Reading, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

263
FXUS61 KPHI 161840
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
240 PM EDT Thu Jul 16 2026

.WHAT HAS CHANGED...
Heat Advisories have been expanded to include the Eastern Shore of
Maryland through 8 PM today.

Confidence in storm occurrence this afternoon has increased
slightly, but no changes have occurred with respect to the severe
weather outlook.

&&

.KEY MESSAGES...
1. Above normal temperatures will continue through today, with Heat
Advisories in place for portions of the area.

2. Smoke from Canadian wildfires will infiltrate the area today,
potentially lingering into the weekend.

3. Isolated severe thunderstorms possible this afternoon and evening
for areas south of I-78.

4. The first half of the weekend is shaping up to be active with
showers and thunderstorms expected for Saturday into Saturday night
along with warm and very humid conditions. Storms have the potential
of becoming severe and also producing heavy rainfall leading to
flash flooding.

&&

.DISCUSSION...
KEY MESSAGE 1...Above normal temperatures will continue through today,
with Heat Advisories in place for portions of the area.

Despite the abundance of wildfire smoke around the area today,
temperatures have risen into the upper 80s to low/mid 90s across
much of the area with dew points in the low to mid 70s. This results
in heat indicies around around 95-102 degrees for most of PA and NJ,
with heat indicies between 101-106 degrees over the Delmarva. Given
this, have opted to maintain heat headlines for the urban corridor,
but opted to add the Eastern Shore of Maryland to the advisory due
to higher dew points residing near the Chesapeake Bay. All
advisories remain in place until 8 PM tonight.

Temperatures on Friday will remain slightly above normal for mid-
July. However, dew points are expected to be more comfortable only
in the mid 50s. Thus, heat indicies will not be far removed from the
actual air temperature.


KEY MESSAGE 2...Smoke from Canadian wildfires will infiltrate the
area today, potentially lingering into the weekend.

Latest HRRR/RAP smoke guidance continues to depict that a slug of
dense near surface smoke from the wildfires originating over western
Ontario will spread into the region tonight. Skies will likely be
quite hazy with visibilities projected to fall between 1 to 3 miles
overnight, before improving some on Friday. With more of a northerly
surface flow expected overnight and into early Friday, this may
suppress the worst of the smoke south of our area by mid-day.
However, as flow shifts to more southerly by Friday night, guidance
is hinting that surface smoke may return into the weekend.

While the smoke is anticipated to result in visibility restrictions
and poor air quality around the region, to what degree is more
uncertain. Given current observations from upstream, this smoke
event is not anticipated to be as severe as the June 2023 event, but
this will be difficult to predict days in advance.

Latest guidance is a bit more optimistic about the smoke clearing
out somewhat on Friday.

For more information about air quality in your area, visit your
state Department of Environmental Protection agency. We will also
relay any Air Quality Alerts they may issue on our website.


KEY MESSAGE 3...Isolated severe thunderstorms possible this
afternoon and evening for areas south of I-78.

A lingering cold front bisecting the region this afternoon is
expected to be the focal point in providing a sufficient area of
convergence to develop showers and thunderstorms. Similar to
yesterday, uncertainty in overall coverage remains high due to
better forcing remaining displaced further north and due to ongoing
wildfire smoke. However, recent satellite imagery shows a developing
cu field over southern Pennsylvania and northern Maryland, now
extending into portions of New Jersey. It is here, where storm
development may occur this afternoon. Current mesoscale analysis
shows MLCAPE will rise to around 2500-3500 J/kg with bulk shear
around 40 kt. Furthermore, forecast soundings show inverted-V
profiles with DCAPE values between 1000-1250 J/kg. These ingredients
and parameters all support the potential for strong downbursts in
any storm that does develop. Given this, the area mainly south of I-
78 down into the Delmarva remains highlighted by SPC in a MARGINAL
risk for severe weather this afternoon into this evening. Any storm
activity should wane by sunset with the loss of diurnal heating.


KEY MESSAGE 4...The first half of the weekend is shaping up to be
active with showers and thunderstorms expected for Saturday into
Saturday night along with warm and very humid conditions. Storms
have the potential of becoming severe and also producing heavy
rainfall leading to flash flooding.

Low pressure will move eastward through the Great Lakes region
Friday night through Saturday before passing by to our north
Saturday night into early Sunday. As this occurs, expect multiple
rounds of showers and thunderstorms to move through...first with the
warm front and then with the cold front.

At this point it looks like conditions stay mainly dry through most
of Friday night. Heading into Saturday, the warm front lifts through
in the morning and this will bring an initial round of showers and
storms through the area. This first round should especially target
areas near and north of the urban corridor where POPs are 70-90
percent. Parts of south Jersey and southern Delmarva could largely
miss this initial round. There will be a threat for heavy rainfall
potentially leading to flash flooding with the morning storms but
the severe weather risk looks more limited until later. Following
this first round, there could be a break of a few hours in the
afternoon during which it will get quite muggy. Highs should range
from the low 80s north to the low 90s south but with very high dew
points expected the heat indices are likely to top out in the mid
and upper 90s around the urban corridor and up to around 105 across
portions of Delmarva. So heat headlines may be needed.

