Scientific Forecaster Discussion
fxus61 kctp 240634
Area forecast discussion
National Weather Service State College PA
234 am EDT Wed may 24 2017
the weather pattern will remain unsettled through Memorial Day.
Temperatures will be cooler than average to end the week with a
modest rebound likely this weekend into early next week.
Near term /until 8 am this morning/...
1am: significant upward adjustment to probability of precipitation early this morning
based on rainfall creeping north of the Mason-Dixon line toward
the PA Turnpike. Hires consensus suggests decreasing rain
coverage over far south-central PA through daybreak with sct
showers becoming more focused over the western 1/3 of the County Warning Area.
Short term /8 am this morning through 6 PM Thursday/...
tomorrow we should be mostly between systems. The clouds and
moisture from the wave to our southeast should be pulling away
overnight. And the clouds and rain from the deep 500 hpa low
will be heading our way from the west-southwest.
Most areas should have a pretty nice day, but once again on the
cloudier side of things. Kept probability of precipitation in the chance range in
southwest before 18 UTC and brought them up higher and into
central PA by 00 UTC.
Sometime from 2100 UTC Wed to about 0300 UTC it's going to get
wet. But highest probability of rainfall in current guidance
will likely be on Thursday. New guidance might change this.
Long term /Thursday night through Tuesday/...
as upper low drops into the Tennessee Valley Wed night, surface low
develops over the Ohio Valley with a warm front extending
eastward across the mid Atlantic states. Initial question will
be timing of onset of precip over County Warning Area. Precip will be working
across west PA by early eve and will spread eastward as flow turns
from the southeast around to the S, overspreading all of central PA by
the overnight hours. System slides through Thu into Thu night,
with a widespread rainfall around 0.75 inch.
On Friday, cool cyclonic flow on backside of departing cyclone
will maintain risk for showers. A lower-amplitude mid level flow
pattern will develop into the weekend with some ridging likely
at 500mb. Uncertainty regarding location and timing of shortwave
impulses rounding the ridge and effect of prior upstream
convection leaves plenty of question Marks for Saturday - but
there is more agreement in area of Max pops over S Ohio/into WV
and SW PA in the afternoon.
Nbm/ece blend yielded the highest pops for Sunday across
central PA associated with cold front moving south/eastward
across the Great Lakes/Appalachians. A severe risk may accompany
the cold front but still to early for details. The large scale
pattern evolves into a broadly cyclonic regime into early next
week around an upper low between the Great Lakes and Hudson Bay.
This should keep the pattern unsettled with continued threat
for showers/tstorms through Tuesday.
Aviation /07z Wednesday through Sunday/...
06z tafs sent.
Some rain pushing slowly to the north into the far south.
MVFR ceilings possible for a brief time across the southeast.
Otherwise it should be a dry day with VFR conditions, as the
rain across the southeast moves out this morning.
Rain will overspread the area Wed evening from the west.
Earlier discussion below.
Most of the flying area is under a blanket of high clouds. Some
MVFR has crept into MDT and this lowering ceiling trend over
southern areas as the area of rain slowly overspreads the
Expect the mainly light rain to move into about the southern
half of the forecast area during the remainder of the overnight
and early this morning with MVFR/IFR conditions developing.
Northern areas will see just spotty light showers and widespread
sub VFR conditions are not expected.
Conditions will improve slowly this morning with most areas
improving to VFR by mid day. MVFR could hang tough over The
Clouds will increase west to east as another system approaches
with rain and reduced conditions overnight Wednesday into
Thu...rain/low cigs likely through at least midday.
Fri...showers/MVFR cigs northwest. Mainly VFR southeast.
Sat...no sig wx expected.
Sun...reduced conditions with scattered showers.