Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 210909

Area Forecast Discussion
National Weather Service State College PA
509 AM EDT Mon May 21 2018

An area of high pressure at the surface will slide by across
upstate New York today bringing mostly sunny skies along with
comfortable humidity. The frontal boundary that pushes southeast
across the region during the late morning and afternoon hours
Sunday is now nearly stationary from Central Virginia to the
Middle Ohio River Valley. This frontal boundary will lift back
quickly to the north as a warm front later today into Tuesday as
a weak area of low pressure over the Mid Mississippi Valley races
to the Lower Great Lakes Region by daybreak Tuesday.

Showers and scattered thunderstorms will spread northeast over
the region, becoming concentrated over the Central and Northern
counties of the state late tonight through Tuesday morning. A
cold front training southwest from the low will sag southeast
across the Commonwealth Tuesday afternoon and evening,
triggering additional showers and a few strong thunderstorms.
a several day period of mainly dry weather with pleasant
temperatures is in store for Wednesday through Friday.


1025 mb sfc high centered near Alpena Michigan early today will
drift to the southeast and supply our region with fair/dry
weather, lower humidity and light wind today.

Recent rains have left conditions moist, so some early morning
fog with vsbys between 1/2SM and 1SM is expected throughout the
valleys of northern PA.

Temps to start the day today will vary from the low to mid 40s
throughout the perennial cold spots across the northern tier
counties, to the 60s in the Southern Valleys.

A warm front will approach the region from the south late today
and tonight with increasing dual to multi layered cloud cover.

Latest runs of the HREF and HRRR indicate that any showers
won`t develop over/move NE into our Laurel Highlands region
until around or shortly afternoon dusk today.

00Z NAM and prior ensembles show PWATs starting to creep up
late today and tonight (first across the SW zones). Sfc based
cape gets moderately high across far SW PA (1500-2000 j/kg) with
llvl based instability in our CWA topping out around 1000 j/kg
across far SW Somerset county late today. Due to some
disagreement between the dry high res versions, and the coarser
regional/synoptic scale models we have a low chc for a few
shra/TSRA in the SW late today, while pops are essentially zero
elsewhere through at least 06Z Tuesday.

Highs today will be rather pleasant topping out in the low to
mid 70s across the northern and western mtns, while the valleys
of Central and Southern see temps in the upper 70s.


Numerous showers along with a few thunderstorms will bring a
several tenths of an inch of rainfall to much of the region
tonight into Tuesday before drier air makes a push in from the
NW behind a weak cold front starting Wednesday. Tuesday looks
like the coolest day of the week, though humidity will be

The low temperature tonight will be mainly between 55 and 60,
with highs on Tuesday ranging from around 70 degrees across the
north, to the mid 70s over much of Central and Southern PA.


The period from Wednesday through Saturday morning will feature
some rare (of late) rain-free conditions, before the chance for
a pop-up shower or storm becomes returns for Saturday

Temps are projected to climb into the 70s each day, with
Saturday being the warmest as highs range from the mid 70s to
the lower 80s. The coolest morning will be Friday with valleys
of the northern mountains dipping into the mid 40s.

More active weather returns for late in the weekend as another
period of showers and scattered thunderstorms begins, thanks to
the persistent north/south plume of tropical moisture that will
be nosing back north into the NE US.


Valley fog will reduce visibility early Monday morning with
highest confidence in IFR at KBFD/KIPT. Fog will mix out between
12-14Z giving way to mainly VFR conditions across the airspace
through Monday evening. There is about a 50/50 chance for MVFR
cigs to develop Monday afternoon over the south central
airspace ( invof KAOO) as relatively moist east/southeast flow
ascends the higher terrain. High confidence in a period of
rain showers w/isolated Tstorm moving across the airspace late
tonight into early Tuesday morning 03-12Z.


Tue...AM rain showers/MVFR-IFR cigs. Sct PM Tstorms.

Wed...AM MVFR/IFR cigs wrn 1/3.

Thu-Fri...VFR/No sig wx expected.




NEAR TERM...Lambert
SHORT TERM...Lambert
AVIATION...Fitzgerald/Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.