Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 220547
Area Forecast Discussion
National Weather Service State College PA
147 AM EDT SUN MAY 22 2016
Cool temperatures and occasional showers will continue into the
second half of the weekend. Rain chances will decrease early next
week with improving weather conditions. Temperatures will trend
noticeably warmer through mid week with most areas likely hitting
80 degrees for the first time this month heading into the holiday
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Late evening water vapor loop showing a well-defined mid lvl vort
max over northwest Pa. Fairly widespread coverage of lgt rain/dz
within assoc moist easterly flow across Central Pa at 02Z. Next
shortwave will dive southward from eastern Ontario overnight,
refocusing the best lg scale forcing and steadiest rain over the
Central Mtns. Blend of latest near term models support up to an
additional half inch of rain overnight across portions of the
central and north central mtns, with significantly less across the
Susq Valley. Thick cloud cover and low dwpt depressions indicate
temps will remain basically steady overnight with lows in the u40s
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
Additional/re-developing showers are likely on Sunday, as the
aforementioned shortwave trough is reinforced by upstream height
falls, eventually closing off as it drops southward from PA into
the southern Mid-Atlantic. The relatively cold air aloft results
in a gradual erosion of stability with mid level lapse rates
forecast to rise to around 6-6.5 c/km. Latest mdl output suggests
cloud cover and numerous showers will hold temps down across the
central/south central mtns, diminishing the chc of tsra. However,
still thinking there will be enough brightening and assoc
destabilization across the nw counties to support a few pm tsra.
Temperatures should get a little warmer than today, but still
remain below normal for late May. Expect a decreasing trend in
shower activity tomorrow night from northwest to southeast, as
upper low sinks south of Pa.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
This forecast is headlined by a strong signal over the CONUS for
large scale pattern shift by the middle to end of the coming
week...finally signaling the arrival of near summer like weather
across the region. How we get there remains to be seen...but
today`s extended range EFS and deterministic models are in better
agreement over this evolution...which will be welcome news for
many should it hold sway heading into the upcoming holiday
Evolution of the slowly filling upper low will be the main focus
early in the period...as today`s guidance meanders the closed low
from the mid Atlantic seaboard to southern New England from Monday
to Wednesday. This will keep unsettled conditions over much of PA
with at least a chance of showers invof the lifting upper low.
Upper ridging is forecast to spread eastward from the Ohio Valley
into western and central PA by Wednesday afternoon...bringing an
end to the blocky regime and a return to more seasonable
conditions. Much warmer conds expected from Wednesday onward as a
result. The zonal wsw flow may bring scattered showers or
thunderstorms to the region Thursday into Friday before massive
amplification of the upper ridge takes place Fri-Sat-Sun. GEFS and
ECWMF support this evolution...and have followed previous shifts
in soaring maxes well into the 80s from Wednesday onward. 5h 588
dm contour flirts with southeast PA by Sunday. This may be the
first very warm and humid air mass of the season...with a strong
ensemble signal for the pattern shift at this time.
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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Main change was to edge off the improvement some later
today. Hard to see much change before Monday.
Earlier discussion below.
Vort max moving through western PA will keep rain showers across
the area through Sunday morning. Expect IFR to MVFR conditions in
ceilings,rain and fog overnight. Winds will be light and
As the upper low pressure moved southeast of the state on Sunday,
expect rain showers to become more scattered with less of a
reduction in flight category. However, conditions may remain MVR
to IFR during the morning hours with gradual improvement through
Mon...VFR/MVFR with sct showers with isold P.M. tsra impacts
possible ern 1/2.
Tue-Wed...VFR/No sig wx expected.
Thu...Slight chance of P.M. showers/tstms wrn 1/2.
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