644
FXUS61 KPHI 191341
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
941 AM EDT Fri Jul 19 2024

.SYNOPSIS...
High pressure will prevail through today across the region with a
frontal boundary stalling out 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/...
The stalled frontal boundary to our south will begin to return
northward on Saturday 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 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. Saturday should also be
fairly cloudy with the approaching system, but 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.

&&

.LONG TERM /SUNDAY NIGHT 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 well into the 70s.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
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 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 and Tuesday...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 through Tuesday...No marine headlines expected. Scattered
showers and thunderstorms possible Saturday night and again by
Monday and Tuesday.

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