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fxus61 kphi 202340 
afdphi

Area forecast discussion
National Weather Service Mount Holly New Jersey
740 PM EDT sun Oct 20 2019

Synopsis...
a low pressure area will track offshore tonight. High pressure will
build in Monday and crest over the area Tuesday morning before
weakening. A cold front attached to low pressure in Canada will
cross the area later Tuesday and Tuesday night. Another high will
affect the weather for Wednesday and into Friday. Late during the
week, another disturbance will move towards the area.

&&

Near term /until 6 am Monday morning/...
wind gusts around 45 mph will be possible through late this
evening along the coasts and shore lines of Cape May County New
Jersey and Sussex County Delaware. Therefore, have issued a Wind
Advisory for those locations through 11 PM. Otherwise no
significant changes with the forecast at this time.

We are starting to see the back edge of the rain, though there
has been some redevelopment behind the initial clearing line, so
haven't made any changes to the pops at this time. Rain should
move out of the area overnight as the remnant low moves further
off shore.

Dew point depressions are already quite low, and although we
will see a wind shift to northerly overnight, significant dry
air advection is not expected until late tonight at the
earliest. This, combined with the wet ground and clearing skies
could lead to patchy fog development. The one factor working
against fog development is wind speeds, which will still be
quite breezy along the coast until very late tonight. Given all
the factors in favor of fog, I don't think it will be enough to
completely preclude fog development, though it may limit the fog
from becoming dense and/or widespread.

Because of the low dew point depressions, we are not expecting
temperatures to drop off too much overnight from Sunday afternoon.
Lows tonight are expected to be in the 40s and lower 50s across the
region.

&&

Short term /6 am Monday morning through 6 PM Monday/...
Monday will be a brief respite from the active weather pattern as a
surface high propagates directly over the region leading to
tranquil and dry weather for the region. Once the fog dissipates in
the morning, we should have mostly sunny conditions through the day.
Thus, despite northerly low level flow, temperatures are expected to
recover into the 60s for most locations, with highs near normal.

&&

Long term /Monday night through Sunday/...
an upper air pattern featuring faster flow and more energy develops
across the Continental U.S. With a large broad trough moving into the plains
and then weakening as it slides east. A ridge tries to develop
across the East Coast late week before another trough deepens across
the Great Lakes.

Temperatures...during the week, temperatures will not vary from
normal readings by very much. Normals for the Delaware valley this
time of year feature highs in the mid 60s with lows in the upper
40s. Across the north/west areas, normals are 6 to 8 degrees cooler than
the Delaware valley normals. Friday will probably be the warmest day
with highs 2 or 3 degrees above normal. The overnight period
Wednesday will be cool with mid/upper 30s across the north and
low/mid 40s elsewhere. More frost across the north/west areas is possible
then.

Precipitation...there are two periods during the long range which
will have the greatest chances for rain. First, a slow moving cold
front will cross the middle Atlantic later Tuesday and into Tuesday
night. This should bring some light rains across most areas during
the period. A weak low may form along the front across Delmarva. If
so, this could delay the ending time somewhat. Either way Wednesday
will be nice after perhaps some morning clouds.

Another system may arrive at the end of the work week and persist
into Saturday. The 12z runs of the ec and GFS differ quite a bit
with the details of the system. Nonetheless, it's possible that
this could bring another opportunity for some rains across the
area. The GFS shows that the low could tap into some Gulf of
Mexico moisture, so the potential for a soaker exits during the
first part of next weekend. Chc pops in the fcst at this point.

&&

Aviation /00z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Tonight...mainly sub-VFR conditions are expected for tonight, with
most areas seeing a slow trend towards improving conditions as the
night GOES on. Mainly IFR or low end MVFR expected through midnight
near and south of phl, with a trend towards VFR by 12z. Out west,
forecast confidence is a little lower. Expecting mainly MVFR
conditions initially, though periods of VFR are possible especially
towards the 04z to 07z time frame. There is then a chance for
another period of visibility restrictions due to fog, mainly near
ridge and Abe. Overall, moderate confidence on both trends and timing
in the tafs.

Monday...patchy fog near ridge and Abe could linger through 13z, but
once it dissipates, VFR conditions are expected through the day.
Northerly winds will veer to easterly or even east-southeasterly
through the day, but wind speeds should be less than 10 kt. High
confidence.

Outlook...
Monday night...VFR. Increasing clouds late.

Tue/Tue night...lower ceilings and visibilities with occasional showers.

Wed thru Fri...mostly VFR.

&&

Marine...
the remnant low of Nestor moves into the Carolina coast this
afternoon, and then out to sea tonight.

Small Craft Advisory conditions have already developed on much of
the waters. Gales force gusts are expected to develop soon on the
Delaware coastal waters and the southern New Jersey coastal waters by this
evening. We have seen a few gale gusts already in the vicinity of
Lewes and Cape Henlopen. Therefore, the Gale Warning was expanded to
include the lower Delaware Bay.

Small Craft Advisory and gales are expected to continue for most, if not all of
tonight, though winds are expected to gradually diminish overnight.
By Monday morning, winds and waves should be below Small Craft Advisory criteria on
the Delaware Bay. On the Atlantic coastal waters, Small Craft Advisory conditions,
primarily for elevated seas, will continue through the day on Monday.

Outlook...
Mon night...sub-sca. Fair.
Tue...sub-sca. Showers.
Tue night into Wed morning...Small Craft Advisory possible. Showers Tue night.
Wed afternoon thru Thu...sub-sca. Fair.
Fri...winds and seas building. Showers possible late.

&&

Phi watches/warnings/advisories...
PA...none.
New Jersey...Wind Advisory until 11 PM EDT this evening for njz023-024.
Delaware...Wind Advisory until 11 PM EDT this evening for dez003-004.
Maryland...none.
Marine...Gale Warning until 6 am EDT Monday for anz452>455.
Small Craft Advisory until 6 PM EDT Monday for anz450-451.
Small Craft Advisory until 6 am EDT Monday for anz430.
Gale Warning until 2 am EDT Monday for anz431.

&&

$$
Synopsis...O'Hara

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