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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 190629
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
229 AM EDT Wed Jun 19 2019

.SYNOPSIS...
An unsettled and at times stormy weather pattern will continue
through Thursday evening thanks to the close proximity of a 
slowly meandering stationary front. There will be several more
rounds of showers and some will contain brief heavy downpours. 
There will be a risk of strong to severe thunderstorms on 
Thursday as a low pressure area moves right over the state. 
Temperatures won't stray too far from normals through the 
period, but could be a little cooler than normal Friday and 
Saturday in the wake of a cold front.

&&

.NEAR TERM /THROUGH TODAY/...
Plenty of cloud cover over the whole CWA at this time. Thus,
little in the way of fog which we expect after a damp day with
very high humidity. Just a couple of patches of rain/showers on
radar now, and not much seen immediately upstream. However, the
daytime heating should pop numerous showers and a few
thunderstorms. The convective activity will be very disorganized
and likely initiated by the weakest of boundaries and (high)
terrain features. The boundary is somewhere overhead, but tough
to nearly impossible to find. It could be over DUJ and IPT where
pressures are a tiny bit lower and a thin line has recently 
developed in the radar returns.

Initial thoughts on a flash flood watch for today/tonight are
mainly negatives. On the positive side: PWATs remain high at
1.3-1.9" from N to S. The western third of the area has received
1-2" of rain in the past 48 hrs, dragging 3hr FFG to 1.25". On 
the negative side: the rainfall numbers are much lower along 
the NY and MD borders, and also on our eastern border. There is
almost no moderate or strong forcing aloft moving overhead 
today. There is a weak wave which could help to push much of the
convection to the east by midnight. But in general, the 
convection/QPF today looks disorganized and no concentrated 
areas of heavy rain are seen at this point. A few of the CAMs do
put more QPF over the srn tier, but that area has been less wet
than the west-central zones. Will hold off on an FFA for the 
time being. 

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
A strong low pressure system for June will track across the 
area on Thursday, and could bring a significant threat of severe
storms and flash flooding. SPC and WPC severe weather and 
excessive rainfall outlooks on day 3 now reflect the increased 
risk levels. Rain continues into Thursday night before shifting 
east/decreasing coverage into Friday morning.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Breezy and drier/less humid conditions will arrive Friday on 
the backside of the departing system. Expect a break from the
persistent rain for at least 1-2 days before more showers and 
storms return to the forecast later in the weekend and into next
week.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
06Z TAFS sent.

Some showers across the south. VAD winds more from the southwest
than the last several days. Winds weaker too than in recent
days. Thus showers creeping back to the north some.

Main change was to back off on the lower end conditions some.

Earlier discussion below.

Abundant low level moisture and light wind in vicinity of a
stalled frontal boundary will lead to developing low cigs and
fog across central Pa overnight, along with the chance of
showers. Latest SREF probability charts indicate IFR conditions
will become likely late tonight over the high terrain of the 
Alleghenies from KBFD south through KJST. Further east,
thickening mid level cloudiness could limit the extent of fog 
formation, but can't rule out patchy IFR vsbys. 

Diurnal heating and resulting mixing of drier air aloft will
yield improving cigs/vsbys later today, with predominantly VFR 
conditions by afternoon. However, a brief reduction will remain 
possible from scattered showers/thunderstorms during the the 
afternoon and evening hours.

.Outlook...

Thu...Rain/low cigs possible north. Scattered PM tsra impacts
possible south.

Fri...AM low cigs possible W Mtns.

Sat-Sun...No sig wx expected.

&&

.CLIMATE...
Astronomical summer (solstice) begins Friday, June 21st at
1154AM EDT (1554 UTC).

&&

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

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Steinbugl
AVIATION...Fitzgerald/Martin
CLIMATE...