Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 161114
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
714 AM EDT Sat Mar 16 2024

.SYNOPSIS...
Temperatures will be unseasonably mild for the start of the
weekend until a cold front ushers in a change by Sunday. The
cold air will persist into the midweek period accompanied by a
several bouts of snow showers over the Alleghenies and Laurel
Highlands. Temperatures start to warm up again in the second
half of the week.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
Not much to change with this update. Tweaks to near term
T/Td/Sky have been made to match current trends.

Prev...
Light NW sfc wind is keeping lower clouds piled up over the
western high terrain. Only patchy clouds may be found SE of
AOO-UNV. A low inversion in the morning will be erased in the
afternoon, mixing the airmass up to 5-6kft. Most of the morning
stratus will burn and/or slide to the east before more clouds
slide into the wrn mtns this morning. Then, the deep mixing
should zap those clouds with few clouds left to mar a mostly
sunny day. The deep mixing and relatively dry air will probably
take the dewpoints/RH below guidance in many places this aftn,
more-so in the NE counties. Maxes are not going to be anywhere
as warm as the last many days, but they will get milder today in
the far NW (by ~1F), and still be 5-10F warmer than normal for
all of Central PA.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH MONDAY NIGHT/...
Vorticity rounding the base (and stretching out) of a
progressive upper low over nrn ONT will drag a cold front into
the CWA and touch off a patch/line of rain showers this
evening. The rain will press from NW to SE thru the night, and
break up as it does since the moisture overhead will be
unremarkable. Temps dip enough behind the front that anything
lingering back behind it may mix with/turn to snow just as the
flow becomes more lake-effect favorable. Not much QPF being
produced by most models after 12Z Sunday, with the straight W-E
llvl winds keeping most/all lake effect to our N. Subsidence
also aids in drying things out, but clouds won`t go away Sun
aftn/night. A gradual decrease in llvl temps will put the 8H
temps down to -2C SE to -8C NW by late in the day Sunday. This
cooling before a wave moves down from the NW on Monday may
decrease the voracity of SHSN/SNSQ that day. But, an upper
trough will be crossing the region during the daylight hours,
and decrease the stability.

See the prev discussion for more on Monday:

Several distinct short waves and rounds of diff PVA will track
SE from the Glakes and bring rather frequent snow showers and a
few bands of heavier squalls to PA`s Northern and Western Mtns
for much of the first half of the long term period, with brief
snow showers making it into the Central Mtns and Middle Susq
Valley at times.

The bulk of medium range guidance then tracks a potent upper
level shortwave and cold front through the region Monday. A
round of snow showers/squalls could accompany the passage of
this feature Monday. Strong large scale forcing, steep lower
tropospheric lapse rates and even some CAPE are evident in some
models with the fropa, signaling a potential of squalls.

The middle and upper portion of the thick stratocu clouds will
reside within the Dendritic Growth Zone across the Laurel
Highlands and NW mtns Sunday night through Tuesday with sfc
temps by day in the low to mid 30s and mins at night in the 20s.

This temp profile will support light snow accums for much of the
Alleghenies with localized accums of several inches, esp across
the perennial snowbelt of Warren and NWrn Mckean Counties.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Still some model spread from day to day and run to run, to how
the fcst plays out after Tuesday. Not real clear cut to how much
warm up will occur mid to late week. Still looking like by late
week it could trend rather wet again.

Below normal temperatures and lake effect snow showers appear
likely Tue/Wed, as upper level troughing and a cold northwest
flow over the Grt Lks remains in place. Fair weather and
moderating temperatures appear likely by next Thursday, as the
upper trough begins to lift out.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
The low clouds which build in overnight will begin to diminish
shortly after sunrise. The central and north west mountains are
currently borderline MVFR/VFR, but conditions are expected to
improve to VFR by mid morning. A west/southwesterly breeze will
develop and gust 15-20 kts by afternoon ahead of an approaching
cold front. Clouds will begin to increase from the northwest
late in the day, as the front nears. Rain chances will begin for
the NW near 00Z Sunday and gradually increase for the central
mountains approaching 06Z. Some increase in LLWS is likely as
the front moves through.

Scattered rain showers are expected to overspread PA from NW to
SE tonight associated with the passing of the cold front. Low
ceilings and reduced visby is likely where rain showers are
heaviest. Confidence is still low as to the exact timing of MVFR
and lower conditions. As temperatures dip to near freezing in
NW PA wet snow will mix in with the rain in the early morning
hours of Sunday and into Sunday afternoon. Elsewhere should
improve to VFR with overcast skies.

Outlook...


Sat night-Sun...Rain showers with MVFR cigs developing,
primarily N/W PA. Some snow could mix in as colder air arrives
on Sunday. Predominantly VFR elsewhere.

Sun night-Tues night...Periodic snow showers and reductions
across primarily N/W PA. Gusty W/NW winds areawide.

Wed...Improving conditions.

&&

.CLIMATE...
Astronomical Spring (vernal equinox) begins on Tuesday March 19
at 11:06 PM EDT.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Jurewicz/Lambert/Martin/Tyburski
AVIATION...Bowen
CLIMATE...Steinbugl


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