Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
952 am EDT Thursday Oct 23 2014
low pressure offshore will strengthen as it slowly tracks
northeastward today and tonight, then moves into the Nova Scotia
area Friday night. High pressure is forecast to build toward our
area from the southwest Friday and Saturday, then a cold front is
expected to move through Saturday night. High pressure builds in
for later Sunday and Monday before shifting offshore Tuesday. A
warm front may lift to our north Monday night and Tuesday, then a
cold front arrives Wednesday.
Near term /until 6 PM this evening/...
the low was centered about 200 miles off the New Jersey coast
this morning and it will continue to drift out to sea during the
balance of the day. The low will lose its influence over our
It should remain cloudy over our area for today with a northwest
wind around 15 to 20 miles per hour with gusts up to 30 or 35 miles per hour. The chilly
northwest flow and the lack of sunshine will prevent temperatures
from getting above the 50s this afternoon.
An area of light rain showers was dropping into the Poconos, the
Lehigh Valley, Bucks County and central New Jersey around 930 am.
It will continue to drift southwestward and it will dissipate
gradually. One final area of showers is forecast to move from
western New England and the Hudson Valley down into our northern
counties for the late morning and early afternoon hours before it
begins to dissipate.
The trend through the afternoon will be a decreasing chance of
Short term /6 PM this evening through 6 am Friday/...
skies will start to become less cloudy, especially across the
southwestern parts of the forecast area, as the surface and upper
lows make their way toward the New England coast.
All rain should have ended across the region and we should remain
dry through the night. Winds will decrease a bit tonight but will
not go light and variable, keeping a chill in the air.
Lows will largely be in the 40s across the forecast area.
Long term /Friday through Wednesday/...
a closed low is forecast to be moving away and weakening some
Friday. This will take surface low pressure with it as it tracks
near Nova Scotia Friday night. A short wave trough may then move
across the area Friday evening. As additional energy drives into
the Pacific northwest, a building ridge occurs across the plains
Saturday into Sunday. This will force another upper-level trough
down into the northeast over the weekend, however as it closes off
it looks to be centered across New England. A cold front tied to
surface low pressure will slide across our area Saturday night.
The aforementioned upper-level ridge then arrives in the east
during Monday into Tuesday, however with the progressive flow
pattern the next cold front is forecast to be driving eastward
late Monday and Tuesday. A return flow Monday night and Tuesday
should send a warm front to our north, then a cold front arrives
later Wednesday. We used a model blend for Friday through Sunday,
then blended the 00z wpc guidance in with continuity. Some tweaks
were then made after additional collaboration with our surrounding
For Friday...it appears drying works in as the closed low and
surface low shift farther to our northeast, and this should result
in a decrease in clouds with time. A tight pressure gradient
initially will result in breezy conditions, although a decrease is
anticipated quickly by evening as high pressure starts to expand
northeastward from the Tennessee Valley. A short wave trough looks
to slide across the area during the evening, however a lack of
deep moisture should only result in perhaps some clouds for a
For Saturday and Sunday...high pressure builds to our south
Saturday, however a strong short wave diving southeastward from
the Great Lakes will dig another upper-level trough across the
northeast later Saturday and Sunday. This will toss a cold front
across our area Saturday night, however limited moisture return
should result in perhaps an isolated shower across the north.
Another closed low is then expected to influence our weather,
however this is forecast to track across New England instead of
right over our area. The 00z NAM/European model (ecmwf) show a more amplified and
southerly solution with the closing low near New England, which
makes sense considering the amplifying ridge upstream. The
associated surface low looks to intensify as is exits New England,
which means a tightening pressure gradient down into the middle
Atlantic Sunday. As a result, a breezy day should occur as mixing
deepens /steepening low-level lapse rates/ under a northwesterly
flow. High pressure then starts to build in Sunday night with
decreasing winds and chillier temperatures.
For Monday and Tuesday...an upper-level ridge arrives in the east
allowing surface high pressure to build across our area Monday
before shifting offshore Tuesday. This is expected to result in
warming conditions, especially as warm air advection develops Tuesday in the wake
of a warm front and ahead of the next cold front. No major changes
were made for this time frame, with just some blending in of the
new 00z wpc guidance.
For Wednesday...the ridge axis is forecast to be shifting to our
east as an upper-level trough slides across the Great Lakes and
Tennessee Valley. A cold front tied to this feature should be
arriving into our area during Wednesday. Much of the energy may
slide to our northwest, however there is the potential for a
broken band of showers with the cold front itself. For now, went
with slight chance to low chance probability of precipitation in the gridded forecast from west
Aviation /14z Thursday through Monday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Ceilings are forecast to vary between MVFR and VFR into the early
afternoon hours as the final areas of rain showers associated with
the departing coastal low drop into our region from the northeast.
Conditions are forecast to begin drying during the middle to late
afternoon with ceilings expected to lift solidly into the VFR
range at that time. The VFR ceilings are forecast to continue into
tonight with perhaps some breaks in the cloud cover developing.
A northwest wind around 12 to 16 knots is anticipated to gust to
25 to 30 knots at times. The wind gusts are forecast to diminish a
bit for tonight. However, sustained wind speeds are expected to be
about 8 to 14 knots.
Friday...VFR. Northwest winds 10-15 knots with gusts to around 20
knots, then diminishing at night.
Saturday and Sunday...VFR overall. There is a low chance for a few
showers late Saturday as a cold front moves through. Southwest
winds Saturday at 10 knots or less, shift to the west and
northwest Saturday night and Sunday. The wind speeds Sunday
increase to near 15 knots with gusts to 25 knots, but diminish at
Monday...VFR. West to southwest winds less than 10 knots.
Gale Warning remains in effect until 6pm on the ocean waters and
lower Delaware Bay. A Small Craft Advisory remains in effect for
the upper Delaware Bay.
A tight pressure gradient will continue today across the area
waters. North to northwest winds 20 to 25 knots with gusts up to
40 knots across the ocean and Lower Bay, gusts will be closer to
30 knots across the Upper Bay. Winds will diminish this evening
and it looks like we lose the gale force gusts before midnight. A
Small Craft Advisory will likely be needed for a time after the
gales come down. Seas will subside gradually today and tonight.
Friday...northwesterly winds will gradually diminish as the
pressure gradient relaxes. This will also result in the seas
subsiding. Therefore, a Small Craft Advisory will be needed for at
least a portion of this time frame.
Saturday...the winds winds turn more west-southwest ahead of a
cold front, but then shift to west and northwest at night behind
the frontal passage. The winds are anticipated to increase, with
the conditions being just below advisory criteria until later at
Sunday...a tightening pressure gradient under a northwesterly
flow along with decent mixing should result in a period of Small
Craft Advisory conditions occurring. This will also build the
seas, however with the highest sets farther offshore given the
Monday...the conditions are anticipated to be below advisory
criteria as high pressure builds in.
spotty minor tidal flooding occurred this morning along the New
Jersey and Delaware oceanfront, on the back bays, on Raritan Bay
and on lower Delaware Bay. The northwest flow will continue to
push water away from the coast and no tidal flooding is
anticipated during the coming high tide cycles.
Marine...Gale Warning until 6 PM EDT this evening for anz431-450>455.
Small Craft Advisory until 6 PM EDT this evening for anz430.