Tredyffrin, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

840
FXUS61 KPHI 140750
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
350 AM EDT Sat Jun 14 2025

.SYNOPSIS...
A front will remain across southern Delmarva through the
weekend. Several waves of weak low pressure with some showers
and thunderstorms will impact the region along with below
average temperatures through early next week. Bermuda high
pressure will then begin to take hold toward the middle of next
week with increasing temperatures and daily chances of showers
and thunderstorms remaining. A cold front may impact the region
later next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

Cloudy, showery, drizzly, and humid conditions expected through the
entire weekend along with below normal temperatures. Overall,
nothing of particular interest to note as far as impacts go with the
convective activity in our region, however the lousy conditions
won`t be good news for any outdoor activities.

Quasi zonal and relatively weak flow will continue to prevail aloft,
though we will remain in the vicinity of the right entrance region
of a zonal jet toward our northeast. This will provide a prolonged
period of modest ascent through tonight, which will lead to
prevailing cloudy skies and periods of showery weather. At the
surface, a stalled to slowly moving frontal boundary will remain in
place across Delmarva into Virginia. Weak low pressure will slide
offshore today, then surface ridging will strengthen some into
tonight, which should push the frontal boundary a little farther
south (south of our area completely).

As far as precipitation chances go, not great confidence through
tonight regarding any details of timing and coverage. There will be
a lot of mesoscale factors at play. Showers and any storms will be
directly influenced by the remnants of whatever happens upstream to
our west and southwest. With that said, the daytime today, perhaps
focused in the first half of the day, looks to have the highest
probability of measurable rain for the entire weekend, though there
will be chances of showers through the period. PWats will be high
(1.5-2.0"), so any robust and persistent convection that can develop
will be capable of locally heavy rainfall.

The forcing from the aforementioned jet streak to our northeast
appears to maximize around mid to late morning, then wanes into the
afternoon. So anticipate the maximum coverage of showers and any
storms in our area to be focused around that time. Later into the
afternoon, more diurnally driven convection should develop within
the vicinity of the frontal boundary to our west and southwest. Some
additional shower activity could impact our area from that activity,
especially in our western and southwestern zones (SE PA into
Delmarva). The latest CAMs tend to support this general evolution as
well. We should get a lull in shower activity overnight due to lack
of forcing and strengthening surface ridging, though cannot rule out
some stray showers. Drizzle may develop across the coastal plain
overnight as well.

Our southern and western most areas remain highlighted in a Marginal
Risk for excessive rainfall by WPC for at least a 5% risk of heavy
rainfall leading to flooding. The severe risk is low overall, and we
are not currently outlooked by SPC. Lightning is certainly possible
with any stronger cells though.

For temperatures, highs will be mainly in the mid 60s to 70s. The 70
degree line looks to extend from around Reading southeast into the
Philly metro, then southeast toward Ocean County. Northeast of there
will be stuck in the 60s all day with 70s to the southwest. Southern
Delaware and portions of the eastern shore of Maryland near the
front could get into the low 80s briefly. Lows tonight in the mid
50s to low 60s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Gradual improvement thru the period with periods of
showers/tstms Sunday/Sunday which will end from North to South
Monday. Fair weather expected Monday night. Temperatures largely
below normal with abundant clouds Sunday. Highs upper 60s/low
70s and lows in the 50s across the north and 60s further S/E.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...

A upper ridge will remain across the Southeast U.S. while a trough
across the Upper Great Lakes and Midwest remains in place into
midweek before getting pushed to the east. This means that unsettled
conditions will be across the Middle Atlantic Tuesday thru Thursday
with a chance for showers or tstms each day. Lower pops for Friday
and into the start of next weekend as the disturbance gets pushed
offshore and high pressure starts to build in from the north.

Temperatures will be near normal Tuesday, but then milder conditions
with above normal temps Wed thru Sat. Readings on Thursday will be
well above normal with low 90s common across much of southern NJ,
metro Philadelphia and Delmarva. Across N/W counties, mid/upper 80s
are the expected highs.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY and surrounding areas.

Through 12Z...MVFR to IFR ceilings and VFR visibility should
prevail. LIFR ceilings cannot be ruled out overnight especially at
KMIV/KACY. MVFR or lower visibilities possible briefly in
showers/fog. Northeast winds 5-10 knots. Low confidence on the
timing/details, but high confidence in prevailing restrictions.

Today...IFR ceilings possibly developing early, though an
improvement to MVFR should occur for most terminals outside of ACY.
MVFR visibilities in showers, mainly before 18Z. Otherwise, mainly
prevailing VFR visibility. Some lightning is possible, though this
should be isolated and brief in nature at best. A few terminals
could briefly scatter out to VFR by 21Z or so, but low confidence in
this occurring. East northeast winds increasing to near 10 knots.
Low confidence on the timing/details, but high confidence in
prevailing restrictions.

Tonight...IFR ceilings likely developing, with some LIFR possible.
Fog development is possible as well, but lower confidence on this.
Northeast winds 5-10 kts. High confidence in prevailing IFR, but low
confidence on details.

Outlook...

Sunday thru Monday night... Lower CIGs/VSBYs at times with
scattered showers/tstms at times.

Tuesday/Wednesday... VFR mostly but scattered showers/tstms
during the afternoon hours may bring restrictions.

&&

.MARINE...
An area of locally dense fog remains across portions of the coastal
waters from southern New Jersey, Delaware, and Delaware Bay.
Visibility should begin to improve after dawn, and a Dense Fog
Advisory remains in effect until 8 AM to highlight this threat.

Conditions will remain below advisory criteria through today,
although winds and seas will build, especially into the afternoon.
By this evening and overnight, seas will build to near 3-5 feet
across the Atlantic waters, and northeast winds will increase to 15-
20 kts with gusts near 25 kts possible north of Atlantic City. The
stronger winds and seas will be near and especially north of
Atlantic City, where a Small Craft Advisory is in effect from 6 PM
this evening through noon Sunday. Periods of showers possible
through the daytime, with a lull expected tonight.

Outlook...

Sub-SCA most of the time. Scattered showers/tstms Sunday/Monday.
More showers Tue/Wed, but mostly during the afternoon/early
evening.

Rip Currents...

For today, northeast winds will increase through the day to around
15-20 mph by late afternoon, but will be lighter through midday.
Breaking wave heights remain around 1-2 feet with a continued weak
southeasterly swell around 1 foot at 9-10 seconds in length. Will
maintain a LOW risk for dangerous rip currents at all beaches given
light winds and low breaking wave heights.

For Sunday, stronger onshore flow will remain with a 15-20 mph
northeast wind. Wave heights increase to around 2 to 3 feet or
higher and with multiple swell groups in the surf zone, there will
be a MODERATE risk for dangerous rip currents at all beaches.

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


&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until 8 AM EDT this morning for ANZ430-431-
     452>455.
     Small Craft Advisory from 6 PM this evening to noon EDT Sunday
     for ANZ450>452.

&&

$$

SYNOPSIS...MJL
NEAR TERM...Staarmann
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...OHara/Staarmann
MARINE...OHara/Staarmann