Overnight:
Rain. Cloudy, with a low around 41. Northwest wind 15 to 20 mph, with gusts as high as 45 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Thursday:
A chance of rain. Mostly cloudy, with a high near 49. Northwest wind 10 to 15 mph, with gusts as high as 30 mph. Chance of precipitation is 30%. New rainfall amounts between a quarter and half of an inch possible.
Thursday Night:
A chance of rain before 7pm, then rain and snow likely between 7pm and 10pm, then rain and snow likely. Mostly cloudy, with a low around 34. West wind 10 to 15 mph, with gusts as high as 25 mph. Chance of precipitation is 60%. Little or no snow accumulation expected.
Friday:
Rain and snow likely before 7am, then rain and snow. Cloudy, with a high near 41. Southwest wind 5 to 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New snow accumulation of less than half an inch possible.
Friday Night:
Rain before 1am. Mostly cloudy, with a low around 33. West wind around 10 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch possible.
Saturday:
Partly sunny, with a high near 49.
Saturday Night:
Partly cloudy, with a low around 39.
Sunday:
Mostly sunny, with a high near 53.
AREA FORECAST DISCUSSION
National Weather Service Mount Holly NJ
956 PM EST Wed Nov 20 2024
Weather Synopsis:
As low pressure tracks into the Great Lakes region, an associated
strong cold front moves across our area later tonight and Thursday
with some much needed rain and higher elevation snow. A new low
develops off the coast and then shifts westward and meanders in our
region during Thursday and Friday keep our weather unsettled. The
low then gradually moves away through the weekend. Weak high
pressure briefly arrives for later Sunday and Monday, followed by a
cold front Monday night into Tuesday.
Near Term:
THROUGH THURSDAY -
955 PM...Strong cold front is now knocking on our doorsteps in
eastern PA. Weather stations across central PA where the front
had just passed have 30-40 mph at times with stations across MD
and VA reporting upwards of 40-50 mph gusts at times. The Wind
Advisory remains in effect across areas around the PA Turnpike
and I-195 corridors where the strongest wind gusts are expected
to be.
Previous discussion...As the initial low begins to lift north
of our region, a new surface low looks to develop at the triple
point of the occluded, warm, and trailing cold fronts, more or
less right over our region. As a result, areas of rainfall
across Delmarva and southern New Jersey may become a bit more
convective in nature in the developing warm sector and a rumble
of thunder can`t be completely ruled out. Areas further north
look to remain within the stratiform region of the system on the
north and west sides of the developing low. The development of
this low and passage of the associated fronts at the surface
will result in a rapid wind shift occuring across the region,
from southeast out ahead to northwest behind, with winds
becoming gusty to at least 30-40 mph as the pressure gradient
tightens as a result of the developing low. In fact we expect a
brief period of a few hours where gusts of 40 to 50 mph are
likely over much of Delmarva, southeast PA, and southern NJ
later this evening into the overnight. For this reason, Wind
Advisory has been issued running from 10pm - 4am. Overall,
rainfall amounts still remain largely unchanged with 0.5 inches
to 1+ inches expected across the area tonight.
Heading into Thursday, the low continues to meander near our area,
as it will be pivoting to the north and potentially northwest as it
moves cyclonically around a large closed upper level low. As a
result, continuing rainfall is forecast across much of the northern
half of the region, particularly north of the I-78 corridor. An
additional 0.25-0.75 inches of rainfall is forecast for this area.
Drier air will begin to move in for areas farther south (SE PA,
south Jersey, Delmarva) so we aren`t expecting a lot more rain here
though there will be some wrap around showers. Cold air advection
will also be ramping up across the region, as gusty west-northwest
winds continue. Highs are forecast to be only in the 40s to low 50s.
By later in the afternoon, temperatures at the highest elevations in
the southern Poconos look to become cool enough for ongoing to
precipitation to crossover from rain to a rain/snow mix, and
eventually snow.
Short Term:
THURSDAY NIGHT THROUGH SATURDAY -
Strong low pressure will be located near New York City Thursday
evening, with strong and gusty northwest winds funneling cooler air
southeastward across the region. The upper low will remain to our
west in the upper Ohio Valley, and as that feature heads east, the
surface low will actually retrograde slightly, with it becoming
"captured" over our northern areas early Friday. Strong forcing over
our northern zones relatively close to the surface low and northeast
of the upper low will result in continuing precipitation through the
night, with precipitation tapering off farther south and mostly dry
conditions in the Delmarva. With the cold advection at the surface
and aloft, odds favor a transition to heavy wet snow across the
higher terrain, especially above 1500 feet on the Pocono Plateau and
possibly a few higher ridges elsewhere in eastern PA and northern
NJ. With the best odds of heavy wet snow being across the Poconos, a
Winter Storm Watch remains in effect though again, it will be mainly
the higher elevations around and above 1500 feet that we are
thinking for amounts of 6+ inches. Lower elevations may see far less
snowfall, in fact the lowest valleys even up there may fail to get
an entire inch of accumulation with this elevation-dependent system.
