NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Dec 23, 6:33 PM EST, 3 hours 27 minutes earlier.
Area forecast discussion, Dec 23, 6:33 PM EST, 3 hours 27 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
633 PM EST Fri Dec 23 2022
.SYNOPSIS...
Low pressure will move northwards through western Quebec
tonight through Saturday. Arctic high pressure will build over
the region this weekend. This high will depart early next week,
followed by a milder Pacific high which will promote a warming
trend through the last week of 2022.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 620 PM...Temperatures continue to plummet this evening
due to strong west winds ushering in an anomalously cold
airmass. Wind gusts have eased slightly over the last few hours,
but continue to gust around 30-40 mph based on the latest obs
and are forecasted to remain elevated overnight, leading to
dangerous wind chills across the area. Additionally, while our
previous Winter Weather Advisory for refreezing roadways has
been allowed to expire, any surfaces that remain wet and
untreated run the risk of becoming icy.
As we head into tonight, the large and very deep low will
advance northward as it moves into western Quebec. However the
circulation around this storm is quite large and a strong
pressure gradient will persist between this system and an
arctic high to the west. For this reason, expect strong winds
with gusts over 40 mph to continue at least into early this
evening before they should abate somewhat by the late evening
into the overnight. But even overnight, still expect winds of 15
to 20 gusting up to 30 mph which will create bitter wind chills
when combined with the very cold temperatures. For this reason,
most of the area remains under a Wind Chill Advisory with the
exception being Carbon and Monroe Counties in PA where we've
upgraded to a Wind Chill Warning. For these latter areas in the
southern Poconos expect wind chills as low as -25! Elsewhere,
expect that wind chills will drop to near or below -10 to as low
as around -20.
Christmas Eve is still shaping up to be a very cold, blustery
day as the large circulation around the big storm continues to
influence the area even though the storm will be well to our
north near James Bay. Highs will only be in the teens to around
20 except staying in the single digits over the southern
Poconos. This combined with west winds 15 to 25 gusting 25 to 35
mph will result in continuing bitter wind chills. Even in the
warmest part of the day, wind chills will generally be in the -5
to 5 range and as low as -15 over the southern Poconos. It will
be dry though with generally a mix of sun and clouds expected
as there may be a fair amount of strato cu around, especially
north.
For Saturday night, it remains very cold and blustery but not
quite as cold and not quite as windy as tonight as the pressure
gradient starts to ease. Lows will be mainly in the range of 10
to 15 degrees except single digits in the southern Poconos.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
Sunday will see a notable moderating trend...still quite cold
for this time of year, but 5-10 degrees milder and a few mph
less of wind. This will be thanks to the high starting to
recenter over the deep south and the low pressure gradually
weakening to our north. Additionally, with the trough aloft
having lifted out a bit, we should also see more sun than on
Saturday.
By Sunday night, the high will be solidly over the deep south,
and the low will start retreating again as it continues
weakening over eastern Canada. The gradient will relax further,
with winds dropping back to around 10 mph. Skies will also clear
out as the trough continues to lift away. However, this will
result in a better radiational cooling set up, so expect lows to
only be a degree or two milder than Saturday night, with
widespread low-mid teens. Wind chills will mostly stay above 0,
however.
For Monday, high pressure will be centered near the area to
start the day and then start to weaken with time as the next
system (a weak one) starts to approach bringing some increasing
clouds. Temperatures will continue to moderate but it will still
be colder than average with highs mainly in the 20s to low 30s.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Moderation is name of the game in the final days of 2022 as the
pattern shifts and the trough over the east gradually becomes
replaced by an upper level ridge. We look likely to see, on
average, a 5 degree gain in high temperatures each day,ending up
Friday nearer to 50. The weather should be generally dry and
fair with the only thing to watch being a weak clipper type
system that looks to move through Monday night into Tuesday.
