North Star, Delaware 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

556
FXUS61 KPHI 160718
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
318 AM EDT Mon Mar 16 2026

.WHAT HAS CHANGED...
Wind Advisory expanded inland to include most of the forecast
area this afternoon into tonight.

Updated Aviation discussion for the 06Z TAFs.

&&

.KEY MESSAGES...
1. We continue to monitor the potential for strong to severe
thunderstorms this afternoon into tonight along and ahead of a
strong cold front. Even outside of storms, strong winds are
likely, especially closer to the coast. Localized flash flooding
will also be possible, especially inland.

2. Cold and dry through mid-week before temperatures moderate
through the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...We continue to monitor the potential for strong
to severe thunderstorms this afternoon into tonight along and
ahead of a strong cold front. Even outside of storms, strong
winds are likely, especially closer to the coast. Localized
flash flooding will also be possible, especially inland.

A strongly amplified upper level trough across the central
CONUS will turn negatively tilted as the day progresses. A
strong mid latitude cyclone will continue to strengthen and move
northeastward across the eastern Great Lakes and into
southeastern Canada into tonight. This system will continue to
push north towards James Bay in Quebec and will usher in a
strong cold front with a sharp temperature gradient through the
region late this evening.

A warm front will lift north of the area this morning, bringing
the warm sector of the cyclone over the Mid Atlantic. This will
usher in both warmer temperatures and higher dewpoints. The
southerly flow associated with this system will transport a deep
moisture plume into the region ahead of the frontal system.
Guidance is depicting significant height falls along with a
strong upper level jet with the right rear located right over
the Mid Atlantic. The combination of strong warm air advection,
rapidly falling surface pressure, and upper level dynamics will
result in significant forcing for ascent across the region this
afternoon and through the evening.

Low level wind shear will be quite strong just ahead of the
frontal passage and the combination of dynamic lift, sufficient
moisture, and modest instability (for mid March standards) will
support organized convection. Instability will be the limiting
factor, however the dynamics should play a strong enough role
in overcoming that instability. High res guidance show
sufficient low level support to see STP values greater than
0.5-1 during a brief window during the late afternoon/evening.
It is worth noting that the outlook from the Storm Prediction
Center continues the ENHANCED risk of severe weather in our
County Warning Area.

Something to note, is that if the temperatures/dewpoints surge
higher than initially forecast, instability will increase quite
a bit. Guidance has a tendency to be too conservative with
surface conditions in strong southerly flow regimes (as we will
have during this event). Higher temperatures/dewpoints in the
warm sector ahead of the cold front could support potential for
some isolated supercells to develop. The primary threat remains
wind, however the threat for tornadoes is increasing. Shear
vectors are generally supportive of QLCS type tornadoes and
these are often the hardest type of tornado to issue warnings
for, as they can be very brief in nature. A potential limiting
factor for this setup could be too much convection. If too much
disorganized, benign convection occurs ahead of the line, it
could weaken lapse rates and instability. But again, we`ll have
plenty of forcing and very strong wind fields to help recover
the environment in the wake of such activity.

Finally, it should be noted that even outside of any
thunderstorms the strong wind fields will support southerly
winds gusting at least 35 to 45 mph this afternoon into
tonight, locally up to 50 mph. The Wind Advisory was
expanded to include most of the forecast area. The strong
southerly winds will help usher in an unseasonably warm and
humid airmass. High temperatures this afternoon and evening will
be in the mid 60s to low 70s inland, and closer to 60 degrees
near the coast and higher terrain.

In addition to the severe weather and strong wind threat, the
showers/storms will likely be producing heavy rainfall as PWATs
are progged to be 1.1-1.4" which is above the 90th percentile
for early March. MMEFS guidance is showing modest rises in
rivers, so we`ll continue to watch for any potential hydro
concerns, especially where any training of convection occurs.

KEY MESSAGE 2...Cool and dry weather expected through Wednesday
before moderating through the weekend.

A much colder airmass filters in for Tuesday and Wednesday as a
deep upper trough will be situated over the eastern CONUS. At
the surface, broad high pressure near the Gulf Coast on Tuesday
will shift northeast over the Mid-Atlantic on Wednesday. This
will yield dry conditions under mostly sunny skies with highs
mainly in the mid 30s to mid 40s. However, the pressure gradient
will be tight over the area, so post-frontal winds with gusts
up to 30-35 mph are possible on Tuesday. Also, with drier air
filtering in, MinRH values are expected to fall into the 25-35%
range.

By late week and into the weekend, temps begin to moderate back
to seasonable and eventually seasonably warm levels. At this
point, the next chance for precipitation is expected to be
Friday night into Saturday with the next disturbance tracking
north of the area. Shower chances range from 20-40%.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of tonight...Lowering CIGs and VSBYs as showers develop
across the terminals. The showers will move N/NE across the area
then decrease by dawn. Mostly IFR or low-end MVFR conditions
with the showers but not all of the time. LLWS with 60 to 65 kts
of winds at 020 thru dawn. Low confid overall.

Monday... Improving conditions following the overnight showers
but just how much is not certain. We`ll use VCSH for much of the
day but bring another period of SHRA for the afternoon many
sites. Mostly MVFR conditions but IFR/LIFR at KACY near the cold
ocean waters. Low confidence overall.

Monday night...A strong cold front will cross the terminals
between 01Z (KRDG/KABE) and 03Z/04Z (KMIV/KACY). LIFR conditions
with +SHRA/+TSRA and very gusty winds with the activity surface
gusts 45kt to 55kt expected. LLWS with S/SSW winds 65 to 75 kts
at 020 and closer to 90 kts at 030. Rapidly improving
conditions following the front with VFR a few hours after the
frontal passage. Low confid overall.

Outlook...

Tuesday through Tuesday night...VFR. Gusty west winds up to 30
kt possible during the afternoon, diminishing into the evening.

Wednesday through Friday...VFR. No significant weather
expected.

&&

.MARINE...
Southerly winds will continue to increase and bring seas of 5-7
feet through the remainder of the overnight period, with SCA in
effect for ocean waters. Continued increase in southerly flow
through today will bring gale force winds, especially late in
the day and during the evening, with Gale Warning remaining in
effect. Gusty thunderstorms also possible, mainly later in the
day and during the evening. Winds start to diminish late in the
night.

Outlook...

Tuesday through Tuesday night...SCA conditions likely. West
winds around 20-30 kt with seas around 5-8 feet.

Wednesday...Lingering SCA conditions possible. Winds generally
below 20 kt with seas around 3-5 feet.

Wednesday night through Friday...No marine headlines expected.
Winds mostly below 15 kt with seas around 2-4 feet.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory from 2 PM this afternoon to 2 AM EDT Tuesday for
     PAZ054-055-060>062-070-071-101>106.
NJ...Wind Advisory from 2 PM this afternoon to 2 AM EDT Tuesday for
     NJZ007-009-010-012>027.
DE...Wind Advisory from 2 PM this afternoon to 2 AM EDT Tuesday for
     DEZ001>004.
MD...Wind Advisory from 2 PM this afternoon to 2 AM EDT Tuesday for
     MDZ012-015-019-020.
MARINE...Gale Warning from 6 AM this morning to 2 AM EDT Tuesday for
     ANZ430-431-450>455.
     Small Craft Advisory until 6 AM EDT early this morning for
     ANZ450>455.

&&

$$

DISCUSSION...Deal/DeSilva/RCM/Staarmann
AVIATION...OHara
MARINE...Deal/DeSilva/RCM/Staarmann