Sunday, December 17, 2017, 4:17 PM EST
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 172020

Area Forecast Discussion
National Weather Service Pittsburgh PA
320 PM EST Sun Dec 17 2017

Light rain will spread across the region this afternoon with a
passing upper level disturbance. Warmer temperatures, cloudy 
skies, and light drizzle can be expected Monday and Tuesday.


Light rain associated with lift from a weakening upper level 
shortwave will spread across the region through this evening. 
For the most part, temperatures are now well above freezing, 
save for the counties in the vicinity of a stationary boundary 
located near I-80. Here, temperatures are right around freezing
and dewpoint depressions suggest that some saturation to wet- 
bulb temperature could support a brief window of snow or a mix, 
that is, if moisture can even make it that far north. Will still
mention this mix in the forecast and continue to monitor ground
temperature as the lack of insolation has slowed warmth of 

While the shortwave departs tonight and little further forcing 
is anticipated, moisture trapped in the inversion may keep light
rain or patchy drizzle across most of the forecast area through
the night, with little difference in reasoning for much of
Monday. Cloud cover and precip will maintain very little diurnal
change for both tonight and Monday with values near seasonal


Zonal flow is maintained, though weak ripples in the upper level
pattern may be enough to generate additional light precip. Have
cut back PoPs significantly since forcing remains weak and much
of the moisture remains under about 2kft. 

Strengthening warm advection Tuesday ahead of a slightly more
amplified wave will support above average temperature with
values closer to normal in cold advection/northwest flow.
Building surface ridge should lend to little more than cloud
cover wednesday. 


Zonal flow returns Thursday with some amplification in the upper
level pattern as wave ejects into the Plains. This will be the 
next notable system progged to approach late in the period, with
some differences between the guidance in timing. Stayed close 
to the Superblend for the end of the week with some moderation 
in warm advection to above average temperature by the end of the


Light fog is stubbornly hanging on at FKL/DUJ, but expect it to
thin out over the next couple of hours. VFR conditions will
maintain through the remainder of the afternoon in most cases,
with some light rain ahead of a warm front likely not causing
significant restriction. Behind this boundary, an increase in
low-level moisture and a developing inversion aloft will spell
deteriorating conditions. Expect ceilings to fall to MVFR
tonight areawide, and likely to IFR in at least some cases
Monday morning. Drizzle and fog will become more prevalent as

Light south/southwest winds will prevail through the TAF period.

Restrictions are likely through Tuesday, as abundant low-level 
moisture may become trapped underneath an inversion for an 
extended period. IFR conditions are possible at times.





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