Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 120913
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
413 AM EST Thu Jan 12 2017

.SYNOPSIS...
An area of low pressure will move out of the Great Lakes today and
into eastern Canada tonight, and will pull a cold front across the
area tonight. High pressure will build just to our north Friday
night and Saturday, then weaken into Saturday night as an area of
low pressure passes to our south. High pressure will reinforce
itself to our north Sunday, then build offshore Sunday night into
Monday. An area of low pressure is forecast to move into the Great
Lakes region Monday night into Tuesday, lifting a warm front across
the area.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
The rain has ended across the region this morning with just a few
isolated showers expected through daybreak. Area to the north and
west of the I-95 corridor are seeing an abundance of low clouds and
there are also areas of patchy fog being reported, especially where
winds have remained light. To the south and west I-95, conditions
improved shortly after the rain ended, although skies remain fairly
cloudy.

With the skies clearing out in some areas, there will be the
potential for fog to develop. One limiting factor will the winds,
which have remained around 10 to 15 mph through much of the
overnight period. Do not expect any fog that develops to be
widespread but there could be some locally dense spots out there
this morning. Fog should dissipate by mid-morning in most areas.

Today we will continue to see warming occur as the southwesterly
flow continues across our area. With the warm moist air pushing into
the area, we will see temperatures rise well above normal, reaching
into the low to mid 60s from the I-95 corridor, south and east.
North and west I-95 may not warm as much as the models are showing
as low clouds/fog may be slower to lift over these areas. For now,
expect temperatures to reach the low to mid 50s across the Southern
Poconos, Lehigh Valley and northwestern NJ, north of I-78. Would not
be surprised to see some of these areas remaining cooler than
forecast if the clouds hang around for a longer period of time.

Winds will be another factor today as gusts up to 35 mph are
possible, mainly along the coast of NJ and Delaware and across
northwestern NJ and the Southern Poconos.

Some rain showers may impact the northwestern areas through this
afternoon associated with a low level and increased moisture of the
area.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
A cold front will cross our area tonight and we should see just a
few showers associated with it. The once robust front appears to
weaken and lose some of its punch as it makes its way towards our
area. As a result, the bulk of the moisture associated with it seems
to be gone by the time it reaches our area, leaving only scattered
showers as it cross the region. As a result, any rain associated
with the front looks to be confined to areas north and west of the I-
78 corridor. Colder air will move in behind the front and
temperatures will start to drop late tonight. Temperatures may drop
enough by late tonight in the Poconos that some flurries or light
snow may occur before the precipitation is completely cut off.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Several periods of unsettled weather possible through the extended
forecast.

The cold front that affects the area today will sweep offshore by
Friday morning, and mostly dry conditions are expected through the
day Friday. High pressure is then forecast to build just to our
north Friday night and nose its way into our area. Most of the night
should be dry, although it is possible that some precipitation could
begin to move into the area toward daybreak.

As we move into Saturday, the high is forecast to weaken and move
offshore late in the day and into Saturday night. There will be
plenty of moisture spreading across the area aloft, and several
short wave/vorticity impulses that are forecast to slide across the
area during this time period. This could lead to a period of
precipitation developing and spreading across the area during the
day and into the night Saturday. The question becomes what kind of
p- type develops across the area. For areas north of a line from
Berks County, PA to Monmouth County, NJ, precipitation should
remain all snow or a mixture of snow and possibly sleet. However,
south of this line things get a little more tricky. There are
indications now that we could have a period of a wintry mix of
snow, sleet, and freezing rain or rain. The freezing rain or rain
will be dependent on the surface temperatures.

High pressure will reestablish itself Sunday and move just to our
north during the day before moving offshore overnight. There will
continue to be a couple of short wave/vorticity impulses move across
the area, which could interact with any lingering moisture and
create some scattered precipitation across the southern areas. A
mix of rain, sleet, and snow is possible.

