Selbyville, Delaware 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

331
FXUS61 KPHI 220000
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
700 PM EST Thu Nov 21 2024

.SYNOPSIS...
Low pressure strengthening off the New Jersey coast will
retrograde north and west overnight into Friday as it gets
captured by an upper level low. The low will linger near the
area through Friday then gradually move away through the
weekend. Weak high pressure briefly arrives for later Sunday and
Monday, followed by a cold front Monday night into Tuesday. A
low pressure system may affect the area around the Thanksgiving
Day timeframe.

&&

.NEAR TERM /THROUGH FRIDAY/...
The first measurable snowfall event of the season expected
tonight through early Friday across portions of the region.
Winter Storm Warnings and Winter Weather Advisories are in
effect.

A large closed upper low pressure system will pass from the
southern Great Lakes this evening toward the upper Mid-Atlantic
and southern New England by late Friday. At the surface,
strengthening low pressure offshore of New Jersey will lift
north into southern New England tonight, then retrograde back
into northeastern Pennsylvania by Friday afternoon.

The stratiform precipitation shield that developed across New
Jersey and eastern Pennsylvania earlier today continue to lift
north with the low pressure this evening. This will likely
result in a cessation of rainfall across much of the area south
of I-78 for several hours tonight, and much of the night in the
Philly metro and south will likely remain dry overnight.
Meanwhile, dynamic cooling will result in a change over from
rain to snow across much of the higher elevations. This has
already begun across the Pocono Plateau. PennDOT cameras
indicate some light accumulations already occurring in grassy
areas as of 6 PM. A change over to snow will occur into
northwestern New Jersey late this evening, with mostly snow
expected by midnight across elevations over 1,200 feet.

As the surface low and precipitation shield shifts back toward
the south and west around daybreak Friday, dynamic cooling
conditions will also shift south resulting in a change over to
snow south into the Lehigh Valley, Berks County, and even as far
south as the Philly metro area. The limiting factor for
accumulating snowfall outside of the higher elevations up north
will be the surface temperatures and southwest winds.
Temperatures likely hovering in the mid 30s much of the night
won`t support much if any accumulation outside of the higher
terrain. However if a heavier band of precip can develop and
pivot southward, the heavy rate of snowfall, dynamic cooling,
and little to no solar insolation early in the morning could be
sufficient to produce a slushy coating in grassy and elevated
surfaces early in the morning. Would not be surprised to see as
much as 1 to 2 inches in the higher elevations in Berks and
Lehigh Counties.

The Winter Storm Warning remains in effect as previously issued
for Carbon and Monroe Counties. Total snow accumulations
between 6 and 10 inches above 1,200 feet in elevation and
between 1 to 4 inches below 1,200 feet in elevation within the
warning area. Winds gusting as high as 35 mph. Would not be
surprised to see a report or two of around 12 inches near Mount
Pocono. A new Winter Weather Advisory was issued for Sussex
(NJ), Morris, Warren, and Northampton Counties. Total snow
accumulations generally between 1 and 3 inches within the
advisory area. Greatest snow accumulations at elevations over
1,200 feet, with totals near 4 to 6 inches possible.

The snow should switch back to mostly rain outside of the higher
elevations before tapering off into Friday afternoon and
evening. Expect high temperatures ranging from near 40 degrees
to the mid 40s near the coast. South to southwest winds 10-15
mph with gusts near 25-30 mph possible. Wind beginning to
diminish later in the day as the surface low center moves into
the forecast area. A rather raw and winter like day to be sure.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
The closed upper low and surface low will depart and strengthen
offshore into the weekend. This will place us on the fringe of a
tight pressure gradient with high pressure settling to our
southwest. This will result in dry, but seasonably cool and
breezy conditions Friday night through Sunday.

Any lingering light rain or snow will taper off by late Friday
evening. Expect highs generally ranging from the upper 40s to
mid 50s Saturday and Sunday. Lows Friday night in the low to mid
30s, and in the mid 30s to near 40 degrees Saturday night. West
to northwest winds 10-15 mph through the period (including at
night) with gusts near 20-30 mph possible during the daytime
periods. Partly to mostly cloudy skies.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Low pressure in the upper levels will slowly drift away from
the region as it continues to move east through Atlantic Canada
Sunday night through Monday. This will allow for a brief period
of ridging to move in bringing dry and tranquil weather. Lows
Sunday night will generally range from the upper 20s to the mid
30s with highs Monday mainly in the 50s except for some low 60s
over our southern most zones in Delmarva and some 40s over the
southern Poconos.

