Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
708 am EST Tuesday Dec 1 2015
an upper low over the plains states will slide across the Great
Lakes through midweek. Rain will continue to fall until late
Wednesday when a cold front will push through. The front will
end the rain but snow showers will come to the northwest
mountains Wednesday night and early Thursday. The temperatures
return to above normal on Friday as high pressure will cover the
eastern half of the country all weekend.
Near term /until 6 PM this evening/...
630 am update...
lull in the precipitation will end in the SW as a short wave trough rolls
up in from the SW. 0.25 inches fell over central WV as the
brighter echoes moved through there. Temperatures and dewpoints are now well
above freezing...so threat for any ice/glaze for the morning
commute is none.
a very heavy drizzle is falling across the area and will likely
continue for the next 6 hours. Precipitable waters climb slightly to near 1.25
inches in the south today. A weak surface low off the NC coast is
creeping nwrd and will likely help increase the easterly flow into
the state today. All this means that confidence is high that it
will continue to rain with very few breaks. It will just be the
intensity of the rain which will Ebb and flow. Temperatures have risen
very slightly since Monday afternoon...and will probably reach 50f in the
far southeast. Since the area is stuck in a cold air damming regime and
the warm air is not very likely to mix down...the temperatures will
struggle to add only 8-10f through the day. Still...it will be
above normal by mid-aftn. Kbfd is already just a hair below their
normal high at 37 degrees.
Short term /6 PM this evening through 6 PM Wednesday/...
the strong upper low closed up over the High Plains will slide to
the east into the upper Great Lakes for Wednesday. Rain will
continue off and on. The modified cold air reaches western PA on Wednesday
morning but takes the daylight to cross most of the County Warning Area. As has
been observed lately...the European model (ecmwf) was the first on The Block to
slow the front down as a strong SW-NE jet streak buckles the flow
aloft. This makes a ripple along the front and should enhance the
rainfall over the east on Wednesday. Quantitative precipitation forecast values still prognosticated to range from
0.50-0.75 inches over the northwest to 1.00-1.50 over the southeast. Even a half
an inch in 3 hours in the southeast should not be enough to cause any
The warm air does seem to mix down just a bit tonight and will
probably keep the odd/rising temperature trend going for the first half
of the night. But cold advection will be occurring before sun up
on Wednesday. Will knock off a few degrees from midnight values there...but
keep it in the m40s in the susq valley and laurels. The clouds and
rain will keep a big inversion in place and continue to make it
difficult to make the surface temperatures go up more than 5-6f through the
Long term /Wednesday night through Monday/...
upper low with steadily falling heights will cross the area
Wednesday night into Thursday. Increasing northwest flow on the backside
of the departing low will direct colder air over the Great Lakes
and produce lake enhanced snow showers focused over the northwest
alleghenies on Thursday. Used wpc winter precipitation guidance for snow
totals which indicate a fairly high confidence for at least minor
accumulations especially in the favored snowbelt in Warren/McKean
counties along and to the north of Route 6. 1-3 inches looking
good for those locations at this point. But have mentioned the
poss of moderate snow in the severe weather potential statement for Wednesday night-Thursday am.
High pressure will dominate the weather pattern and provide fair and
tranquil conditions into early next week. After a seasonable "cool"
down on Thursday...look for temperatures to climb back above normal
on Friday and keep getting warmer into next week.
Aviation /12z Tuesday through Saturday/...
areas of low ceilings...fog...drizzle...and light rain will be across
the region today and tonight. IFR conditions will prevail for the
most part. Some improvement possible later on Wednesday.
12z tafs sent.
Temperatures above freezing overnight...thus not seeing any
freezing rain at the current time.
Wednesday...rain/low ceilings likely.
Thursday...am shsn/visible reductions poss kbfd.
Fri-Sat...no sig weather expected.
November was a warm and dry month.
For Williamsport...it was the 5th warmest...with a
mean temperature of 47.0 degrees. The old value of
46.3 degrees was set in 1913. The high temperature of 74
degrees on the 6th broke the old record of 73 degrees set
For Harrisburg...it was the 3rd warmest...with a
mean temperature of 49.5 degrees. The old value of
49.3 degrees was set in 1999.