905
FXUS61 KCTP 120245
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1045 PM 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 /THROUGH SUNDAY/...
Low pressure continues to move in from the NW, but not in a
hurry. Short wave trough touched off numerous TSRA over wrn PA
and they dropped across the srn tier and are into north-central
MD at 02Z. A few lightning strikes left north of the border,
but we`ve dropped mention of TS from the wx grids for the rest
of the night.

Un-concentrated forcing thru the rest of the night will keep
the showers sct with breaks in between. As with last night, the
breaks will allow fog to form, but there is a little more wind
tonight than last (Fri) night. The low afloft and sfc will be
coincident over the CWA in the morning/12Z. Thus, the moisture
feed will still be lifting moisture into the eastern half of the
area, and wrap-around moisture/flow under the upper low will
keep the showers going over the N and far wrn mtns, too, into
the morning. The best/biggest breaks will probably be the
south-central mtns (Bedford, Fulton, Huntingdon, Franklin
Counties, mainly). They won`t be clear all night, but will be
the best place to see the Aurora tonight. But, they have just
had rain, too, and will be almost sure to get fog form
overnight.

Sunday will be mainly cloudy for about the eastern 2/3rds to
half of the CWA. Numerous SHRA are expected, mainly in the Susq
Valley north of Harrisburg. But, likely PoPs are o/o for the
morning with a taper to sct (30-50pct) coverage in the aftn as
the upper heights rise. However, convergence still likely in the
llvl flow and we can`t shake the SHRA totally before sunset.
Maxes Sunday will be 65F S and 55F NE.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
The upper low lifts out Sunday night and Monday with improving
conditions for Monday, and temperatures moderating thanks to a
milder southwest flow. A cold front trailing low pressure in
eastern Canada is fcst to stall out over the lower Great Lakes
Monday and will trigger some showers or a t-storm over the NW
mtns Monday afternoon, but it appears most of Central PA should
start the week rain-free.

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.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Lingering unsettled weather is possible into Wednesday, before
a ridge builds in Wednesday night into Thursday. This will
support the longest period of dry and sunny weather we have seen
in awhile. 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.
Such a pattern supports changeable weather with temperatures
oscillating around average for this time of year. 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 /03Z SUNDAY THROUGH THURSDAY/...
At 21z, A band of rain showers is pushing from the central mtns
into the Susq Valley. This band could briefly drop vsbys to
MVFR across the Susq Valley during the early evening hours.

Additional showers (and some thunder) are pushing into western
PA early this evening. This activity should make it into the
western highlands before sunset, and then weaken as it
progresses eastward from there late this evening.

Expect cigs to drop to IFR at BFD and JST overnight, as
upsloping westerly flow develops. Farther to the east, the
central mtns and Susq Valley are progged to see their cigs dip
to MVFR overnight.

Sunday will see northwesterly flow develop across the area, with
gusts to 15 kts possible across the southern Alleghenies (JST,
AOO). Cigs should slowly improve as the day progresses, with the
slowest improvement expected across the western highlands.
There could be a few diurnal rain showers by afternoon, esp
across eastern PA.

Outlook...

Mon...Morning fog across the east/Susq Valley. Showers return
across the north by aftn.

Tue...Showers/tstms and reductions developing.

Wed...Showery weather and reductions continue.

Thu...Slow improvement, with a few lingering showers possible.

&&

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

&&

$$

SYNOPSIS...DeVoir/Dangelo
NEAR TERM...DeVoir/Dangelo
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Banghoff
AVIATION...Banghoff/Evanego