High pressure sitting nearby combined with light winds and clear skies with a moist lower atmosphere promoted fog development over central and southern Delaware before dawn on August 27th. The fog shortly after sunrise.
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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.
High pressure sitting nearby combined with light winds and clear skies with a moist lower atmosphere promoted fog development over central and southern Delaware before dawn on August 27th. The fog shortly after sunrise.
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 Aug 26, 11:16 PM EST, 1 hour 44 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
1216 AM EDT Tue Aug 27 2024
.SYNOPSIS...
A weak surface trough will drift offshore tonight, before high
pressure builds into the region on Tuesday. A cold front will move
across the area late Wednesday into Wednesday night. The front
slowly pushes south, while a disturbace aloft move across the area.
High pressure shifts into the Canadian Maritimes Friday, before a
cold front moves across the area Saturday into Saturday night. Yet
another cold front is expected Sunday night.
&&
.NEAR TERM /THROUGH TODAY/...
Dry conditions can be expected overnight. With light and
variable winds and mostly clear skies, we should see some patchy
fog develop, particularly in areas that received rainfall
earlier. Expect low temperatures in the low to mid 60s in most
areas.
Increasing influence from the offshore high pressure looks to keep
the area dry Tuesday through Tuesday night. Temperatures look to be
a few degrees warmer though as we continue to move towards more
humid conditions for the mid-week. Highs mainly in the upper 80s
with a few spots hitting 90 daytime Tuesday.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
On Wednesday, our area will be under the influence of return flow,
leading to warming temperatures and increasing dewpoints. In fact,
we've issued an Excessive Heat Watch for much of eastern
Pennsylvania, portions of northern, central, and southern New
Jersey, as well as northern Delware where heat index values are
expected to approach 105 degrees Wednesday afternoon due to
temperatures in the mid 90s and dew points in the low 70s.
Another concern for Wednesday into Wednesday night will be the
potential for severe weather. Showers and thunderstorms are expected
to develop ahead of an approaching cold front. Much of the guidance
does not have the showers and thunderstorms reaching our area until
closer to sunset, which could limit severe potential. However, there
will likely be enough instability from the daytime lingering, as
well as a potent short wave, that strong to severe storms could
continue into the evening hours. With PW values over 2 inches, any
storms could also have heavy rainfall as well.
As we move into Thursday and Thursday night, the front will sag to
our south. However, another short wave/vorticity impulse will move
across the area, which could lead to another round or two of showers
or thunderstorms.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
The potential for unsettle weather remains for much of the long term
period, with the main focus on Saturday. On Friday, high pressure
shifts into the Canadian Maritimes, but there could be some shower
activity as a short wave/vorticity impulse moves across the area.
By Saturday and Saturday night, a cold front is forecast to move
across the area. This will lead to another round of showers and
possible thunderstorms. Instability will be limited, so the severe
threat will be limited as well. However, PW values exceed 2 inches
again, so heavy rainfall will be possible with any showers or
thunderstorms.
Yet another cold front is expected late Sunday into Sunday night
with another round of showers. Little if any instability is
forecast, so thunderstorms are not expected.
Dry weather is expected by early next week as high pressure begins
to approach the area front the west Monday.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...VFR with just some passing clouds are expected.
Patchy fog development is possible. Winds 5 kts or less and
variable early, potentially settling out of the northeast by
06Z. High confidence.
Tuesday...VFR conditions expected through the period with no
significant weather. Light winds around 5 knots becoming
southwesterly except at KMIV/KACY where sea/bay breeze influence
may keep winds more south/southeasterly. High confidence in
prevailing VFR.
Outlook...
Wednesday-Wednesday night...VFR through much of the day. Showers and
thunderstorms possible later in the day and into the night which
could temporarily lead to lower conditions.
Thursday-Thursday night...Sub VFR conditions possible with a chance
of showers or thunderstorms.
Friday-Friday night...Sub-VFR conditions possible, a chance of VFR
conditions during the day.
Saturday...Sub-VFR conditions possible with a chance of showers and
thunderstorms.
&&
.MARINE...
Conditions are forecast to remain below advisory conditions
through Tuesday night. Winds bottom out to less than 10 knots
tonight and continue through Tuesday night. Seas 1-3 feet
throughout the period.
Outlook...
Wednesday-Wednesday night...Conditions expected to remain below
advisory levels. Chance of showers and thunderstorms which may lead
to locally higher winds and waves.
Thursday-Saturday...Seas could approach Small Craft Advisory levels
with seas 5-6 feet. Chance of showers and thunderstorms Thursday and
Thursday night, as well as Saturday which may lead to locally higher
winds and waves.
Rip Currents...
For Tuesday, winds turn more east/southeasterly, though will decrease
to around 5-10 MPH. With light onshore flow, an 8-9 second period,
and breaking waves of 1 to 2 feet, a LOW risk for the development
of rip currents is in place for all beaches.
For Wednesday, winds turn more southwesterly, though will
increase to 10-15 MPH. However, with a 6-8 second period, and
breaking waves of 1 to 2 feet, a LOW risk for the development of
rip currents continues for all beaches.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Excessive Heat Watch from Wednesday afternoon through
Wednesday evening for PAZ060>062-070-071-101>106.
Air Quality Alert from 11 AM this morning to 11 PM EDT this
evening for PAZ070-071-101>106.
NJ...Excessive Heat Watch from Wednesday afternoon through
Wednesday evening for NJZ007>010-012-013-015-017>020-027.
Air Quality Alert from 11 AM this morning to 11 PM EDT this
evening for NJZ012>019-021.
DE...Excessive Heat Watch from Wednesday afternoon through
Wednesday evening for DEZ001.
MD...None.
MARINE...None.
&&
SYNOPSIS...Robertson
NEAR TERM...AKL/Kruzdlo/Staarmann/Wunderlin
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...AKL/Kruzdlo/Robertson
MARINE...AKL/RobertsonThe national radar mosaic for the moment the first event began.
2 dense fog. Local standard time, as filed.
Dense fog was observed for several hours at Delaware Coastal Airport.
Dense fog was observed for several hours at Delaware Airpark.
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, August 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: 1206306, 1206307.