Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
503 PM EST Friday Feb 5 2016
warmer temperatures are expected through the weekend...but low
pressure is likely to spread precipitation over the region on
Near term /until 6 am Saturday morning/...
generally clear skies will continue into the evening hours as a
surface ridge moves across the area. Some higher clouds will work
into the area overnight...however they should largely not be thick
enough to obscure much of the sky.
The clear and calm conditions this evening will allow for rapid
temperature fall offs. However...with the departure of the surface
ridge to the east overnight...some southerly flow is expected to
develop in the bondary layer. This combined with some high
cloudiness should put a floor under temperatures at that point.
Thus...generally normal temperatures are expected. Fries
Short term /6 am Saturday morning through Monday/...
warm advection will continue...and drive Saturday temperatures a few
degrees above the normals...I.E. Around...or a cpl degrees above
the 40 f mark until passage of the disturbance by evening. That
passage is prognosticated to be precipitation free with a lack of ascent and
Ridging between upper MS valley and southeastern U.S. Low pressure systems
is likely to support a dry Sunday...with further...albeit minor
moderation of temperature.
The upper MS low is currently forecast to deepen over the Great Lakes
and Midwest...hence amplifying the southwest to southerly flow
over the upper Ohio on Monday. Likely probability of precipitation in the improved moisture and
ascent fields were thus maintained via superblend guidance...but
a marginal temperature profile and warm boundary layer in the warm
advection on the eastern flank of that system should compromise
snow potential and preclude serious accumulation.
Long term /Monday night through Friday/...
the aforementioned low is GFS/European model (ecmwf) forecast to cutoff and
develop eastward before filling/phasing into the longwave portion by
midweek. Nevertheless...upper troughing is prognosticated over the Great
Lakes/upper Ohio region for the long term period. Sub average temperatures and
persistent snow shower chances may be anticipated for the
period...with focus toward the I 80 corridor and ridges as the
work week draws to a close.
The long term was constructed using the superblend guidance.
Aviation /22z Friday through Wednesday/...
as high pressure builds into the region...winds should back to
the south and become light this evening. Scattered-broken middle level clouds
should move in from the northwest late this evening into the early
morning hours and reach all terminals by mgw. There does appear to
be a low chance that ceiling heights could drop to MVFR levels
shortly after sunrise at fkl/duj. Clouds should then begin to
diminish Saturday morning...with southwest winds increasing during
the late morning.
Outlook.../Saturday through Wednesday/...
the next chance for widespread restrictions will be Monday with a
cold front...with restrictions persisting Tuesday and Wednesday
under an upper level low.