Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 221858

Area Forecast Discussion
National Weather Service State College PA
158 PM EST Thu Feb 22 2018


A nearly stationary frontal boundary will remain just south of
out Pennsylvania today through Saturday, before lifting north
across the commonwealth as a warm front Saturday night. A cold
front will ultimately usher in cooler and drier air Sunday.



Water vapor loop shows a well defined upper level shortwave
with an almost classic baroclinic leaf feature lifting into the
entrance region of a powerful upper jet streak moving through
eastern Canada. The trough axis is entering western Pa as of
early afternoon and the radar confirms this with the back edge
of the precip beginning to look more ragged as it moves through
my western counties.

Weaker UVVs have led to snow going back over to some sort of
wintry mix at BFD where the temp has recovered above freezing.
The advisory for mixed precip is set to expire at 21Z and this
looks reasonable as temperatures nudge to just above freezing
and the precipitation tapers off to spotty showers or drizzle.

From earlier...

The lower branch of the thermally direct circulation into the
upper jet streak is providing a potent ageostrophic component to
the flow out of the NE helping to keep the cold air filtering
south into the ridge-valley region. This will keep the
possibility of isolated pockets of freezing rain or drizzle in
the forecast until things taper off between about 3 and 5PM,
according to the latest HRRR timing.


Residual low level moisture, combined with an upsloping
easterly flow, is likely to yield lingering drizzle over much of
the region into this evening with occasional light rain, -FZRA
or FZDZ possible over the higher terrain of northern Pa tonight
through Friday morning. Throughout the central valleys, patchy
light drizzle and freezing drizzle will be found.

Temps tonight will be in a rather tight range tonight in the
30-35 deg F range.


The weekend still looks similar to the last few days with a few
periods of rain, drizzle and ridge shrouding fog Friday night
through Saturday night, before the frontal boundary to our
south, lifts north as a warm front. Temps will slowly moderate
through the weekend.

The best chance for a warm up is system lifts to
the north and west of central PA. This track is a little further
west now...which would keep the heavy rain threat further away
from our area. Depending on the mixing...more record highs could

Looks dry after Sunday evening.

More information below.

Forecast for Thursday into Friday looks cloudy and damp with
periods of light rain/drizzle and areas of fog. The fog will be
locally dense at times, especially on East-Facing slopes and
ridgetops during the overnight and early to mid morning hours.

Stalled out sfc front across the Virginias and Ohio River
Valley and SW flow aloft will be the conduit for a few waves of
low pressure to ripple NE along, and bring us this rather dismal

There is the potential for a significant change in practical
weather...if frontal position changes north or south very much.



Widespread MVFR/IFR will continue into the evening and
overnight. Rain continues to fall from about I-80 southward
with a wintry mix over the northern tier. BFD has gone back to a
wintry mix and the temp has risen to 34. Timing of the back edge
of the steady rain/mix looks good to taper off between about

Active weather will continue into the weekend with several
disturbances bring widespread rain and sub VFR conditions.


Fri...Widespread restrictions in periods of rain. Some
improvement poss SW late.

Sat...Widespread restrictions with rain.

Sun...Widespread restrictions likely in periods of rain.

Mon-Tue...No sig wx.


Active hydrologic pattern through Sunday. Recent snow melt and
rainfall has soils quite saturated. Streamflows are also running
high. Recent rainfall has stream flows above average. So focus
will turn to where the heaviest rain falls and if it is heavy
enough to produce flooding. Models consistent with heaviest
rain west of the CWA but still close enough to keep a flood
threat over the western half of the CWA. Issued a Flood Watch
for this area to address the threat. Right now no river
forecast to flood, but expect significant rises and will monitor
closely. Some poor drainage and small stream flooding is


Record high temp of 69 tied at KIPT for Wednesday while an all-
time Feb high was reached at KMDT with 79 degrees, and breaking
the old record for the day pf 71F in 1997.


Flood Watch through Sunday evening for PAZ004>006-010>012-
Winter Weather Advisory until 4 PM EST this afternoon for


NEAR TERM...La Corte
SHORT TERM...Fitzgerald/Lambert
LONG TERM...Lambert/Martin
AVIATION...La Corte/Lambert
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