Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
348 PM EDT Sat Apr 25 2015
low pressure located over the middle Mississippi River valley
this afternoon will progress to the east and it should pass off
the North Carolina coast late tonight. High pressure is forecast
to build gradually into our region from the northwest during the
early and middle parts of the new week. Another area of low
pressure is expected to pass off the North Carolina coast and move
out to sea on Thursday. A cold front from the northwest is
anticipated to pass through our region at that time with high
pressure following in its wake for Friday and Saturday.
Near term /until 6 am Sunday morning/...
into this evening and tonight, some light rain will gradually
spread across far southern portions of our forecast area, namely
the southern Delmarva, as an area of surface low pressure
approaches our region from the west and then redevelops just off
the North Carolina coast in early morning Sunday. As this system
will remain off to our south, it's only the northern edge of the
precipitation shield that will affect parts of our forecast area,
mainly our central to southern Delaware-Maryland-Virginia zones, where we do have
some likely to categorical probability of precipitation for rain from the late evening to
early morning hours of Sunday. We have also maintained some
chance/slight chance probability of precipitation extending a little farther north,
especially into southern NJ, where some light rain is possible
depending on the moistening of the boundary layer.
Otherwise, mainly cloudy skies are expected for the rest of the
forecast area through the bulk of tonight, except possibly for our
northern zones. It's there that the high cloud cover may not be as
thick, allowing temperatures to possibly fall off a little more
efficiently with light winds. This may allow for the opportunity
for some patchy frost to form, mainly for areas north of
Interstate 78. With this in mind, we have issued a frost advisory
for portions of northern New Jersey and adjacent areas in eastern
We mainly used a blend of met/mav guidance for overnight
temperatures, and we expect lows to range mostly from the middle
30s to the lower 40s.
Short term /6 am Sunday morning through 6 PM Sunday/...
low pressure off the North Carolina coast will advance farther
east and out to sea through the course of the day. Through the
morning, though, thicker clouds and a chance for some light rain
will remain for our southern zones as this system pulls away. The
rest of the forecast area can expect more of a partly cloudy day
with some light northerly winds and temperatures only slightly
below late April averages, milder than the last few days. Maximum
temperatures are expected to reach mostly the lower to perhaps
middle 60s, with some cooler 50s along the coasts of New Jersey
and Delaware and into the higher terrain of the Poconos.
Long term /Sunday night through Saturday/...
a partly cloudy sky is expected for Sunday night. Temperatures
are forecast to drop into the upper 30s to middle 40s range in
much of our region by daybreak on Monday. Some locations in
northern New Jersey could fall into the middle 30s with patchy
We should remain under the influence of a middle level low off Nova
Scotia during the period from Sunday night into Tuesday night. A
middle level trough rotating around the low is forecast to pass
overhead on Monday. The trough is expected to bring clouds to our
region for Monday into Monday night. Also, there is a chance of
showers on Monday into Monday evening. Any rain showers are
expected to be light being that the air mass is anticipated to be
quite dry and a fair amount of evaporation is likely.
A weak middle level ridge is forecast to approach from the west and
northwest on Tuesday as the middle level low moves farther out to
sea. The ridge should pass overhead on Wednesday. Both days are
expected to be dry.
The models continue to differ on the handling of the middle level
low that is anticipated to drop southeastward across the eastern
states late in the week. Also, there is disagreement in the
development and track of the associated surface features. We will
continue to favor the European model (ecmwf) solution with a coastal low passing
off the North Carolina coast. It continues to appear as though
most of its impact will remain to our south and east. We should be
influenced by a cold front dropping through our region on Thursday
and we will mention some clouds and a chance of showers for that
period of time.
Surface high pressure from the west and dry weather are
anticipated to follow for Friday and Saturday. A short wave trough
in the northwesterly middle level flow may pass overhead on Saturday.
It will have limited moisture associated with it and we are
expecting no more than scattered clouds at this time.
Daytime temperatures are anticipated to be below normal for
Monday and Tuesday. They are expected to be near normal for
Wednesday, Thursday and Friday, and they may go a bit above normal
Aviation /20z Saturday through Thursday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Through tonight...continued VFR conditions with some broken to overcast
high/middle level clouds at times. Winds will be mainly out of a
westerly direction around 10 knots or less into this evening, then
becoming more light and variable into the overnight. Leading up to
daybreak Sunday, winds will become more northerly and in the 5 to
10 knot range. Some light rain in the vicinity of the kmiv and
kacy sites is possible during tonight to early Sunday, and vcsh
has been included in the taf for these sites.
Sunday...overall, VFR conditions will prevail, with mainly
scattered clouds through the daytime. Northerly winds are
expected, mainly in the 5 to 10 knot range.
Sunday night...mainly VFR.
Monday...mainly VFR with a chance of showers.
Monday night through Wednesday night...mainly VFR.
Thursday...mainly VFR with a chance of showers.
sub-advisory conditions will continue for the coastal waters and
for Delaware Bay. A low pressure system is expected to pass to the
south of the region during the overnight to early Sunday, but
other than some light rain and a few wind gusts to 20 knots for
the southern coastal waters, little impact is anticipated.
Sunday night and Monday...no marine headlines are anticipated.
Monday night...a northwest wind may gust around 25 knots.
Tuesday through Thursday...no marine headlines are anticipated.