The next system will affect the area Monday night into Tuesday
as an upper level trough and associated surface low move
eastward through Ontario into Quebec. This will drag a cold
front through the area with some showers mainly for the Monday
night into early Tuesday time frame. This system will be
relatively moisture starved so not expecting large precip
amounts. Tuesday will still be relatively mild with high
temperatures similar to Monday but will be followed by colder
but dry weather for Wednesday as high pressure briefly returns.
Expect highs Wednesday mainly in the 40s to around 50 except 30s
in the Poconos.

As we turn our attention to the end of next week, most of our
available model guidance indicates a low pressure system
developing and affecting the east coast around about
Thanksgiving Day into that night. However given that this is a
week out, there is lots of uncertainty regarding the system`s
strength, track, and overall evolution including timing. The
track will help determine precip type (rain, snow, or a mix) but
it`s worth mentioning this looks like a setup where there won`t
be a strong, cold antecedent high. Therefore, currently not
looking like the best setup for a major snowstorm in the urban
corridor.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...A variety of conditions across the terminals. VFR will
give way to MVFR CIGs going through this evening from KRDG to
KABE and down to KTTN, KPNE, KPHL with timing generally between
03Z and 06Z. RA will develop after 06Z, with a RA/SN mix at
KRDG, KABE, KTTN and possibly KPNE and KPHL. A period of SN
possible prior to 12Z at KRDG and KABE. For KILG, KMIV, KACY,
VFR conditions. NW winds around 10 kt, backing to the W and
increasing to 10 to 15 kt with 20 to 25 kt gusts. Low confidence
overall.

Friday...IFR conditions develop at KRDG, KABE, KTTN, KPNE,
KPHL. Any SN will mix with RA late in the morning before
changing to plain RA by 18Z. For KILG, KMIV, KACY, VFR
conditions in the morning become MVFR and by 18Z, and then down
to IFR prior to 00Z. For these terminals, precip will be plain
RA. W to SW winds generally 10 to 15 kt with 20 to 25 kt gusts,
diminishing late. Low confidence overall.

Outlook...

Sunday night through Tuesday...VFR with no significant weather
through the day Monday. Some showers and associated restrictions
will be possible for a time Monday night into early Tuesday.

&&

.MARINE...
Conditions will remain at Small Craft Advisory criteria through
Friday, with a few periods of winds gusting to near gale force
across the ocean waters. Westerly winds shifting southwest on
Friday near 20-30 kts. Seas 4-6 feet. Small Craft Advisory
remains in effect for Delaware Bay and a Gale Warning remains in
effect for all Atlantic coastal waters through Friday.

Outlook...

Friday night through Sunday...Small Craft Advisory criteria
conditions expected. West to northwest winds 20-25 kts with
gusts up to 30 kts and seas 3-6 feet. Gale force wind gusts may
linger into the first half of Friday night near Delaware Bay.

Sunday night through Monday...The conditions are anticipated to
be below Small Craft Advisory criteria.

Tuesday...Small Craft Advisory conditions may develop behind a
cold front.

&&

.CLIMATE...
Driest autumn (Sep-Nov) on record, and any 3-calendar month
period on record, plus current status as of 4 PM EST Thursday:

                   9/1-11/20   Driest          Driest 3         Year/
Site              2024 precip  Autumn Year  Calendar months    months
Allentown (ABE)       2.51      3.81  1922      3.58        Oct-Dec 1928
A.C. Airport (ACY)    2.17      3.34  2001      2.35        Oct-Dec 1946
A.C. Marina (55N)     1.58      2.89  1941      2.52        Aug-Oct 1895
Georgetown (GED)      1.17      2.67  2001      2.20        Aug-Oct 2024
Mount Pocono (MPO)    4.17      4.21  1931      3.36        Oct-Dec 1928
Philadelphia (PHL)    1.98      2.37  1922      2.37        Sep-Nov 1922
Reading (RDG)         2.20      2.89  1922      2.89        Sep-Nov 1922
Trenton (TTN)         1.78      3.18  1922      2.66        Jun-Aug 1966
Wilmington (ILG)      1.61      3.17  1922      3.17        Sep-Nov 1922

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 10 AM EST Friday for PAZ062.
     Winter Storm Warning until 4 PM EST Friday for PAZ054-055.
NJ...Winter Weather Advisory until 10 AM EST Friday for NJZ001-007-
     008.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EST Friday for ANZ430-431.
     Gale Warning until 6 PM EST Friday for ANZ450>455.

&&

$$

SYNOPSIS...Fitzsimmons
NEAR TERM...Staarmann
SHORT TERM...Staarmann
LONG TERM...Fitzsimmons
AVIATION...Gorse/MPS
MARINE...Fitzsimmons/Staarmann
CLIMATE...RCM