Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 260915
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
515 AM EDT FRI AUG 26 2016

.SYNOPSIS...
A weak cold front will move across the area today and push to our
south tonight. High pressure builds to our north Saturday, then
offshore later Sunday. An area of low pressure is expected to pass
to our north Monday, bringing a front across the area later on
Monday that will slowly sag southward through Tuesday. Another
cold front is forecast to move across the area around Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Early this morning, there is an incoming pre-frontal trough and
while the instability is weakening with time there remains enough
to maintain or redevelop some showers across portions of our area.
The forcing is not well defined, therefore it appears that a
warm/moist airmass combined with the pre-frontal trough and mid
level instability is just enough to keep some showers going for
awhile. While a rumble of thunder cannot be ruled out, the
instability looks low enough and therefore did not include
thunder especially given such low coverage. Slight chance to
chance pops is carried early this morning across much of the area
given some renewed small showers across the southern zones.

An upper-level ridge still centered to our south will become the
main weather feature today. This ridge is forecast to actually build
a bit northward into our area by late afternoon. This will keep the
stronger flow from the Midwest to the Great Lakes then to New
England. At the surface, a weakening cool front will continue to
settle south and eastward across our area through midday. This
boundary may then end up dissipating during the afternoon as it is
mostly just a dew point boundary. Given the building ridge, there is
a very small window of opportunity for a shower or thunderstorm
mainly through midday. There will be more of a cap across the
southern areas due to the building ridge and then some drying occurs
from northwest to southeast during the course of the day across much
of the region. This coupled with a lack of defined forcing is not
good for convective chances. As a result, the forecast is currently
dry after 12z.

Some convective cloud debris is expected to move across at least
parts of the region this morning, however some increase in
subsidence especially this afternoon along with some drying should
allow for less cloud cover through the day across much of the area.
It will be hot however for most areas as the boundary layer flow
turns to the west and northwest for areas behind the weakening cool
front. The heat indices will be driven by how much the dew points
lower, however a humid day overall is expected with the highest heat
indices anticipated from about the Philadelphia metro on south and
east. It still appears that the heat indices fall short of advisory
criteria.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
As the upper-level ridge continues to build across our region
tonight, surface high pressure near the Great Lakes will slide
eastward. This will allow for a more northeasterly low-level flow,
although most places should have the winds decouple during the
evening. While some high level clouds may drift across from time to
time, overall a mostly clear sky is anticipated. It will be
mild/warm, however the dew points should actually drop some allowing
for a bit more radiational cooling. This is especially the case
across the northern areas where dew points are forecast to be the
lowest.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
The frontal boundary will continue to push to our south Saturday and
stall or wash out south of the area over the weekend while high
pressure builds to our north. This high will keep dry weather in
place across the area through the weekend. Temperatures will remain
warm over the weekend, but humidity levels will be much lower with
dewpoints only in the 60s.

The high pressure will build offshore of New England Sunday night
into Monday, and a cold front will move into the area Monday. The
front is expected to slowly move south of the area into Tuesday.
Several vorticity impulses should move across the area Monday into
Tuesday, which could help lead to isolated/scattered showers or
thunderstorms.

Another frontal boundary is forecast to move across the area
Wednesday, then push south of the area into Thursday. There could
continue to be some isolated/scattered showers or thunderstorms
Wednesday or Thursday, but the chances remain small.

Temperatures through next week will continue to be several degrees
above normal, but not as warm and humid as today.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...VFR overall, however MVFR conditions linger early at ABE.
Otherwise, a ceiling mainly at and above 5000 feet for a time this
morning, then thinning out. A weak cool front settles across the
area, therefore most terminals will have a wind shift to the
northwest with an increase to around 10 knots. ACY should take the
longest to have a wind shift to the west. A few showers will move
across the region mainly early this morning.

Tonight...VFR. Northwest winds diminish early, then become northeast
or locally light and variable.

OUTLOOK...
Saturday through Sunday night...VFR conditions expected.

Monday-Tuesday...Generally VFR expected. A chance of isolated
showers or thunderstorms.

&&

.MARINE...
A weakening cool front arrives during the course of the day, however
the wind shift to the northwest looks to hold off mostly until
tonight. If a lingering pre-frontal trough however moves through,
then a wind shift to westerly would occur sooner. The southwesterly
flow has diminished some across much of the waters early this
morning, and while some uptick may occur for a time we are expecting
the conditions to remain below Small Craft Advisory criteria. Once
the wind shift to the northwest occurs this evening, a turn more to
the north and northeast is expected overnight as high pressure
builds from the Great Lakes to New England.

OUTLOOK...
Saturday through Tuesday...Sub-Small Craft Advisory conditions
expected to continue across the waters.

RIP CURRENTS...
For today...The risk for the formation of dangerous rip currents
is low as the winds look light enough, and there should be a wind
shift to more westerly by late day as a weak cool front settles
through.

For the weekend into early next week...With increasing long
period swells (10-15 seconds), we will have an enhanced rip
current risk. Monday and Tuesday could have the highest risk.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$
Synopsis...Robertson
Near Term...Gorse
Short Term...Gorse
Long Term...Robertson
Aviation...Gorse/Robertson
Marine...Gorse/Robertson



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