As we get into the mid to latter part of Saturday afternoon into the
evening another round of heavy showers and storms looks to move
through ahead of the cold front. It`s with this round that we`ll see
the best chance of severe weather and flash flooding as well. In
terms of the parameters, ML CAPE looks likely to top out in the 1000-
2000+ j/kg range with deep layer shear around 35 to 50 knots. This
will support a threat for damaging winds and even some potential for
supercells which, if these occur, could also produce large hail.
PWATs will also be surging to over 2 inches (well above the 90th
percentile for this time of year) so there`s an increasing potential
for very heavy rainfall leading to flash flooding. The greatest
threat for this will be for urban, low lying areas, and areas near
creeks and streams. Also, any locations that get especially hit hard
by both rounds of convection will have a greater potential for flash
flooding. Rain amounts of over 2 inches per hour will be possible.

Shower/storms should weaken by the late evening into the overnight
Saturday night as the cold front moves through. Sunday is now
shaping up to be largely dry with seasonable temperatures and
comfortable humid levels. Only our southern most zones over
portions of the MD eastern shore, southern Delaware, and far
southern NJ have chances for some lingering showers or storms but
even here the POPs are only 20-30 percent.

&&

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

Rest of Today...Generally expect MVFR visibilities to prevail
through the rest of the afternoon (although some brief periods of
IFR visibilities may be possible). A chance of showers and
thunderstorms at all terminals this afternoon with the exception of
KABE which should remain dry. Best timing would be between 20-02Z
timeframe from north to south. Uncertainty in coverage remains, so
have opted to keep VCTS. West-southwest winds around 10-15 kt with
gusts up to 20 kt. Moderate confidence overall.

Tonight...MVFR visibilities expected through the evening are
expected to drop to IFR visibilities tonight, mainly between 00-03Z
from north to south as denser smoke arrives. Any shower or storm
activity should end by 03Z as well. West winds early, will shift to
north-northwest overnight around 5 kt or less. Moderate confidence
overall.

Friday...IFR visibilities expected early, improving to MVFR
visibilities by mid-day. There is a chance some VFR visibilities may
return by mid-afternoon as smoke attempts to clear out briefly.
North winds in the morning, will settle out of the west around 5-10
kt in the afternoon. Moderate confidence.

Outlook...

Saturday through Saturday night...At least some restrictions likely
at times due to showers and storms.

Sunday...Mainly VFR except some lingering showers possible at MIV
and ACY especially early in the day which could still cause some
restrictions for these sites.

Monday...VFR expected.

Tuesday...Potential for some restrictions by late day and at night
as the next system approaches with shower/storms.

&&

.MARINE...
No marine headlines are in effect through Friday. South-southwest
winds around 10-20 kt this afternoon will shift to north-northwest
around 10-15 kt tonight following a frontal passage. By Friday
morning, north-northeast winds around 10 kt are expected, before
settling out of the southeast in the afternoon. Seas around 2-3 feet
through Friday.

A chance for showers and thunderstorms are possible late this
afternoon into the evening, where locally erratic winds are
possible. Also, wildfire smoke will continue to filter into the
region tonight into Friday. This may cause localized areas of
visibility restrictions. Will have to monitor observations closely
tonight as denser smoke arrives, where marine dense smoke advisories
may become warranted if visibilities drop to 1 mile or less.

Outlook...

Saturday through Saturday night...South to southwesterly winds near
or above SCA criteria expected. Expect winds around 15-20 kt with
some gusts 20-30 kt. Seas likely 4-6 feet. Showers and thunderstorms
likely.

Sunday...Seas may linger near SCA levels early in the day but
otherwise the conditions should be sub SCA.

Monday...Fair weather expected with winds under 25 knots and seas
around 2-4 feet.

Tuesday...Winds and seas may approach SCA levels by late day.


Rip Currents...

Today, south to southwest winds will average 10 to 15 mph with
a light southeast swell with a period of 6 to 8 seconds.
Breaking waves will average 1 to 2 feet. As a result, there is a
LOW risk for the development of dangerous and life threatening
rip currents at the Jersey Shore and at Delaware Beaches.

On Friday, north winds around 10 mph in the morning will veer to
the southeast in the afternoon with a light southerly swell
with a period around 6 seconds. Breaking waves will average 1
to 2 feet. As a result, there is a LOW risk for the development
of dangerous and life threatening rip currents at the Jersey
Shore and at Delaware Beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Air Quality Alert until midnight EDT tonight for PAZ054-055-
     060>062-070-071-101>106.
     Heat Advisory until 8 PM EDT this evening for PAZ070-071-102-
     104-106.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ015-017>019.
DE...Air Quality Alert until midnight EDT tonight for DEZ001>004.
     Heat Advisory until 8 PM EDT this evening for DEZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
     020.
MARINE...None.

&&

$$

DISCUSSION...DeSilva/Fitzsimmons/RCM
AVIATION...DeSilva/Fitzsimmons/RCM
MARINE...DeSilva/Fitzsimmons/RCM