Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 271540
Area Forecast Discussion
National Weather Service Mount Holly NJ
1140 AM EDT Thu Oct 27 2016
Low pressure tracks just north of our area later today into tonight,
but then redevelops near the southeastern New England coast early
Friday. An associated warm front will lift north during today,
following by a cold front moving through our area tonight. High
pressure briefly builds in Friday night before shifting to our south
over the weekend. Low pressure then tracks to our north Saturday,
pulling a cold front across our area Saturday night. High pressure
arrives for Monday, then a cold front arrives Tuesday night into
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Temperatures at MPO are still around 30 deg F with freezing rain
reported. Therefore the freezing rain advisory has been extended
Events so far this morning seem to be playing out more or less as
expected, with light rain overspreading areas mainly north of PHL
from west to east. Also temperatures in the higher Poconos, e.g.
MPO, are holding a couple of degrees below freezing with freezing
rain reported. Not sure how much accumulation can occur on ground
surfaces, but will keep the freezing rain advisory in place. It is
set to expire at 1100 am but will monitor the temperatures in case
it needs to be extended a couple of hours. Again, the advisory
applies mostly to the higher terrain where temps are colder.
It looks like areas south of PHL will not see much precip until
later this afternoon if/when convection develops in the warm
sector ahead of the approaching cold front. There is already a 20
deg F spread in temps from Sussex Co NJ to Sussex Co DE, and this
contrast will continue as a warm front works its way north from
Delmarva into south NJ and southeast PA.
Previous discussion below:
Strong warm advection will develop aloft today ahead of the system
approaching from the west. Rain will overspread eastern Pennsylvania
and northern and central New Jersey this morning with showers
reaching our southern counties. Widespread rain and showers are
anticipated for this afternoon.
Cold air will remain trapped near the surface in our northern
counties this morning. As a result, we continue to expect areas of
freezing rain in the Poconos and in far northern New Jersey. A
Freezing Rain Advisory is in effect for the counties of Carbon,
Monroe and Sussex (NJ) until 11:00 AM. Also, we have added the
mention of some sleet for those counties, as well as for some
adjacent areas. Only a light accumulation of freezing rain and sleet
Highs should be only in the 40s in our northern counties with
readings rising into the 60s in our far south. The wind should veer
from the northeast and east to the southeast and south this
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
Rain and showers will continue into this evening. A cold front is
expected to pass through our forecast area around midnight bringing
and end to the rain. The clouds should begin to clear late tonight.
Conditions are forecast to become marginally unstable this evening
in our southern counties so we have maintained the mention of
Rainfall amounts for the event should total around a tenth to a
quarter inch in our southern counties, with close to an inch of rain
possible in the north.
Minimum temperatures tonight should favor the 40s in our region. The
wind will shift from the southwest to the northwest with the arrival
of the cold front.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The synoptic setup is comprised of a strong trough that exits the
Northeast during Friday. A fairly active but progressive pattern
looks to be in place, therefore a weak ridge slides across our area
Friday night into Saturday before the next trough arrives. This
trough should also amplify as it arrives in the Northeast later
Sunday but then exits Monday. Some stronger ridging is then forecast
to return Monday into Tuesday before the flow turns more zonal into
Wednesday. This pattern will offer a few days of much milder
temperatures followed by a cool down, however since the systems are
more progressive any significant warming should be short in
duration. We used a model/continuity blend through Saturday night,
then blended in the 00z WPC Guidance thereafter. Some adjustments
were then made following additional collaboration with our
For Friday...Surface low pressure is forecast to strengthen as it
tracks northeastward from coastal New England. This will allow for a
tightened pressure gradient across our area. The cold air advection
surge is more notable across the northern half of our area, and it
is also forecast to be mostly short in duration. The forecast
soundings indicate steepening low-level lapse rates though which
promotes good mixing. This combined with stronger flow aloft will
result in a gusty northwesterly wind through the day, which will
diminish later in the afternoon and especially at night as high
pressure starts to arrive and warming aloft occurs. The first half
of the day could start off with a decent amount of stratocumulus,
especially across the northern and western areas, however this
should then thin and dissipate by late afternoon as additional
drying and incoming subsidence occurs.
