Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Mount Holly New Jersey
347 am EDT Sat Nov 1 2014

an area of low pressure to our east across the Atlantic will move
northeast through the day, while a second area of low pressure
moves off the Carolina coasts and intensifies as it moves
northward as well. These two lows will merge Saturday night into
Sunday and continue to move into the Canadian Maritimes through
Sunday night. High pressure will build to our south Monday into
early Tuesday, before moving offshore Tuesday night ahead of the
next frontal boundary expected early Wednesday. An area of low
pressure and its associated frontal boundary is expected to move
in from the west around Thursday.


Near term /until 6 PM this evening/...
as the now cutoff upper level low makes quick progress towards the
Carolina coast, the off shore low will continue to lift north until
it is east of the region by middle day. In response, the onshore flow
has already begun to increase and a broad area of light and moderate
rain will continue to propagate further inland. Pressure gradient
will continue to increase through the day, so expect the windy
conditions to continue through the day. At this time however, do not
expect Wind Advisory conditions today as abundant cloud cover will
limit the depth of the mixing layer. But will continue to monitor
especially for locations near the coast which could see a few gusts
near 40 miles per hour.

As the center of the middle and upper level low moves off shore this
afternoon, will see dry air begin to filter in to the region,
resulting in the precipitation dissipating from west to east.


Short term /6 PM this evening through 6 am Sunday/...
precipitation will dissipate for most land locations this evening. Even
though it is unusual to see windy or even breezy conditions continue
over night, the pressure gradient and low level height gradient will
continue to increase through the overnight hours. Thus, expect the
windy conditions to continue.


Long term /Sunday through Friday/...
on Sunday, the strong low pressure system will be moving through
the Gulf of Maine and into the Canadian Maritimes. Meanwhile, an
area of high pressure will be trying to build in from the west.
Between the two, a strong pressure gradient will remain across the
area through the day Sunday, which will lead to very strong winds.
Winds in the lowest 2,000-3,000 feet are forecast to be around
35-45 knots. This could lead to wind gusts well into the 30-40 miles per hour
range at the surface, and we could even have some gusts approach
Wind Advisory levels. Any left over rain is expected to have
pulled to our northeast by daybreak, and precipitable water values will be
dropping significantly, so we do not expect any precipitation
during the day.

By Sunday evening, the pressure gradient slackens some, but not
completely. So there will still remain a steady breeze, but as
daytime mixing is lost, the strong gusts should diminish through
the night.

On Monday and Monday night, high pressure will build to our south
and nose its way northward across our area. With little moisture
to work with and no short wave/vorticity impulses in the northwest
flow aloft, no precipitation is expected. There may be an increase
in clouds late Monday into Monday night as a piece of moisture
slides across the area, otherwise, dry weather will prevail
through Monday night.

On Tuesday, the high pushes off the southeast coast, which will
allow a return flow develop across the area with warming
temperatures and a increase in surface dewpoints. We do not expect
any precipitation through the day Tuesday, although an increase in
cloud cover is likely.

As we move into Tuesday night and early Wednesday, a cold front
is expected to approach from the west. Models are showing the
precipitation drying out/dissipating before it reaches our area.
However, there is a chance some isolated/scattered showers may
move into mostly our northwestern areas.

As we go through Wednesday night and Thursday, an area of low
pressure and its associated frontal boundary will swing out of the
Great Lakes and across the northeast. This should bring another
chance of precipitation to the area from Wednesday night through
at least Thursday and maybe lingering into Thursday night.

Friday looks to be another breezy day as low pressure remains to
our north. It's possible that some lake effect showers could
stream down from the northwest, but this is still pretty far in
the future so we kept them out of the forecast for now.


Aviation /18z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

For the 06z tafs...MVFR ceilings will soon overspread across the
region. The MVFR conditions are expected to continue through at
least middle day. Localized IFR ceilings are possible through middle
morning with some of the heavier areas of rain. Starting around 18z,
should see ceiling height increasing from west to east in conjunction
with -ra also ending from west to east. Expect all taf sites to
return to VFR by 00z, with the exception of Acy which should remain
MVFR (or lower) through Saturday night at least.

Winds will be shifting from northeasterly now to more northwesterly
after 18z. Speeds are also expected to increase through the day with
at least 15g25kt expected at all taf sites by 18z. Winds should be
strongest at kacy where 20g30kt or higher will be possible after 00z.

Sunday-Sunday night...VFR, but windy with northwest wind gusts 30-40
knots during the day. Gusts diminish overnight.

Monday-Tuesday night ... west-northwest wind gusts 15-20 knots
Monday afternoon. Winds diminish after sunset Monday.

Wednesday-Wednesday night...VFR with increase in clouds and possible
showers overnight.


gale conditions are expected to begin shortly on the New Jersey Atlantic
coastal waters, and on the Delaware Atlantic coastal waters and the Delaware Bay
after sunrise. Seas will build to 10 feet on the Atlantic waters and
up to 5 feet on the Bay later today. The gale conditions will continue
overnight tonight.

Sunday-Sunday night...Gale Warning remains in place through Sunday
night, but winds may begin to lower to Small Craft Advisory levels
overnight into Monday morning.

Monday-Monday night...Small Craft Advisory levels early, then
dropping below advisory levels during the day.

Tuesday-Wednesday night...sub Small Craft Advisory level conditions,
although winds may increase and get close Wednesday and Wednesday


Tides/coastal flooding...
a strong northeast flow associated with the strengthening low
pressure system off the East Coast will produce elevated water
levels down the shore through the weekend. Current guidance suggests
minor tidal flooding along both the New Jersey and Delaware coasts
for this afternoons high tide...and perhaps again at the time of
high tide early Sunday morning. The coastal Flood Advisory continues
for Sussex County in Delaware and Cape May and Atlantic counties in New Jersey
where minor tidal flooding is likely this afternoon. Based on the
latest guidance (which seems to be handling the current high tide
cycle well) minor tidal flooding is also expected for the coasts of
Burlington, ocean, Monmouth, and Middlesex counties. Though rainfall
amounts are not expected to be over an inch, any rainfall with high
tide could exacerbate the tidal flooding issues.

Right now elevated water levels are also expected in the Delaware
Bay, with pockets of minor tidal flooding possible at the time of
high tide Saturday afternoon and evening up through Reedy Point. No
flooding is expected at this time in the tidal portions of the
Delaware River...including Philadelphia.

No problems are currently expected along the shores of the
Chesapeake Bay affecting the middle and upper portions of the
Maryland Eastern Shore.


Phi watches/warnings/advisories...
New Jersey...coastal Flood Advisory from 1 PM this afternoon to 7 PM EDT
this evening for njz012>014-020-022>027.
Delaware...coastal Flood Advisory from 1 PM this afternoon to 7 PM EDT
this evening for dez003-004.
Marine...Gale Warning until midnight EST Sunday night for anz450>453.
Gale Warning from 8 am EDT this morning to midnight EST Sunday
night for anz430-431-454-455.



near term...Johnson
short term...Johnson
long term...Robertson
tides/coastal flooding...Johnson

National Weather Service Glossary of Abbreviations