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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 180413
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1113 PM EST Sun Feb 17 2019

.SYNOPSIS...
A fast flow aloft will keep the weather active through the week.
The first weak disturbance will move across the region tonight.
A stronger storm will approach for the middle of the week. A 
third storm is possible next Sunday.

&&

.NEAR TERM /THROUGH MONDAY/...
Radar shows very spotty precip streaking across the region,
pretty much in line with forecast expectations with the
exception being over the far north where snow has not been
terribly impressive. 

Models are in good agreement tracking the storm through 
northern PA overnight. Precipitation is already becoming spotty
with the changeover line up into Bradford. The best chance for
any remaining snow will be over the very far N and NE. Over the
bulk of the remainder of the CWA it will be a pig's breakfast 
of precipitation types, but not an especially impressive amount 
of any one thing. The presence of any ice will of course make 
travel on untreated roads hazardous, and we don't expect any 
appreciable warming during the overnight.

The sleet/freezing rain mix will make for a mess - especially 
on untreated surfaces. 

Temps will remain very constant overnight...near freezing in 
much of the area south of I-80. The Laurels and SE could rise 
above freezing later in the storm, but the E/SE flow in place 
for most of the night doesn't give up the cold air very easily.

&&

.SHORT TERM /MONDAY NIGHT/...
As the low moves into NY, a small low may form over the 
DelMarVA, and briefly hang precip up in the SE. But, temps will 
also be warming after daybreak, and much of the area will be out
of the threat of FZDZ by 8-10 am. The temps will get cold 
enough over the NW half to make anything left over into snow 
showers. The downslope in the wake of the low will make it mild 
in the SE, and help to break up the clouds there. The west wind 
could gust to 30 mph in the southern tier in the afternoon.

Surface high pressure expands into the region Monday night. Once
breezy winds die down, temps will fall into the single digits
north of I-80, and in the teens/20s elsewhere.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Main change to the package was to take out snow for Tuesday
evening, to fit in better with others. Also ridge still over 
the area and models show little if any QPF into the area before
12Z Wednesday.

For Wed, low pressure lifting northeast across the Great Lakes
will result in some snow, given warm advection. By late morning
and early afternoon, looks like sleet and freezing rain would
mix with the snow. This based on thickness coming up fast, as
the system is weaker and faster than the one we had last week.
Thus did not hit the snow real hard, and did not want to go too
high on ice. This in part due to QPF on NAM across the far south
was looking too high. Other models have the .25 inch line just 
brushing the far south. Hard to see much more than .25 in any 6 
hour period. The NAM had .75 inches across the south in a 6 
hour window.

This event looks like the event last week, most of the precipitation
would be east of the area by Midnight.

For most of the period from Thursday into at least early Saturday,
not a lot going on. I did cut back on POPS and weather where I 
could. Temperatures borderline, so used a mix of rain and snow.

Main question is if a deep low will form and lift across the
lower Great Lakes on Sunday. For now, went close to the
superblend. EC and GFS runs not close. GFS has much weaker 
systems. If EC was to verify, Monday would be the first real
windy day of the late Winter, early Spring season.

&&

.AVIATION /04Z MONDAY THROUGH FRIDAY/...
Spotty mixed precip associated with an approaching storm will 
taper off late tonight. However, model output supports lingering
low cigs through around dawn. At 04Z, IFR cigs were widespread 
across the western half of Pa and latest model output supports 
those IFR cigs spreading into the eastern half of the state 
around or shortly after 06Z. 

Expect rapid improvement between 10Z-14Z, as the storm system 
exits the area and is followed by a drier westerly flow. Model
soundings indicate there will be lingering MVFR stratocu across
the mountains of central Pa, while downsloping flow yields a
return to VFR conditions in the Susquehanna Valley from KIPT
south through KMDT/KLNS. A tight pressure gradient behind the
departing storm will produce gusty west-northwest winds. Bufkit
soundings support gusts ranging from around 20kts over the
northwest mountains (KBFD) to between 30-35kts over southeast Pa
(KMDT/KLNS).

Outlook...

Tue...No sig wx expected.

Wed...Wintry mix likely. 

Thu...AM wintry mix/low cigs possible.

Fri...No sig wx expected.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 PM EST Monday for PAZ004>006-
010>012-037-041-042.
Winter Weather Advisory until 10 AM EST Monday for PAZ017>019-
024>028-033>036-045-046-049>053-056>059-063>066.

&&

$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Dangelo/RXR
LONG TERM...Martin
AVIATION...Fitzgerald