Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 271934

Area Forecast Discussion
National Weather Service State College PA
334 PM EDT Sun May 27 2018

A weak upper level trough is pushing slowly across the area
this afternoon. Anomalous upper level ridging will build east
across the region during the first half of the week bringing
more settled weather before moisture from the remnants of
Alberto stream north bringing daily chances for showers and
thunderstorms for the second half of the week.


Convection firing in high PWAT air under weak upper trough along
convergence of a couple of boundaries over southern tier of PA.
Interaction of this convection with back door cold front will
shunt the storms slowly off to the ESE into MD. But concerns
about potential for excessive rain prompted issuance of a Flash
Flood Watch in that area. Did see a couple cells produce a quick
one inch of rain, with one storm in Bedford county estimated
around two inches rainfall in an hour. Bulk of activity now
looks to be shifting southward out of the region, but a few
cells that developed in the sunshine over Adams/York developing
some structure - enough to prompt a couple of SPS`s.

The upper trough will push through early this evening with
drier air allowing for showers to diminish in coverage. The
SREF/GEFS show the anomalous PWATs settling south between
03-12Z. Far SERN zones may hold on to some scattered showers,
but most areas will see showers ending. With low-level moisture
remaining high and a weak boundary lingering over the area,
expect low clouds and areas of drizzle and fog late tonight
into early Monday.


Memorial Day will dawn rather murky in most locations with areas
of low clouds, drizzle and fog. Clouds will gradually mix out
with most locations enjoying a brighter afternoon. A stray
shower or storm cannot be ruled out in the still humid airmass,
but rising heights and temperatures aloft will limit shower
activity. SERN areas will be slowest to clear with a low level
SSE flow helping keep it cooler in the 70s. Otherwise most areas
will rise into the low to mid 80s as it turns out to be not too
bad of a day.


Monday night into Tuesday high pressure ridge across central PA.
An isolated shower or tstm may pop up in the afternoon over the
mountains but the forecast is so wet, I prefer to emphasize that
Tuesday will be the driest day of the forecast period. It will
be warm and humid with temperatures in the mid 80s and heat
indices in the lower 90s.

Tuesday night into Wednesday there a strong candian high center
dropping southeast across New England nudging into Northeast PA
as sub-tropical moisture streams northward from the Gulf up the
Appalachians and across Virginia. Tuesday night the moisture is
held at bay by the high pressure ridge but by Wednesday
afternoon, the high center slides southeast off of Long Island.
This allows the deep southerly moist flow to move north through
Central PA increasing clouds and the chances for showers and
isolated thunderstorms. Showers are likely by Wednesday night
into Thursday with the possibility of heavy rain through Central
PA. The center of what is left of Alberto at this time is
forecast to move north across the Great Lake region. However
models suggest high PWATs and convergence through Central PA.

Unsettled weather continues into next weekend with seasonable


Showers and some thunder developing across southern PA this
aftn, generally along and south of the PA Turnpike. Locally
heavy downpours will remain possible with these showers into
this evening.

MVFR cigs have worked into the Susq Valley /IPT MDT LNS/ behind
a backdoor cold front.

Expect fog to develop late this evening into tonight, with
gradual improvement after sunrise on Monday.


Mon-Tue...Potential for fog each morning. Otherwise, generally
VFR conditions.
Wed-Fri...Reductions possible in scattered showers/storms.


Flash Flood Watch until midnight EDT tonight for PAZ033>036-


LONG TERM...Watson
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