092
FXUS61 KPHI 270722
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
322 AM EDT Fri Sep 27 2024

.SYNOPSIS...
A cold front moving in this morning will stall over the southern
half of the area, as moisture from Tropical Cyclone Helene moves in
today and tonight. An unsettled pattern will continue for the
weekend and into next week as an upper level low meanders off to the
southwest. A pattern change potentially comes by the middle of next
week as a sweeping cold front approaches.


&&

.NEAR TERM /THROUGH TONIGHT/...
130 AM...Overnight, low pressure with its associated upper
trough moves from Quebec towards the Canadian Maritimes dragging
a cold front southward into the area. This could result in some
additional scattered showers and storms, mainly over eastern PA
into central and northern NJ. In fact the front is expected to
slow and stall overnight as it reaches southern NJ and the
Delmarva. The other thing that will have to be watched for
overnight is areas of fog as we`ve already seen visibility down
to a quarter to half a mile in spots. These low visibilities
could become a bit more widespread overnight which would then
warrant a Dense Fog Advisory. It will be another warm night for
this time of year with lows mostly in the mid to upper 60s
except some upper 50s over the southern Poconos and NW NJ.

Helene is forecast to be over northern Georgia on Friday
morning, becoming absorbed into a closed upper level low over
the southeast US. This system is expected to be quite expansive,
and some moisture from the edge of Helene is anticipated to
move in Friday into Friday night.  A stalled boundary over the
Delmarva peninsula will be the focus for precipitation and
currently where the highest PoPs are for Friday
afternoon/evening (around 60-80%). Then rain should then spread
north overnight Friday night into portions of eastern PA and
adjacent NJ. Generally speaking, rain amounts through Friday
night should not be too impressive for most areas...mainly a
tenth to a quarter of an inch or less. That said, expect it to
be a bit heavier at times over Delmarva into southern NJ where
some areas could see a half inch to an inch of rain overnight.

In terms of temperatures for Friday/Friday night, near and
south of the front, high temperatures will be in the mid to
upper 70s, with upper 60s/low 70s north of the front. Overnight
lows on Friday night will be in the upper 50s to low 60s north
and west with upper 60s to around 70 south and east.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Some guidance hints at a potential dry slot setting up for Saturday,
especially over Delmarva with a warm front expected to set up right
around the Philly area. South of the warm front, it looks to be a
relatively dry day, with potentially even some peaks of sunshine.
North of the warm front, expect clouds with periods of showers and
cooler conditions with onshore flow persisting. With the warm front
bisecting the region, temperatures will be in the upper 60s/low 70s
from Philadelphia on north, and upper 70s/low 80s for South Jersey
and Delmarva. Mild overnight lows are expected with lots of clouds
around for Saturday night, with 60s expected.

For Sunday, the upper level low off to the southwest begins to
migrate eastward. This will result in another unsettled day with
some scattered showers around with mostly cloudy to overcast
conditions with a moist onshore flow. Again, won`t be a washout, and
some spots could stay dry, but will not be the nicest Sunday either.
Temperatures will only get into the upper 60s/low 70s. Scattered
showers linger into the night, with overnight lows in the upper
50s/low to mid 60s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The upper level low that will linger over the Tennessee Valley looks
begin to weaken on Monday and likely will devolve into an open
trough. The open trough will gradually move eastward and should move
offshore by Tuesday night. Up until then though, periods of
unsettled weather are likely, but no day will be a washout. Highest
PoPs around 50-60% are concentrated on Tuesday. Once the trough
moves offshore, a brief break comes in, with a period of dry weather
possible on Tuesday night. However, a cold front looks to come in
mid-week, ushering in a pattern change (finally). Guidance has
trended weaker and drier with the front, but some showers look
possible on Wednesday. Long range guidance indicates that once the
front passes, an expansive area of high pressure will try to move
in, with a ridge building in eastward, resulting in a period of dry
weather, and kicking the onshore flow pattern.

