Liberty Mountain

000
FXUS61 KPHI 111205
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
805 AM EDT Fri Sep 11 2026

.WHAT HAS CHANGED...
Updated Key Message 1.

There is increasing concern for a heavy rain/flash flood threat
with showers and storms late Saturday into Sunday.

Increasing concern for a moderate risk for rip currents
Saturday.

&&

.KEY MESSAGES...
1. A cold front will continue to dig south through early this
morning, bringing a round of showers.

2. A low approaching the area Saturday into Sunday will bring a
warm front followed close behind by a cold front.

3. During the later half of next week, a stationary front may
set up just north of our region.

&&

.DISCUSSION...
KEY MESSAGE 1...A cold front will continue to dig south through
early this morning, bringing a round of showers.

A cold front continues to slide south over the region this
morning, and a round of showers are sliding across Delmarva and
southern New Jersey. There is still ample low level moisture as
evidenced by the 70+ degree dew points ahead of the front, but 
lift is on the weaker side, and instability is quite limited. 
Given radar trends however, issued a quick update to increase 
the PoPs quite a bit early this morning across Delmarva and 
across portions of southern New Jersey. Some moderate to briefly
heavy downpours will occur at times. Also, increased the cloud 
cover for a time.

Following any morning showers, today will shape up to be a nice
day with clouds breaking later in the day. Highs in the upper 
70s to low 80s in most areas.


KEY MESSAGE 2...A low approaching the area Saturday into Sunday
will bring a warm front followed close behind by a cold front.

Once the cold front this morning slides south of our region, our
attention next turns to the Saturday/Sunday time period when
first a warm front will lift through the region on Saturday,
followed closely by a cold front Saturday Night into Sunday. The
exact evolution of the mid level short wave trough and surface
low or trough is still uncertain. Regardless, there should be
plenty of lift, even just with the fronts, for widespread
showers and thunderstorms, particularly ahead of the cold front
Saturday Night into Sunday.

As for the hazards, the main threat remains heavy rain and flash
flooding. Model soundings continue to indicate precipitable
water values well above the 90th percentile and even at or
exceeding many of the daily max values for surrounding sounding
locations. Model soundings also show remarkably deep warm cloud
layers (for mid September), further increasing the concern for
heavy rain. The big questions at this point are how quickly are
the fronts (and thus storms) going to move through our region, 
and where will the axis of heaviest rain be. Given that we've
had at this point a week of little rain, rivers are in pretty 
good shape in terms of lower water levels limiting the concern 
for river flooding. The bigger concern with this event will be 
flash flooding, particularly if the heavier rains fall in our 
more flash flood prone urban areas, and flooding on smaller
creeks and streams.

Given the forecasted timing of this event, instability looks to
be quite limited. Thus the threat for severe thunderstorm
hazards (damaging winds, large hail, and tornadoes) is very
limited. 

In the wake of the cold front on Sunday, drier air should start
to settle in to the area. A few models are depicting a secondary
cold front moving through the region Sunday Night. That could
bring some isolated showers to the region, but given the drier
air in place, the vast majority of the region should stay dry.


KEY MESSAGE 3...During the later half of next week, a 
stationary front may set up just north of our region.

Once we get through this weekend, attention will turn to
Thursday and Friday of next week. Models are depicting a
stationary front setting up north of our region. The northern
half of our region already has 40 to 60% chance for showers and
storms through this period. However, of bigger note, the pattern
has similarities to the Maddox frontal event heavy rain pattern.
Given how it is currently depicted on most models, even if the
similarities continue, the main area of heavy rain rain would be
north of our region. However, if we see any trends of the front
setting up further south, that could increase the risk for heavy
rain within our region.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, 
KILG, KMIV, KACY and surrounding areas.

Today...Prevailing VFR. Winds start north/northeasterly around 
5 to 10 kt, eventually becoming light and variable after 18Z. A 
sea breeze may develop resulting in more east/southeast winds 
at KACY/KMIV but winds should be rather light. Moderate
confidence.

Tonight...VFR. Winds light and variable as they slowly settle
out of the southeast. High confidence.

Saturday...Prevailing VFR. Scattered SHRA and TSRA may 
temporarily lower conditions to MVFR or even IFR, particularly 
after 18Z, and particularly for KILG and KRDG. Low confidence.

Outlook...

Saturday Night through Sunday...Periods of sub-VFR conditions 
will be possible with scattered showers and storms. 

Sunday night through Tuesday...VFR.

&&

.MARINE...
Winds and seas should stay below Small Craft Advisory criteria
through early next week. However, gusty and erratic winds will
be possible in the vicinity of any showers and thunderstorms
particularly Saturday Night into Sunday. 

Outside of storms, a few wind shifts are expected over the next
few days. First a gradual shift to southeasterly winds is
expected tonight into tomorrow as a warm front lifts through the
region. Second, a more abrupt wind shift is possible on Sunday
Morning to southwesterly winds as a cold front moves through.
Finally, another abrupt wind shift (this time to northwesterly
winds) is possible with a secondary cold front on Sunday night.

With northwesterly winds on Monday, there is a potential for
funneling effects down the Delware Bay, so locally higher wind
gusts can be expected there. However, even with funneling
effects, wind gusts should be less than 25 kt.

Rip Currents...

Although we are within a day of the new moon, the risk for the
formation of dangerous rip currents today is expected to be LOW
due to light winds, lower wave heights and mostly wind driven
waves.

For tomorrow (Saturday), however, winds start to increase and
will have more of an onshore component to them. Additionally,
there could be an underlying 10 second swell (even if it is not
the dominant period). Therefore the risk for the formation of
dangerous rip currents is expected to be MODERATE tomorrow at
both the Delaware and New Jersey coast.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...Gorse/WFO PHI
AVIATION...WFO PHI
MARINE...WFO PHI