Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
551 PM EST sun Nov 29 2015
weak high pressure will bring mainly dry weather tonight before
low pressure returns unsettled weather late Monday into middle week.
Near term /until 6 am Monday morning/...
drier middle-level air has managed to overcome upper divergence from
the right entrance region of the upper jet streak slowly moving
eastward through the area. This has managed to curtail
rainfall...even in the southern tier of the forecast area.
However...low-level moisture has not been fully eroded generally
south of the PA/WV line as represented by dewpoint depressions
becoming much wider farther north. This has allowed for some fog
development this evening...however progressively drier air should
slowly work southward overnight...making fog a more local and
Model solutions do seem to be overplaying the spread of quantitative precipitation forecast across
the northern half of West Virginia this evening. Likewise...they
are having problems initializing the upper moisture field
advecting toward the area from the central Ohio Valley. The net
result is a drastic increase in cloud expectations overnight. This
will keep temperatures from falling off rapidly even with drier
air moving it. It should also preclude the chance of any freezing
precipitation amongst the ridges toward morning as the rain field
starts to advance northward again. Fries
Short term /6 am Monday morning through Wednesday/...
a continued increase in clouds and rain chances are expected
especially late Monday as the next shortwave approaches ahead of
developing low pressure across the Midwest. That surface low is
expected to track into the upper Great Lakes Tuesday as its associated
cold front crosses the upper Ohio Valley region. Categorical probability of precipitation
were maintained with the approach and passage of the front.
Rain shower chances are expected again Wednesday...especially late...as
a deep upper trough crosses the Great Lakes and Ohio Valley
region. Above seasonal average temperatures are expected to start
the week...with a return to near average temperatures by middle week using
the latest blended guidance.
Long term /Wednesday night through Sunday/...
rain and possible snow shower chances should continue through Wednesday
night as the upper trough completes its passage. Surface high
pressure is prognosticated to build in thereafter through the weekend
with dry weather an near to above seasonal average temperatures.
The latest guidance blend was used for the gridded long term
Aviation /00z Monday through Friday/...
MVFR ceilings continue today from about I-70 and south as low level
clouds and moisture are slowly eroding away. Expect clouds to
slowly break even in southern areas. Near Mason/Dixon line
locations like mgw...where low clouds will hold past sunset there
may be a period of some fog later as skies clear until dry air
works in. Light NE winds are expected through the period.
Outlook...Monday through Friday/...
low pressure will return restriction chances late Monday through