A warm front lifting northward across the area resulted in areas of dense fog starting late on February 6th and lasting into the early hours of February 7th. By dawn on the 7th, a cold front swept the fog away.
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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.
A warm front lifting northward across the area resulted in areas of dense fog starting late on February 6th and lasting into the early hours of February 7th. By dawn on the 7th, a cold front swept the fog away.
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 Feb 6, 9:58 PM EST, 2 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
958 PM EST Thu Feb 6 2025
.SYNOPSIS...
A cold front will cross the region late tonight into Friday
morning. High pressure will briefly return later Friday before
another low pressure system passes through the region late
Saturday into Saturday night. High pressure will temporarily
return on Sunday into Monday before two additonal systems
approach the region on Tuesday and Wednesday and again on
Thursday.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 955 PM, expanded the Dense Fog Advisory to now include
all of the I-95 corridor from Wilmington, Philadelphia toward
Trenton.
Otherwise, moisture continues to be trapped beneath a strong
inversion as much warmer air streams in over the lingering
colder air at the surface. This is resulting in widespread low
clouds and also areas of fog. The visibilities continue to lower
and with several PennDOT cameras in eastern Pennsylvania
showing poor visibility, issued a Dense Fog Advisory for much of
southeastern Pennsylvania (goes until 3 AM). It is possible
this will need to be expanded a bit more. A cold front will
eventually move through late tonight and erode the low-level
moisture and therefore ending the fog. Made some adjustments to
the hourly temperature, dew point and wind grids based on the
latest observations and trends and expanded the mention of fog.
The low clouds have dissipated across portions of Delaware and
Marylands Eastern Shore, however with the winds diminishing
there some fog is also developing.
Otherwise, cannot rule out a few showers around southern
Delmarva and far South Jersey as the front goes through
overnight but nothing of significance. The initial frontal
passage will result in the low-levels drying out late in the
overnight, with just some mid to high level clouds remaining.
Lows will generally be in the 30s.
A secondary cold front comes in late Friday morning, with winds
picking up in the wake of it and some sun mixed with clouds.
Gusts from the late morning to mid-afternoon will be around 30
MPH, with gusts as high as 40 MPH along the ridges in the
Poconos. Temperatures will be near normal with mid to upper 30s
north of Philadelphia with low to mid 40s from Philly on south.
Winds begin to drop off quickly in the afternoon as high
pressure moves in and the gradient weakens.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Friday night, with surface high pressure in place, will be dry.
Overnight lows will be in the teens and 20s.
When we wake up on Saturday, low pressure will be organizing across
the mid-Mississippi Valley. The low will strengthen some during the
day as it moves east. Energy will then transfer off the Mid-Atlantic
coast Saturday night before continuing northeast off the New England
coast on Sunday.
In terms of sensible weather, light snow, and maybe some
freezing rain, will break out on Saturday morning across our
southern zones. The snow will expand north Saturday afternoon,
but change over to a mix or just plain rain across southern NJ
and Delmarva. While all of the Delmarva and the NJ coastal plain
will likely change over to plain rain on Saturday night, areas
along and NW of the I-95 corridor can expect a mix bag of winter
weather. As the low pulls east offshore, all precipitation will
come to an end early on Sunday with the last of it being felt
across our northern NJ zones.
The current thinking is that the storm total precipitation will
resemble what we just experienced last night and today. But how it
manifests itself will be a little different. That is in the form of
more wintry mix including freezing rain across the northern 2/3rds
of the forecast area as well as more snow (compared to today)
across the southern Poconos and NW NJ.
Sunday does appear to be mostly dry during the afternoon. High
temperatures will be quite seasonable under a mix of sun and
clouds.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
While a lot can change between now and next week, models do continue
to showcase an active long range period with the potential of
multiple wintry events. The first being Tuesday into Wednesday. The
second being on Thursday. As we move into next week, we'll hone in
on more precise timing and p-type.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...
Tonight...IFR/LIFR ceilings through about 07z then these lift
quickly to MVFR and VFR in the wake of a cold front. Areas of
fog will reduce the visibility to IFR or less before improving
late tonight. Southwest to west-southwest winds less than 10
knots will become light and variable to calm at some terminals,
then become west to west-northwest late tonight near 10 knots.
Low confidence regarding the fog and timing details for
improving conditions.
Friday...VFR. West-northwest winds 12-18 knots with gusts up to
30 knots. High confidence.
Outlook...
Friday night...VFR. No precipitation expected.
Saturday through Saturday night...VFR to start the period. Sub-VFR
conditions developing. Precipitation starting as snow and
then gradually changing over to a wintry mix or rain.
Sunday through Monday...Other than some lingering restrictions early
Sunday morning, VFR is expected. No precipitation is expected.
Monday night into Tuesday...VFR to start Monday evening. Sub-VFR
conditions developing Monday night and persisting through Tuesday.
Precipitation starting as snow and then gradually changing over to a
wintry mix or rain.
&&
.MARINE...
A Small Craft Advisory is in effect through Friday for all
ocean zones due to seas 4-6 feet. Southwest to west winds
tonight, then west-northwest winds increase Friday to 15-20
knots with gusts up to 30 knots. A Small Craft Advisory goes
into effect for the day Friday for Delaware Bay given west to
northwest wind gusts forecast to be right around 25 knots.
Outlook...
Friday night...We'll need to watch for lingering SCA conditions
early Friday evening. Outside of those few hours on Friday evening,
sub-SCA conditions are expected.
Saturday through Saturday night...Sub-SCA conditions are expected.
Sunday...A period of SCA conditions are likely as winds gust up to
25 kt and seas top out at 5 feet.
Sunday night through Monday...SCA conditions may briefly linger into
Sunday night, other than that, sub-SCA conditions are expected.
Tuesday...As the next frontal system approaches, area waters may
approach SCA levels.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 3 AM EST Friday for PAZ070-071.
Dense Fog Advisory until 3 AM EST Friday for PAZ060>062-
101>106.
NJ...Dense Fog Advisory until 3 AM EST Friday for NJZ016>019.
Dense Fog Advisory until 3 AM EST Friday for NJZ007-009.
DE...Dense Fog Advisory until 3 AM EST Friday for DEZ001.
MD...None.
MARINE...Small Craft Advisory from 7 AM to 4 PM EST Friday for ANZ430-
431.
Small Craft Advisory until 6 PM EST Friday for ANZ450>455.
&&
SYNOPSIS...Kruzdlo
NEAR TERM...Hoeflich
SHORT TERM...Kruzdlo
LONG TERM...Kruzdlo
AVIATION...Gorse/Hoeflich/Kruzdlo
MARINE...Gorse/Hoeflich/KruzdloThe national radar mosaic for the moment the first event began.
2 dense fog. Local standard time, as filed.
Several hours of dense fog was observed at Delaware Airpark.
Several hours of dense fog was observed at Wilmington Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Delaware in 2025Every state in 2025This day in weather historyWarnings in Delaware, February 2025
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: 1238270, 1238271.