Warm air advecting over a cold air mass near the surface resulted in widespread dense fog from late in the 28th thru the morning of the 29th.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PHI wrote it up.
Warm air advecting over a cold air mass near the surface resulted in widespread dense fog from late in the 28th thru the morning of the 29th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Dec 28, 8:42 PM EST, 2 hours 18 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
842 PM EST Sat Dec 28 2024
.SYNOPSIS...
A warm front will lift north of the area tonight into Sunday, before
a cold front moves across the area Sunday night. High pressure
builds offshore of the Mid Atlantic region Monday night, followed by
a low pressure system Tuesday night. This low will move into the
Canadian Maritimes later Wednesday into Saturday, setting up
northwest flow for the end of the week into the weekend.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
A damp and dreary Saturday evening in progress. The weather
features overcast skies with rains, which have been diminishing
the past few hours, as well as areas of drizzle and fog across
the region. A stationary front remain across New Jersey and down
into Delmarva. This front won't move much tonight, but towards
dawn will begin to lift towards the north/west as low pressure
well west of the area strengthens. Pops were lowered for the
next several hours, but were tapered across the south/west to
rise again towards morning to blend with the previous forecast.
Fog which formed earlier today has become locally dense across
the higher elevations of the southern Poconos and north NJ this
evening. It appears that conditions will remain favorable for
this dense fog to continue overnight in these and adjacent
areas. The Dense Fog Advisory for the western/northern areas
will continue until 9AM Sunday.
Temperatures will likely remain rather stable across the
region tonight, only cooling into the 40s to 50s and possibly
warming by a few degrees come early Sunday morning. Rainfall is
also expected to become better organized as this front becomes
more organized during the predawn hours of Sunday, increasing
the chance for some more steady rain.
As the warm front shifts north across the area through the day
on Sunday, rain chances will decrease from south to north. Most of
the rainfall during the afternoon and early evening hours will be
confined to locations northwest of the fall line.
With continued warm advection through the day, and at least a few
breaks in the clouds, temperatures during the day on Sunday will be
well above normal with highs in the middle 60s across portions of
the Delmarva into southern New Jersey. Farther north, highs in the
low to mid 50s can be expected where cloud cover will likely be more
extensive and at least a low chance for rain continues through the
day. See Climate section below for record high temperatures on
Sunday.
Beginning Sunday evening, a negatively tilted trough at the mid and
upper levels, and a cold front trailing a deepening surface cyclone
will begin to bring increased rain chances areawide. During the
overnight hours, a strong low-level jet will develop across the
area, with 850 mb winds of 50-60 kt. Some elevated instability will
be present, and therefore some thunder cannot be ruled out with this
activity, particularly across the Delmarva and into portions of
southern New Jersey. Gusty winds of 30-40 mph cannot be ruled out
with any thunderstorms, though this potential will remain limited
due to the elevated nature of this instability.
Rainfall totals through the weekend of up to 1 inch are possible
across central and southern portions of the forecast area, with
perhaps up to 1.5 inch across portions of the Lehigh Valley and into
the Poconos.
This activity will clear the area from west to east by around
daybreak Monday, ushering in cooler temperatures and clearing skies.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The cold front that affects the area Sunday night will be moving
away from the area early on Monday. There could be some lingering
showers early in the day Monday, but most of the day will remain dry
behind the front. Dry conditions will continue into the night Monday
as high pressure builds offshore of the Mid Atlantic region.
