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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 170946
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
546 AM EDT Fri May 17 2019

.SYNOPSIS...
A dying cold front will push south across the region today, then
return north as a warm front on Saturday. Low pressure will
track north of Pennsylvania Monday, as its trailing cold front 
comes through the state. 

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Regional radar loop at 09Z is showing a few showers pushing 
into northwest Pa along axis of approaching low level jet. As 
this feature shifts east, expect scattered showers to work
through central Pa later this morning. Latest model guidance,
including HREFV2, supports POPs in the 40-50pct range over most
of the area. 

A second chance of precipitation will come with the passage of 
a dying cold front this afternoon. Some modest model cape noted 
ahead of the front across the southern half of the state, where
a shower or tstorm is possible in spots. The best combination 
of instability and shear is expected across the far southwest 
part of the forecast area, where SPC has highlighted a slight 
risk of severe weather late today. 

Warm advection ahead of approaching cold front should push 
temperatures above seasonal normals today across the southern
half of the state. Model 850mb temps close to 13C should 
translate to highs near 80F in the valleys near the MD border,
while the northern tier peaks in the upper 60s. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Scattered convection over the southern counties is expected to
dissipate this evening, as dying cold front sags south of the
Mason Dixon Line. By late tonight, the chance of a shower will
shift to the northwest mountains in association stalled front
buckling northward over the Grt Lks. A fairly significant
gradient is expected with regards to overnight temperatures. High
pressure and cooler air mass nosing into northern Pa will
allow readings to dip into the low 40s up there, while lows only
expected to fall to around 60F over the southern tier. 

Warm front is progged to push north into the region Saturday.
Heating of warm, humid air mass south of this boundary will 
likely result in scattered diurnally-driven convection, focused
mainly along the spine of the Appalachians. 

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Rising heights and building upper level ridging will spell a 
warmer and more humid sensible wx trend Sunday-Monday. While 
there will be plenty of dry breaks, we still cannot rule out a 
few spotty showers or isolated t-storm during this time. Expect 
sparse coverage with limited rainfall. 

Medium range guidance lends increasing confidence in a period 
of dry/cooler weather Tuesday, as high pressure and low pwat air
mass builds southeast into the area. 00Z NAEFS indicates 
Pennsylvania will be on the northern periphery of a building 
subtropical ridge the second half of next week. Shortwave riding
over the top of the ridge will bring back the chance of showers
both Wednesday and Thursday. 

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Clouds will gradually thicken and lower overnight. Ceilings 
should drop to MVFR (possibly IFR) over the western highlands 
/KJST and KBFD/ by daybreak, with brief vsby reductions 
possible in showers.

Included LLWS at all airfields overnight into Friday morning, 
as a 30-45 kt WSW low-level jet is expected to push across 
central PA.

A weakening area of shra/tsra could brush SW PA towards 
daybreak on Friday. A few additional shra/tsra are expected to
develop by afternoon, as a weak cold front crosses the area.

.Outlook...

Fri...AM low cigs and shra possible NW mtns. Scattered aftn 
shra/tsra impacts possible.

Sat...Isolated aftn shra/tsra possible western highlands.

Sun...Scattered aftn shra/tsra possible area-wide.

Mon...AM low cigs possible NW mtns. Scattered aftn tsra impacts
possible eastern PA.

Tue...mainly VFR.

&&

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

&&

$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald/Steinbugl
AVIATION...Evanego