801
FXUS61 KCTP 211420
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1020 AM EDT Sat Sep 21 2024

.SYNOPSIS...
A frontal system will fall apart as it moves into Central PA
this afternoon and evening. It will make scattered showers and
thunderstorms, a few of which may be severe. Drier weather
returns for Sunday, before a slow-moving trough brings the next
chance of rain from Monday through midweek.

&&

.NEAR TERM /UNTIL 10 PM THIS EVENING/...
Temps heating up away from the stratus deck in the east. Surface
winds out of the east will keep it more-stable in the east this
afternoon and evening. The SPC MRGL risk for today remains as
is, with the central and western zones still under a risk of
severe, but mainly near-severe storms. However, a lightning
risk is there for most of the area, so factor this into any
outdoor activities you may have planned for the aftn/eve. The
front i more an occlusion already and still back over OH. As the
upper flow nudges it this way, storms will continue to fire up,
but coverage should be sct for much of the time in the axis of
best instability. As we get into the evening hours and early
night, the upper low/storm off the coast will exert more
influence and stall out the showers/storms, and the increasing
stability from earlier rain and loss of daylight/heating should
take away the thunder risk. Showers may linger (per most
guidance) well into the night over the eastern half of the CWA.
The near-severe threat also decreases in the evening, perhaps
very early in the evening.

&&

.SHORT TERM /10 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Model guidance indicates the shortwave and weak surface low
pass east of the region tonight. A cold air damming scenario
renews as the flow in the east remains from the east. Typical
CAD sfc features make this pretty clear. Forecast soundings
indicate an upsloping southeast flow will result in persistent
stratus and perhaps a bit of fog or drizzle over the
central/east zones for Sun and Sun night. The cloud cover and
flow off of the Atlantic should result in markedly cooler
afternoon temps Sunday than on Saturday, with highs likely stuck
in the 60s over the Central Mtns.

Sun night looks mainly dry with prev anticipated forcing holding
off a bit longer/later.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Upper trough energy and wavy frontal systems will be kicked
from the Plains/Midwest into the Great Lakes/Ohio Valley and
northern Mid Atlantic next week. An associated threat of
rain/showers will accompany these systems with some potential
for heavier rainfall within an amplifying mid/upper level
upstream flow pattern during the second half of next week.

Given model variability/growing uncertainty by later next week,
we did not identify any actionable targets of opportunity and
therefore weighted forecast basis heavily toward the National
Blend of Models (NBM). These data indicated a modest cooling
trend from the 9/21 weekend warmth trending closer to climo
(near or slightly below average) for daytime highs in the
60-70F range. Meanwhile, overnight low temps continue to run
above the historical average for late September in the 50-60F
range.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Much of the area clear still. Lower clouds came into portions
of the Susquehanna Vly. These clouds could break up for a
while late morning into the afternoon hours.

At the same time, showers and isolated thunderstorms across
the far northwest, in the area with stronger warm advection.
As noted by guidance, expect this activity to weaken some.
This makes sense, as heating will be limited for a while.

Most of the showers and storms would be later this afternoon
into this evening. Some cloud be on the strong to severe side,
as SPC has noted. As noted above, CIGS could go back up later
this afternoon, but likely will fall into the IFR and MVFR
ranges.

Next week gets off to a cloudy start.

Outlook...

Mon-Wed...Scattered showers.

&&

.CLIMATE...
The high temperature in Bradford on Friday set a new record
high of 82 degrees. This broke the record of 81 degrees set in
1978 and 2016.

The first day of autumn 2024 (Fall Equinox) begins at 8:44 am
EDT on Sunday September 22nd.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo/Tyburski
LONG TERM...Steinbugl
AVIATION...Martin
CLIMATE...Steinbugl/Martin/NPB