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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 220359
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1159 PM EDT Thu Mar 21 2019

.SYNOPSIS...
Low pressure over Delmarva late this evening will lift 
northward and deepen overnight. This system will bring a soaking
rain to the area along with some snow to the higher elevations
before moving into eastern New England late tonight. 

In addition, winds will become gusty on Friday, as the low
continues to lift northward on Friday.

High pressure will return for Sunday with warmer temperatures 
on Sunday into Monday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Biggest story late this evening is rainfall over the southern
tier and Lower Susq Valley where plenty of reports of 1.5-2.5
inches have been noted. This is bringing minor flooding issues
to the southern tier with notable rises on area streams. Rain
will persist over eastern sections of CWA through the overnight
before the storm lifts into New England. Several river points 
will likely get close to flood stage, with updated forecasts
issued as necessary. Some snow is also mixing in at higher 
elevations across the central mountains, with a coating already
noted on the ridges around State College and even on webcams
east of Breezewood. This snow won't amount to much, but light
snow will develop over western/northern elevations as well in
upslope flow, with light accums expected. Will need to keep an
eye on northeast, where potential for a more notable elevation
snow exists, with bigger threat off to our NE.

Precipitation will taper off from south to north late tonight, 
as the best low level easterly winds lift north of the area.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
For the second full day of spring, Friday will be miserable. 

The surface low will deepen along the New England coast as the
upper low/trough digs down over the region. A strong NW flow
will develop in the tightening gradient with wind gusts in the
35-45 mph range likely during the day.

With the strong March sun and cold air aloft, any sun will 
result in convective showers. 

Any snow showers should be over by 12Z Saturday.

I adjusted the grids to back off on the activity some
after midnight Friday night.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
High pressure will build in for the weekend with drier
conditions. After a cold day Saturday, Sunday will rebound back
above normal as the high builds off to our SE.

Models are in better agreement tonight with an approaching low 
and frontal system for Monday. It could be cold enough along the
northern edge of the precip shield for some wet snow to fall, 
but as yet the models keep it only marginally cold so I hedged 
on the snow potential. 

With the passage of the wave and front, it will turn cooler and
dryer through the middle of next week.

&&

.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Widespread rain event ongoing across central Pennsylvania this
evening. Conditions generally MVFR to IFR across the area, with the
exception of the far northwest, where KBFD is still VFR. Also of
note, KJST is socked in with VLIFR conditions, with little
expected improvements overnight.

Short range models slowly pull rain off to the east overnight. 
Heaviest rain corridor will be situated across the eastern 
portions of the Susquehanna Valley region (in central 
Pennsylvania) by around 06z-08z.

As colder air fills into the region, backside of the rain and
rain showers will transition to snow and snow showers. Late
overnight and into Saturday, KBFD and KJST could see rather
persistent snow shower/snow conditions, with restrictions.
Afternoon destabilization with cold advection could even produce
a few low topped thunderstorms in the late morning and
afternoon, but coverage far too low to mention in the TAFs.

Winds will be the other factor Friday. Gusts in the 30-35 mph 
range look quite likely from mid/late morning, probably 
increasing as the day continues.

.Outlook...

Sat...Morning snow showers possible west and north. Diminishing
winds.

Sun...No significant weather expected.

Mon...Restrictions in rain possible, mainly central and southern
areas.

Tue...No significant weather expected.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 8 AM EDT Friday for PAZ057>059-065-066.
Flood Watch until 2 AM EDT Friday for PAZ036-063-064.

&&

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