Scientific Forecaster Discussion
fxus61 kphi 150216
Area forecast discussion
National Weather Service Mount Holly New Jersey
916 PM EST Thu Nov 14 2019
high pressure off the New England coast will shift northeastward
through tonight. A cold front will drop southward into the area
Friday night with high pressure building to our north. Low
pressure will develop off the southeast coast on Friday, moving
slowly east northeast into the weekend, remaining well off the
coast. Another coastal system may track northward off the
Carolina coast once again toward the middle portion of next
Near term /until 7 am Friday morning/...
surface high pressure centered off the New England coast will
lift northeastward overnight as a weak frontal boundary nears
the Ohio Valley region.
A mid to upper trough will dig southward into the Ohio/Tennessee valleys
as a frontal boundary develops along the eastern Seaboard
tonight. As warm air advection increases along the mid-Atlantic, a broad area
of low pressure develops along the aforementioned boundary,
spreading precipitation northward. The models continue to show
an area of precipitation skirting Delmarva and southern New
Jersey late tonight, keeping the bulk of the precipitation to
our south. Continue to mention a slight chance/chance of showers
overnight into the early morning. On the northern fringes of
the precip shield, low level temperatures could favor some very
light wintry precip, but with marginal temps and limited qpf,
do not anticipate that much, if any, wintry precip will reach
the ground. With plentiful mid to upper level clouds persisting
in a warm air advection regime, temperatures will be a touch warmer, ranging
from the 20s across our northern zones to the low to middle 30s
Made some adjustments to the temperatures and dew points mostly
as some warming has occurred as the cloud cover has increased
this evening. Otherwise, the forecast looks to be on track for
Short term /7 am Friday morning through Friday night/...
low pressure is expected to develop off the southeast coast
on Friday, as the frontal boundary along the coast nudges
eastward. Locally, any precipitation will come to an end early
Friday morning as drier west northwesterly winds develop. This
will lead to dry conditions and a decrease in cloud cover
throughout the day, although still expecting some high clouds
as the upper jet takes its time to exit to the northeast.
Temperatures on Friday will moderate again, extending well into
the 40s to lower 50s. A dry cold front will push southward from
the Great Lakes region Friday night, weakening as it settles to
our south Saturday morning, and strong Canadian high pressure
builds to our north. This will result in an increasing pressure
gradient and an uptick in northerly breezes by daybreak
Saturday. Lows Friday night will fall back into the 20s to
lower 30s as cold air advection commences.
Long term /Saturday through Thursday/...
dry and mostly clear throughout the day on Saturday, as high
pressure builds into the northeast U.S. This will result in cooler
than average temperatures across the forecast area, with highs into
the mid 40s. Cold conditions continue into Saturday night as well,
with overnight lows in the mid 20s inland, and low to mid 30s along
The forecast becomes trickier for the end of the weekend into
next week. Friday into Saturday a potent upper level system
will move through the southeast Continental U.S. And spawn a strong coastal storm
developing off the southeast coast. This storm will then begin to drift
slowly north by Sunday. However its northward progress will be
impeded by strong high pressure over the northeast. The upshot
is that by Sunday some moisture from this slow moving ocean
storm will be trying to work northwestward towards the area and
could bring some light precip mainly to areas S/east of the I-95
corridor. Elsewhere clouds will at least be on the increase
leading to a mostly cloudy day across the region. The other
story will be the winds as NE winds will be increasing due to
the pressure gradient between the ocean storm to our south and
the strong high to our north. NE winds along the coast may reach
20-30 mph with some higher gusts possible. These onshore winds
will also bring a threat of coastal flooding and this is
detailed in the tidal section below. Highs Sunday will be
mostly in the 40s so it will be a cool, raw, day.
Uncertainty in the track and evolution of the storm off the
coast increases as we head into next week. The GFS kicks the
storm north and east fairly quickly and also keeps it far enough
east to spare US much precip. Meanwhile, the European model (ecmwf) and the Gem
swing another strong upper level disturbance around the base of
the long wave trough over the east and indicate this feature
will tend to capture at least a piece of this storm bringing
more widespread, and potentially heavier precip into the region
by Monday. Given the consensus of these two models and that they
can tend to perform quite well in these types of cases pops were
raised for Monday. For most of the region any precip should be
mostly rain but the other fly in the ointment will be the
coolish airmass this precip would be moving into and this could
result in some wintry precip over northern parts of the County Warning Area
towards the southern Poconos and northwest New Jersey. Given that marine air
may tend to move in over this cooler air in place these areas
that get wintry precip in the north could see some sleet or
freezing rain. But again, this is several days out so confidence
in these details is low at this point. It's possible precip from
this system could even linger into next Tuesday and Wednesday
but any that remains should be trending lighter by this point
with the trend being towards drier weather for the middle to
end of next week.
Overall, temperatures will be colder than average through the
long range but trending warmer by next Wednesday and Thursday.
Aviation /02z Friday through Tuesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Tonight...VFR. Light and variable winds. Some rain may move
through kacy and possibly kmiv between 06-12z with brief
restrictions possible. High confidence with low confidence that
sub-VFR conditions occur at kmiv/kacy.
Friday and Friday night...VFR. Winds turn west-northwest on Friday,
around 5 to 10 knots. VFR continues Friday night, with winds
picking up out of the northeast, gusting upwards of 15-20kts by
Saturday and Sunday...VFR ceilings seem likely for the
most part, though a lingering coastal low pressure system just
offshore on Sunday could bring some MVFR ceilings, and possibly some
rain, into the region, particularly along the coast. Winds from the
northeast at 10-15 knots on Saturday, gusting up to 25 knots inland.
Stronger winds along the coast (kacy) as well, with gust in the 30-
40 knot range possible (lower confidence). Gusty winds continue into
Sunday as well, continued out of the northeast at 10-15 knots,
gusting up to 25 knots.
Monday and Tuesday...rain from a coastal storm could affect the
region and also bring sub-VFR conditions. However winds should
tend to decrease during this period and be out of the north at
around 10 knots or less.
high pressure centered off of New England will drift
northeastward tonight while sub Small Craft Advisory conditions prevail, and seas
hover around 2 to 3 feet. Winds remain 15 knots or less on
Friday, before the gradient increases Friday night as strong
high pressure builds to our northwest and low pressure off the
southeast coast strengthens. Small Craft Advisory to borderline gale conditions
likely to develop Friday night.
Saturday and Sunday...gale force winds are quite possible
Saturday through Sunday, as an area of coastal low pressure
moves along the East Coast, remaining well offshore. A gale
watch has been issued for all areas except for the upper
Delaware Bay late Friday night through late Saturday night.
Monday and Tuesday...winds should diminish some into Monday, but
Small Craft Advisory conditions are still likely. Winds begin to
diminish Monday night into Tuesday.
northeast winds will increase through the weekend due to a strong
coastal storm to our south. This long fetch will result in a
piling up of water along the coast with at least minor coastal
flooding becoming likely in places in New Jersey and Delaware along the
Atlantic coast and Delaware Bay by sunday's high tide cycle.
It's possible some points could even reach moderate flooding but
this is still several days out so confidence in the details of
how high the tide gets is not high at this point.
Marine...gale watch from late Friday night through late Saturday night