Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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257
FXUS61 KPHI 250720
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
320 AM EDT Sun Jun 25 2017

.SYNOPSIS...
Surface high pressure over the Midwest gradually builds east as
an upper trough encompasses the Great Lakes and Northeast. High
pressure moves offshore Monday night, and then a cold front and
upper trough passes through the region Tuesday and Tuesday
night. High pressure returns on Wednesday, and then a series of
frontal boundaries will pass through the region through the end
of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure will be ridging across the area today while low
pressure remains to the north. A dry day with mostly sunny skies
is expected by-in-large. There could be a few isolated showers
across the southern Poconos this afternoon. We have reduced the
pops slightly from the earlier fcst. Temperatures will be
seasonable for late June with low 80s across the north and mid
80s over Delmarva and metro Philadelphia. Winds will be west to
northwest around 10 mph.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
Fair weather will continue tonight with mostly clear skies and
light winds. Low temperatures will drop into the low/mid 50s
across the north and upper 50s to low 60s elsewhere. Winds will
be light and variable.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
The first half of the new week will feature surface high
pressure building into the Southeast U.S. as an upper trough
digs into the Great Lakes and Northeast. Several shortwaves will
pass through the base of the trough Monday and Monday evening,
and this may touch off some isolated showers and thunderstorms,
mainly north and west of the Fall Line. Monday will end up being
dry for most of the region due to the influence of the surface
high south and west of the region, and temperatures will be
several degrees below normal, topping off in the mid to upper
70s. Humidity levels will be quite comfortable, as surface
dewpoints will be in the 40s and low 50s.

On Tuesday, a stronger shortwave will dig through the OH/TN
Valleys and into the Appalachians and will push a cold front
into the region through the region during the afternoon and
evening. Weak surface low pressure develops off the Mid-Atlantic
coast, but this low looks to be too far south and east to have
much of an impact for the Mid- Atlantic and Northeast coasts.
However, the 00Z ECMWF is showing a closer track to the coast
than the NAM/GFS/CMC-GDPS, so this does bear watching. For now,
will keep PoPs capped at slight chance- chance with the passage
of the cold front. Another relatively cool day on tap with highs
once again in the 70s.

High pressure builds into the Mid-Atlantic on Wednesday, and
then moves offshore Wednesday night. Dry with plenty of
sunshine, and temperatures tick up a few degrees as compared to
Tuesday with comfortable humidity levels.

From there, an upper trough digs into the Northern Plains and
gradually works its way east into the end of the week. Several
strong shortwaves will dive into the base of the trough, and
surface low pressure develops out ahead of the trough. Each low
will pass north of the region from Thursday through Saturday,
but each low will drag a weak frontal boundary through the
region. This will touch off scattered showers and thunderstorms
during this time, but the forecast may end up reading worse than
it may actually end up being.

With surface high pressure now offshore for the end of the
week, SW flow will tap into Gulf moisture and brings a return to
the heat and humidity across the region. Highs climb back up
through the 80s to around 90 with dewpoints building through the
60s and into the low 70s by the weekend.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Good flying weather across the region today and tonight. Low
pressure remains to the north while a ridge of high pressure
builds over our area. Winds will generally be from the west or
southwest much of the day. Winds speeds will mostly be around 10
knots after mid-morning. A few gusts closer to 20 knots are
possible. Tonight, mostly clear skies expected and winds under 5
knots.

OUTLOOK...

Monday and Monday night...Mostly VFR, but isolated SHRA/TSRA
possible at KRDG/KABE. SW winds 10-15 KT with gusts to 20 KT
during the day and less than 10 KT at night.

Tuesday...Mostly VFR, but isolated SHRA/TSRA possible, mainly
in the afternoon/evening. SW winds 10-15 KT with gusts to 20 KT
during the day and less than 10 KT at night.

Wednesday...VFR conditions expected.

Thursday...Mostly VFR. Isolated SHRA/TSRA possible.

&&

.MARINE...
Good weather expected on the waters today and tonight. The
remaining SCA flag that was up for the northern NJ coastal
waters will be taken down with the 330 issuance. Seas will
mostly remain around 3 ft on the ocean today and 1-2 ft across
Delaware Bay. Winds will be northwest this morning and then west
or southwest tonight.

OUTLOOK...

Monday through Wednesday...Winds and seas should stay below SCA
criteria. Isolated SHRA/TSRA possible Monday through Tuesday.
Dry on Wednesday.

Thursday...SCA conditions may develop in the afternoon.

.RIP CURRENTS...
We will forecast a low risk for rip currents for today and tonight.

&&

.TIDES/COASTAL FLOODING...
Tide levels may approach but not quite exceed minor coastal
flooding thresholds with the evening high tide tonight. Will not
issue a Coastal Flood Advisory at this time. A similar
situation may develop again with Monday evening high tide.

&&

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

&&

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



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