By Monday, the high builds offshore to our north and return flow
develops across the area which will allow for some warming across
the area. A warm front is forecast to lift across the area overnight
Monday and move to our north Tuesday as high pressure remains to our
east. Several short wave/vorticity impulses will continue to move
across the area in the westerly flow aloft. This will keep the
chance for precipitation to develop and spread across the area
into early next week. Any precipitation that develops Monday into
Monday night could be a mix of rain, sleet, or snow for the
northern half of the area, with a mix of freezing rain possible
across the far north. As the warm front lifts north of the area by
Tuesday, any precipitation should turn to all rain.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rain has ended at the terminals. However, some low clouds continue
to have an impact at the terminals. Mainly MVFR ceilings have
remained at KPNE, KTTN and KABE through early this morning. It may
take a while for the low clouds to clear today

Fog has developed at KABE where the winds have gone light overnight.
As we head through this morning, winds should pick up and help to
clear out some of the fog. The guidance shows that low clouds will
impact the terminals through mid-morning with a period of VFR
conditions through this afternoon.

KPHL, KILG, KMIV, and KACY have been VFR for several hours already.
With clouds remaining over these terminals and stronger southwest
winds around 10 to 15 knots, fog is not expected to be much of a
factor. Low clouds may creep back in for a period of time this
morning.

Southwest winds will continue through the day today. Winds around 10
to 15 knots with gusts up to 25 knots this afternoon. The gustiness
may not be as pronounced in areas where the lower clouds hang on
longer. We should love the gustiness by late tonight.

Overall for tonight...mainly VFR conditions are expected. Southwest
winds around 10 knots or less.

OUTLOOK...

Friday-Friday night...Generally VFR.

Saturday-Saturday night...Deteriorating conditions with MVFR or IFR
conditions developing Saturday and continuing into Saturday night.
Wintry mixture of precipitation possible, with mainly snow/sleet for
ABE/RDG/TTN, and snow/sleet/freezing rain possible for the remainder
of the TAF sites.

Sunday-Sunday night...Conditions improving to VFR. Slight potential
for precipitation for southern New Jersey and Delmarva.

Monday...Generally VFR early, possibly lowering to MVFR. ABE/RDG
could possibly lower to IFR. Slight chance of precipitation.

&&

.MARINE...
Winds will pick up out of the south to southwest today 15 to 25
knots with gusts up to 30 knots on the waters. Wind gusts may drop
off for a period of time overnight on the ocean. Winds on the
Delaware Bay should subside this evening. Seas will remain elevated
and above 5 feet through tonight.

OUTLOOK...

Friday...Small Craft Advisory extended through Friday with gusts up
to 25 knots and seas of 5 feet possible.

Friday night-Monday..Sub-Small Craft Advisory conditions expected as
high pressure builds to the north with the waters on the southern
edge of the high.

&&

.TIDES/COASTAL FLOODING...
Model guidance continues to show low tides today approaching blow
out tide thresholds. With the full moon today, astronomical low
tides will be between -0.8 and -1.0 ft MLLW. However, local
regression equation suggests that the tidal departures should be
between 0 and -0.5. Additionally, the south southwest or southwest
winds expected today are not optimal for blow out tides.
Therefore, we still expect the total water level to stay above
blow out tide thresholds.

&&

.CLIMATE...
Today should be quite mild with current forecast within a couple
of degrees of record highs for many of our climate sites. Here are
the records for January 12:

Location/     Record/Year
Atlantic City   63/1913
Wilmington      63/1913
Allentown       60/1932
Reading         61/1913
Georgetown      70/1975
Mount Pocono    56/1975
Trenton         68/1890

At this time, we are forecasting that Philadelphia will stay well
below its record of 72 set in 1890.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EST Friday for ANZ450>455.
     Small Craft Advisory from 7 AM this morning to 7 PM EST this
     evening for ANZ430-431.

&&

$$

Synopsis...Robertson
Near Term...Meola
Short Term...Meola
Long Term...Robertson
Aviation...Robertson/Meola
Marine...Robertson/Meola
Tides/Coastal Flooding...
Climate...



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