Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 160254
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1054 PM 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 /UNTIL 6 AM SUNDAY MORNING/...
Numerous showers cover areas along and north of I80 late this
evening, with upstream regional radar indicating a slight break
over NW PA and a larger and heavier area of rainfall to come
from central and eastern OH overnight. This as deep moisture
and large scale forcing spreading eastward from the Ohio Valley
with POPs continuing to increase from west/north to east/south
overnight, ramping up to categorical coverage over the
northwest and likely POPs over the southeast after midnight. A
few heavy downpours are possible with mean QPF in the 0.50 to
0.75 inch range, with heaviest amounts north. Hires models show
a better signal for heavy rainfall across the Ohio Valley.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Isolated strong to severe storms may occur across parts of
central PA 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 /SUNDAY NIGHT THROUGH SATURDAY/...
A showery and muggy week in store as several waves ride along a
lingering frontal boundary that will remain nearly stationary
near the Mason/Dixon line.

Latest guidance indicates a persistent southeast Canada trough
with confluent flow along the southern periphery in the OH
Valley 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 much of 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. But looks
like best chances for most sig rains will be Mon/Tue across the
west and Thursday areawide (though best prob in the NW).

Models hint at a drier period toward the end of the week into
first half of the weekend, which translates to just isolated
showers focused on the NW half. But precip chances increase
again with another storm system by Sunday.

Though elevated dewpoints will keep muggy conditions in place
with above average low temps, highs will top out a bit below
normal each day.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Low pressure approaching from the midwest will spread rain and
lowering cigs into northwest Pa tonight. Latest NAM/RAP
soundings support predominantly IFR/LIFR cigs overnight at KBFD.
For the rest of central Pa, model soundings still support a VFR
forecast overnight. However, tempo mvfr is possible toward dawn
over the northern half of the state, as rain edges south.
Another issue overnight will be the possibility of low level
wind shear early Sunday morning across the Laurel Highlands
(KJST). Models show a core of strong winds aloft moving over the
region at that time. However, the height of the inversion and
associated wind shear should remain above 2kft over the rest of
central Pa.

IFR cigs appear a good bet Sunday morning across the northern
mountains of Pa in association with a moist southerly flow ahead
of low pressure system. Model soundings support progressively
higher cigs further south, with VFR most likely at the low
elevation airfields of southeast Pa (KMDT/KLNS).

The low pressure system will lift into New England by Sunday
afternoon, resulting in rising cigs. However, MVFR cigs may
linger all day over the high terrain of northern and central
Pa. In addition, scattered afternoon thunderstorms are expected
to form ahead of the trailing cold front, possibly resulting in
brief reductions across the southern half of the state during
the afternoon and early evening.

.Outlook...

Mon...AM low cigs/fog poss N and W Mtns. Scattered PM tsra
poss, mainly south.

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

Wed...Patchy AM fog possible. Isold PM tsra impacts possible
western half of Pa.

Thu...AM rain/low cigs possible. Scattered PM tsra impacts
possible.

&&

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

&&

$$
SYNOPSIS...Gartner
NEAR TERM...DeVoir/Gartner
SHORT TERM...Gartner/Steinbugl
LONG TERM...RXR/Steinbugl
AVIATION...Fitzgerald



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