Scientific Forecaster Discussion
fxus61 kctp 071820
Area forecast discussion
National Weather Service State College PA
120 PM EST Sat Dec 7 2019
after a fair weather weekend, a volatile and stormy pattern is
expected to begin during the second week of December.
Temperatures are forecast to surge well-above normal Monday and
Tuesday, followed by a sharply colder trend Wednesday into
Thursday. The warm-up will be accompanied by rounds of rain
early the week with the potential for a period of snow as cold
air catches up with the back end of the rain around midweek. A
significant storm system possible around mid month.
Near term /through tonight/...
a mix of clouds and sun will continue for the rest of today. It
will be chilly relative to daily averages with highs in the
upper 20s north to around 40f in the southern valleys (5 to 10
degrees below normal). Mainly clear to partly cloudy skies are
expected tonight with lows in the mid teens and 20s.
Short term /Sunday/...
dry weather expected for tonight and most or all of Sunday as
high pressure slides east across the state. After a chilly
start over the NE Sunday morning with temps in the teens, temps
will warm to near seasonal normals in the mid 30s (ne) and low
Long term /Sunday night through Friday/...
big temperature swings are expected during the period.
A significant warming trend is forecast through early next week
with Max temperature departures +10-15 degrees above normal
(widespread 40s and 50s).
Unseasonably mild minimum temps are forecast Monday night with
departures on the order of 15-20 degrees above normal as the
primary precipitable water axis (with values around +2 sigma) slides east
across the region.
The mild surge will be accompanied by periods of light to
moderate rain Monday and Tuesday. Rainfall amounts between 0.50
to 1 inch are forecast early next week.
The warm air and rainfall will help to melt the snow over the
Allegheny Front into the upper Susquehanna River basin. Areas of
fog are likely as the mild air moves over colder ground. Rises
on rivers/streams are expected and will need to monitor risk of
minor flooding across the northern tier. Wpc indicates a marginal
risk of rainfall heavy enough to cause flooding of small streams
and poor drainage areas over our far western counties Monday
into early Tuesday.
It will turn sharply colder through midweek as Arctic air blasts
into the region. Temperatures will be on the decline Tuesday
afternoon through Tuesday night (non diurnal over the northwest 1/2
during the day tuesday). There will be some potential for
residual water or slush to freeze up quickly by Wednesday.
Highs are forecast to drop by 20-30 degrees between Tuesday and
Thursday, with minimum wind chills in the single digits and
teens Thursday morning.
There is also a chance that the cold air could catch up to the
back edge of the rain and result in a period of snow at the end
of the precipitation event on Wednesday. There should be some
lake effect snow that develops in the wake of the system, but
trajectories appear to be focused more into southwest New York.
The active weather pattern next week may continue into the
weekend with the GFS and European model (ecmwf) both showing a large, dynamic
storm system impacting the region.
Aviation /18z Saturday through Thursday/...
VFR conditions this afternoon through 18z Sunday. Bfd remains
on the southern edge of a field of cu downwind of Lake Erie,
with cigs teetering between bkn-few at 025. Cigs will continue
to lift and improve this afternoon-evening.
Will have to watch potential for swrly low level wind shear of 40+ kts starting
in bfd Sunday afternoon/evening and overspreading the rest of
the area Monday afternoon into Tuesday morning, as a few waves
of low pressure pass to our west.
Cigs and vis will be reduced in periods of rain Monday and
Sun night...lowering cigs. Low level wind shear poss at bfd
Mon-Tue...widespread shra/MVFR. IFR and low level wind shear poss. Cfropa tues.
Wed...restrictions northwest half. Breezy northwest wind.&&