For Saturday and Sunday...An upper-level ridge weakens allowing the
flow to turn more zonal Saturday, with surface high pressure
centered to our south. This will promote a southwesterly wind along
with warm air advection as a trough in the Midwest slides eastward.
There may be an initial impulse that zips across New England
Saturday with a trailing boundary to our north. This front looks to
settle southward late Saturday into Sunday as low pressure tracks
toward the Canadian Maritimes. There may not be much in the way of
moisture return for this front to work with, however a stronger
short wave trough Sunday could produce more shower activity.
Therefore, limited slight chance POPs across the north to Saturday
afternoon and then expanded low chance POPs across much of our area
during Sunday. It should be warm Saturday across much of the area
ahead of the cold front, with perhaps even warmer air depending on
cloud cover. The mild air should linger Sunday but some cooling is
anticipated given more clouds and the south and eastward progression
of the surface front.
For Monday through Wednesday...As a sharpening trough shifts east to
start Monday a more pronounced ridge is forecast to arrive. This
allows surface high pressure from the north to build across our area
Monday before shifting offshore Tuesday. Low pressure then tracks up
across the Great Lakes sending a warm front to our north Monday
night into Tuesday, followed by a cold front arriving late Tuesday.
Given the general quick progression of the systems, moisture return
may tend to be limited and therefore any POPs were kept on the low
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Conditions will continue to deteriorate gradually through the
remainder of today with the arrival of additional rain. Ceiling
and visibility values will drop to MVFR at most locations, if they
have not already, and they will likely fall to IFR in spots,
especially around KRDG, KABE and KTTN. Rain is expected to
continue into this evening. It should come to an end around
midnight with the arrival of a cold front. Conditions are
anticipated to improve to VFR late tonight.
The wind should be from the east to southeast around 5 to 10
knots into the early afternoon. It is forecast to veer toward the
southeast and south for this afternoon at 8 to 14 knots with gusts
into the 20s. The wind is expected to become southwest this
evening with speeds decreasing to 5 to 10 knots. A cold front is
anticipated to sweep through our region around midnight with the
wind shifting to the west northwest at 8 to 14 knots gusting
around 20 to 25 knots.
Friday...VFR overall, with any cloudiness becoming less by evening.
Northwest winds around 15 knots with gusts to around 25 knots,
diminishing early in the evening.
Saturday...VFR, with some increase in clouds later in the day as a
weak cold front arrives. Southwesterly winds increasing to 10-15
knots, diminishing at night and becoming west-northwest.
Sunday and Monday...Generally VFR, however some showers are possible
Sunday. Mainly light northerly winds.
The Small Craft Advisory has been started now for the Delaware Bay
as winds are gusting around 25 knots this morning already. The
Small Craft Advisory for Atlantic ocean will remain with its start
time of 4 pm as winds have not begun to gust there and should not
for a few more hours.
A east to southeast wind 10 to 15 knots is forecast to become
southeast to south at 15 to 20 knots with gusts around 25 knots
this afternoon. The wind is expected to veer toward the southwest
this evening. A strong cold front is anticipated to arrive after
midnight with the wind shifting to the west.
Wave heights on our ocean waters should build from 2 to 3 feet this
morning to 4 to 6 feet for tonight.
Friday...A Small Craft Advisory remains in effect through the day,
however it may need to be extended for the ocean zones through the
evening. Decent mixing should promote gusts in the 25-30 knot range,
however some gusts may reach 35 knots (gale force) especially across
the northern coastal waters. This appears to be marginal and it may
be short in duration, therefore maintained the advisory for now. The
overall conditions are expected to subside during Friday night from
south to north.
Saturday...Winds (perhaps seas) should reach Small Craft Advisory
criteria for a time during the afternoon and evening before
Sunday and Monday...The overall conditions should be below Small
Craft Advisory criteria.
PA...Freezing Rain Advisory until 2 PM EDT this afternoon for
NJ...Freezing Rain Advisory until 2 PM EDT this afternoon for
MARINE...Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
Friday for ANZ450>455.
Small Craft Advisory until 6 PM EDT Friday for ANZ430-431.