Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 191351

Area Forecast Discussion
National Weather Service Mount Holly NJ
851 AM EST Thu Jan 19 2017

High pressure will build into the region today and move offshore
early Friday. Meanwhile, weak low pressure will impact the region
Friday afternoon into Friday evening. High pressure will return
for Saturday.  Then a stronger and more complex area of low
pressure will impact the Mid-Atlantic beginning Sunday and
continuing through Tuesday.


Special Weather Statement for patchy fog across northwest NJ was
allowed to expire as it continues to subside. No major changes to
the current forecast. With high pressure overhead today, there
will be some lingering clouds below the low-level inversion, and
light winds. High temperatures are on track to be around 10
degrees above normal.


High pressure at the surface and shortwave ridging aloft will result
in a quiet weather pattern for tonight. Expect temperatures to drop
rather quickly after sunset this evening under mainly clear skies
and light winds. Forecast low temperatures range from the mid to
upper 20s in the rural areas N of I-78 and the NJ Pine Barrens to
the mid 30s in the cities, at the coast and in the Delmarva region.
The arrival of mid to high clouds from our SW overnight is the
primary motive for keep low temps slightly higher in E MD and DE.


630 AM...A storm total ice grid for Friday afternoon/evening was
sent. Similar to this past event on Tuesday, the freezing rain
potential looks confined to the higher elevations of Monroe
County, PA and Sussex County, NJ.

Previous Discussion...
Fri mrng starts off dry, but a wk low will bring rain to the area
by aftn and continue into the eve. Overall, this shud be a quick
hitter and most areas will see light qpf. This precip moves out
durg Fri night and high pres builds in, bringing a dry day Sat
into erly Sun.

Then, an area of low pres over the srn plains will move newd and
begin to impact the region durg the day Sun. Mdls differ on the
timing of onset with the ECMWF being faster than the GFS. The
NAM/WRF and CMC are supportive of the slower timing so have
trended the fcst in that direction.

Nevertheless, rain will develop durg the day from s to n and
continue into Sun night. As the low approaches, ely flow will
increase and wind will pick up and precip will get steadier and
heavier Sun night into Mon. The guid is still differing on where
the axis of heaviest precip will be as well as the timing, but it
appears that there will be one wave of precip Sun night into early
Mon, then potentially a break and another shot later Mon into Mon
eve. Precip will then end from s to n Monday night into Tue.

Certainly by the time this is over we could be looking at 1 to 2
inches of rain, and possibly more depending on the track and
strength of the low.

Once the low passes by, wk high pres will build back in making for
an improving Tue and dry Wed.

ATTM, temps genly look to bee way too warm for any precip type
other than rain. However, there is at least a small potential for
some freezing rain Fri night before the precip ends in the
Poconos. If temps end up being colder than currently fcst than
that potential cud increase.

With that said, temps are expected to be aoa nrml thru the pd, in
some cases by 10 to 15 degrees. Monday will likely be the coolest
day, with an abundance of clouds and rain. Many areas will be aoa
50 degrees thru the pd.


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

Skies will clear later in the morning with mainly VFR conditions
expected today. However, with stratocu developing this afternoon,
there is a possibility that we see localized MVFR CIGs develop
sometime between about 18-22Z. Forecast soundings hint at this
happening at ABE-RDG but overall confidence in MVFR CIGs this
afternoon is low.

Under mainly clear skies and light winds tonight, there is a
potential for radiational fog overnight at the typical fog-prone
rural TAF sites. IFR conditions would be a possibility where fog

Fri through Fri night...Sub-VFR conditions possible in -RA.
Moderate confidence. Fog possible Fri night.

Sat/Sat night...Improving conditions Saturday morning, otherwise
VFR.  High confidence

Sun...E winds 10-15 KT. Conds deteriorating from s to n durg the
day. Moderate confidence.

Sun night thru Monday...IFR and lower conds possible in RA. E
winds 15-20 KT with 20-30 KT gusts. LLWS possible with 60-65 KT
LLJ Mon aftn. Moderate confidence.


A Small Craft Advisory for Hazardous Seas is in effect for the
coastal waters of central NJ (ANZ450/451). Observed wave heights
overnight continue to be in the 5-6 ft range at buoys 44091, 44065
and 44025. Seas are modeled to slowly diminish today before dropping
below 5 ft sometime during the mid to late afternoon. Elsewhere,
winds and seas will be below SCA criteria.

No marine headlines expected tonight. W winds 5-10 kt early this eve
will veer out of the N late this eve and overnight, then NE before
daybreak Friday

Fri through Sun morning...No marine headlines anticipated durg
this time. Seas will genly be around 2 ft with wind 10 kts or

Sun aftn thru Mon...Ely flow increases to 15-20 KT with 25-30 KT
gusts starting Sun aftn, and then gale force gusts of 35-40 KT
likely Monday and Monday night. Moderate to heavy rain with low
VSBY expected. Storm conds can not be ruled out for a time,
especially n on Mon. Conditions improve late Monday night, and
winds decrease to sub-SCA levels. However, seas on the ocean
should remain above SCA criteria.

Mon night thru Wed...wind decreases below headline criteria, but
ocean seas will remain above SCA criteria. It is psbl that some
areas, especially s may drop below SCA seas on Wed.


Due to the persistent ely flow around a coastal low Sunday-Monday,
there could be several tidal cycles of coastal flooding, but
this will also be dependent on the track of the low and will
become more evident as we approach Sun night and Mon.


MARINE...Small Craft Advisory for hazardous seas until 6 PM EST this
     evening for ANZ450-451.


Near Term...Franck/Klein
Short Term...Klein
Long Term...Klein/Nierenberg
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