-- Discussion containing changed information from previous version are highlighted. --
739
FXUS61 KPHI 211058
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
658 AM EDT Sat Sep 21 2024

.SYNOPSIS...
Low pressure continues to meander off the East Coast before
drifting to the south and east early in the new work week.
Meanwhile, the base of surface high pressure over eastern Canada
will build down into the Appalachians before moving offshore
late Sunday. A slow moving cold front approaches from the west
next week, and low pressure may develop on that front and impact
the region late next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure continues over the region nestled in between a
meandering low offshore and a system to the northwest over
interior Canada. This allows for another day of generally quiet
sensible weather with breaks in the clouds and mostly sunny
skies for the day. Highs continue to be seasonable warm by a few
degrees and overnight lows this evening will not drop that far
staying in the upper 50s to low 60s.

During the early morning, as the temps drop close to yesterdays
crossover temps there may be some light patchy fog that
develops generally over the non urbanized areas however that
should quickly lift and mix out after daybreak if it ends up
developing.

Heading into the overnight hours a piece of weak shortwave PVA
digs into central PA and starts to provide enough lift to result
in a moderate (30-50%) chance of showers across portions of
eastern PA. The forcing isn`t that strong and broad in general
so I wouldn`t expect the rainfall to be significant nor would it
likely as the previous shift mentioned "put a dent in the dry
conditions". Guidance does suggest that there`s some weak
surface based instability around and EL`s are sufficiently tall
enough that we will carry a small chance (20%) of thunder during
the overnight hours. The rain chances, at least with this round
will be short- lived as short wave ridging starts to build
closer by Sunday morning, resulting in a return to dry
conditions.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Low pressure continues to meander several hundred miles east of
the Jersey Shore on Sunday, but will drift to the south and
east on Monday. A mid-level trough with strong shortwaves diving
into the base of the trough will be along the East Coast Sunday
morning, and there may be some showers associated with those
shortwaves over Delmarva and extreme southern New Jersey Sunday
morning. QPF will be minimal, and showers taper off by midday as
the trough departs. PoPs will be capped at slight chance.

Meanwhile, the base of high pressure centered over eastern
Canada will build down through the Northeast and into the Mid-
Atlantic Sunday afternoon. Skies clear out, and temperatures on
the first day of autumn will be within a few degrees of normal
levels, topping off in the low to mid 70s.

High pressure will be over the Northeast and Mid-Atlantic
Monday before lifting away Monday night. A slow-moving cold
front then approaches late Monday, and by Monday night, the
front should be into western New York and western Pennsylvania.
Shortwave energy diving out ahead of the front may trigger some
showers late Monday and Monday night. PoPs will mostly be slight
chance from late Monday through midnight or so Monday night,
but then PoPs increase to chance after midnight Monday night. As
has mostly been the case, QPF will be light.

Lows Sunday night and Monday night will generally be in the
50s, though around 60 at the immediate coasts due to the warmer
ocean temperatures. Highs on Monday will once again be in the
low to mid 70s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The Long Term period will feature a prolonged period of
unsettled weather.

Low pressure will move through the Great Lakes and Ohio Valley,
and a cold front will extend down from that low. Meanwhile,
high pressure will be over the Canadian Maritimes, and the the
base of that high will extend down into the Northeast. While
this should keep the front from making much headway on Tuesday,
the high should depart by Wednesday, and then low pressure drags
the front into the local area. Models are suggesting that by
Wednesday, a trough moves in from the west, and with some
shortwave energy, low pressure could develop on that front. This
would bring more in the way of rainfall to the area from
Tuesday night through Wednesday night. Will follow NBM and go
with likely PoPs during that time. However, there are
inconsistencies among the models, so this may change.

The front may not fully clear the region until Friday or so,
and unsettled weather may remain in place until then.

Temperatures will be at or a few degrees below normal during
this time.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Briefly lowered MVFR cigs should become VFR by mid
morning. NE to E winds 5 to 10 knots.

Tonight...VFR with a moderate chance (30-50%) of showers west
of I95 resulting in brief MVFR/IFR at KABE/KRDG.

Outlook...

Sunday through Monday...Primarily VFR conditions, though sub-
VFR VSBYs possible in fog Sunday night/Monday morning.

