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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 202019

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

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


Wind has picked up very nicely, with dewpoints crashing over the
Laurels and at UNV. AOO still arnd 40F dewpoint, but they may
drop soon, too. 

Clearing has come to much of C PA due to the passage of a short
wave trough. The few showers left over the nrn mtns should be
off into NY shortly. There is a convergence zone over wrn PA,
though, where cumulus are congesting and a few showers have
already started to pop up in the aftn heating. The CAMS all
point to a training of very light/low-topped showers just to the
west of JST-FIG-BFD into the evening hours. There could still be
some ltg with the taller cells, but only a few cloud flashes in
Warren Co very recently. SPC still mentions potential for a
weak/low-topped supercell this aftn/evening. So, we can't look 
away for a minute. 

As the sun sets, the showers should dwindle. Will keep the high
chc PoPs over the west for the time being, as the upper low
nears and positions itself right over there later tonight. Lack
of forcing across the rest of the area should allow for nil 
pops overnight. Some fog is possible, esp in wrn highlands where
any rain this evening and light upslope could keep moisture 
high. Will hold off on any mentions for now. 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 making for many 
LLWS reports as the wind gusts into the 20s, and even 30s
locally. Isold SHRA across the north should be into NY by 19Z,
but llvl convergence zone between JST-LBE and just W of BFD  
will likely continue to light up with more SHRA and perhaps a
TSRA for the aftn. 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...Dangelo
SHORT TERM...Dangelo
LONG TERM...RXR/Steinbugl