Sunday, December 17, 2017, 2:36 PM EST
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KPBZ 171735

Area Forecast Discussion
National Weather Service Pittsburgh PA
1235 PM EST Sun Dec 17 2017

Another upper level disturbance will result in scattered light
precipitation developing later this afternoon. Warmer
temperatures, cloudy skies, and light drizzle can be expected
Monday and Tuesday.


Stationary boundary remains situated aoa I-80 early this
afternoon with below freezing temperature and fog prevalent on 
the northern side of the front. Expect conditions to improve
here, with warm advection and mixing allowing for fog to scatter
out and surface temps to warm. Precipitation with the
approaching shortwave over the mid Ohio Valley will not reach
these zones until much later, so while some wet-bulbing could
occur, it looks like any wintry precipitation would be snow 
versus freezing rain. Will still monitor local road sensors for
any quick glazing concerns.  

Further south, adjustments were mainly made to timing and PoPs
for precipitation associated with the weakening shortwave as it
crosses through this evening. Again, while some wet-bulbing is
expected, temperatures have warmed enough to overcome any wintry
precipitation. That being said, while we've warmed nicely 
despite cloud cover, this may slow to a halt with precipitation
through the afternoon.

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. Temperatures should not fall off too much either so
values were forecast above seasonal averages.


Latest guidance shows decent continuity with previous
runs with zonal flow aloft and the forecast area remaining within
the warm sector through Tuesday. Weak forcing and saturated
lower levels also continue to be forecast...and expect 
extensive cloud coverage, patchy drizzle, and periods of light
rain to persist through the period.

Despite expected cloud cover, warm advection should lead to
temperatures at least near seasonal averages with a somewhat
limited diurnal range through Tuesday.


Tuesday night the upper level flow will amplify and the 
aforementioned boundary is progged drop back south over the 
area...finally scouring low-level moisture but also resulting in
temperatures 10 degrees lower on Wednesday. Some locations may 
see some light snow Wednesday but no significant accumulations 
are expected.

Drier and warmer conditions are expected the latter part of the
week as zonal flow is reestablished. 

Models have slowed the arrival of the next system to impact the
region to late Friday early Saturday. Changes in the extended
were largely based on latest Superblend guidance.


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
signficant 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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