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000
FXUS61 KCTP 060725
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
325 AM EDT Thu May 6 2021

.SYNOPSIS...
Drier, breezy and cooler conditions are expected tonight and
Thursday as a cold front exits off the Mid Atlantic Coast this
evening. Rounds of rain are probable again on Friday and Sunday
(Mother`s Day). A chilly pattern with below average temperatures
will continue through early next week.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
Radar loop at 07Z is showing just a few sprinkles across north
central Pa associated with a mid level shortwave, which should
pass east of the forecast area by 10Z. Weak returns suggest
there is little chance of measurable rain anywhere, and low
level wv loop/model soundings both indicate some very dry air
just above 850mb.

The arrival of surface ridging and a low pwat-air mass should
result in diminishing cloud cover toward dawn, with the most
persistent stratocu along the spine of the Appalachians. Diminishing
wind and breaking clouds has already resulted in patchy valley
fog across eastern Ohio and based on latest trends, suspect
some valley fog/frost will form over parts of Warren Co toward
dawn also.

Temperatures are on track to bottom out this morning from the
mid 30s across portions of the Allegheny Plateau, to the mid 40s
over the Lower Susq Valley.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TODAY/...
Subtle upper level ridging and low-pwat air should ensure fair
and cool weather today across central Pa. Warm advection aloft
in advance of upstream trough should spread cirrus into the
region from northwest to southeast during the day. Overall,
expect partly sunny wording to suffice for the northwest
counties and a transition from mostly to partly sunny in the
southeast.

Mixing down from 800mb today yields expected highs ranging from
the mid 50s over the higher terrain of the Alleghenies, to the
mid 60s across the Lower Susq Valley, a solid 5 to 10 degrees
below early May climo.

&&

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
This evening`s update centered on the two rain events Fri & Sun
PM. All signs (models/ensembles) point to a high liklihood of
rain for both time periods. Thus added 10-30pct to the blended
model PoPs. Added a few degs to the Sun PM temps, too,
accounting for more cloud cover.

Prev...
Upstream troughing should amplify Thursday night as a couple of
shortwave impulses rotate around broad/deep closed H5 low
centered near James Bay. This should result rain shower risk
ramping up across the western 1/3 of the CWA into Fri. A.M.

Upper-level trough will dominate the northeast through at least
much of the weekend with some suggesting that the main axis
lift north of PA by late in the weekend. Regardless, this
pattern will result in a high confidence of below normal
temperatures lasting into the weekend.

There is increasing model consensus with regard to timing of
the trough, so have ramped up the chance of showers for Friday.
Cooler, but drier, conditions appear likely by Saturday, as the
trough axis lifts out and surface ridging builds into the
region.

After that, there is an increased chance of rain on Sunday
associated with low pressure lifting northeastward through the
Ohio Valley. Latest trends in medium range guidance suggests
that a front will slip south of the area on Monday as high
pressure builds over the Grt Lks. The GFS/GEFS do not push the
front quite as far to our south as the ECMWF/ECENS, so held
onto to slight chc PoPs into early next week.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Aside from a few showers over north central PA at 1 AM, not much
left on the radar.

For the 06Z TAFS, will leave showers out of the fcst. Main thing
will be to slow down clearing this morning, given a northwest
flow of cold air across the Great Lakes.

Expect VFR conditions this afternoon and evening, with an
increase in clouds this evening.

Outlook...

Fri...MVFR to IFR conditions in periods of rain.

Sat...Brief MVFR to IFR cigs and MVFR vsbys possible in rain.

Sun...Deteriorating conditions with a steady rain likely (esp
Central and Southern PA).

Mon...Poor conds early. Improving west to east late in the day.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Dangelo/Gartner
AVIATION...Martin/Wagner