It certainly will be feeling like fall with cloudy and cool
conditions expected for the first half of next week. Temperatures
will be a few degrees below normal for late September/early October,
with upper 60s/low 70s for highs. Overnight lows may actually end up
a few degrees above normal with limited diurnal ranges continuing
with an abundance of cloud cover in place. &&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Overnight...Cigs/visbys will continue to lower overnight with
widespread IFR/LIFR expected. Some sites such as ACY could see
visibility get down to a quarter mile. Winds backing to E/NE
around 5 knots as a cold front pushes south into the area.
Moderate confidence on overall trends but low confidence on
specific details.

Friday...IFR, possibly VLIFR cigs/vsby to start the day with
gradual improvement possible to MVFR possible by the afternoon.
Showers possible, mainly across the southern tier. Low
confidence.

Friday Night...Cigs expected to go back down to IFR for most
sites with periods of rain moving through. ABE could stay mainly
MVFR. East winds 5-10 knots backing slightly to ENE overnight.
Low confidence.

Outlook...

Saturday through Sunday Night...IFR/MVFR conditions expected with
periods of rain, with low clouds hanging around through the weekend.
Some periods of VFR could come from KPHL on south, especially on
Saturday afternoon/evening.

Monday through Tuesday...sub-VFR conditions likely with 50-60%
chance of showers and low clouds hanging around in between periods
of rain.


&&

.MARINE...
Small Craft Advisory for our waters south of Cape May was
extended until 6 AM due to seas lingering around 5 feet.
Southerly winds will generally average 10 to 20 kts.

Sub-SCA conditions Friday with easterly winds less than 10 kts
in the morning, becoming 10 to 20 kts in the afternoon.

Winds and seas increase through Friday night and could be close
to Small Craft Advisory levels by Saturday morning.

Outlook...

Saturday through Saturday Night...SCA conditions possible (40-60%)
with seas approaching 5 feet and gusts on the northern waters
approaching 25 kt.

Sunday through Monday...Small Craft Advisory conditions likely (60-
70%) with seas around 5 feet and gusts nearing 25 kt.


Rip Currents...

For the remainder of today...A High Risk of Dangerous Rip
Currents is in effect until 8 PM for both the Jersey Shore and
Delaware Beaches.

For Friday...East winds around 5-10 mph. Breaking waves heights
of 2-3 feet with a 10-11 second period. As a result, have
maintained a MODERATE risk of the development of dangerous rip
currents for both the Jersey Shore and Delaware Beaches.

For Saturday...East winds around 10-20 mph for Monmouth, Ocean,
and Atlantic Counties with breaking wave heights of 3-4 feet.
Due to onshore flow and higher wave heights, have opted to go
with a HIGH risk of rip currents for these areas. For Cape May
and Sussex Counties, east-southeast winds around 10-15 mph and
breaking waves of 2-3 feet. Due to lesser wind/wave values,
opted for a MODERATE risk of rip currents for these areas.

Rip currents occur often in the vicinities of jetties and piers
and the speed of the currents are generally maximized at low
tides. For specific beach forecasts, visit weather.gov/beach/phi

&&

.TIDES/COASTAL FLOODING...
Tides and water levels continue to diminish through today, but
with onshore flow strengthening this weekend, a return of minor
tidal flooding remains possible, mainly for the New Jersey and
Delaware Coast.

The Coastal Flood Advisory remains in effect through Friday
evening for Sussex County, DE as Little Assawoman Bay and the
Indian River Inlet have been slow to drain. Minor tidal flooding
remains likely through the end of the week within the back bays.

The Coastal Flood Advisory for Ocean County has been allowed to
expire. Some spotty minor tidal flooding remains possible within
Barnegat Bay around the times of high tide, but not expecting
tidal flooding to have any significant impacts.

Along the Eastern Shore, some spotty minor tidal flooding
remains possible through the end of the week around the night-
time high tide, though no advisories are expected to be needed.


&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...Coastal Flood Advisory until 8 PM EDT this evening for DEZ003-
     004.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
     ANZ454-455.

&&

$$

SYNOPSIS...Hoeflich
NEAR TERM...Fitzsimmons
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Fitzsimmons/Hoeflich
MARINE...Fitzsimmons/Hoeflich
TIDES/COASTAL FLOODING...Hoeflich