038
FXUS61 KCTP 310715
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
215 AM EST Fri Jan 31 2025

.SYNOPSIS...
* Patches of freezing rain are possible early this morning over
  mainly northeastern PA.
* Periods of rain will continue through the day and evening.
* After a brief bout of chillier weather on Saturday, milder
  temperatures will return for early next week.

&&

.NEAR TERM /THROUGH TODAY/...
Temps on the sfc analysis are largely above freezing on the
higher ground south and west of UNV. However, there is a wide
range of air temps across the rest of the area, with some upper
20s in the valleys of Centre County. Therefore, until the mild
air gets down into those places, there could be patches of ZR
here and there out side the current advy area. The advy area is
the most likely (90% chc) for a glaze of ice to form as the rain
starts today. But, a 40-50%pct chc of icing is there for a few
hours. We have issued an SPS to mention this possibility in
broadcasts, etc. We do not anticipate the necessity for the advy
to expand in area. We will continue to monitor the near term
temp trends, especially those in locations to the S/W where
they should be warming up, too. Dewpoints are still in the 20s
and upper teens except in Bedford and Somerset counties at 02Z
where they have risen to the upper 20s after an hour or two of
very light rain. The dry air below the clouds will help some of
the rain to evaporate at first, and may even allow for a few
flakes or pellets during onset.

As temps rise this morning, even the advy area should see the
threat for a glaze end. Maxes today will be near 50F in the S
and upper 30s NE. It will be a chilly rain for the most part,
but some relief from the long stretch of cold (esp in the
middle of the month) will be welcomed by most. KJST hasn`t seen
50F since 2024 (Dec 29th).

The minor upper ridge overhead will hold on until mid-day when
heights fall some. The sfc low will still be out in the worst
state (OH) at that time, but it should slide to the east and be
right overhead by 00Z/7 PM. So, it will take the morning to
really get some moderate rain anywhere, but breaks in the rain
will start to occur in the SW late around sunset.

See Hydro section for that wisdom.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
As the surface low continues eastward Fri night, the steadier
rain will taper off during the evening hours. The upper trough
will be sliding past us by 09Z, so the light precipitation should
taper off by 12z Saturday. However, as colder air begins to
filter in on the backside of the low, scattered rain and snow
showers are possible from the Laurels through north-central PA
and into the Endless Mountains for a good portion of the night.
Any snow accums will be very minor (<1"), and only in the far
nrn tier and/or Laurels as the temps go below freezing around
midnight N and later in the night in the SW.

Saturday looks like a winner with lots of clearing over most of
the CWA. Some higher clouds may dim the sun a bit. Morning lows
in the mid teens far N, but u20s-m30s S of I-80. The temps
won`t go up by much, probably not getting to 20F N, thanks to
slight cold advection and more clouds there than elsewhere. The
quickly veering flow will bring clouds down from the lower
lakes, but the crashing inversion should keep them shallow and
limit any LES from them to very near the lakeshores. Maxes
within 4F of temps at sunrise will be the norm.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Much of next week will feature relatively zonal upper-level
flow, which should result in relatively mild temperatures
compared to what we saw through much of January.

Weak systems will periodically pass to our north, bringing at
least a slight chance of (mainly rain) showers, especially
across northern PA. However, the timing of these quick-moving
systems is difficult at this time range.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Current observations indicate that only a small amount of the
precipitation depicted on radar as of 05Z is actually making it
to the ground. Model soundings indicate that the column will
quickly saturate over the next few hours, and as this happens,
precip will begin falling at BFD, JST, and AOO. Ceilings will
also become MVFR as the rain begins to fall, with further
deterioration to IFR cig/vsby expected into the morning. As the
rain spreads northeastward, restrictions will expand to all
central PA airfields. Confidence has decreased in any -FZRA
occurring at IPT early this morning, and the 06Z TAF package now
shows plain rain.

There is a lot of spread in the guidance as to how low
visibility gets across the region during the day, with some
models showing LIFR visibility across the region for much of
the day, while others show 2-3SM. Since the HREF only shows a
30-40% chance of most airfields dipping below 1SM, decided to
stick closer to the 1-2SM range. Periods of LLWS will also be
possible, especially south of UNV as a 40-50 knot low level jet
traverses the region. Rain will gradually come to an end east of
AOO and UNV after 00Z Saturday, while rain showers and possible
some snow showers will continue at BFD and JST.

Outlook...

Fri Night...Rain could end as snow/showers late Friday night
with 20-25kt wind gusts from 310-340 degrees.

Sat...Sub-VFR cigs possible early with diminishing wind.

Sun...Chance of light snow north central PA.

Mon...Breezy with rain/snow shower possible

Tue...Mainly VFR.

&&

.HYDROLOGY...
Storm total QPF still looks like a widespread 0.35-0.7" which
is no worry at all for most of the CWA. However, the water pent
up in the snow cover over Somerset County may yield enough melt
water to make rises on the smaller creeks and streams. Some ice
on those same creeks may clog up the works, too, and cause some
minor flooding. The larger rivers (Yough, Casselman) do not seem
to be in any danger of flooding due to currently low flows.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 7 AM EST this morning through late tonight
for PAZ033.
Winter Weather Advisory until 9 AM EST this morning for PAZ037-
041-042-053-058.

&&

$$

SYNOPSIS...Dangelo/Evanego
NEAR TERM...Dangelo
SHORT TERM...Dangelo/Evanego
LONG TERM...Evanego
AVIATION...Bauco
HYDROLOGY...Evanego/Dangelo