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000
FXUS61 KPHI 210052
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
852 PM EDT Thu Jul 20 2017

.SYNOPSIS...
A cold front will approach the area tonight and cross through by
Friday morning. Weak high pressure will then prevail through
Saturday. Another front and associated low pressure will be across
the area Saturday night through Monday. High pressure will then move
in next Tuesday and remain into the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
     
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Severe Thunderstorm Watch till 10 pm trimmed back to only
Burlington, Ocean and Monmouth counties...

Our main concern is the convective complex that is moving across
central New Jersey. This complex of storms has a history of
wind damage as it moves southeast. Lapse rates are steep along
with mixed layer CAPE of 1,000 J/KG CAPE and sufficient 0-6 km
bulk shear around 30 knots. Storms will decrease in coverage and
intensity late this evening.

The sky over our region should become clear to partly cloudy. A
surface trough trailing the convective complex is expected to
pass through our forecast area late tonight.

The wind is anticipated to become light and variable overnight. Low
temperatures should be mostly in the 70s.
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&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...

Maximum temperatures on Friday will be similar to those of today.
However, the humidity is forecast to be slightly lower. We will
leave the Excessive Heat Warning in place for the urban corridor.
However, other areas should fall a bit short of their criteria for a
Heat Advisory.

The sky is expected to be mostly sunny on Friday. We will not
mention any precipitation due to the lack of any significant
triggering mechanism along with the continued existence of a capping
inversion aloft.

The wind should favor the west and southwest on Friday around 5 to
10 MPH.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
The heat wave will continue on into the weekend, but it will gradually
weaken with temperatures more in line with normal after Monday. A
few recent model runs are showing than high temperatures around 90
degrees readings  are possible Monday, something which has
changed since yesterday, but for now we will continue with upper
80s across the Philadelphia metro area and for Delmarva too.
Dew point temperatures will be lower over the area Saturday, but
then climb back to steamy values Sunday and early Monday. A
front will cross the area Monday and drier and cooler air will
arrive behind that for the middle of next week.

Shower and tstm chances will be rather low Friday night and into
Saturday morning, but then increase from w to e through the afternoon
as the the front and humid air return to the area. High chance
to low likely pops will be over the area Sunday into Monday as
the system passes the region. Lower pops will be over the area
Tuesday and Wednesday with high pressure settling over the
region.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

VFR conditions are expected through much of the TAF period with one
notable exception.

Any sub-VFR conditions and thunderstorms in TAFS to be removed
shortly. Thunderstorms ending and weakening.

Also, patchy visibility restrictions are possible during the late
night and early morning hours especially in areas where rain falls
this evening.

We are not anticipating any showers or thunderstorms on Friday.

A light southwest wind this evening is expected to become light and
variable tonight. A light northwest wind is anticipated for Friday
morning, then it should become west and southwest as the day
progresses.

OUTLOOK...
Fri night thru Saturday morning...VFR expected.
Saturday afternoon thru Monday...Mostly VFR. Sct showers and
tstms with lower conditions possible. Tue...Mostly VFR.
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&&

.MARINE...
High pressure over the Atlantic will continue to influence the
coastal waters of Delaware and New Jersey for tonight. A weak
frontal boundary from the northwest is forecast to arrive early on
Friday. The wind should favor the south and southwest at less than
15 knots tonight, becoming west to southwest on Friday. Wave heights
on our ocean waters will remain around 2 to 4 feet and waves on
Delaware Bay should be 1 to 2 feet. Thunderstorms on the
coastal waters from ACY northward may result in gusty winds for
a few hours this evening.

OUTLOOK...
Sub-SCA conditions overall. The main hazard will be sct tstms
mainly between Saturday afternoon and Monday. Locally higher
winds and seas with tstms. Bring your NOAA weather radio along
to get alerts.

RIP CURRENTS...

The underlying 10 to 14 second southeasterly swell is forecast to
persist into Friday. As a result, we will continue the moderate risk
for the development of dangerous rip currents through that time.

&&

.EQUIPMENT...
The KDOV dew point readings are unrepresentative of the area
and should not be used when diagnosing humidity/heat indices and
meteorological analysis of meteorological items which use
dewpoint in a calculation.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Excessive Heat Warning until 8 PM EDT Friday for PAZ070-071-
     102-104-106.
NJ...Excessive Heat Warning until 8 PM EDT Friday for NJZ015-
     017>019.
DE...Excessive Heat Warning until 8 PM EDT Friday for DEZ001.
MD...None.
MARINE...None.

&&

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