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Area forecast discussion
National Weather Service Mount Holly New Jersey
1022 am EDT Wednesday Apr 16 2014
a strong cold frontal system will continue moving offshore today
with high pressure building into the region for this afternoon and
tonight. The high pressure system will move into New England on
Thursday. By Friday another cold frontal boundary will approach the
region moving through the region on Saturday. High pressure will
once again move back into New England for Sunday and Monday as a low
pressure system develops in the plains. This low pressure system
will bring a warm front through the region Monday night and a cold
frontal boundary through the region Tuesday.
Near term /until 6 PM this evening/...
the current forecast seems to be on track so only minor
adjustments were made to temperatures and winds. Gusty northwest winds are
continuing to blow this morning causing wind chills in the 20s in
spite of ample sunshine. The morning visible satellite imagery
shows some patches of snow cover over parts of eastern PA and New Jersey.
All rain, sleet, and snow has moved offshore this morning and we
are left with partly to mostly cloudy skies early this morning.
The only exception to this is some lake effect snow
showers/flurries across the Poconos within the northeast flow.
These could continue for a few hours, but as the winds begin to
swing more north then northeast, the flow off the lakes will get
cut off and end the snow shower chance. We will keep isolated snow
showers for a few hours across the Poconos this morning.
High pressure will build across the area today allowing dry air to
settle across the area through the day. Winds will be gusty
through the morning hours into the early afternoon, but as the
high builds over the area, the winds will lighten and the gusts
should drop off. Temperatures today will not be able to warm much
as 925 mb temperatures top out around -1 to -2 degrees celsius.
MOS numbers were fairly close, so we used a blend of mav/met MOS,
MOS guide, and European model (ecmwf) grids. This yields afternoon highs well below
Short term /6 PM this evening through 6 am Thursday/...
high pressure will build across New England overnight tonight into
Thursday morning, but still extend southward across our area. This
will keep dry weather across the area through tonight and Thursday
morning. MOS numbers were fairly close, so we used a blend of
mav/met MOS and MOS guide. This yields overnight lows well below
normal once again. The freeze watch will remain in place as
temperatures are expected to drop to or below freezing by Thursday
morning. We will keep frost in the grids as winds will be lighter
than last night/this morning, but there may still be enough of a
breeze in most places to prevent widespread frost from occurring.
Long term /Thursday through Tuesday/...
Thursday and Thursday night: looks to be a relatively quiet period
under northeasterly flow from the frontal boundary offshore and high
pressure to our north. The one concern may be some low clouds and
drizzle that advect in from the ocean along the immediate coast. For
now left it less than a slight chance for the far southeast portions of the
County Warning Area in line with the sref and 00z NAM/GFS. Thinking the frost threat
may be more limited this period due to several factors such as cloud
cover and some wind with slightly warmer temperatures. Took frost
out of the grids in this timeframe though some isolated frost can
not be totally ruled out. Think once again the raw modeled two meter
temperatures will be to cool with the 850 mb temperatures over 0c. Went
close to mav/met guidance for temperatures during the day then
went slightly warmer than mav/met at night due to clouds.
Friday through Saturday night: low clouds and some spotty showers/
drizzle may still advect in for coastal regions on Friday going more
in line with the NAM/GFS and sref. Though confidence on the extent
on any potential low clouds and drizzle is lower than ideal. This
should break up by Friday night along the coast with inland sections
remaining partly cloudy. It appears that a frontal boundary
will move from the Great Lakes through the region as a low pressure
system tracks along the southeast coast staying separate,
preventing a larger impacting event. Moisture ahead of the frontal
passage on Saturday looks limited so only a few hundredths for
quantitative precipitation forecast. Pretty tight spread among models and mex guidance with
temperatures in these periods.
Sunday and Sunday night: looks like a good weather day across the
region. With plentiful sunshine went more toward mex/wpc guidance on
Monday through Tuesday night: next system will be a cold front
approaching from the west by Monday night will include a chance of
showers from Monday night through Tuesday night. Went more in line
with the 00z GFS in this period as the new 00z European model (ecmwf) has a anomalous
cut-off low over the southeast United States which acts a block for
the front. Did go lower than wpc guidance for temperatures on Tuesday
given potential rainfall.
Aviation /14z Wednesday through Sunday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
VFR conditions will prevail through the taf period. Gusty northwest
winds will diminish through the day as high pressure builds across
the area. Winds will become more northeast later this evening and
overnight as high pressure builds across New England.
Thursday through Friday night... mainly VFR, some scattered low
ceilings Thursday night and Friday morning southeast of kphl.
Saturday: mainly VFR, possible brief periods of MVFR in scattered
Saturday night and sunday: VFR.
although still gusty...winds have diminished somewhat over the
forecast waters as of middle morning. Therefore the gale warnings
will be lowered at 1000 am and replaced by a Small Craft Advisory.
Winds are expected to diminish below Small Craft Advisory criteria by late
afternoon...however seas will likely remain at or near Small Craft Advisory levels.
So the Small Craft Advisory for coastal waters GOES through tonight and will likely
need to be extended beyond that.
Otherwise...winds will remain gusty across the waters until high
pressure builds across the area and helps diminish the winds.
However, winds may remain gusty around 15-20 knots through
tonight. Seas are expected to subside to around 4 feet later today
into this evening, but should build again overnight as a northeast
fetch takes place and will likely increase seas once again to 4-6
Thursday through Friday night: Small Craft Advisory seas throughout the period on
the ocean and some Small Craft Advisory gusts likely Thursday.
Saturday and sunday: sub Small Craft Advisory seas and winds.
PA...freeze watch from late tonight through Thursday morning for
New Jersey...freeze watch from late tonight through Thursday morning for
Delaware...freeze watch from late tonight through Thursday morning for
Maryland...freeze watch from late tonight through Thursday morning for
Marine...Small Craft Advisory until 8 am EDT Thursday for anz450>455.
Small Craft Advisory until 2 PM EDT this afternoon for anz430-