Scientific Forecaster Discussion
fxus61 kctp 210749
Area forecast discussion
National Weather Service State College PA
249 am EST Thu Nov 21 2019
high pressure will build in from the Ohio Valley today,
bringing mainly fair weather that will continue into Thursday.
Our next chance of rain will come later Thursday into Friday
associated with an approaching cold front. A new storm system
will move through the region Saturday and Saturday night,
followed by drier conditions with temperatures near to slightly
above normal to start the new work week.
Near term /until 6 am this morning/...
an area of low clouds is shrinking in coverage over the Laurel
mountains this evening; however, another area is moving south
from western New York into the northern mountains. Tried to
paint this cloud coverage in current sky grids. Overall, the
overnight will feature partly cloudy skies with some light
patchy fog by sunrise.
Short term /6 am this morning through 6 PM Friday/...
Thursday will be the transition day between high pressure passing
off to our southeast and a frontal system approaching from the west.
Clouds will be on the increase, but most of the region will
remain dry with the exception of the far northwest where a rain shower
may sneak in before the day is over.
Highs will vary from the mid 40s to lower 50s from north to S.
Long term /Friday night through Wednesday/...
there is good model consensus on a cold front crossing central
PA late thurs night into Friday. The front doesn't have a lot
of moisture to work with, and rainfall is expected to be a tenth
of an inch or less in most places.
The front will clear south of the region Friday night, taking
any precip and most of the clouds with it. However, a wave of
low pressure will develop over the Tennessee Valley Friday night
and push towards Pennsylvania on Saturday. This system will
bring increasing clouds and a chance for rain or a bit of a
wintry mix back into the area from southwest to northeast as
the day progresses on Saturday.
Most locations will see a period of plain rain later Saturday
into early Saturday night. However, chillier air will work back
into the area Saturday night, as a secondary area of low
pressure develops over eastern Virginia or the Delmarva Peninsula.
This could allow the precip to change back over to snow showers
for many locations before it tapers off on Sunday.
After a chilly day on Sunday, temperatures look like they will
rebound nicely heading into early next week.
Aviation /07z Thursday through Monday/...
the arrival of high pressure has brought clearing skies and
diminishing wind to most of central PA tonight. The main focus
in the near term will be the potential of patchy fog. Satellite
loops at 07z is already showing some fog development over
northwest PA and latest sref and namnest support the idea of
patchy valley fog across northern and western PA early this
Any patchy valley fog should dissipate by late morning
with a near certainty of widespread VFR conditions during the
afternoon. Will have to watch for potential low level wind shear
this evening associated with strong southwest winds aloft linked
to low pressure over the grt lks. Model soundings indicate the
greatest threat will be over the northern and western part of
Fri...west-northwest wind gusts around 25kts. Am low cigs possible west mtns.
Sat...PM low cigs/rain likely.
Sun...am low cigs/rain possible. Sct shsn possible west mtns.
Mon...no sig wx expected.