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fxus61 kphi 270359 
afdphi

Area forecast discussion
National Weather Service Mount Holly New Jersey
1159 PM EDT Wed Apr 26 2017

Synopsis...
a weakening low near Long Island this evening will move slowly
northeast overnight. A cold front will move across the area late
Thursday night and early Friday morning before another cold
front crosses Saturday night. A warm front is then expected to
lift north across the area Sunday night, followed by another
cold front Monday night. High pressure is then expected for the
middle of next week.

&&

Near term /until 6 am Thursday morning/...
as the weak low drifts northeastward, some clearing took place
over eastern Pennsylvania. However, the clouds began to build
back to the west once the sun set which is a bit faster than
previously thought. We will forecast a cloudy to mostly cloudy
sky for the balance of the night throughout our counties in
eastern Pennsylvania, New Jersey, Delaware and northeastern
Maryland. The quick return of the cloud cover should limit the
amount of fog we have overnight. We will continue to mention
only patchy fog in spots.

The wind is forecast to remain light and variable. Minimum
temperatures should favor the lower and middle 50s.

&&

Short term /6 am Thursday morning through 6 PM Thursday/...
mostly cloudy to start...but all model tsections fcst a much
brighter and warmer day... with a decent amount of afternoon
sunshine so have used the 12z/26 GFS/NAM MOS blend for the fcst
basis. Fcst temps are 7 to 13f above normal. Max T at phl may
reach 82 or 83.

&&

Long term /Thursday night through Wednesday/...
a cold front associated with low pressure moving north through
eastern Canada is expected to cross the region Thursday night,
then move off the coast Friday morning. Mainly scattered showers
are expected at this time, primarily from midnight through 6 or
7 am. A southerly flow aloft will maintain low temperatures in
the mid to upper 40s and high temperatures in the upper 70s to
low 80s, above normal for this time of year. The daytime hours
on Friday will feature mainly dry weather has high pressure
briefly builds into the region.

By Friday night, another frontal boundary is forecast to begin
approaching the area from the northwest as it crosses
Pennsylvania and New York. The front will sag south through the
area during the day Saturday, bringing with it some additional
shower activity, then stall to our south Saturday night into
Sunday. The subsequent onshore flow will cool temperatures down
to the 60s north and low 70s south on Sunday,but with mainly dry
conditions. This front is then expected to lift back north as a
warm front Sunday night into Monday morning, with an increasing
chance of showers as the day wears on with the approach of a
cold front from the west late in the day. Showers and
thunderstorms may accompany this front...especially later Monday
night into Tuesday morning. Instability in the warm sector
ahead of this front could even produce shower and thunderstorm
activity as early as Monday afternoon. High temperatures in the
70s are expected on Monday.

The front will move offshore by Tuesday morning, but a
secondary surface trough may move across the area during the
day. With a short wave/vorticity Max moving across the area
during the day, there could be some isolated showers across
northeastern Pennsylvania and northern New Jersey. Cooler
temperatures are expected through mid week, with lows generally
in the 50s and highs in the 70s.

&&

Aviation /04z Thursday through Monday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.

MVFR ceilings were being reported around 0130z at all eight of
our taf sites. The clearing that took place in eastern
Pennsylvania has proven more short lived than we originally
thought it would be. As a result, we have adjusted the tafs
accordingly.

We are expecting MVFR ceilings to prevail during the first part
of the night. Ceilings may lower near 1000 feet late tonight
and they could even drop a bit below that level in spots. Our
confidence in that occurring and where it would happen is low,
so we have limited our decrease in ceiling heights to the 1000
foot level. The cloud cover should prevent any dense fog from
forming at or near our taf sites.

We are anticipating that conditions will improve through MVFR
late on Thursday morning into the VFR category for Thursday
afternoon.

A light and variable wind overnight is forecast to settle into
the southeast and south on Thursday with speeds increasing to 5
to 10 knots.

Outlook...

Thursday night...generally VFR. A chance of showers overnight
which could temporarily reduce conditions to MVFR.

Friday...VFR conditions expected.

Friday night...VFR early. Patchy fog and low ceilings may develop
overnight.

Saturday...becoming VFR during the morning, then a chance of
showers during the afternoon. Conditions may temporarily be
reduced with any showers.

Saturday night-Monday...low clouds and fog may develop
overnight Saturday and continue into Sunday leading to reduced
conditions. There will also be a chance of showers.

&&

Marine...
starting to see visibilities along the coast to decrease near
one mile. Thus, have issued a marine dense fog advisory through
14z. Hard to determine how far off the coast the fog GOES, but
expect widespread fog at least near the shore. Will continue to
monitor through the night.

The Small Craft Advisory hazardous seas continues through
Thursday. Waves (virtually all se swell at 10-11 seconds) are
currently around 7 ft and will gradually subside through
Thursday.

Outlook...

Thursday night...Small Craft Advisory for hazardous seas
through Thursday night.

Friday...winds expected to remain below advisory levels, but
seas may remain elevated to advisory levels.

Friday night-Monday...winds are expected to remain below
advisory levels. Seas may approach 5 feet at times, but mostly
remain around 4 feet.

&&

Climate...
presuming our forecast temps these last 5 days of April are
accurate, we are assured of a top 3 warmest April on record in
much of our forecast area. Sunday is the critical day for
determining record or not.

Below: April projected within the top April avg temps, the
normal for April and the period of record (por).

Phl normal 54.0 por 1874

59.4 1994
59.2 2017?
58.5 1921
58.4 2010
57.9 1941

Abe normal 49.9 por 1922

56.6 projecting record
56.4 1941
54.7 1994

Acy normal 51.7 por 1874

57.2 projecting record
56.3 2010
56.1 2011

&&

Phi watches/warnings/advisories...
PA...none.
New Jersey...none.
Delaware...none.
Maryland...none.
Marine...dense fog advisory until 10 am EDT Thursday for anz430-431-
450>455.
Small Craft Advisory for hazardous seas until 6 am EDT Friday
for anz450>455.

&&

$$
Synopsis...miketta
near term...iovino

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