Currently, we are not carrying any mentionable POPs with this
system as moisture should be very limited but it could end up
producing some flurries or very light snow.
&&
.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Overnight...VFR. Some lingering ceilings mainly 035-045 range near
and northwest of I-95 corridor, but possibly SCT at times there.
While snow showers have largely ended, some blowing snow
tonight may reduce visibilities across the Poconos. Westerly
winds will remain, but gusts generally drop into the 18-25 kt
range after midnight.
Saturday...VFR. BKN to OVC 030-050 most sites especially NW of
ACY/MIV as a fairly thin/shallow layer of stratocumulus even fills
back in during the day. Wind W or WSW 15-20 kts with up to 30 kt
gusts. High confidence.
Outlook...
Sunday...VFR. Wind west 10-15 kts with 20 kt gusts. High confidence.
Monday...VFR. Wind west 5-10 kts. High confidence.
Tuesday...VFR. Wind west around 5 kts. High confidence.
Wednesday...VFR. Wind southwest around 5 kts. High confidence.
&&
.MARINE...
We saw a fairly brief period of 45-55 kt gusts locally along
portions of the S NJ/DE coast and lower DE Bay with the passage of
the cold front, and some embedded thunderstorms along it toward
midday today. While those winds 'eased' with gusts generally in the
35 to 45 kt range from the west, we will see a bit of a secondary
surge of winds for several hours into the early evening.
Brandywine Shoal in lower DE Bay is gusting to 50 kt at 3 PM.
While not all of the nearshore buoys may see that, esp portions
of the coastal waters just downwind of shore, the strong push of
cold air should allow for near storm force gusts over a good
portion of the coastal waters and lower DE Bay...hence a Storm
Warning through 9 PM. Seas accompanying that are mainly in the 8
to 12 ft range, highest of course in outer/offshore portions of
our marine forecast zones. While there is still some SSE swell
mixing in, these will be increasingly mainly comprised of steep
short-period SW to W waves. Gale warnings will likely be needed
where the storm warning is in effect, later tonight and possibly
early Saturday morning. Otherwise, W to WSW winds 20-30 kt
linger Saturday while still rough seas lower into the 5 to 7 ft
range.
As if this wasn't enough, given air temperatures dropping into the
teens tonight into Saturday, and only recovering into the 20s
offshore later Saturday into Saturday night, have issued a Freezing
Spray Advisory. Even though water temperatures are generally in the
40 to 50 F range (highest in deeper water offshore), the strong
winds blowing spray from breaking waves into that very cold air and
onto vessels, that water may still freeze on contact and accumulate
as ice. That will be a concern for any brave mariners heading out
through Saturday and even into early Sunday morning.
Outlook...
Small Craft Advisory conditions may continue through
Sunday evening at least over the ocean waters, with stiff west winds
and 25 to 30 kt gusts. Conditions improve substantially heading into
next week, winds W to WNW 10-15 kt Monday and Tuesday with seas
generally 2 to 3 feet.
&&
.TIDES/COASTAL FLOODING...
The onshore flow caused tidal departures to increase into the +2 to
+3 foot range along the coasts of New Jersey and Delaware, and into
Delaware Bay and the tidal Delaware River.
A southerly wind on the Chesapeake Bay also caused tidal departures
to increase to around +3.0 feet.
The west wind has begun to push water away from the Delaware and New
Jersey coasts this afternoon. Tidal departures should begin to
decrease at most locations. As a result, we are not anticipating any
additional tidal flooding with the exception of some of the back
bays, especially in Ocean County, NJ and Sussex County, DE. Tidal
piling has occurred in Barnegat, Rehoboth, and Little Assawoman Bays
and it will take additional time for the water to evacuate.
&&
.CLIMATE...
A very cold Christmas weekend remains in the forecast. Highs
are currently projected to get no higher than the 20s both
Christmas Eve and Christmas Day. This is a decent cold snap for
any December, as the last time we had two or more days in a row
with highs in the 20s at PHL was back in 2017, 5 years ago.
