Area Forecast Discussion
Issued by NWS State College, PA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 250002
Area Forecast Discussion
National Weather Service State College PA
802 PM EDT Mon Oct 24 2016
Northwesterly winds will continue tonight and Tuesday, occasionally
producing light showers over the mountains. High pressure overhead on
Wednesday morning will allow temperatures to near or drop below
freezing over most of Central PA.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Mins tonight will be controlled by the cloud cover. Trouble is,
that is a tough forecast. RH remains high in the LLVLs, but
downsloping and some mixing due to still-strong gradient flow will
duke it out for how much cloudiness exists overnight and where.
Will keep the forecast very climo with mostly cloudy to the NW of
IPT-UNV-AOO. Current partly-cloudiness should fill in with some
stabilization this evening. Will go for mins close to freezing on
the highest elevations, but m30s-m40s elsewhere. Of course, some
showers will run off the lakes all night, and some may be a mix
instead of plain rain. Snow accums are not expected due to warm
ground and --precip.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday looks very much like Monday just a few degs colder. The
wind should start to slacken later in the day but may not go calm
Temps again the trouble for Tues PM/Wed AM. In this case, the
5-10F temp drop from Mon PM to Tues PM will spell a moderate-high
threat for freezing temps across the whole CWA, and could kill off
the rest of the vegetation across the SE, ending the growing
season. Have posted a freeze watch for that possibility.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
With tail end of CAA Wed morning and surface high pressure in
place, could be a freeze ongoing to start the extended period.
During the day, CAA comes to an end as weak progressive upper
ridge moves through and low-level flow turns back to the S/SW.
A compact low developing over the Midwest will already be
knocking on our door late Wed night. Drier air remains in place
over the east Wed night, but expect showers to work into the west
overnight. With overrunning precip potentially falling into low
dewpoint air, wetbulbs may fall enough to mix some snowflakes in
at the onset over the northern mtns. Then, Thursday looks like a
rainy day with QPF values of 0.50-1.00 likely northern half.
Cool northwest flow Fri followed by subtle ridging within main
flow Fri night. Though model guidance still somewhat divergent
after that, the weekend continues to look unsettled as a series
of shortwave troughs slide through.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --Moisture flowing off of Lk Erie will continue to produce a varying
amount of stratocu across Central PA into Tuesday, with the most
persistent cloudiness and lowest cigs across the higher terrain
from KBFD south to KJST. Although widespread VFR conds noted at
23Z, model soundings suggest CIGs will dip a bit as the boundary
layer cools/moistens overnight, with MVFR becoming likely at
KBFD/KJST late tonight. The gusty wnw winds will abate a bit after
sunset as the atmosphere cools/stabilizes, but winds still
expected to remain in the 7-10KT range for most of the terminals.
Tuesday should be similar to Monday, as the flow changes little
in direction but does get a little lighter. Diurnal heating and
resulting mixing within deepening boundary layer will cause cigs
to rise during the day, with widespread VFR conds anticipated by
Wed...Patchy AM fog possible.
Thu...Rain/low cigs possible.
Fri...AM showers/low cigs possible W Mtns.
Sat...Showers/MVFR CIGS possible NW Mtns.
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Freeze Watch from late Tuesday night through Wednesday morning