Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 181134

Area Forecast Discussion
National Weather Service State College PA
734 AM EDT Sun Mar 18 2018


Fair and dry conditions will finish off the weekend and start
the new workweek with a slow moderation in temperatures
anticipated. A storm system is expected to move south of the
region Monday night and Tuesday. High pressure will return for
the end of the week.



Clear skies dominate the weather over central PA as of 4AM. A
light to moderate breeze has kept a lid on what otherwise would
be prime radiational cooling conditions.

We expect a bright day with a light wind. Highs will average in
the 40s to lower 50s, which will finally start nudging closer to
normal after the very chilly beginning to March we have endured.

Clear skies will continue overnight with lows dropping back into
the teens and 20s.



Monday will remain fair and dry, but with a gradual increase in
clouds late in the day. Highs will range from the mid 30s north
to around 50 south.



The main weather maker of concern is a low that will slide
across the TN Valley and central Appalachians Monday night and
moves off the VA coast on Tuesday. After trending south over the
last couple of days, guidance has crept north with the precip
shield. Last night`s ECENS painted an almost total miss from the
storm, then tonight it changed course and now shows anywhere
from about .25-.50" QPF from around I-80 southward.

Still doesn`t look like a big threat for significant snow with
several factors expected to play a role. This time of year with
marginal temps, we generally need good precipitation rates to
keep the atmospheric column cold enough to be all snow, and so
far the indications are that on the northern periphery of the
precip shield, rates will not be impressive. Also with the bulk
of whatever falls expected to be during the daylight hours of
Tuesday, the high sun angles usually limit accums this time of
year. So we stuck pretty close to HPC guidance for little more
than a coating over the Mason-Dixon counties.

After a period of dry weather in the wake of the Tuesday storm,
the upcoming weekend poses another potential threat for rain or
snow. The scenario is far from clear. The 00Z GFS takes a
robust surface low pretty much straight east and tracks it
through southern Pa during the day. The ECMWF is slower but
shows a very similar scenario with the low passage favoring
Saturday night. The interesting thing is each model`s ensemble
partner almost completely washes the surface lows as they
approach, losing them along some sort of frontal boundary off to
our south. With the forecast upper pattern showing the lows
moving into a broad ridge, the lows washing out looks like a
reasonable scenario.

Below normal temps will persist though mid week with a
moderating trend for the end of the week into next weekend.

The Vernal Equinox will be Tuesday at 1215 pm EDT.



VFR conditions across the area as of 7 am. No clouds...haze
or fog outside.

No big changes for the 12Z TAFS.

Model data continues to support a high confidence of widespread
VFR conditions today. However...there is a chance of MVFR
stratocu spreading into northern Pa late this evening
associated with the passage of a weak cold front from the
northeast. However...the airmass is quite dry over our area and
to the northeast over eastern New York state.


Mon...No sig wx expected.

Tue...Snow likely southern Pa...mainly early AM.

Wed...AM light snow possible Laurel Highlands.

Thu...No sig wx expected.


The Spring (Vernal) Equinox will be at 12:15 PM on Tuesday,
March 20. Sunrise in State College, PA will be 7:14 AM and
sunset at 7:23 PM, for a total daylength of just over 12 hours.




NEAR TERM...La Corte
LONG TERM...La Corte
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