Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 250549
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
149 AM EDT Tue Jul 25 2017

.SYNOPSIS...
A cold front will move offshore overnight. A broad high
pressure system extending from the Great Lakes into eastern
Canada will gradually build southeast into our area through
Wednesday. As this high slides offshore late Wednesday, a warm
front will move through our region on Thursday, followed by
another slow moving cold front on Friday. High pressure is
expected to make a return this weekend into the beginning of the
work week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
The last of the showers and tstms are exiting the SE corner of
the forecast area attm. Plenty of low clouds remain across the
area and should stay through the morning. Patchy fog will
develop in areas where the few breaks in the OVC. Temperatures
and dew points running OK overall.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Another cloudy day is expected across the forecast area. Easterly
flow will keep us cool and highs are expected to remain below
normal. Upper 60s to mid 70s across the Poconos and NW New Jersey
with upper 70s to mid 80s from about the I-78 corridor and points
south. With the boundary exiting the region, much needed drier air
will filter in and we should be free of the extra humid conditions
we have had lately.

Showers may linger through the morning hours but as high pressure
build into the region, expect dry conditions through the
afternoon.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
One mid-level trough exits the east coast Tuesday night, with a
brief zonal flow and some short wave ridging for Wednesday, followed
by continued troughiness through the end of the long term period.
A frontal system in the Thursday thru Friday time frame features the
greatest chance of sensible weather, in terms of increased humidity,
and the chance for showers and thunderstorms. This front will slow
as it moves offshore, and stall to our south through the weekend
into early next week, as waves of low pressure traverse it. All of
the available guidance keeps our region dry in the Saturday thru
Monday period, but lingering cloudiness is possible, especially
south Jersey into Delmarva. In addition, if the guidance slows the
southward progress of this feature, this could result in a more
pessimistic forecast for the aforementioned area.

Showers and thunderstorms with heavy downpours and gusty winds are
possible Thursday into Friday. It`s still too early to nail down the
spatial and temporal details, as the GFS is much more progressive
with the front compared to the Euro, so there is low confidence due
to the uncertainty. In fact, the GFS event window would be Thursday
into Thursday night, with the Euro window is centered on Friday.
Nevertheless, effective bulk shear values rise to near 40 knots,
while surface-based cape is in excess of 2.0 kJ across portions of
the area. In addition, the front slows as it moves trough or area,
while Precipitable Water values rise to around 2.0 inches. These
indicators point to some potential for strong thunderstorms and
heavy rainfall in the Thursday and Friday period, and we have
mentioned this in the Hazardous Weather Outlook.

Temperature-wise, slightly below normal temperatures on Wednesday
rebound to at or slightly above average from Thursday thru Friday.
Average to slightly below average temperatures are expected in the
post-frontal air mass on Saturday, with a moderation to near normal
in the Sunday thru Monday time frame. In fact, Thursday and Friday
are shaping up to be the warmest days, with temperatures well into
the 80s to near 90. The only exception may be closer to the coast,
where a prolonged onshore flow may develop over the weekend into
early next week, keeping temperatures cooler.

Finally, depending on the extent of the aforementioned onshore flow,
astronomical tides are much lower over the weekend into early next
week as we move away from the new moon. This should limit the
potential for coastal flooding.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Overnight...Mostly IFR or low end MVFR CIGS overnight. Much of
the showers have moves E/SE of the taf sites. Fog could develop
if there are breaks in the OVC. Slow improvement Tue morning.
Light E/SE winds overnight.

Tuesday...MVFR/IFR conditions will prevail through much of the TAF
period. Guidance shows that some clearing to VFR may occur by early
afternoon but confidence is low that things will clear out that
quickly. Easterly flow will remain at the terminals with winds
around 10 knots or less.

OUTLOOK....
There is some potential for MVFR in low clouds associated with
a frontal system from Thursday into Friday. This potential may
linger into Saturday in ACY and MIV as the southward progression
of the front slows. In addition, any showers or thunderstorms
during this time frame may briefly reduce ceilings and
visibility`s to IFR. Otherwise, VFR for the remainder of the
period.

&&

.MARINE...
Most of the showers and tstms have moved away from the waters,
except for Delaware / SE NJ where showers and tstms will be
around for a few more hours. SW winds over the srn waters and
E/NE elsewhere.

OUTLOOK...
Wednesday through Saturday...A Small Craft advisory may be
needed on Thursday and Friday.

RIP CURRENTS...

A low risk of rip currents is currently expected for the
Delaware and New Jersey beaches on Tuesday. However, an
underlying longer period swell may raise the rip current risk to
moderate along the New Jersey coast.

&&

.TIDES/COASTAL FLOODING...
Coastal Flooding Advisory lowered. Minor tidal flooding much
like Sunday evening occurred along the coastal areas.

&&

.EQUIPMENT...
Dew point readings at KDOV continue to measure too high
compared to surrounding locations and should be treated as
unrepresentative of the area.

&&

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

&&

$$
Synopsis...Franck
Near Term...PO
Short Term...Meola
Long Term...Franck
Aviation...PO/Meola/Franck/
Marine...PO/Meola/Franck/99
Tides/Coastal Flooding...PO
Equipment...



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