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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 202354

Area Forecast Discussion
National Weather Service State College PA
754 PM EDT Sat Apr 20 2019

An upper level low pressure system will move slowly east across the
Mid-Atlantic states, keeping unsettled weather around through Sunday.
Much of the time from late Sunday into mid week will be dry. However,
a very small chance of showers exists almost every day. A weak front
will drop down during the middle of the week and could linger near
PA for the second half of the week.


Upper level low back over Southern WV. A nice dry slot moved
into central PA with winds 20-30 kt dew points dropped into the
30s. Just as I thought the showers were done, mid-level moisture
streamed up from the south and more showers and a couple
thunderstorms popped. With the sun setting, this is still
expected to diminish. Dew points should rebound some as the
mixing cuts off and satellite also shows clouds moving north
from VA toward southern PA so will make some adjustments for
these trends. Best chances through midnight for showers and
thunderstorms remains over Warren, Elk and McKean Counties. 
Some fog is possible, esp in wrn highlands where any rain this 
evening and light upslope could keep moisture high. Mins of 
40-50F will be mild for this time of year.


Upper low will be centered right along/over the wrn mountains in
the morning. Flow will probably bring in some lower clouds by
morning. This may limit instability, but the steeper lapse rates  
due to the cooler temps aloft will make it easier for showers to
pop up. Will keep on with 40-60 PoPs for the daytime on Easter
Sunday, generally sliding from west to east.


Expect improving conditions/dry wx early next week as high 
pressure moves into the area between the departing low and the
next wave approaching from the west. Look for a nice rebound in
temperatures with highs in the 60s on Monday with a weakening
north flow followed by 65 to 75 degree range on Tuesday. 80F 
not out of the question in the Lower Susquehanna Valley Tuesday 

There is decent model agreement in the next frontal system
moving through the area midweek. Showers and poss a tstm impact
mainly NW areas Tue night, with scattered light showers poss 
areawide early Wed. 

Beyond Wednesday, weak frontal boundary gets hung up south of
the region with a breezy Wed in store. Models showing some 
divergence for late week, but trend looks to be a transition to
SW flow. Looking like a chilly morning Thursday with dry air in
place and light winds, with lows potentially dipping into the
upper 30s in the valleys of the northern mountains.

A potent shortwave progged in around Friday will bring another 
shot for showers/tstms followed by dry, breezy and cooler to
start the weekend with another chilly morning Sat before
trending toward warmer temps on Sunday.


Deep mixed layer tapping the winds aloft and still making for 
some LLWS reports as the wind gusts into the 20s over central
and eastern airfields. Isold SHRA (lcl T) across the northwest 
should be into NY by 22Z, but llvl convergence zone between 
JST- LBE and W of BFD will keep isold SHRA or TSRA possible 
through early evening. 

Loss of heating will allow these to die off, but perhaps not 
all at once. Expect the gusty wind to simmer down after 00Z, 
with the ern valleys going light/var. Isold SHRA still poss over
the western fringe of our airspace through the night, but the 
rest of the area should be dry/VFR. Places that are still wet at
sunset will likely have some fog/low clouds read:IFR develop 
tonight. Will only call for that at JST and BFD
- most likely at BFD. The rest of the area is drying out so 
nicely that no fog should form even if the dewpoints recover 
some overnight.

Upper level low pressure will be centered over JST-BFD at
sunrise, and it will move slowly eastward through the day. Under
the cool pocket aloft, sct SHRA are expected to slide eastward
through the day. Most of the day will be VFR, but any low
clouds/fog will take a bit to burn off in the west considering
the upper low and clouds will be there in the morning. 

Sun evening should be the end of any SHRA across the region. A
dry time with no sig wx will follow into Tues under rising
heights/high pressure.


Mon...AM MVFR cigs psbl N/W. 

Tue...VFR. SCT SHRA/TSRA poss far NW late.


Wed-Thurs...Mainly VFR. SHRA poss far S.




NEAR TERM...Watson
SHORT TERM...Dangelo
LONG TERM...RXR/Steinbugl