750
FXUS61 KCTP 181359
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
959 AM EDT Thu Jul 18 2024

.SYNOPSIS...
- A cold front will exit Southeast PA early today.

- High pressure will build in from the Great Lakes later today
  and bring mainly fair weather with seasonable temperatures
  through the end of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Sfc cold front has settled southeast of the Lower Susq at mid
morning, with a secondary trough/moisture boundary draped across
the SC Mountains through the ridge and valley region, separating
lower 60s dewpoints from upper 60s/lower 70s dewpoints over the
Lower Susq. Plenty of clouds streaming across central and
southeast portions of the area, and a sprinkle can`t be ruled
out over the SC and SE along and ahead of the aforementioned
boundary, but by and large it will be a drier and more
comfortable day for most in the wake of the exiting FROPA.

Upstream satellite imagery and model soundings indicate cirrus
will continue to stream into PA ahead of the upper trough
approaching from the Grt Lks. Therefore, partly sunny wording
should suffice for most of the region. Model soundings indicate
mixing this afternoon to 800mb, where model temps support highs
from the mid 70s across the N Mtns, to the mid and upper 80s in
the Lower Susq Valley.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A bit of high cloudiness could linger into this evening over
the eastern counties, then mainly clear skies are anticipated
with the passage of the upper trough. The arrival of surface
ridging and an associated low-pwat airmass should result in the
coolest night we have seen a quite a while. The weakest gradient
and most efficient radiational cooling is anticipated over the
NW Mtns, where we have slightly undercut NBM min temp guidance.
Air/water temp differences of >25 degrees should result in
patchy late night fog in the deep river/stream valleys of the
Alleghenies.

Fair and seasonable conditions with light winds are expected
Friday, as high pressure ridge remains over the state. An
approaching warm front is likely to spread increasing clouds
into at least Southern PA Friday night, but the odds of any rain
look slim.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
On Saturday, there could still be enough moisture working into
the state from the south that a shower or two could develop over
the SE and/or ridge-and-valley region if the ridge tops can help
nudge the moisture high enough. It`s only worth a 20pct chc at
this point based both on coverage and probability. This is the
only mar in an otherwise stellar weekend forecast.

During the early part of the new week, the humidity levels will
creep back up as the deep upper low over ern Canada slides a
little more to the east and the Bermuda High pushes moisture
farther to the north and into the state. The stationary
boundary to our south may struggle to move northward, so we`ll
keep the increase in precip chances slow for the time being.

Overall, we will see muggy nights again by mid week and a
gradual increase in cloud cover and PoPs. By Wed, PoPs get close
to 70pct. Confidence is higher than normal in the extended
pattern. Of course, confidence is lower on the day- to- day
details. But, normal diurnal trends in convection have been
leaned on for most of the long range.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
Decreasing post cold frontal upslope IFR/MVFR CIGS across the
NW Mtns and Laurel Highlands through 15z, while generally VFR
conditions will be found elsewhere across much of the Central
Ridge and Valley region of the state.

As vertical mixing deepens around this morning and afternoon,
much drier air will be entrained from aloft will help to erode
the clouds leaving excellent vsby and mainly varying amounts of
high level, cirrus and cirrostratus clouds for the late morning
and afternoon hours. SCT-BKN but shallow VFR (3500-4000 FT AGL)
stratocu clouds will form across the Northern and Western Mtns
later this morning and continue this afternoon.

Outlook...

Fri-Mon...AM valley fog. Otherwise, no sig wx/VFR.

&&

.CLIMATE...
The max temperature hit 100 degrees at Harrisburg Tuesday,
7/16/24. The last time KMDT hit 100 was back on July 19, 2020.

&&

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

&&

$$

SYNOPSIS...DeVoir/Bowen
NEAR TERM...DeVoir/Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Dangelo/Gartner
AVIATION...Lambert
CLIMATE...Steinbugl