Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 020239

Area Forecast Discussion
National Weather Service Mount Holly NJ
939 PM EST Thu Dec 1 2016

A strong low pressure system will continue to move slowly through
northeastern Canada over the next couple of days keeping a cool
northwest flow over our region. High pressure over the Ohio Valley on
Saturday will move into the area on Sunday and then will move off to
the northeast late Monday. A complex low pressure system will track
through the plains into the midwest and impact our weather through
the mid week period.


A short wave ridge within the fast westerly flow aloft will
settle over the region. As a result, expect the stratocumulus deck
to continue to dissipate over the region. Given the pressure
gradient, northwest winds will maintain around 10 knots, with less
gustiness due to the loss of the daytime boundary layer. Low
temperatures will be near normal.


As the aforementioned shortwave ridging moves east, another short-
wave will approach the northwest late in the day. This will lead to
an increase in cloudiness, mainly owing to low-level instability/
moisture transport through the boundary layer, mainly north of I-78.
But the model mass fields indicate the deeper moisture and better
lift associated with the shortwave remaining to the northwest of
this area through the day. The 12Z NAM does generate some flurries
over the Poconos, although it is an outlier, as the rest of the
guidance suite is void of precip. In addition, the NAM was too far
southeast with its QPF on Thursday afternoon over NY/PA. We kept the
forecast dry.

High temperatures will be near normal, with northwest wind gusts of
20 to 25 mph from late morning into the afternoon.


Friday night...a shortwave will rotate through the
mid level flow and this will keep a northwest flow across our
area. Temperatures Friday night will drop down into 30s across the
region with some upper 20s in the southern Poconos. Moisture is
limited but with the strong northwest flow there may be some
flurries that make it into the Poconos late Friday night.

Saturday and Sunday...High pressure will start to build towards the
region on Saturday, reaching our area on Sunday. For the most part
we should remain dry during this time frame. Saturday will be
cloudier than Sunday but overall both days make for a decent
weekend. The northwest flow will remain and this will keep the
temperatures on the cool side, moreso on Sunday than on Saturday.
Highs will generally remain in the 40s, near 50s south and in the
30s across the north. Overnight lows both nights will range from
the upper 20s to low to mid 30s across the area.

Increasing cloudiness arrives in advance of an approaching
weakening shortwave. A shortwave arrives Sunday night but
enough moisture may be around for some light rain or snow showers.
We maintain low pops for Sunday night with the best chances to the
north and west of Philadelphia.

Monday through Thursday...The surface high starts to weaken as
strengthening low pressure near the Gulf of Mexico starts to move to
the northeast. The low moves into the Ohio Valley on Tuesday and
then splits. The southern low will track just south of our area as
it moves off to the east. The northern low tracks northward and into
the Great Lakes region. This split system will bring in some more
much needed moisture to the region. Precipitation will move in late
Monday night into Tuesday morning. As the low moves across Delmarva
and offshore, we should see the heavier rain across our southern
zones. With cold air in place, there will be a chance for some mixed
precipitation or rain changing to snow, mainly north of the I-95
corridor. A cold front will then drop down from the northwest and
cross the region Wednesday into Thursday. This feature should bring
more steady precipitation to our northern zones, where drought
conditions are ongoing. Temperatures are expected to be near normal
through through midweek.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

VFR conditions will continue through the TAF period. Lingering mid
level clouds (4000 to 6000 ft AGL) will continue to dissipate over
the next few hours. Gusty conditions have continued as some of the
TAF sites, but still expect wind speeds to diminish overnight,
remaining near 10 kt through 15Z, before increasing again with
gusts up to 20kt possible tomorrow.


Friday night through Sunday...mainly VFR conditions are expected.
West to northwest winds around 10 to 15 knots expected with gusts up
to 25 knots Saturday afternoon. Winds are expected to be less gusty
on Sunday.

Sunday night through Tuesday...mainly VFR conditions are expected.
Rain or snow showers are possible late Sunday night into Monday
morning and then again late Monday night and Tuesday. Best chances
for precipitation exist to the north and west of KPHL.


On the Delaware Bay and Delaware coastal waters, wind gusts above
20 kt are possible, but should stay just below SCA conditions. On
the coastal waters adjacent to NJ, SCA conditions for both winds
and seas continues with peak gusts generally between 25 and 30 kt
and seas right at 5 feet. Winds and seas should slowly diminish
late tonight.

Friday...Sub-SCA northwest winds thru the day, then increasing in
the evening with gusts up to around 25 knots likely on the ocean
waters after 21Z, especially northern NJ.


Friday night and Saturday...Increasing winds, especially late Friday
night, expected as cold air advection takes place over the waters.
Strong northwest flow of 20 to 25 knots with gusts up to 30 knots on
the ocean. Winds will start to subside late Saturday. Seas will also
increase into Saturday but look to remain just below 5 feet. A Small
Craft Advisory will likely be needed. There is also a small
possibility for same gale force gusts but confidence is low at this

Sunday and Monday...Sub-advisory conditions are expected on the area
waters as high pressure builds into and over the region.

Tuesday...a low pressure system will move into the area. Seas will
start to build on Tuesday and may exceed 5 feet. A Small Craft
Advisory may be needed.


MARINE...Small Craft Advisory until 3 AM EST Friday for ANZ450>453.


Near Term...Franck/Johnson
Short Term...Franck
Long Term...Meola
Marine...Franck/Johnson/Meola is the U.S. government's official web portal to all federal, state and local government web resources and services.