Scientific Forecaster Discussion
fxus61 kctp 220319
Area forecast discussion
National Weather Service State College PA
1119 PM EDT Thu Jun 21 2018
high pressure noses in from the northeast early tonight, keeping
the light rain to our south at Bay, or at least sloweing the
northward progression. The nearby warmfront will be the pathway
for a low pressure system to track across the eastern Great
Lakes Friday and Saturday. The cold front trailing along will
move through Pennsylvania Sunday. But, a wet, unsettled few days
are in store for the weekend.
Near term /until 8 am Friday morning/...
dewpoints are a slightly more homogenous now. Some of the latest
mdls do spread very light rain to the east into the lower susq
before sunrise. Will bump pops up a little more there. The only
other sig change was to add mention of minor flooding into the
srn tier (esp Somerset and Bedford co.S, as latest hrrr/rap and
00z NAM all generate convection just to our south and move it up
into those counties where wpc also has a marginal risk of excessive
rainfall. The day2 slight risk just barely touches the far
southern border counties. Overnight shift and day shift will
need to monitor developments/trends to see if a Flash Flood Watch is
mid clouds overspreading the County Warning Area with just a sprinkle or two
trying to reach the groud just off to our SW. Lower clouds now
nudging into Somerset and Bedford counties where they can do
without the rain. But this stuff does not look heavy as we have
lost the daytime instability. While the dewpoints are all over
the place as of 8 PM, they should settle down to pretty dry
u40s in the north and still-moist l60s in the S overnight. Thus,
the rain shield expected to slide overhead should take a while
to saturate the lower atmosphere overnight. Just minor tweaks
made to the pops and dewpoints mainly with this update.
Short term /8 am Friday morning through 6 PM Friday/...
a tight pressure gradient between high pressure east of New
England and low pressure over the Midwest will result in a
moist, southeasterly low level jet focused over southwest PA
early Friday, likely resulting in a wet start to the day across
The Laurels and south central mountains. But, rainfall should be
light for the morning there. Gefs indicates this anomalous
southeasterly low level jet and plume of higher precipitable waters will lift
slowly northeast Friday, resulting in an good chance of rain
across all but the extreme eastern portion of the forecast area
by late in the day. Some thunder is possible, but not likely
across the far S and far west in the aftn.
Cloud cover, rainfall and easterly flow north of warm front will
result in a cool day for June with readings likely stuck in the
60s across the central mountains and only reaching the low 70s
over the susq valley.
Long term /Friday night through Thursday/...
all medium range guidance is in agreement on a large upper level
low that will be tracking through the mid west and to the
northeast across the Ohio Valley and into the mid Atlantic
region Saturday. Overrunning rain appears likely Friday night
into Saturday morning, as the region remains north of the warm
front. The models seem to have a consensus and the closed low
should slowly open as it moves to the northeast. Thew warm moist
flow with anomalous precipitable waters will bring lift the warm front
through Saturday, with a cloudy wet day in store. The low should
open to a weak wave and the trailing cold front should move
through Sunday. The GFS/ec differ at this point with the GFS
deepening the trough and colder upper level air. Dry air will
filter into the region early next week with milder summerlike
weather dominating the region through the first half of next
Aviation /03z Friday through Tuesday/...
no real change to the late evening taf update.
Earlier discussion below.
Not a lot of change to the 00z taf package.
Nice evening across the region.
Expect VFR conditions to prevail for most of the overnight.
Rain and lower conditions will overspread from the south
and west to the north and east during the day on Friday.
Saturday will feature warmer temperatures and more in the
way of showers instead of rain. Thus ceilings should be higher.
Sat...am MVFR-IFR cigs gradually improving Saturday afternoon.
Scattered to numerous showers; isolated ts possible SW 1/4.
Sun...scattered showers/isolated thunderstorms.
Mon...no sig wx.
Tue...dry with VFR conditions.
astronomical Summer (june solstice) began at 6:07am. Today
Marks the longest day and shortest night in the northern
hemisphere, and the exact moment when the sun's rays reach as
far north as they get during the year, appearing straight
overhead along the Tropic of cancer, at 23.5 degrees north
latitude. As a result, the sun will took its highest and
longest path through the sky.
For State College sunset is 8:46pm. The total daylength is 15
hours, 6 minutes and 10 seconds.