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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 190208
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1008 PM EDT Tue Jun 18 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 potent area of surface low pressure 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 /UNTIL 6 AM WEDNESDAY MORNING/...
Sfc quasi-stnry frontal boundary snaking its way from the NW
Mtns of PA to the Lower Delaware Valley this evening. Although
isolated, small showers were drifting ENE across the region this
evening (and expected to do so for the rest of the overnight),
subsidence beneath the left entrance region of a jetlet
extending from SERN Pa to Southern New England will keep any
deep or organized convection suppressed overnight and Wednesday
morning. 

Anomalously high sfc dewpoints in the 60s, and nearly +2 Sigma PWAT
air will combine with variable amounts of Stratocu and Altocu
clouds to give us a mild night with patchy fog forming during
the wee hours of Wednesday, especially throughout the deeper
valleys of northern PA. 

Min temps tonight will range from the upper 50s across the
Northern Tier of PA to the mid and upper 60s in the Lower Susq
Valley.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Wet pattern with repeat rounds of showers along a nearly 
stationary frontal zone will continue for primarily the
afternoon and evening hours Wednesday.

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 /02Z WEDNESDAY THROUGH SUNDAY/...
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 Wednesday, 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...Lambert/RXR 
NEAR TERM...Lambert
SHORT TERM...Lambert/Dangelo 
LONG TERM...Steinbugl 
AVIATION...Fitzgerald 
CLIMATE...Lambert