Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 300742
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
342 AM EDT SAT JUL 30 2016

.SYNOPSIS...
As a weak frontal boundary remains near our area today into early
next week, a few weak low pressure systems will track along it.
High pressure will build across our area Tuesday through Wednesday
before shifting offshore Thursday, then a cold front is scheduled to
arrive Friday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The rain showers that developed along a convergence zone late
yesterday persisted well into the overnight hours. Their motion and
redevelopment have been difficult to forecast being that they seem
to have been generating and feeding off mesoscale boundaries. The
showers were located between Hershey, Hazleton and Allentown around
3:30 AM. We expect them to weaken as they continue to drift
northeastward early this morning.

We will mention patchy fog for the early morning hours due to the
light wind and the abundant low level moisture.

We are anticipating a break in the potential for showers in our
forecast area for a few hours around and shortly after daybreak. The
chance of showers will begin to spread into our region from the west
during the mid to late morning. Showers are expected to become more
numerous during the afternoon as an impulse traveling in the mid
level flow begins to approach from the west. A developing south to
southeast surface flow will draw additional moisture into our
region. Precipitable water values are forecast to increase to around
2.0 to 2.1 inches. As a result, the rain may become heavy at times.
Marginal instability is expected to develop for this afternoon so we
have mentioned scattered thunderstorms.

We are expecting an increase in overall cloud cover today and
temperatures should not get above the 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
We continue to expect showers and scattered thunderstorms for
tonight as a couple of mid level impulses affect our region and as a
warm front approaches from the southwest and south. We will keep the
mention of rain, heavy at times, due to additional low level
moisture advecting into our region on a southeasterly flow off the
ocean.

Overnight minimum temperatures are forecast to be in the upper 60s
in the Poconos and far northern New Jersey and mainly in the lower
70s in the rest of our region.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
The synoptic setup is comprised of general troughing in the
Northeast to start that then becomes more amplified during early
next week. This should shift offshore midweek as some ridging starts
to migrate eastward from the Plains. The ridge axis may not arrive
until Friday, therefore a cooler airmass is for a few days next
week. We used a model blend for Sunday into Tuesday, then mostly
went with the 00z WPC guidance. Some adjustments were then made
however following additional collaboration with our neighboring
offices.

For Sunday and Monday...A couple of short waves will move across our
region as a frontal boundary remains in the vicinity. The result
will be some showers and thunderstorms. While the specific timing of
the short waves is less certain, the more widespread convective
activity should occur during peak heating and potentially be more
focused initially along a weak surface convergence zone. The PW
values are forecast to be around 2.00 inches and therefore locally
torrential downpours can occur. While any flood threat should be
localized Sunday, weak low-level flow may result in slow movers and
back building of any thunderstorms. Any robust convection may
produce quite a bit of lightning. Overall, the severe weather threat
looks rather low at this time. For Monday, an upper-level trough
sharpens and with some cooling aloft and increase in the wind
fields, a few locally stronger storms may occur during the afternoon.

For Tuesday through Thursday...A cold front should be south and east
of our area to start Tuesday, as high pressure builds in. This
surface high is forecast to be in place through Wednesday before it
shifts offshore Thursday. We are anticipating some lowering of the
dew points and also the temperatures. Some return flow however
starts to develop on Thursday, which should allow the dew points
to inch back up some.

For Friday...High pressure to our south and east will yield to a
warm front lifting well to our north. This will help assist in a
more south-southwest flow as a cold front approaches in the
afternoon, then the front should start settling across our area at
night. An area of warm air advection ahead of the front will allow
for afternoon temperatures to approach 90 degrees especially from
the Interstate 95 corridor on south and east. The overall timing of
the front will govern any convective threat as it appears that a lee
side trough may not be present. We carried slight chance to low
chance pops from west to east Friday afternoon and night.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Scattered showers will continue to affect areas around KRDG and KABE
early this morning. Also, we are anticipating early morning ceiling
and visibility restrictions at most locations. Most spots should
drop into the MVFR range for a time. However, IFR conditions are
possible at KRDG which received moderate rainfall during the night.

The daylight hours are forecast to be mainly VFR. However, showers
and scattered thunderstorms are expected to be on the increase as
the day progresses. Ceilings and visibility values are anticipated
to lower to MVFR and perhaps IFR tonight as a warm front approaches
from the southwest and south.

The wind direction should favor the south for today and it will
likely become southeast for tonight. Speeds are forecast to be
mostly less than 10 knots.

Outlook...
Sunday and Monday...Potential for MVFR ceilings to start each
morning, otherwise VFR with scattered to broken cloud cover. Some
showers and thunderstorms will be around especially Sunday and this
will lead to mainly local and brief restrictions.

Tuesday and Wednesday...VFR overall as high pressure builds in.

&&

.MARINE...
The wind is expected to settle into the south and southeast for
today around 5 to 10 knots. The wind is forecast to favor the
southeast for tonight and speeds may increase to 10 to 15 knots as a
warm front approaches from the southwest and south.

Wave heights on our ocean waters are expected to be 2 to 3 feet for
today and tonight. Waves on Delaware Bay should be 2 feet or less.

Showers and scattered thunderstorms are anticipated from this
afternoon into tonight.

Outlook...
Sunday through Wednesday...An onshore flow Sunday should increase
some especially across the northern coastal waters, with gusts to
about 20 knots. It appears at this point that that conditions remain
below advisory criteria. Otherwise, a weak pressure gradient should
keep winds and seas mainly below Small Craft Advisory criteria
through Wednesday. Main concern will be the threat of some
thunderstorms Sunday and Monday, however the greatest concentration
of storms may be inland.

Rip Currents...
For today, there is a low risk for the development of dangerous
rip currents along the coasts of New Jersey and Delaware. The
wind direction should favor the southeast at 5 to 10 MPH with wave
heights in the 2 to 3 foot range. We are anticipating a southerly
swell with a wave period around 6 seconds.

For Sunday, a low risk overall. However a moderate risk is
possible mainly along the northern New Jersey coast although this
will be dependent on the strength of an onshore flow.

&&

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

&&

$$
Synopsis...Gorse
Near Term...Iovino
Short Term...Iovino
Long Term...Gorse
Aviation...Gorse/Iovino
Marine...Gorse/Iovino


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