080
FXUS61 KCTP 170740
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
340 AM EDT Fri Jul 17 2026

.WHAT HAS CHANGED...
* All the CWA is now in the Day2 (Sat/Sat night) SPC severe
  slight risk category and the WPC excessive rainfall marginal
  risk.
* Added smoke into the wx grids for Sat (AM for W and all day
  for the E).

&&

.KEY MESSAGES...
1) Wildfire smoke will result in very unhealthy (purple) air
quality and reduced visibility today and into Saturday.

2) Strong to severe thunderstorms with damaging winds and heavy
rainfall are possible Saturday afternoon and the first half of
Sat night.

&&

.DISCUSSION...
KEY MESSAGE 1: Wildfire smoke will result in very unhealthy
(purple) air quality and reduced visibility today and into
Saturday.

Widespread smoke continues to reduce visibility, even overnight,
(generally 1-3 miles in FU and HZ) and degrade air quality
across much of the region. The PA DEP has placed all of the
state into a Code Purple (very unhealthy) alert as PM2.5
(particulate matter) remains high, especially in the southern
tier of the state. Somewhat of a dip in smoke
density/concentration is possible for the northeastern
counties today. But, it waggles right back into there out of the
south overnight. RRFS progs continue to press the highest near-
surface smoke to the north and east during the day Sat. The
precipitation Sat/Sat night may temporarily help by literally
precipitating the smoke out of the air, but the concentrations
rise again on Sunday as the plume of higher smoke is progged to
come back in from the west.

Kept on with a 2F nudge downward on the daytime temps vs
straight NBM mean today. Made no adjustments to T for Sat as
warm advection and sct-nmrs SHRA offer no clear direction to
tilt away from NBM temps.

-------------------------------------------------------------

KEY MESSAGE 2: Strong to severe thunderstorms with damaging
winds and heavy rainfall are possible Saturday afternoon and the
first half of Sat night.

A potent cold front trailing a deepening sfc low tracking up
the St. Lawrence River Valley is expected to trigger one or more
rounds thunderstorms Saturday afternoon and evening.

severe...
SPC level 2/5 severe thunderstorm risk continues cover most of
central PA for day 2/Saturday into Saturday night. A warm front
will attempt to lift north-east across the area during the
daytime. A potent cold front will cross the area Sat night.
Storms will likely initiate before and along the front. Some
storms ahead of the cold front will have the chance to spin as
the shear from the warm front and other boundaries could
contribute to localized higher helicity values. However, the
bigger worry is for damaging wind gusts as clusters could
organize better and produce long-lived bow(s). Reduced
instability may be a limiting factor if clouds and showers
persist from early in the day. How the smoke may play into all
of this is unclear. No pun intended. It could help keep temps
and instability down. But, the extra condensation nuclei could
make it more efficient at producing rainfall and evaporative
cooling. On the other hand, the smoke does seem to get pushed NE
thru the day, and may not play any role in the precipitation and
severe threats.

rain...
Southwesterly low-level flow ahead of the front will transport
a high PW airmass into CPA. Strong synoptic forcing, driven by
an amplifying trough over the Northeast and favorable upper jet
dynamics, will support the potential for heavy rain rates to
produce isolated flash flooding concerns. WPC has the entire
area in the MRGL risk for ex rainfall on Day 2 (Sat-Sat night).
Convection earlier in the day will be followed by more SHRA/TSRA
later in the day and through the first half or more of the
night.

A drying trend is expected Sunday with noticeably lower
humidity allowing for a pleasant day and relatively cool night.
But, the RRFS progs of smoke do bring some back into the state
from the W on Sunday. That may keep it from being a refreshing
day. Additional bouts of rain/t-storms are possible into the
workweek. Temperatures will trend near to slightly below
historical averages through late week with some noticeably
cooler nights possible.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
The primary concern for the next 24 hours continues to be
visibility restrictions due to wildfire smoke from Canada and
northeastern Minnesota. Tonight may bring the most widespread
restrictions as winds lighten behind the front with high
pressure moving in, with the HRRR/RRFS models showing IFR to
LIFR visibilities across much of Central PA. Improvements from
overnight IFR-LIFR on Friday is favored across the northeastern
edge of the smoke plume (currently forecast to be KBFD/KIPT),
where the wind`s northerly component may linger enough to bring
smoke south of those sites, with improvements looking less
likely over southwestern Pennsylvania (KJST/KAOO) where the
winds may lighten as the core of the smoke plume moves overhead.

As of right now highest confidence remains in smoke hanging on
until after 06Z on July 18th. A frontal system will approach us
very late Friday night into Saturday morning and usher the
smoke out, only to replace it with showers and thunderstorms
through the day on Saturday.

Outlook...

Sat-Sun...Chance of showers and t-storms, mainly during
the afternoon hours on Saturday into early Sunday aft. Smoke
moving out.

Mon...Mainly VFR.

Tue...Restrictions possible in showers/t-storms.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Air Quality Alert until midnight EDT tonight for PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.

&&

$$

WHAT HAS CHANGED...Dangelo
KEY MESSAGES...Dangelo/Steinbugl/Colbert
DISCUSSION...Dangelo/Steinbugl/Colbert
AVIATION...Colbert/Bowen