587
FXUS61 KCTP 220527
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
127 AM EDT Tue Jul 22 2025

.SYNOPSIS...
* Rain-free dry spell kicks off today with comfortably lower
  humidity and refreshingly cooler temperatures through Tuesday
* Hot and humid mid summer conditions return by late week with
  moderate to major Heatrisk Thursday into Saturday (peaking
  Friday)
* Rain/scattered thunderstorms return to the forecast for Friday
  and the weekend

&&

.NEAR TERM /THROUGH TODAY/...
Today will kick off a 48hr period of refreshingly cooler and
less humid conditions as a seasonably strong 1020+ mb sfc high
pressure area builds southeast from the Upper Great Lakes.

This weather feature will deliver mostly sunny and rain-free
days with low humidity followed by comfortably cool night; ideal
for campfires and sleeping with the windows open!

Speaking of fire - you may notice the sky is surprisingly hazy
considering rel hum in the 40s%. That`s due to some more
wildfire smoke that advected in on the leading edge of the
Canadian airmass. Just enough concentration at the sfc to pick
up a bit of wildfire smell at the office in State College as of
12 PM.

We continued to manually adjust Td lower this afternoon based
on pattern recognition and dry air mixing signal in the sounding
profiles which depict a wedge dry air above the base of weak
subsidence inversion.

Max temps this afternoon will be about 3-8 degrees cooler vs.
Sunday, but the most noticeable/refreshing change will be to
overnight temps which should dip into the 50s in most locations
with even some mid 40s in the northern tier. Under favorable
radiational conditions, the cooler min temps should trigger the
20-25F water-air threshold and allow fog to form in some of the
river and stream valleys, particularly in the northern tier.
Temps will reach a nadir tonight with a floor close to 40F in
the usually colder spots in the northern mtns based on min Td
and NBM 5th percentile min T.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
After a seasonably cool start, Tuesday is another really nice
day to be outside on Tuesday. MaxT trends are neutral/flat
with similar values to Monday. The HRRR smoke model shows less
smoke in the air Tue compared to Mon. Tuesday night min temp
fcst prints a higher low (vs. Monday night). This will signal
the start of a warming trend and eventual return to sweltering
mid summer heat poised to return for late week into the weekend.

Add 5-10 degrees to max temps (low-mid 80s) and 10+ to dewpoints
(60-65F) on Wednesday as SSW return flow transports warmer and
more humid conditions back into CPA. Odds for rain stay below
10% through Wednesday night.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Model and ensemble data show a building heat dome/590+dm 500mb
ridge expanding over the area for late week into the weekend.
This will translate into a return of hot/humid late July
sensible wx conditions. Heatrisk ramps up to moderate to major
with heat index values fcst to approach or reach the century
mark across the central and eastern valleys. This will be
something to monitor in the coming days and will continue to
highlight elevated risk of heat impacts in the HWO.

Isolated airmass or terrain induced convection is possible
beneath the upper level ridge Thu afteroon, but odds favor a
continuation of dry wx across the vast majority of CPA due to
warm temps aloft/effective capping inversion. Higher/max POPs
are over weekend tied to the approach and arrival of the next
frontal system. Several shortwaves rippling from west to east
through the southern edge of westerlies/northern periphery of
hot upper ridge may result in more than 1 round of t-storms.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
High confidence in VFR conditions through the 06Z TAF period.
Some clouds with bases around 6000 feet have formed south of a
line extending from UNV to IPT and these will stick around
through much of the night before gradually breaking up in the
morning. Winds through the TAF period will generally be less
than 5 knots.

Outlook...

Wed...VFR with mainly dry conditions.

Thu...Mainly dry. Perhaps a shower or storm across the
west late.

Fri-Sat...Mainly dry and hot, with isolated to scattered TSRA
and brief restrictions possible each afternoon/evening.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Steinbugl/Colbert
NEAR TERM...Steinbugl/Colbert
SHORT TERM...Steinbugl/Colbert
LONG TERM...Steinbugl
AVIATION...Bauco