Scientific Forecaster Discussion
fxus61 kpbz 241236
Area forecast discussion
National Weather Service Pittsburgh PA
736 am EST Fri Nov 24 2017
dry weather is expected today. Shower chances return with the
approach and passage of a Saturday cold front.
Near term /until 6 PM this evening/...
morning update simply tweaked some hourly temp and dewpoint
grids. Forecast is on track. Surface high pressure should
maintain mainly clear skies and dry weather today as it slides east
across the area. Temperatures should return to near or just
above seasonal levels with warm advection.
Short term /6 PM this evening through Sunday night/...
a shortwave in broad upper troughing, and it's associated cold
front, are progged to track from the Midwest to the Great
Lakes/Ohio Valley region by Saturday. Shower chances should
return by Saturday morning as the front crosses, though limited
pops to the chance range with limited moisture and upper
support. Warming temperatures are expected overnight with warm
advection and increasing surface winds, keeping all precip rain.
The broad trough is progged to deepen as it tracks E, with the
trough axis crossing the area Saturday evening. Rain and
eventual snow shower chances should continue, though cold
advection isn't strong for this time of year. Lake/terrain
enhancement is limited with marginal 850-lake surface
temperature differences and a lack of significant moisture in
the snow growth region. Capping inversions are also progged to
quickly lower Saturday night. Any accumulation is expected to be
less than an inch in the favored areas. A clearing trend is
expected Sunday under building high pressure.
A weak surface trough should result in some cloud increase
Sunday night mainly north of pit, though precip is not expected.
After near to above average temperatures tonight and Saturday, a
return to temperatures below seasonal levels is expected
Long term /Monday through Thursday/...
generally dry weather is expected through early in the week
with a de-amplified flow aloft. A weak trough is progged for a
Tue night/Wed passage, with mainly just an increase in clouds.
Another trough could result in better precip chances by late
week, though maintained a guidance blend for slight chance for
now due to model uncertainty. Temperatures are expected to
average near to several degrees above seasonal levels.
Aviation /13z Friday through Tuesday/...
high pressure should maintain VFR conditions through tonight as
it slides east. A low level jet ahead of an approaching cold front
should result in a low level wind shear potential tonight, though this should
end Sat morning as the front crosses and the jet weakens/exits.
MVFR ceilings are expected after frontal passage.
restriction potential should continue through early sun with
cold northwest flow and upper troughing.