Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 270102
Area Forecast Discussion
National Weather Service Mount Holly NJ
902 PM EDT Wed Oct 26 2016
High pressure will move across eastern Canada through Thursday while
nosing down across our area tonight. An area of low pressure will
move north of our area Thursday into Thursday night, lifting a warm
front into the area during the day, then a cold front during the
evening. High pressure briefly affects the area Friday night, then
builds south of the area over the weekend. Another low pressure
system is forecast to slide to our north Saturday, pulling a cold
front across the area Saturday night. High pressure is then expected
for Monday. A cold front may affect the area around the middle of
the week as an area of low pressure moves into eastern Canada.
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Center of a ridge of surface high pressure lies off the Mid-
Atlantic coast. Low pressure is pushing through the Great Lakes,
and a warm front extends out ahead of that low into the OH Valley.
Clouds are beginning to spill into the region from the west. Where
there are clouds, temps have held steady and even risen by a few
degrees. Elsewhere, radiational cooling allowed temps to drop into
the 30s and 40s. For most areas, temps will rebound a bit when
clouds move into the region.
Clouds will continue to increase from the west and thicken
overnight as moisture spreads east ahead of the next shortwave
trof now over the Mississippi valley. The increasing cloudiness
will tend to limit radiational cooling overnight, however it looks
like temps in the Poconos only need to drop a few degrees to reach
freezing. Light precip will be spreading across that area by late
tonight so there is the potential for freezing rain or a wintry
mix. Although precip type is uncertain, it seemed prudent go ahead
and issue a freezing rain advisory for Carbon and Monroe counties
in PA, and Sussex county in NJ.
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
For Thursday, rain will continue to spread across the forecast
area, with some pockets of freezing rain perhaps continuing into
mid-morning for higher elevations northwest. Precip should be all
rain by mid day if not sooner, with heavier amounts up to an inch
possible across northern NJ and adjacent PA.
Low pressure will be moving across the lower Great Lakes and an
associated warm front will works its way into our region. Max temps
tomorrow afternoon should be a few degrees warmer than today
especially from PHL south.
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Rain is expected to be ongoing at the start of the period Thursday
evening as the area of low pressure passes to our north. It`s
associated frontal boundaries will be making their way through the
area during the evening as well. The warm front may not lift north
of the area before the cold front approaches and occludes near
the area. The triple point low may begin to form right across
northern New Jersey/Pennsylvania during the evening, but will
strengthen as it passes to our northeast. There is some weak
instability forecast south of the warm front and ahead of the cold
front, so there could be an isolated thunderstorm as the cold
front sweeps through the area. Would not be surprised to see a
narrow squall line with no thunder or lightning however. As the
front sweeps through during the evening however, regardless of
thunder, we will likely have a period of gusty winds of at least
20-30 mph. Precipitation will end overnight as drier air moves
in behind the front. The warmest temperatures Thursday may occur
during the evening and just before midnight, before the cold air
filters in behind the front.
Friday is expected to be dry as the low pulls away from the area and
high pressure approaches from the west. We expect gusty winds during
the day Friday with gusts of 25-30 mph possible. With the cool
northwest wind, it would not be surprising to see some lake effect
showers approach the area from the northwest during the morning
hours. However, we`ll keep the forecast dry for now. The high
briefly affects the area Friday night, which should keep dry weather
in the forecast.
Saturday, the high pushes well to our south, while an area of low
pressure passes well to our north Saturday into Saturday night.
A cold front is forecast to pass across the area late Saturday into
Saturday night. There will be a slight chance of showers Saturday as
the front sweeps across the area, but most of the precipitation may
dry out as it approaches.
On Sunday, an area of low pressure, or a clipper type low, may move
along the frontal boundary to our south. If it wavers farther north,
it could bring some showers across our area during the day Sunday.
So we`ll keep a chance/slight chance of showers in the forecast.
High pressure once again is expected to move into the area later on
Monday and Monday night, bringing dry weather to the area.
Another low pressure system is expected to move well north across
eastern Canada Tuesday into Wednesday, potentially bringing a cold
front across our area around the middle of the week. If the front
gets stretched out too much, and all the forcing passes well to our
north, our forecast could remain dry.
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
VFR conditions through the overnight period, and then CIGs will
lower to MVFR Thursday morning. Light rain will also spread across
the area on Thursday. Timing should be shortly before sunrise at
ABE/RDG and mid to late morning for PHL and vicinity. ACY and MIV
could stay VFR. Light and variable winds expected for the
overnight, and then winds will pick up from the SE as low pressure
approaches Thursday morning.
Thursday night...MVFR or IFR conditions with rain during the
evening, then improving conditions overnight.
Friday...Generally VFR, some MVFR CIGS possible for northern
areas. Gusty northwest winds 20-30 knots.
Friday night...Generally VFR.
Saturday...Generally VFR, some MVFR CIGS possible for northern
areas. Gusty northwest winds 20-25 knots.
Saturday night-Monday...Generally VFR.
A ridge of high pressure over the mid Atlantic this evening will
move offshore overnight. This will result in fairly light winds
shifting from north to east. On Thursday and trof of low pressure
and associated frontal system will approach from the west. Winds
will increase and veer to the south by afternoon ahead of the
front. Seas will also build from 2-3 feet up to 4-5 feet by late
in the day. A small craft advisory has been issued for NJ/DE
coastal waters and Delaware Bay, starting at 400 pm.
Thursday night-Friday...Small Craft Advisory remains in place,
with a brief period of Gale force gusts possible during the
evening near the timing of a cold frontal passage. The gusts may
actually occur with a squall line or any convection.
Friday night...Small Craft Advisory conditions likely to continue
into the evening Friday. Conditions should drop below Advisory
Saturday-Saturday night...Winds and seas may approach Small Craft
Advisory levels during the day into the evening Saturday.
Sunday-Monday...Conditions return to below Small Craft Advisory
PA...Freezing Rain Advisory from 2 AM to 11 AM EDT Thursday for
NJ...Freezing Rain Advisory from 2 AM to 11 AM EDT Thursday for
MARINE...Small Craft Advisory from 4 PM Thursday to 6 PM EDT Friday for