-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 190451
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1251 AM EDT Wed Jul 19 2017

.SYNOPSIS...
A weak front will dissipate across the area tonight. It will be
followed by weak high pressure which will settle across the area
Wednesday and remain through Thursday. Another front will affect the
area later Friday into Friday night. The front will not move
far from the area and continue to bring unsettled conditions for
the upcoming weekend and into early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Frontal boundary continues to dissipate over the region. Most
of the convection has ended, but there are a few diminishing
thunderstorms west of Chester County. Those should end before
making it into SW portions of the forecast area.

Otherwise, warm and muggy tonight with abundant low level
moisture.

While some low clouds and patchy fog may develop toward
daybreak, it should not be as widespread as it was Tuesday
morning being that we will be more squarely in the tropical type
air mass.

Overnight temperatures are anticipated to be mainly in the
mid to upper 60s and the lower 70s. Winds should stay light and
variable.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
A fair amount of sunshine is expected for Wednesday along with a
southwest wind around 5 to 10 MPH.

Conditions will remain very warm and humid. Maximum temperatures are
forecast to be in the lower 90s at most locations, with readings not
getting above the 80s in the elevated terrain and along the
immediate coast. Maximum heat index values are expected to be
generally in the upper 90s, which is below the Heat Advisory
criteria.

The guidance is suggesting that an instability maximum may develop
over or near the Philadelphia metropolitan area on Wednesday
afternoon. Mixed layer CAPE values could rise into the 1000 to 1500
J/kg range. As a result, we will keep a low or slight chance of
showers and thunderstorms for that time period.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A pattern which favors above normal temperatures and occasional
showers is in the long term part of the forecast. Temperatures will
continue to be above normal Thursday through next Monday in many
areas. The heat will not be excessive however although heat indicies
may approach advisory levels at times. High temperatures will be
mostly in the low or mid 90s through Sunday and then a few degrees
less for next Monday. After that, temperatures should slip back to a
little below normal for Tuesday.

Precipitation will be typical for summer with mostly dry days and
chances for scattered showers and tstms. Thursday and Friday will
likely be the two days with the lowest chances for precipitation.
A front may bring some showers Friday night however. The front
will stall across the area, so the period Saturday through next
Monday will have almost daily chcs for showers and thunder. The
favored times are afternoon and evening.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Patchy fog/stratus may briefly lower conditions to MVFR/IFR in
the pre-dawn hours, and then that fog/stratus burns off between
12-13Z. Predominantly VFR thereafter.

Isolated to scattered SHRA/TSRA possible again this afternoon.
Best chances will be from KTTN-KPNE-KPHL-KILG, but confidence of
a storm developing over any given terminal is low, so will not
mention in 06Z TAF package.

Generally VFR conditions continue late tonight into Thursday
morning. Patchy fog possible, but less so compared to early this
morning.

LGT/VRB to calm winds through mid-morning, then W-SW winds 5-10
KT. Winds become nearly calm after 00Z Thursday.

OUTLOOK...
Wed night thru Fri...VFR conditions expected. A little early
morning haze or fog possible in rural areas.

Fri night thru Sunday...Mostly VFR, but sct showers and tstms
could bring lower cigs/vsbys at times. Favored times are
afternoon and early evening. Patchy pre-dawn fog psbl too.
-- End Changed Discussion --

&&

.MARINE...
High pressure over the Atlantic will continue to influence the
coastal waters of Delaware and New Jersey for tonight and
Wednesday. The wind should favor the south and southwest at less
than 15 knots. Wave heights on our ocean waters will remain
around 2 feet and waves on Delaware Bay should be 2 feet or
less.

OUTLOOK...
Generally sub-SCA conditions expected through the period. Sct
showers and tstms are possible mostly between Fri night and
Sunday night. Locally higher winds and seas in tstms.

RIP CURRENTS...

We will keep the moderate risk for the development of dangerous rip
currents along the New Jersey coast into this evening. There is a
low risk at the Delaware beaches.

We are anticipating a low risk for both New Jersey and Delaware on
Wednesday. However, an underlying 10 to 12 second southeasterly
swell may reach the coast on Wednesday afternoon possibly resulting
in a developing moderate risk at that time.

&&

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

&&

$$
Synopsis...O`Hara
Near Term...MPS
Short Term...Iovino
Long Term...O`Hara
Aviation...MPS
Marine...Iovino/MPS/O`Hara