Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 230139
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
939 PM EDT Thu Sep 22 2016

.SYNOPSIS...
A cold front will move across the area later on Friday into Friday
night. High pressure will build across the northeast over the
weekend into early next week. A warm front is expected to lift north
of the area around Tuesday, while a cold front remains to our
west.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
High pressure off the coast will move away from the area tonight.
This will keep quiet and dry weather conditions over the region.
Though temperatures have dropped off quickly and there will be
prime radiational cooling, lows are expected to be at or slightly
above normal.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A weak front will pass to the n late Friday as large high
pressure builds down from Canada. This front may trigger some
showers or even a thunderstorm mainly over northern areas late
Fri aftn. There is some disagreement in the guidance with respect
to this feature. The NAM/WRF brings the precip further s, even to
the 1-95 corridor. The ECMWF, on the other hand, is virtually dry.
For now, the GFS seems like a good compromise, keeping the precip
over the n. Temps will be more summer-like in the mid to upper
80s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
The cold front will fully push south of the area Friday night.
There will be a slight chance of showers, mainly across the
northern third of the area, as a short wave/vorticity impulse
slides across the area and interacts with the front. High pressure
will then build across the northeast over the weekend and into
Monday of next week. This will bring cooler weather to the area,
along with dry conditions.

There are differences between the GFS and ECMWF as we move into
Tuesday, as the GFS lifts a warm front through the area, while the
ECMWF moves a cold front across the area. We decided to stay
closer to WPC and continuity. This would keep the cold front to
our west through the end of the week, before it possibly reaches
the area Thursday into Friday. There will remain a slight chance
of showers each day from Tuesday through the end of the week,
although it will only be 20 percent at this time.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

VFR conditions are expected tonight and tomorrow. There remains a
small chance for fog, primarily at the more rural TAF sites, but
have removed any mention from the TAFs as dew points are running
lower than they were at this time last night, and there was
limited fog development last night. Winds are expected to be
light and variable through at least 12Z, before settling in out of
the west by 15Z. Even after 15Z, wind speeds should be less than
10 kt.

A cold front will begin to work south late in the day tomorrow
(and may not arrive at the TAF sites until Friday evening). There
is a slight chance of rain showers with the front at KABE, but do
not expect any TAF sites will see much impact other than a quick
shift to northerly winds.

OUTLOOK...

Friday night-Tuesday...VFR conditions expected.

&&

.MARINE...
Wind gusts near 20 kt are possible through the overnight hours,
and seas should stay in the 2 to 4 foot range tonight and
tomorrow. However, winds and seas are expected to remain below SCA
criteria.

OUTLOOK...

Friday night-Saturday...Conditions may approach Small Craft
Advisory levels. Winds may gust around 20 to 25 knots at times
behind a cold frontal passage Friday night into Saturday morning.
Seas could approach 4-5 feet during the day Saturday as well.

Saturday night-Tuesday...Sub-Small Craft Advisory conditions
expected through. Winds may gust around 20 knots at times.

RIP CURRENTS...
The probable risk for the formation of dangerous rip currents on
Friday is low, but it may be on the cusp of moderate depending on
how quickly winds will shift out of the west.

Weekend...There is a chance of a moderate risk for the formation of
dangerous rip currents on at least one of the weekend days, as a 3
to 4 foot east-southeast swell from Tropical Cyclone Karl arrives
along with a gusty northeast wind. Karl`s lack of development may
result in a lower swell which would help reduce the potential
risk for the formation of dangerous rip currents.

&&

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

&&

$$
Synopsis...Robertson
Near Term...Johnson/Nierenberg
Short Term...Nierenberg
Long Term...Robertson
Aviation...Johnson/Nierenberg/Robertson
Marine...Johnson/Nierenberg/Robertson


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