On Tuesday, the weather will begin dry as the high pressure offshore
moves away from the area. However, showers will begin making their
way into the region from the south ahead of an approaching storm
system. A low pressure system will move right over the forecast area
Tuesday evening, so a period of moderate to heavy rainfall can be
expected. In fact, there may be enough instability for a few
thunderstorms to occur along and south and east of the I-95
corridor.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The aforementioned low pressure system will move to the northeast
during the day Wednesday, with a surface through moving across the
area during the daytime. This could keep some showers affecting the
area during the day Wednesday. The temperatures could be cold enough
for snow to mix in at times across portions of Northeast
Pennsylvania and northern New Jersey during the day Wednesday. The
low will then move into the Canadian Maritimes Wednesday night and
remain near that region into Saturday. This will set up a northwest
for the end of the week. There may be enough cold air and moisture
to create snow showers for portions of northeast Pennsylvania and
northern New Jersey Wednesday night into Thursday. Otherwise, the
remainder of the week into the beginning of the weekend will likely
remain dry.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...Latest guidance shows prolonged IFR/LIFR ceilings
will continue through the overnight hours. In addition, calm
winds and plentiful moisture at the surface will be favorable
for areas of fog tonight, becoming dense at times. Another low
level jet could bring back low level wind shear concerns closer
to 12Z.
Sunday...IFR cigs (possibly LIFR) to start the morning due to low
ceilings and reduced visibility in rain, drizzle and fog. Terminals
look to improve by the afternoon to MVFR/IFR by the afternoon with a
dry pocket ahead of the cold front approaching Sunday night. Small
chance (15 percent or less) of thunderstorms Sunday night. S-
SSE winds gusting up to 20-30 kt.
Outlook...
Monday-Monday night...Mostly VFR conditions expected.
Tuesday..VFR early. MVFR conditions developing later in the day as
showers move in from the southwest.
Tuesday night...MVFR/IFR conditions expected with a period of
showers and a chance of thunderstorms along an south and east of the
I-95 corridor.
Wednesday-Wednesday night...MVFR ceilings possible Wednesday into
Wednesday evening, improving overnight.
Thursday...VFR conditions likely
&&
.MARINE...
Winds and seas will remain below Small Craft Advisory
conditions through tonight. Periods of visibility restrictions
in rain and fog will be possible through this time.
Small Craft Advisory goes into effect Sunday afternoon through
the end of the period. Seas 3-5 feet during the afternoon will
build into 6-8 feet Sunday night. A line of heavy showers will
be possible during the predawn hours Monday morning.
Outlook...
Monday and Monday night...Small Craft Advisory remains in
effect due to seas.
Tuesday..Sub-advisory conditions likely.
Tuesday night-Thursday...Small Craft Advisory conditions due to wind
and seas.
&&
.CLIMATE...
Temperatures on Sunday will be up to 20 degrees above normal.
However, in general the forecast is still well below the record
highs. Currently only Reading, Mount Pocono, and Georgetown
have a forecast within 5 degrees of the record high.
Record High Temperatures for December 29th
SITE...............RECORD...YEAR
Allentown (ABE)........72...1984
AC Airport (ACY).......75...1984
AC Marina (55N)........72...1984
Philadelphia (PHL).....72...1984
Wilmington (ILG).......74...1984
Reading (RDG)..........64...1982
Trenton (TTN)..........74...1984
Mount Pocono (MPO).....56...1982
Georgetown (GED).......69...1988
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 9 AM EST Sunday for PAZ054-055-
060>062-101>103.
NJ...Dense Fog Advisory until 9 AM EST Sunday for NJZ001-007.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 1 PM Sunday to 7 AM EST Monday for
ANZ430-431.
Small Craft Advisory from 1 PM Sunday to 5 AM EST Tuesday for
ANZ450>455.
&&
SYNOPSIS...Robertson
NEAR TERM...Cooper/MJL/po
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...MJL/Robertson/po
MARINE...MJL/Robertson
CLIMATE...Preliminary Local Storm Report
National Weather Service Mount Holly NJ
836 PM EST Sat Dec 28 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0836 PM Rain South River 40.45N 74.38W
12/28/2024 M0.70 Inch Middlesex NJ Trained Spotter
&&
RCMThe national radar mosaic for the moment the first event began.
1 dense fog. Local standard time, as filed.
Wilmington Airport reported several hours of dense fog.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Delaware in 2024Every state in 2024This day in weather historyWarnings in Delaware, December 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1225915.