Scientific Forecaster Discussion
fxus61 kctp 060915
Area forecast discussion
National Weather Service State College PA
415 am EST Fri Dec 6 2019
weak low pressure moving across New York state today will drag
a weak cold front across the region late this afternoon. A few
snow showers will be possible today, mainly across the north.
The snow may mix with rain this afternoon across the south.
Dry conditions with near normal temperatures will follow for
the weekend. A warm up is in store for Monday and Tuesday.
Near term /until 6 PM this evening/...
a few snow showers will be possible across north central PA
this morning, based on the models and radar.
Temperatures this afternoon will be just warm enough for some
rain to mix in. Dewpoints not real high, so rain may still mix
with some snow. Main change was to edge probability of precipitation down some across
the Laurel Highlands and far southeast. Radar and models hint
that better moisture across the south central states may be
hard to tap into.
Short term /6 PM this evening through Sunday/...
as noted above, another cold front brings a chance for snow and
rain showers today as a wave of sfc low pressure slides by just
to our north. Prefrontal moderating return southwest flow will
allow for frontal precip to be in the form of rain at times
today. A changeover to snow showers is expected as the front
passes late this afternoon and evening. Any snow accumulation
will be very minor. Weather situation similar to what we had on
Wed, when the snow mixed with rain at times after lunch, and the
cold air took a while to work back into the area.
Left some mention of snow showers in tonight across the far
north. 500 mb height fields not real low, so very little snow is
expected, once the cold front moves east of the area.
Dry weather expected for Saturday and Sunday. Slight trend to
be colder on Sunday now, then it was looking a few days ago.
Long term /Sunday night through Thursday/...
some very minor changes made to this part of the package.
I tried to cut probability of precipitation down some prior to 12z Monday. Hard to see
much going on before 06z Monday. Also did bring lows Sunday
night up a little, given warm advection and expected cloud
Otherwise, just very minor changes to temperatures.
More detail below.
Long range guidance in good agreement that a large ridge of
high pressure builds over the western US towards the middle of
the week and ultimately pushes eastward into the eastern US
later next weekend. As the high pressure system moves off the
East Coast, temperatures moderate on Monday, with some Gomex
moisture streaming northeast along the Appalachians bringing
periods of rain for next Monday into Tuesday. Models hint at
two areas of rain at the start of the event.
Aviation /09z Friday through Tuesday/...
lower/VFR clouds starting to erode from S-N, but the next wave
is on it's way from the northwest. Wind will continue to die off, with
some sites going light/var or even calm. Radar echoes over
lower Michigan are still aloft for the most part. However, by 09-10z a
few -shsn could reach bfd. However, the lift will stay
generally to the north of the New York border. A cold front will zip
through during mid-day Fri, but is starved for moisture. Thus,
while the clouds may lower to MVFR by late in the day, the only
other site to have a chc for precip is jst where temps should be
warm enough for -shra which could occur in the aftn. Post-
frontal winds pick back up to 12-15kt with gusts in the 20s,
perhaps upper 20s in jst. The upslope flow will quickly close up
any clearing immediately behind the front. But, lack of moisture
and rather high inversion at first which crashes overnight
should keep any time of IFR at bfd and jst rather brief Fri
PM/early Sat am. Ipt/MDT/lns should scatter out, but could have
VFR cloud bkn deck.
Sun night...mainly VFR. Lowering cigs.
Mon-tues...widespread shra/MVFR. IFR poss. Cfropa tues.