641
FXUS61 KCTP 181925
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
325 PM EDT Sat May 18 2024

.SYNOPSIS...
An upper trough overhead will slide east through the evening.
High pressure will start to build into the region on Sunday
accompanied by generally rain-free conditions that are expected
to persist through the middle of next week. A storm system
should arrive Wed, and perhaps generate severe weather and heavy
rain.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Numerous SHRA have popped up over the Allegheny Mountains where
they have cleared out quite a bit but not completely. Vertical
wind profiles are lazy, so they are slow-moving cells. Have not
seen any TS yet wit them, but we will keep a mention in the wx
grids for a short time. Some 1+" pixels showing up in the 3-hr
precip estimates from KCCX, but this is well-above FFG for the
area. Will monitor for further developments. The cloud cover
over the SE is showing some weakness/thin spots thanks to the
high May sun angle. There is also a bit of enhancement to the
radar echoes in the far SE, too, but rainfall amounts are
lighter than in the west with higher stability likely helping
keep the SHRA more tame.

As the sky begins to clear under the influence of NVA/rising
heights, there will be some fog form, esp in the places that
have rain later in the day. Some locations may have enough
drying time to avoid fog. But, would not be surprised to see a
widespread fog later tonight. Mins will be 55-60F.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
High pressure rolls in for Sunday. Clouds/fog in the AM clear
out nicely. However, just enough instability develops and enough
moisture lingers to pop a couple of SHRA. Literally just a few
with the highest probability (30pct) over the SErn hill tops.
Maxes in the 70s will be pretty normal. We are likely to see
some areas of fog again Sunday night with the sky clearing out
better, but dewpoints not dipping out of the m50s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
No real changes or updates from the previous long term
discussion. Monday and Tuesday will be dominated by high
pressure ridging and dry conditions before the next system makes
its way into the region by Wednesday for the return of the
unsettled pattern.

Previous discussion...
A dry start to the extended period will be likely with high
pressure ridging building over the mid- atlantic region and a
deep surface low parked over the central plains. High pressure
and dry air will stay in place through Tuesday before the upper
level trough pushes them both out by Wednesday afternoon. 850mb
temps of near 16C along with surface warm air advection suggest
high temperatures could reach the mid 80s on Tuesday and
Wednesday.

By the middle of next week, upper troughing will move across
Pennsylvania and support a better chance for showers and
thunderstorms. At the surface, there remains plenty of model
uncertainty about the timing of a cold front. The mean timing is
Wednesday afternoon, but individual models bring precipitation
as early as Tuesday evening and as a late as Thursday morning.
If the front moves through Wednesday afternoon or evening, it
could produce the first threat for severe weather in some time
given the aforementioned WAA bringing greater instability.

After the front moves through, considerable uncertainty exists
in terms of how much and how frequent rain will be. A chance of
showers remains in place through the end of the week despite
zonal flow aloft providing little in the way of synoptic
forcing. The next chance for a widespread soaking rain will come
during the weekend with a center of low pressure developing
across the Ohio Valley by Friday afternoon.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Lots of SHRA popped over the Alleghenies, and are moving only
slowly. MVFR cigs in the SErn half of the area will linger into
the night but probably break up some more. Rain showers should
mostly be over by the early evening hours as the upper level
trough drifts east. Remaining low level moisture and night time
cooling will make for fog development for Sunday morning likely.
Most sites will likely drop to IFR for a time as low clouds and
fog take hold of the region through the early morning hours
Sunday.

Outlook...

Sun...Morning low cigs/fog possible. Becoming VFR by afternoon.

Mon...Patchy AM fog possible. Otherwise, becoming VFR.

Tue...Predominantly VFR, w/ no sig wx expected.

Wed...Sct to widespread SHRA/TSRA return.

Thu...Chc of TSRA.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Bowen
AVIATION...Lambert/Bowen