Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 251349
AFDPHI

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

.SYNOPSIS...
A cold front will continue to move south of the region today. High
pressure eventually builds in from the Great Lakes tonight and
Wednesday morning before moving offshore Wednesday afternoon and
night. A warm front approaching from the southwest on Thursday is
expected to stall over the area Thursday night and Friday.
Meanwhile, a wave of low pressure tracking along the boundary will
move through the Mid-Atlantic states. The front should progress
south and east of the region Friday night once the low moves
offshore. High pressure returns for the weekend and into early next
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The cold front which brought the showers and tstms to the area last
night has moved offshore. Lingering patches of low clouds/fog
and some isolated light showers remain across much of the area.
The showers should start to dissipate through the morning as
drier air moves into the region. Drier air will arrive across
the area today, but with the onshore low level flow and the
upper trough moving across the area, it may take until afternoon
for breaks develop in the clouds. We`ll keep the fcst mostly
cloudy early today then bring in improved conditions for the
afternoon. Across the western parts of the area, there has been
less low cloud cover and a few more breaks have been seen.
However, some lower clouds may move through that area through
mid morning.

High temperatures will be in the 70s across the north and low
80s over Philadelphia and Delmarva with the high occurring later
in the day. Parts of the Poconos and the higher elevations of
northwest New Jersey may not break out of the 60s today as cloud
cover remains thicker in those areas. Winds will remain mostly
E or NE at around 10 mph.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
High pressure will be across NY and NE tonight. The onshore flow
over our area will result in cloudy periods, but no precipitation is
expected. It will remain seasonably cool with lows in the mid/upper
50s over the north areas and low/mid 60s over srn NJ and much of
Delmarva.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Long term forecast remains mostly unchanged as most of this
shift was focused on short-fused products (convective and flood)
and monitoring (e.g., radar and river gauges).

The next round of active weather for our area looks to be Thursday
night through Friday night with another threat of heavy rainfall and
severe thunderstorms. Global model guidance is in fairly good
agreement regarding the synoptic pattern (a wave of low pressure
tracking eastward along a stationary front through the Mid Atlantic)
and timing of the heaviest rain falling on the calendar day Friday.
Both the WPC excessive rainfall outlook and SPC severe thunderstorm
includes our area in a slight risk for D3. There is quite of bit of
support from operational guidance (and its ensembles) QPF fields for
2-4 inches of rainfall. The wet antecedent conditions will heighten
the concern for flooding with this event. Will continue to mention
both potential hazards in the HWO.

Outside of the late-week event, the long-term period looks to be
quiet and void of any significant heat (possibly below 90F for
the next seven days).

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Ceilings have been bouncing around a bit this morning but for
the most part MVFR, with patchy IFR, conditions prevail. Some
clearing is noted to the west and some of the terminals may see
a brief period of VFR this morning. However, widespread VFR
conditions are not expected at the terminals until this
afternoon.

The synoptic onshore flow will likely keep enhanced moisture
over the area today and tonight. We will have mostly cloudy
skies with VFR cigs over the area much of the afternoon and
early evening. A change back to MVFR is possible tonight, but
confid in this is medium at best.

OUTLOOK....
Wednesday-Thursday...Potential for MVFR CIGs with moisture
trapped below subsidence inversion, particularly outside of peak
heating (e.g., early morning and night time).

Thursday night-Friday night...Potential for MVFR or IFR
restrictions with moderate to heavy rainfall. Chance for TSRA as
well.

Saturday...Slowly improving conditions to VFR in wake of the
previous storm system. Breezy N-NE winds possible early in the
day.

&&

.MARINE...
The cold front has moved offshore and high pressure will build in
from the north today. Winds should remain mostly E or NE on the
waters today and tonight. Winds will likely remain short of SCA
levels, although there will probably be s few gusts over 20 kts at
times. Seas should mostly be in the 3-4 ft range. We will hold
off on any SCA flags for now. Fair weather expected across the
waters today and tonight.

OUTLOOK...
Wednesday-Thursday...Winds and seas below SCA criteria.

Thursday night-Saturday...SCA may be required for SW winds near
25 kt ahead of an approaching low pressure system Thursday
night and Friday, then NE winds behind it Friday night and
Saturday.


RIP CURRENTS...
A moderate risk for the formation of dangerous rip currents is
expected for the New Jersey beaches in Atlantic, Ocean and
Monmouth Counties owing to an underlying longer period swell and
a relatively strong northeast wind (15-20 mph). Farther south
along the coast, where the winds will be lighter and backed out
of the north or northwest, the risk is lower.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides tonight will be lower than the past few. Onshore
flow will continue however. There will probably be higher than usual
water levels tonight, but it will probably come short of minor tidal
flooding levels. No statements will be issued with this package.

&&

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

&&

$$
Synopsis...Klein
Near Term...Meola/O`Hara
Short Term...O`Hara
Long Term...Klein
Aviation...Klein/Meola/O`Hara
Marine...Klein/O`Hara
Tides/Coastal Flooding...


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