Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 262359
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
759 PM EDT Mon Jul 26 2021

.SYNOPSIS...
High pressure builds into the region tonight into early
Tuesday. A couple of weak disturbances will cross the region
late Tuesday and Wednesday. A stronger cold front will then
arrive on Thursday. High pressure follows for Friday and
Saturday, with the approach of another cold front possible by
Sunday.

&&

.NEAR TERM /THROUGH TUESDAY/...
Cold front has sunk through most of the forecast area and is
just south of New Jersey, extending through central Delmarva.
North of the front, surface dew points have dropped into the 50s
and 60s. South of the front, dew points are still well in the
70s. Convection has tapered off, and with mid level dry air
spreading into the region, that pretty much should be it for the
night, but cannot rule out a few showers and/or storms through
sunset or so.

Temps this evening should remain in the upper 60s to low 70s.
With humidity levels still relatively high towards the coast and
across DelMarVa, patchy fog certainly seems likely and MRi`s
from Bukfit soundings support this.

Heading into the day Tuesday, brief high pressure develops and
skies should be mostly clear skies with northwesterly flow
becoming westerly. With mostly clear skies and efficient
heating, temperatures will warm to several degrees above normal
sitting in the low to possibly mid 90s for most of the region
with the mid 80s towards the higher terrain of the Poconos.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
The short term period begins Tuesday night with a shortwave
trough streaming in from the northwest. Ongoing convection
should be making its way into eastern PA and northern NJ, but
will be encountering a rather dry and increasingly unfavorable
environment for maintenance of convection. This activity should
thus wane in coverage in intensity and coverage into the evening
hours. However, some showers or storms may be possible as far
south as the I-95 corridor as the mid-level wave moves across
the area into the overnight hours though.

Northwesterly flow will continue into Wednesday and some
isolated to scattered convection is possible during the
afternoon hours associated with another much weaker mid-level
wave. The thermodynamics in place won`t be particularly
supportive of severe convection, thus the SPC has our area in a
general thunderstorm risk. Any diurnal activity will diminish
quickly into the evening.

Another more potent mid-level wave will approach the area on
Thursday. Intensifying surface low pressure to our north along
with an approaching frontal boundary from the northwest will
result in low-level moisture return as the mean low-level flow
turns southwesterly. This pattern could be quite favorable for a
typical northwesterly flow MCS developing across the region,
but the details and timing of this remain unclear.

Expect seasonable temperatures Wednesday and Thursday with high
mostly in the 80s and lows in the 60s to around 70 degrees.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The long term period starts Thursday night into Friday with the
primary synoptic trough axis moving offshore. This will bring a
rather modest cold front across the region by mid-summer standards
with low-level cool/dry air advection ramping up during the day
Friday. Dewpoints are forecast to fall into the 50s amid a
northwesterly breeze. A rather pleasant Friday and Saturday will
result with temperatures below normal. Highs will be in the upper
70s to mid 80s with lows in the 50s to low 60s Friday night.
Needless to say, the Friday-Saturday time frame looks dry.

Moisture and warm and return resumes Sunday as another trough axis
approaches from the northwest. Chances for showers and thunderstorms
appear to also return Sunday and into Monday.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...Generally VFR. Patchy MVFR fog development possible
after 06z especially at KMIV/KACY. I-95. Winds light and
variable or calm. Moderate confidence.

Tuesday...VFR conditions are expected. Showers and
thunderstorms will approach the TAF sites from the northwest,
but will likely be weakening. Winds should initially be
northwesterly turning westerly by mid day. A see breeze at ACY
may result in southerly winds of 5 to 10 kt early in the
afternoon. Moderate confidence.

Outlook...

Tuesday night...Isolated showers or thunderstorms possible north of
PHL, otherwise mostly VFR. Winds westerly around 5 kts or less
becoming more northwesterly after 06Z. Moderate confidence.

Wednesday...Prevailing VFR. Isolated to scattered showers and
thunderstorms. North to northwesterly winds around 5 kts. Moderate
confidence.

Thursday...Initially VFR with showers and thunderstorms developing
during the afternoon or evening. Winds southwesterly around 5-10
kts. Moderate confidence.

Friday...VFR. Winds northwesterly around 10-15 kts. High confidence.

&&

.MARINE...
Winds and seas should stay below SCA criteria through Tuesday.
Southwest winds of 10 to 15 kt with seas 3 to 4 ft are expected
through this evening with a thunderstorm possible in the early
evening. Overnight winds weaken and seas drop as the winds
eventually shift towards the northwest. By mid day Tuesday,
winds will flip back around to out of the south with 1 to 2 ft
seas.

Outlook...

Sub-advisory conditions are forecast through the remainder of the
week. Northeasterly winds around 10 kts Wednesday will become south
to southwesterly Thursday and increase to around 10-15 kts. Winds
then become northwesterly for Friday around 10-15 kts. Seas 2-4
feet. Showers and thunderstorms possible, mainly Thursday.

Rip Currents...

Light offshore flow in the morning will become onshore in the
afternoon both Tuesday and Wednesday. Seas will average 1 to 3
feet. As a result, there is a LOW risk for the development of
dangerous rip currents at New Jersey and Delaware beaches both
Tuesday and Wednesday.

&&

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

&&

$$
Synopsis...O`Brien/Staarmann
Near Term...Deal/MPS
Short Term...Staarmann
Long Term...Staarmann
Aviation...Deal/MPS/Staarmann
Marine...Deal/Staarmann


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