988
FXUS61 KPHI 191642
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1242 PM EDT Fri Jul 19 2024

.SYNOPSIS...
High pressure will prevail through tonight across the region
with a frontal boundary stalled south of the area. A weak
system passes by Saturday night, then high pressure will remain
offshore through much of next week with daily chances for
showers and thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
Previous forecast remains on track.

Looks like the front may be about to stall to our southeast. In
the wake of the front high pressure will build in combined with
a little bit of dry air advection. Consequently, will see
dewpoints in the 50s (60s near the coast) by this afternoon,
which will be a nice change especially from the humidity earlier
in the week. This is lower than what a blend of guidance is
depicting, but suspect that many components of the blend may not
be capturing how deep the mixed layer will be. Temperatures
will be near normal, with highs generally in the 80s (though 70s
will be possible in the higher terrain of the southern Poconos
and near the coast).

With high pressure building in, expect large scale subsidence to
be in effect, so don`t expect any precipitation, and only few
mid level cumulus clouds through the day. May see more high and
mid level clouds build in Friday night as a weak low pressure
system begins to develop to our southwest.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The stalled frontal boundary to our south will begin to return
northward into the area by Saturday night as a shortwave trough
nears the region. The trough and associated jet streak will
pass through Saturday night, then zonal flow returns by Sunday.

The main story for the weekend will be temperatures and humidity
levels starting creep back up, though not to oppressive levels
as dew points should top out mainly in the 60s. Temperatures
will be seasonable with highs mainly in the 85 to 90 degree
range, warmest Sunday, and lows mostly in the 60s to low 70s.
The passing trough will yield an increasing chance for
convection by late Saturday into Saturday night. The question is
how much instability will be around during the overnight period
though since diurnally driven instability will be waning, so we
continue to advertise only 20-40% PoPs. Following a mostly
cloudy Saturday, more sun can be expected by Sunday. Some
isolated lingering convection will be possible Sunday across
southern Delmarva with the boundary remaining in the vicinity
but it will be an otherwise dry day. Severe thunderstorms are
unlikely during this period, but gusty winds and heavy downpours
may be possible. Remaining tranquil through Sunday night and
remaining mild.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The area will be in a deep layer moist south to southwest flow
for much of next week due to a long wave trough over eastern
North America and ridging over the western Atlantic. At the
surface, Bermuda high pressure remains offshore and the frontal
boundary will lift well north of the area. This will translate
to increasing chances for convection with each day as synoptic
support increases with each passing day. Generally expect
isolated to scattered showers and thunderstorms each day,
favoring the typical diurnally driven hours. Some severe
thunderstorms are possible, though the daily details on the
convective evolution remain unclear. PWATs will also be quite
high given the moist set up so we will also have to watch for
possible flooding. Temperatures will remain seasonable with
highs generally ranging from the mid 80s to near 90 degrees and
lows in the mid 60s to low 70s. Humidity will increase though
and may become quite oppressive by the middle of the week with
dew points potentially in the low to mid 70s.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through Today...VFR conditions with only few cumulus clouds
around 5000 ft AGL developing in the afternoon. Winds may start
northerly or variable, but should settle out of the west by mid
day. A seabreeze after 18Z may cause SE-S winds at KMIV/KACY.
High confidence.

Tonight...VFR with increasing high and mid level clouds
especially after 06Z. Winds expected to be light and variable
for much of the night. High Confidence.

Outlook...

Saturday night through Sunday...Generally prevailing VFR. A
20-40% chance of showers or thunderstorms mainly late day
Saturday into the first part of Saturday night. Patchy fog
possible at night.

Monday through Wednesday...Generally prevailing VFR expected,
but scattered showers and thunderstorms likely each afternoon
and evening, which could bring some restrictions if they move
over any of the terminals.

&&

.MARINE...
Winds and seas should stay below Small Craft Advisory criteria
through tonight.

Outlook...

Saturday night through Wednesday...No marine headlines
expected. Scattered showers and thunderstorms possible Saturday
night and again by Monday through Wednesday.

Rip Currents...

For Today...with a slight onshore component to the wind, and a
medium period swell continuing, the risk for dangerous rip
currents along the NJ shore is MODERATE today. The on shore
component is slightly less at the Delaware Beaches, therefore,
the risk there is LOW today.

On Saturday, wave heights and the dominant period is expected to
decrease. Therefore, the risk for dangerous rip currents is LOW
for the coasts of NJ and DE.

For specific beach forecasts, visit weather.gov/beach/phi

&&

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

&&

$$

SYNOPSIS...Fitzsimmons/Staarmann
NEAR TERM...Johnson/MJL
SHORT TERM...Fitzsimmons/Staarmann
LONG TERM...Fitzsimmons/Staarmann
AVIATION...Fitzsimmons/Johnson
MARINE...Fitzsimmons/Johnson