ft, mainly vcnty
KACY and KILG. No issues with visibility expected overnight,
except maybe some ground fog in the most prone areas. Winds will
be light out of the NW-N.

Saturday...VFR. Light northwest winds. Lots of blue sky.


Sunday and Monday...mostly VFR conditions are expected.

Tuesday and Wedensday...mostly VFR conditions expected. There is a
slight chance for showers both days. Northeasterly wind up to 10 KT


SCA seas continues. The north winds are expected to continue
through the period. Speeds will mainly be in the 10 to 15 kt
range on the ocean. The dominant long period easterly swell
will continue. Seas will range in the 4 to 6 foot range on the
ocean and mainly in the 1 to 3 foot range on Delaware bay.

Saturday...The SCA advisory will remain posted. Saturday conditions
will be very much like tonight with northerly winds occasionally
gusting up to 25 kt, a large easterly swell, and seas in the 3 to 5
foot range. On the Delaware Bay, winds and seas are expected to
slacken a bit from where they`re forecast to be tonight.

Saturday night and Sunday...elevated seas on the Atlantic Coastal
waters  are expected to continue through at least part of the night
Saturday night. However, we are expecting a lull in elevated seas
before the swells from Hurricane Maria arrive. Some guidance has
seas increasing by mid day, but trends with recent storms have
guidance showing swells arriving too quickly. If this trend
continues, we may see a lull in elevated seas for much of the day.

Monday through Wednesday...Swells from Hurricane Maria are expected
to result in a prolonged period of hazardous seas on the Atlantic
Coastal Waters. A few gusts near 25 KT are possible especially
Wednesday, but in general, winds should stay below SCA criteria
through this period.

Rip Currents...

Into the evening...Long period swells emanating from Post-Tropical
Cyclone Jose will continue to reach the coasts of Delaware and
New Jersey. As a result, we continue a high risk for the
development of dangerous rip currents this evening.

Saturday...Tomorrow looks to be somewhat of a transition day as
the beaches see leftover NE swells of 3-4 feet from Jose at 9
second intervals and the introduction of 2-3 foot se swells of
15 second intervals from Maria. Maria`s swells will grow with
time. More about that in the outlook. Looks like at least a
moderate risk for tomorrow and the surf zone may be a bit
chaotic as swells from differing directions and energy collide.
So while the surf height will be less, it still looks troublingly
difficult to safely enjoy the surf zone swimming.


Sunday...There may be a brief lull in the larger swells but for
now...a se swell of 4-5 feet is modeled at 15 second intervals
from Maria. Thats a strong moderate risk if not a high risk for
the formation of dangerous rip currents.

Monday...a 5 or 6 foot se swell of 15 seconds is expected to be
dominant and result a strong moderate risk, if not high. 8 foot 15 second swell should be dominant by that
time...lots of energy and a solid high risk.

Wednesday...around an 11 to 13 foot se swell at 15 seconds. Even
higher risk and if this materializes as constantly modeled...we`d
need a high surf advisory as well, allowing 70 percent for
breaking waves at the beach (8 to 9 foot).

Thursday the 28th...still a 10 foot se swell at 14 seconds.
High risk.

Friday...maybe down to 5 or 6 feet and a mdt or high risk.


We are still feeling the effects from Post-Tropical Cyclone Jose and
the new moon. The Coastal Flood Advisory expired at 3 pm. Minor
flooding occurred up and down the DE/NJ coasts...more spotty across
northern NJ and more widespread across southern NJ and Sussex county

For this evening`s high tide, spotty minor flooding is expected
along the NJ and DE coasts. This evening`s high tide is the lower of
the two today by about 1/2 foot. As a result, we don`t think the
flooding will be widespread enough to issue another advisory.


With high temperatures making a run at 90 Sunday and Monday
across the region, some record high temperatures may be tied or
broken. The highest chances are on Monday where all locations
but Georgetown are expected to be within three degrees of a

Here are the records for both days.


PHL 95(1970)


GED-92(2010 and 1970)

Monthly climate: Depending on whether there is any rain at KILG,
if none for the remainder of the month, the current monthly
total of 1.12 inches would rank 12th driest in the period of

September temps: PHL is projecting a 71.7 average or 2.6 degrees
above average, which would make it the 13th warmest September
in the PHL period of record. ABE is projecting a 68 degree avg
or 4.1 degrees above normal which would be 9th warmest September
in the ABE period of record.

These projections took into account todays high/low, the PHI
330 PM forecast through the 29th and a normal high/low for the


NJ...High Rip Current Risk until 10 PM EDT this evening for NJZ014-
DE...High Rip Current Risk until 10 PM EDT this evening for DEZ004.
MARINE...Small Craft Advisory for hazardous seas until 6 AM EDT Sunday
     for ANZ450>455.


Near Term...Drag  757
Short Term...Kruzdlo
Long Term...Johnson
Aviation...Drag/Johnson 757
Marine...Drag/Johnson 757
Tides/Coastal Flooding...757
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