Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
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FXUS61 KPHI 142345
Area Forecast Discussion
National Weather Service Mount Holly NJ
645 PM EST Sat Jan 14 2017
High pressure off the New England coast and weak low pressure over
the waters off North Carolina will both move farther out to sea
tonight and Sunday. Another area of high pressure is anticipated to
build into our region from the west for Sunday night and Monday. A
warm front is expected to approach from the south on Tuesday
followed by another frontal boundary from the west on Wednesday
morning. High pressure is forecast to build in for much of Thursday
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A challenging forecast given a variety of precipitation types
occurring. We appear to be losing the isentropic lift across the
north which is diminishing the precipitation, with the most focus
now shifting to our southern zones. In addition, some drying aloft
following the initial wave of precipitation is resulting in a loss
of ice crystals. As a result, the light snow is mixing with or
changing to some light freezing rain/drizzle in spots north and west
of Philadelphia. This is resulting in some slippery conditions being
reported. The precipitation may be ending in the very near term
Farther south, enough warming is resulting in mostly plain rain with
temperatures above freezing. Some sleet however has mixed in
especially earlier. The grids were completely updated to hopefully
better capture this (PoPs increased substantially with an earlier
update), although it is challenging. Looks overall like little in
the way of additional snow/ice accumulations from here on out. A
Special Weather Statement was issued earlier to cover some icy spots
mainly north and west of Philadelphia. The precipitation will end
from west to east later this evening overall, then lots of clouds
should linger through the overnight especially for the southern and
The hourly temperature and dew point grids were adjusted based on
the latest observations, then the LAMP/LAV guidance was blended in
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
A dry, warmer and mainly sunny day is expected for Sunday, albeit
with a nw flow so it won`t feel quite as temps in the 40s would
have it seem. Still not bad for mid-January.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The general mid level pattern features a ridge axis passing
overhead on Tuesday followed by a couple of short wave troughs on
Wednesday then a trend toward mid level ridging over the east
during the period from Thursday through Saturday. The GFS is more
progressive with the arrival of the mid level ridge than is the
The center of surface high pressure is expected to build across
our region from the west early on Monday bringing dry weather and
seasonable temperatures for Sunday night and Monday.
A warm front is forecast to lift toward our region on Tuesday. A
lobe of mid level moisture in the warm advection is anticipated to
pass overhead on Monday night. There may be some light
precipitation associated with it. Additional moisture is expected
to arrive on Tuesday during the daylight hours along with an
increasing chance for precipitation.
The forecast temperature profiles continue to suggest warming
aloft with the arrival of the precipitation. However, sub-freezing
air may linger near the surface in parts of eastern Pennsylvania
and central and northern New Jersey for Monday night into Tuesday
morning. As a result, we will continue to mention the potential
for some freezing rain at that time.
The last of the sub-freezing air in our northern counties should
erode and mix out of that area by Tuesday afternoon. While the
potential for rain will continue, the threat of freezing rain will
come to an end at that time. High temperatures on Tuesday should
be mainly in the 40s in eastern Pennsylvania and northern and
central New Jersey,and in the lower and middle 50s in southern New
Jersey, Delaware and northeastern Maryland.
A cold front approaching from the west is anticipated to arrive
early on Wednesday. We will carry a chance of showers for both
Tuesday night and Wednesday. Also, abundant low level moisture in
advance of the front will likely result in the development of
areas of fog at that time. Temperatures should remain mild even
with the arrival of the front. Lows on Tuesday night are forecast
to be mostly in the upper 30s and 40s and highs are expected to
range from the upper 40s in the north to the lower 60s in the
The air mass in the wake of Wednesday`s front will not be
particularly cold. In fact, it appears as though dry and
relatively mild conditions will affect our region for Thursday,
Friday and Saturday. We should be mainly under the influence of
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...VFR/MVFR ceilings lowering to IFR, then improving back to
VFR after 09z. Light snow and rain will taper off from west to east
later this evening, with some terminals experiencing some light
freezing rain/drizzle (mainly RDG). Winds light and variable
overall, becoming northwest after 06z near 5 knots.
Sunday...VFR. North-northwest winds increasing to mainly 10-15
Sunday night and Monday...Mainly VFR.
Monday night...Mainly VFR. A chance of light rain late at night.
There may be light freezing around KRDG, KABE and KTTN.
Tuesday...Conditions lowering to MVFR and IFR in rain. Some
lingering freezing rain is possible in the morning around KRDG and
Tuesday night...IFR and MVFR conditions are expected with fog and
Wednesday...IFR and MVFR conditions are expected with fog and
rain showers in the morning. Improvement to VFR is anticipated in
Wednesday night and Thursday...Mainly VFR.
No marine headlines are expected thru the nr and short term pds.
Seas will genly be 2-3 feet. Wind cud gust as high as 20 kts for
awhile Sun mrng.
Sunday night through Thursday...No marine headlines are
PA...Winter Weather Advisory until midnight EST tonight for PAZ101-
MD...Winter Weather Advisory until midnight EST tonight for MDZ008-