As this will be a heavy wet snow with significant wind in the 20-30
mph range, a big potential is there for downed trees and power
lines. Travel Thursday night in particular is discouraged.
There are a few simulations which imply snow could reach
significantly farther south across our region, even down to the I-95
corridor and Philly metro, particularly the Canadian models. For the
moment we`ve mostly discounted that guidance as being outliers, but
will be keeping it in mind as we watch further progress with this
system. Have allowed for some mixing across areas just north and
west of the I-95 corridor Thursday night into early Friday, but
little to no accumulation is currently expected outside the Poconos.
Either way, brisk and cold will be the them for Thursday night, with
lows in the 30s for most, upper 20s perhaps in the higher terrain of
the Poconos.
For the bulk of Friday, the surface low will remain captured under
the upper low over our region, resulting in continuing showers.
Enough insolation likely develops to allow a transition from a
rain/snow mix to just plain rain at the lower elevations, with
significantly less accumulation in the higher terrain as well, with
precipitation starting to taper off towards the end of the day as we
start to see some movement eastward and the surface low begins to
slowly fill. Regardless, a chilly, raw day will be had by most with
temps generally no higher than the 40s region-wide, with temps not
straying far from freezing in the Poconos.
Precip should mostly end during the evening Friday as the surface
and upper lows begin moving further east, but the brisk conditions
continue. Lows in the 30s for most, upper 20s Poconos. We expect
storm total liquid precip amounts to be highest north and lowest
south. Generally expect upwards of 2 to 3 inches quantitative precip
over NE PA into NW NJ (some of this falling as snow) with 1 to 2
inches total farther south over SE PA into adjacent south Jersey
with a half inch to an inch over Delmarva.
As the storm pulls further away to our northeast Saturday, a gusty
northwest wind will continue and clouds will linger, with some
spotty showers in the Poconos, but overall, significantly improved
compared to Friday. Expect highs mostly in the upper 40s to low
50s.
Long Term:
SATURDAY NIGHT THROUGH WEDNESDAY -
Summary...Temperatures should turn milder Monday ahead of a cold
front, then cooling takes place. Some low shower chances late
Monday into Tuesday with a cold front.
Synoptic Overview...A strong closed low is forecast to gradually
move across portions of the Canadian Maritimes through Sunday. As
this occurs, the cyclonic flow across our region eases into Sunday
with the flow aloft becoming more zonal through early next week. A
shortwave trough however may slide across the Northeast Tuesday. At
the surface, strong low pressure is forecast to shift northeastward
across portions of the Canadian Maritimes in tandem with the closed
low through Sunday. Weak high pressure briefly builds in later
Sunday into Monday, then low pressure tracking to our north pulls a
cold front across our area Monday night into Tuesday. High pressure
then starts to extend eastward toward our area Wednesday.
For Saturday night and Sunday...A closed low gradually shifts across
parts of the Canadian Maritimes and therefore the cyclonic flow
eases into Sunday with the flow turning more zonal thereafter.
Strong surface low pressure will follow the closed low, however a
tightened pressure gradient remains across our area Saturday night
through much of Sunday as high pressure approaches from the west and
south. A notable breeze therefore will continue, however this should
start to ease some Sunday and especially Sunday night. Temperatures
may edge upward a little Sunday given heights aloft starting to
rise. Other than a snow or rain shower Saturday night into the
Pocono region, drier air is expected to continue to overspread the
area. Some more sunshine should also occur especially during Sunday
as the influence of the closed low wanes, then clouds may start
to increase some again Sunday night ahead of the next cold front.
For Monday through Wednesday...The flow is forecast to be more zonal
with weak high pressure cresting briefly across our area Monday.
This will result in much less wind. A fairly quick moving system
crossing much of eastern Canada may sharpen some across the
Northeast Monday night and especially Tuesday. This should drive
surface low pressure to our north with a cold front crossing our
area Monday night into Tuesday. As of now with moisture potentially
being more limited, continued with slight chance PoPs (20 percent)
with this system. The front may then settle to our south Tuesday
into Wednesday. High pressure centered across the Midwest may then
start to extend toward our area during Wednesday.
Climate:
Driest autumn (Sep-Nov) on record, and any 3-calendar month
period on record, plus current status:
9/1-11/19 Driest Driest 3 Year/
Site 2024 precip Autumn Year Calendar months months
Allentown (ABE) 1.61 3.81 1922 3.58 Oct-Dec 1928
A.C. Airport (ACY) 0.99 3.34 2001 2.35 Oct-Dec 1946
A.C. Marina (55N) 0.79 2.89 1941 2.52 Aug-Oct 1895
Georgetown (GED) 0.85 2.67 2001 2.20 Aug-Oct 2024
Mount Pocono (MPO) 3.17 4.21 1931 3.36 Oct-Dec 1928
Philadelphia (PHL) 1.09 2.37 1922 2.37 Sep-Nov 1922
Reading (RDG) 1.42 2.89 1922 2.89 Sep-Nov 1922
Trenton (TTN) 0.71 3.18 1922 2.66 Jun-Aug 1966
Wilmington (ILG) 0.86 3.17 1922 3.17 Sep-Nov 1922
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