National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 170545
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1245 AM EST Mon Feb 17 2020

.SYNOPSIS...
A weak upper level level disturbance in conjunction with a
surface trough of low pressure could bring some areas of very
light snow to the southern half of Pennsylvania this evening.

Low pressure moving across the Great Lakes and it`s associated
warm and cold frontal boundaries, will bring our next round of
precipitation late Monday night into Tuesday. The precipitation
should begin as a period of wet snow across the Central and
Northern counties of the state with mainly rain expected
elsewhere. Colder air will return for the second half of the
week with below average temperatures.

&&

.NEAR TERM /THROUGH TODAY/...
High pressure building southeast from the Grt Lks will ensure
dry weather for the rest of the night, with clearing skies. Low
temperatures should range from around 20F in the northwest to
around 30F in the southeast. Latest obs and near term guidance
indicate patchy fog will form in the valleys of the Alleghenies.

High pressure ridge will remain over the region Monday,
accompanied by partly to mostly sunny skies and light wind.
Mixing down model 900mb temps yields expected highs ranging from
the mid and upper 30s over the northern mountains, to the mid
and upper 40s in the Lower Susq Valley.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
Latest model guidance tracks a surface low through the Great
Lakes into southern Ontario/Quebec Monday night into Tuesday,
with the trailing cold front coming through Tuesday PM.
Moderately strong WAA/moisture transport via southerly low
level jet supports high confidence in precipitation late Mon
night into Tuesday morning.

An initial few-several hours period of snow still appears
likely over the central mtns and northern tier of PA late Monday
night/early Tuesday, as precip encounters the retreating dry
and cold sector. This could lead to some minor travel impacts
during the early AM commute over the northern mountains and will
continue to message risk via HWO.

The latest NBM/WPC blend supports less than an inch of
accumulation along the I-80 corridor, but 1-3 inches over the
mountains of northern Pa. 18Z model soundings indicate even the
mountains north of KIPT are likely to change to rain by 12Z-15Z
Tuesday. The rain should taper off from northwest to southeast
Tuesday afternoon, as the trailing cold front crosses the
region.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
An upper trough and pool of anomalously cold air is progged to
swing through the northeast CONUS Wed-Thu. Surface ridging and
associated low inversion heights indicate lake effect snow showers
will be quite light, with only light accumulations possible across
the Allegheny Plateau.

By late week, large surface high is progged to overspread the
region, ending the threat of lingering lake effect flurries and
likely accompanied by abundant sunshine Friday-Saturday. Below
normal temperatures should give way to milder conditions by next
weekend, as the high passes off the coast and a return
southwest flow develops. Several weak waves within the flow may
provide for a few periods of snow showers, mainly across the
northern mountains, late next week.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
06Z TAFS sent.

Most of the area clear now, with a slight west wind.

Have a tempo group in at JST, as low clouds have been moving in
and out of that area.

Earlier discussion below.

00z update... Lower clouds (MVFR to fuel alternate restrictions)
will be prevalent at KBFD and KJST for much of the overnight
period into early Monday, owing to some low-level moisture and
an upslope W-NW flow. Lower clouds are expected to have
dissipated at these terminal sites by 12-15z, with VFR returning
for the balance of the day.

Elsewhere for the central PA terminal sites (KAOO, KUNV, KIPT,
MDT, and KLNS), generally unrestricted conditions are foreseen
through the day Monday.

W-NW surface winds at 5-8 kt for much of tonight, will diminish
to light and variable (3-5 kt or less) for most of Monday. SE
winds at 5-8 kt are expected to develop late in the period
(after 21-22z Monday).

.Outlook...

Mon night-Tue... Restrictions probable in lower ceilings and
either rain or a wintry mix. KBFD and KIPT are the most likely
terminal sites to see a period of snow late Mon night or early
Tue.

Wed-Fri...Mainly VFR anticipated.

&&

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

&&

$$
SYNOPSIS...Lambert
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Lambert
LONG TERM...Fitzgerald/Gartner
AVIATION...Jurewicz/Lambert/Martin