981
FXUS61 KCTP 111102
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
702 AM EDT Sat May 11 2024

.SYNOPSIS...
Upper level troughing will remain over Pennsylvania this
weekend with a potent shortwave tracking over the state tonight
into early Sunday. The upper trough will lift out early next
week, then a cold front will likely push through Tuesday. A wave
of low pressure is likely to track south of Pennsylvania next
Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Upper level ridging in between shortwaves will result in fair
weather the first half of today, with fog dissipating between
12Z-14Z. However, expect a return of showers this afternoon and
evening associated with height falls ahead of a potent upper
level shortwave diving across the Grt Lks. Strong large scale
forcing, in combination with some minimal model cape, supports
high POPs with a tsra possible in spots. Highest POPs should
accompany the passage of the southerly low level jet and plume
of best pwats. Convection-allowing models, which should perform
well with this strongly forced system, indicate the most
concentrated band of showers/tsra should arrive over the
Alleghenies around 18Z, reach peak intensity over the Central
Mtns at peak heating around 20Z, then push into the Susq Valley
this evening. Although a brief, heavy downpour will occur in
many locations, modest PWAT values indicate that rainfall
should generally not be very heavy. Ensemble mean qpf of 0.2 to
0.4 inches represents the most likely rainfall by late this
evening.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
The upper trough is progged to cut off and track along the
PA/NY border tonight into Sunday morning. Low level instability
associated with this feature should result in plenty of cloud
cover and at least scattered showers lasting into Sunday
afternoon, especially over the eastern half of the forecast
area. Brightening skies and diminishing showers look likely by
late Sunday afternoon, as the upper trough exits the state and
surface surface ridging builds in from the west. Mixing down
progged 850mb temps of around 4C translates to expected highs in
the low to mid 60s over much of the forecast area, with upper
50s over the higher terrain of Eastern PA.

The upper trough is progged to lift out early next week, with max
temps rebounding +10-20F on Monday aided by a milder SW flow. A
cold front trailing low pressure in eastern Canada is fcst to
stall out over the lower Great Lakes Monday and could trigger a
shower or t-storm over the NW mtns. Most of CPA should start
the week rain-free.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A wave of low pressure will approach from the Ohio Valley
Tuesday before crossing the area Tuesday night. This system
will be accompanied by a renewed chance of rain and perhaps
some thunder.

Lingering unsettled weather is possible into Wednesday, before
a ridge build this system Wed night into Thurs. The overall
upper level pattern heading into next weekend looks rather
blocky - which is typical for this time of year - but also
results in much lower confidence/predictability. Some data
suggest a cut- off low pressure system could bring a slight risk
of heavy rainfall on 5/18 per the latest CPC 8-14 day hazards
outlook.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
Morning fog and low clouds are present across much of central
PA this morning. The western airfields had clouds clear
overnight, but ample low level moisture allowed for valley fog
development. Central and eastern sites are still under low cloud
cover, but some breaks in the clouds are expected after mid-
morning. A wide range of conditions are present this morning
given the variable cloud cover and patchy fog, areas
experiencing dense fog are under LIFR conditions.

Cigs and vsbys should improve to VFR areawide by midday on
Saturday, before another round of rain showers pushes from west
to east across the area Saturday aftn/eve with the approaching
low pressure system from the west. This line of storms is
expected to reach our western most airfields near 18Z today.
Limited instability will allow for some thunder with these
storms, but thunder is likely to decrease the further east the
showers progress.

Outlook...

Sun...AM low cigs possible W Mtns. Sct afternoon showers/brief
reductions possible.

Mon...AM dry and mainly VFR. Showers return across the north by
aftn.

Tue...Showers/tstms and reductions developing.

Wed...Showery weather and reductions continue.

&&

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

&&

$$

SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Steinbugl/Evanego
AVIATION...Bowen