Monday night through Tuesday...VFR, though MVFR or IFR possible
in SHRA.

Tuesday night through Wednesday...Periods of MVFR or IFR in
SHRA.
-- End Changed Discussion --

&&

.MARINE...
Small Craft Advisories remain in effect for the ocean waters
through Sunday, primarily for 4 to 6 ft seas. NE winds will
generally average 15 to 20 kt.

Sub-SCA conditions for Delaware Bay. Northerly winds around 10
kt this afternoon will turn easterly overnight.

Outlook...

Sunday through Sunday night...SCA in effect for the ocean
waters, mainly for elevated seas.

Monday through Wednesday...SCA may be needed for elevated seas
into the middle of next week.

Rip currents...

There is a HIGH risk for the development of dangerous and life
threatening rip currents at the Jersey Shore and at Delaware
Beaches through Sunday. N to NE winds will range from 10 to 20
mph with gusts up to 25 mph along with 3 to 6 ft breaking waves.

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...
A prolonged period of onshore flow has resulted in and will
continue to result in a piling up of water along the coasts with
this water unable to drain within tidal waterways. At least
minor tidal flooding is expected for the next several high tide
cycles for most portions of the area. Moderate tidal flooding
will occur for portions of the area this morning, and possibly
again on Sunday.

Changes to headlines:

A Coastal Flood Warning is now in effect for the Atlantic coast
and Delaware Bay for the high tide cycle this morning for
moderate coastal flooding. The Coastal Flood Warning extends
through the Sunday morning high tide cycle for Cape May and
Cumberland counties in New Jersey and for Kent county in
Delaware. Coastal Flood Advisories are now in effect for the
high tide cycles starting Sunday morning for the rest of the
Atlantic coast of New Jersey, as well as Sussex county,
Delaware, and Delaware Beaches for minor coastal flooding.
These Coastal Flood Advisories are in effect through the high
tide cycle on Monday afternoon. Coastal Flood Advisories are in
effect for Cape May and Cumberland counties in New Jersey and
for Kent county in Delaware starting with the high tide cycles
SUnday afternoon and evening.

For the tidal Delaware River, Coastal Flood Advisories are now
in effect through the late Monday high tide cycle for minor
coastal flooding.

For the northeastern shore of Maryland, it looks like minor
coastal flooding will begin with the high tide cycle tonight.
This also now includes Kent county, Maryland. Will go ahead and
issue Coastal Flood Advisories through the Monday evening high
tide cycles, although it looks like it will be the evening high
tide cycles that will be most impacted by minor coastal
flooding.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory until 10 PM EDT Monday for PAZ070-071-
     106.
NJ...Coastal Flood Advisory until 6 PM EDT Monday for NJZ016.
     Coastal Flood Warning until 5 PM EDT Sunday for NJZ021-023-024.
     Coastal Flood Advisory from 5 PM Sunday to 5 PM EDT Monday for
     NJZ021-023-024.
     Coastal Flood Warning until 5 PM EDT this afternoon for
     NJZ012>014-020-022-025>027.
     Coastal Flood Advisory from 5 PM this afternoon to 5 PM EDT
     Monday for NJZ012>014-020-022-025>027.
     High Risk for Rip Currents through Sunday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 10 PM EDT Monday for NJZ017>019.
DE...Coastal Flood Advisory until 6 PM EDT Monday for DEZ001.
     Coastal Flood Warning until 5 PM EDT Sunday for DEZ002.
     Coastal Flood Advisory from 5 PM Sunday to 5 PM EDT Monday for
     DEZ002.
     Coastal Flood Warning until 5 PM EDT this afternoon for DEZ003-
     004.
     Coastal Flood Advisory from 5 PM this afternoon to 5 PM EDT
     Monday for DEZ003-004.
     High Risk for Rip Currents through Sunday evening for DEZ004.
MD...Coastal Flood Advisory from 10 PM this evening to 3 AM EDT
     Tuesday for MDZ012.
     Coastal Flood Advisory until midnight EDT Monday night for
     MDZ015-019-020.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>455.

&&

$$

SYNOPSIS...MPS
NEAR TERM...Deal
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...Deal/MPS
MARINE...Deal/MPS
TIDES/COASTAL FLOODING...WFO PHI