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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 180614
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
214 AM EDT Mon Mar 18 2019

.SYNOPSIS...
A weak area of low pressure will pass south of the state 
tonight. It may produce a light coating of snow along the MD 
border. Dry and mainly colder than normal temperatures are 
expected for Mon- Tues. But, some light snow or rain is possible
Wednesday or Thursday and temperatures will be close to 
normals. A slight cool down is expected for week's end.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Shearing and weak upper trough bringing increasing mid level
clouds to central and western PA at this hour. Deepest moisture
is being pooled along the Mason Dixon line in the entrance
region of a 115kt ULJ, and is supporting vlight snow south of
the PA/MD border. Earlier echoes tracking eastward from OH have
dissipated as increasingly dry boundary layer air is
encountered.

Very weak area of low pressure at the SFC will move just south 
of PA through early morning. Some very light snow will brush 
our southern tier counties through 12Z...with latest hi res CAMs
suggesting only spotty QPF of a few hundreths near the PA/MD
border, with most of my area remaining dry. 

Places most likely to get a light dusting (less than an inch) 
would be folks right along the MD border in Somerset County, 
and mainly across the highest elevations. The temps in the 
cloud layer are ripe for big dendrites, but it is very dry 
underneath the 4-5kft cloud bottoms. 

A few flurries are still possible as far north as I-80 in
Central PA and the Susq Valley, and also across the NW mtns, as
a separate sfc and upper level trough drops SE from the Glakes 
and shifts the mean LLVL wind to the NW. No accums are 
expected north of a JST-AOO-THV-LNS line. 

Mins should be well below normals, with dewpoints only in the 
single digits across much of the northern half of the area. The 
srn half of the area will be closer to normal, with m-u20s 
there, mainly thanks to the lower/thicker clouds. Wind goes 
light/calm with a small nose of high pressure pretty much 
overhead tonight.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
The effects of the fast moving wave should pretty much be over
by morning, but some flurries/sprinkles could linger into mid- 
aftn over the far SE, and some flurries are never out of the
question in the Laurels.

Northwesterly flow aloft will continue with temperatures 
holding around 10 degrees below normal. Sfc wind will be light 
in the morning, but pick up out of the NW through the day over
the Alleghenies as slightly cooler air aloft slides over the 
area during the day. The cold advection will also lead to an 
increase in low clouds and some flurries/sprinkles across the 
north. There is just a small chc of an accum over the nrn mtns 
in the aftn. However, daylight hours in mid-March are a very 
difficult time to accum snow. Thus, PoPs will remain 30pct or 
less. 

Mon night looks like we should clear out over most of the area,
but strato cu may linger over the NErn mtns. Mins a carbon copy 
of tonight.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Surface high pressure will move across Tuesday and Tuesday
night. Long-wave trough aloft will aid keeping temperatures
about 5 degrees below normal for this time of year and help
generate some afternoon clouds across the north. Surface high 
center moves off the coast Wednesday. Southerly flow ahead of
next system along with March sun will warm temps to near normal.
Next system will move in Wednesday night with good chance for
rain and snow...snow mountains and colder locations north.
Thursday a short-wave rotates around upr level trough bringing a
chance for scattered light showers. Drier and warmer conditions
heading into and through the weekend. Near normal highs and lows
on Friday and Saturday with about a 10 degree jump on Sunday
climbing into the 60s many areas through central PA and across
the south. Warmer trend looks to last into the 8-14 day period.

Spring officially begins at 5:58PM on Wednesday 3/20.

&&

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

Main focus in the near term forecast will be on low pressure
and associated light snow approaching from the Ohio Valley. All
model data keep the snow along and south of the Mason Dixon Line
late tonight and early Monday, with VFR conditions very likely 
at the southern Pa airfields and nearly certain elsewhere. 

High pressure building in from the Grt Lks should ensure
widespread VFR conditions and light winds Monday afternoon and
evening across all of central Pa. 

.Outlook...

Tue-Wed...No sig wx expected.

Thu...AM low cigs possible W Mtns.

Fri...AM low cigs/snow showers possible W Mtns.

&&

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

&&

$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...Dangelo/DeVoir/Lambert
SHORT TERM...Dangelo
LONG TERM...Watson/Steinbugl
AVIATION...Fitzgerald/Ceru