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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 151059
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
659 AM EDT Sat Jun 15 2019

.SYNOPSIS...
The weather pattern will turn unsettled and stormy into Father's
Day with the potential for rounds of heavy thunderstorms across
parts of Central Pennsylvania into next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The weekend will start on a warmer note (+3-10 degrees vs. 
yesterday but still AOB mid-June climo) with a gradual uptick 
in humidity. HREF mean favors showers developing across the 
northwest Alleghenies this evening and eventually spreading 
southeastward into early Sunday morning. A few heavy downpours 
are possible with mean QPF in the 0.50 to 0.75 inch range. Hires
models show a better signal for heavy rainfall across the Ohio 
Valley.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Isolated strong to severe storms may occur across parts of CPA
Sunday and Monday afternoon. Periods of heavy rain will also
pose a marginal risk for localized/isolated flash flooding. 

A weak surface front should be located just south of Lake Erie
on Sunday. Conditional instability to the southeast of this
boundary yields thunderstorm development with potential for 
sufficient CAPE/shear combination to support isolated strong to 
severe storms. If confidence increases in destablization, SPC 
may increase categorical risk from marginal to slight. 

The aforementioned frontal boundary should sink slowly southward
across CPA Sunday-Monday and become quasi-stationary near the 
Mason Dixon line. Above normal precipitable water along the 
frontal zone could lead to rounds of heavy rainfall. There is 
low confidence in the location of heavy rain given uncertainty 
in the position of the frontal boundary. WPC excessive rainfall
outlook places a marginal risk across most of the area on 
Sunday and over the southern tier on Monday. 

Total rainfall forecast through 12Z Tuesday has 1-2 inches
across most of the area.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Latest guidance indicates a persistent southeast Canada trough
with confluent flow along the southern periphery in the the OH 
to the northern Mid Atlantic. This persistent pattern will allow
a quasi-stationary frontal system and waves of low pressure to 
maintain stormy weather across CPA next week with multiple 
rounds of heavy t-storms possible. Timing and location of
multiple episodes of convection will be difficult given low
predictability especially at this range. Models hint at a drier
period toward the end of the week, but confidence is low. 

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
No large changes to the 12Z TAF package.

Mid and high clouds a little more extensive than I had 
earlier in the fcst.

Earlier discussion below.

The main change was to add LLWS at BFD until just after sunrise.
Borderline for this.

A nice night outside with a bright moon.

Expect VFR conditions to hold at least into the late afternoon
hours.

Winds will pick up some from the southwest by late morning or 
early aft.

BFD may see some showers toward sunset, followed by JST
a few hours later. Lower CIGS possible late across the northwest
and west, as showers and a more humid airmass works into the
area, ahead of a cold front.

.Outlook...

Sun...AM low cigs poss N Mtns. Scattered PM tsra impacts poss.

Mon...AM fog possible, mainly north. Scattered PM tsra poss.

Tue...AM low cigs/fog possible. Scattered PM tsra impacts
possible south.

Wed...Rain/low cigs possible, especially south.

&&

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

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...Martin