Scientific Forecaster Discussion
fxus61 kctp 220215
Area forecast discussion
National Weather Service State College PA
1015 PM EDT Wed Mar 21 2018
Long-duration, early Spring snow storm will begin to finally
loosen its grip on the region this evening. The rest of the
week will feature cooler than average temperatures and
occasional flurries. The weekend now looks to be dry as the next
weather system passes to the south of PA.
Near term /until 6 am Thursday morning/...
The snow is pretty much confined to about the southeastern 1/3 of my
County Warning Area and the hrrr continues to show it melting away over the
next several hours. There is good consensus that any measurable
precip will be over by midnight with little more than a few
lingering flurries into the wee hours.
Final storm totals will range from 10 to 20 inches and will
make this the biggest snow event for the 2017-18 winter season.
A check of snowfall records at Harrisburg indicates a 2-day
snowfall over 1 foot would crack the top-10 2-day March
snowfalls, with the benchmark of course being the 1993
As temperatures fall overnight, slick spots could form on
untreated roads, sidewalks and elevated surfaces as areas of
slush and standing water from melted snow refreeze.
Short term /6 am Thursday morning through 6 PM Thursday/...
models showing a trailing shortwave diving southeast across the
region on Thursday. Upper level diffluence ahead of this feature
should result in a fair amount of cirrus. Low precipitable waters and temps
aloft not cold enough to generate moisture flux from the grt
lks, so not anticipating anything more than scattered flurries
across the Laurel Highlands.
Nbm/superblend indicating Max temps Thursday ranging from the
low 30s over the highest terrain of the alleghenies, to the low
40s in the susq valley. However, a tight pressure gradient west
of coastal low will produce gusty winds, making it feel even
chillier. Bukfit soundings support frequent gusts between
Long term /Thursday night through Wednesday/...
all models tracking closed upper level low southeast across PA
on Friday, likely supporting scattered, diurnally-driven snow
showers and flurries, mainly over the northern and western
After that, focus will shift toward low pressure lifting out of
the miss valley next weekend. Naefs/ecens indicate this system
will likely pass too far south to affect central PA, but will
maintain the slight chance for a period of snow.
After that, all Med range guidance is showing upper level
ridging building into the region, supporting a high confidence
forecast of fair weather and warming temperatures early next
week. A dying cold front could approach the area late Tuesday,
potentially spreading showers into the state.
Temperatures should remain below seasonal normals through most
of the long term forecast, as upper trough remains over the
northeast conus. However, moderation is anticipated by Tue/Wed,
as upper trough lifts out.
Aviation /02z Thursday through Monday/...
widespread restrictions in snow from winter storm will persist
across the southern half and especially southeast into the early
evening. But trend will be for improving conditions to drop
down from the north and work in from the west as storm pulls
away. By late evening, VFR conditions should take hold in most
locations, though increasing northerly flow should keep ceiling
restrictions in the higher elevations of the west and possibly
parts of the southern mountains.
Thu...no sig wx expected.
Fri...cig restrictions poss northwest.
Sat-Mon...no sig wx expected.
record daily maximum snowfall set at Harrisburg PA...
A record snowfall of 8.1 inch(es) was set at Harrisburg PA today.
This breaks the old record of 7.5 set in 1964.
near term...la corte