Area Forecast Discussion
Issued by NWS -- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KPBZ 202338
Area Forecast Discussion
National Weather Service Pittsburgh PA
638 PM EST Fri Jan 20 2017
Mild weather will continue through the weekend. Widespread rain is
expected to move back into the region by Sunday.
.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --The last vestiges of rainfall along the warm front that has surged
northward across the area will be traversing the I-80 corridor
over the next few hours. In the wake of the warm front, abundant
boundary layer moisture remains as evidenced by dewpoints largely
in the lower 50s across the southern two-thirds of the area. This
air mass will continue northward slowly overnight, while warm
advection will be even stronger off the deck. The net result looks
to be strengthening inversions and the trapping of a fair bit of
moisture below them. With this in mind, fog looks to be a concern
over much of the area as no areas have really managed to mix out
at this juncture.
With warm advection off the surface and the likelihood of stratus
development, model soundings look to also be supportive of some
drizzle across the northern two-thirds of the CWA as well as in
the ridge. Thus, while measurable rainfall seems unlikely, patchy
drizzle may be an issue in spots into the morning hours of
-- End Changed Discussion --
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
The short term portion of the forecast will be the wettest part of
the week ahead. ECMWF/GFS/NAM have come to a bit of a compromise
over the last couple of days for the track of the upper low that
will develop across the Southern Plains, track near the Gulf
Coast, then north up to central Pennsylvania. While there is still
some run to run variability, occasional rain is expected and it
appears that Sunday night and Monday will likely have the most
rain. Temperatures will remain warm enough that only a few
snowflakes are expected to mix in with rain Monday morning in the
ridges, and precipitation could begin to wind down as snow Monday
night as temperatures drop back towards the freezing mark.
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Any remaining showers should wind down Tuesday, with cold enough
air that many locations could see some minimal snow accumulation.
There should be a bit of a break between systems before low
pressure races across the Great Lakes on Wednesday. Behind the
low, northwest flow aloft will allow for scattered showers to
continue through the rest of the forecast period. Temperatures
will drop through the end of the work week, with below normal
values expected by Friday.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Rain will continue to diminish as the supporting shortwave trough
progresses northward, but IFR to low end MVFR cigs will linger
into Saturday as a warm front shifts northward.
More restrictions are likely Saturday night into Monday with slow
moving low pressure.