However, for Christmas Eve and Christmas Day itself, it's more
notable, as we've been on quite a stretch of warm Christmases of
late. The last time the high on Christmas Day itself stayed
below 30 was back in 2000, when the high was only 27. The last
time both Christmas Eve and Christmas Day stayed below 30 was
back in 1989, when the high Christmas Eve was only 21 and the
high Christmas Day was only 28. So, this year's Christmas
weekend has the potential to be the coldest in over 30 years.
Something to think about if you are planning any outdoor
services.
All this having been said, it will be be tough to match the
coldest Christmas eve and Christmas Days on record, which for
much of our area dates back to 1989 and 1983. Particularly in
1983, we had some of the coldest weather we ever see in our
region, with many areas below zero at night and not even
reaching 10 above during the day.
Record coldest high and low temperatures for Christmas Eve and
Christmas Day are listed below:
Record Coldest High Temperatures
12/24 12/25
Site Record/Year Record/Year
Allentown (ABE) 18/1960 8/1983
AC Airport (ACY) 21/1989 10/1983
AC Marina (55N) 19/1906 12/1983
Georgetown (GED) 27/1989 26/1983
Mount Pocono (MPO) 15/1935 & 1983 1/1983
Philadelphia (PHL) 21/1906 & 1989 10/1983
Reading (RDG) 16/1906 20/1983
Trenton (TTN) 18/1872 8/1983
Wilmington (ILG) 21/1989 10/1983
Record Coldest Low Temperatures
12/24 12/25
Site Record/Year Record/Year
Allentown (ABE) -5/1989 -2/1983
AC Airport (ACY) -1/1983 -2/1980 & 1983
AC Marina (55N) 6/1983 4/1983
Georgetown (GED) 9/1989 2/1989
Mount Pocono (MPO) -20/1989 -13/1980
Philadelphia (PHL) 3/1983 1/1980 & 1983
Reading (RDG) 4/1989 -2/1980
Trenton (TTN) -4/1983 -3/1983
Wilmington (ILG) -5/1983 -7/1983
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory until 7 PM EST this evening for PAZ054-055-
060>062-070-071-101>106.
Wind Chill Advisory until 10 AM EST Saturday for PAZ070-071-
101>106.
Wind Chill Advisory until 1 PM EST Saturday for PAZ060>062.
Wind Chill Warning until 1 PM EST Saturday for PAZ054-055.
NJ...Wind Advisory until 7 PM EST this evening for NJZ001-007>010-
012>027.
Wind Chill Advisory until 10 AM EST Saturday for NJZ009-010-
012>027.
Wind Chill Advisory until 1 PM EST Saturday for NJZ001-007-008.
Coastal Flood Warning until midnight EST tonight for NJZ020-
026.
DE...Wind Advisory until 7 PM EST this evening for DEZ001>004.
Wind Chill Advisory until 10 AM EST Saturday for DEZ001>004.
Coastal Flood Advisory until midnight EST tonight for DEZ003-
004.
MD...Wind Advisory until 7 PM EST this evening for MDZ012-015-019-
020.
Wind Chill Advisory until 10 AM EST Saturday for MDZ012-015-
019-020.
Coastal Flood Advisory until 9 PM EST this evening for MDZ012-
015-019-020.
MARINE...Gale Warning until 1 AM EST Saturday for ANZ430.
Freezing Spray Advisory until 7 AM EST Sunday for ANZ430-431-
450>455.
Storm Warning until 9 PM EST this evening for ANZ431-450>455.
&&
SYNOPSIS...Fitzsimmons/MJL
NEAR TERM...Brudy/Fitzsimmons
SHORT TERM...Fitzsimmons
LONG TERM...Fitzsimmons
AVIATION...Dodd/MJL
MARINE...Dodd
TIDES/COASTAL FLOODING...
CLIMATE...