Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
104 PM EST Sat Dec 27 2014
we can expect dry conditions today with mild temperatures. A cold
front will bring a chance of showers tonight and Sunday morning. A
return to normal and below normal temperatures will start Tuesday.
Near term /until 6 PM this evening/...
boosted the high temperatures today by a couple of degrees.The
strato-cumulus deck has moved inot the northeast part of the County Warning Area.
Several hours of sunshine before Alto-cumulus deck moves in from the
west. Initial onset of rain showers slowed a bit from previous
Short term /6 PM this evening through Monday/...
timing and location of front and precipitation shield become an
issue tonight and Sunday. Feel confident that most areas will see
showers tonight with the passage of the boundary...however
confidence decreases Sunday on location of the precipitation shield and
how fast the colder air moves in. The bulk of the precipitation should
remain in the warmer air mass...meaning mostly showers. But by
Sunday afternoon...as the colder air begins to dive southward...
models are hinting that some precipitation may linger to the north of
the boundary. This would mean that any precipitation behind the front
will change to snow. Any snow that falls will be light and it will
take time for surface temperatures to react to the colder air aloft...so
any snowfall should be negligible...but it does make for a
On Sunday night...shortwave trough will swing through the upper
Midwest and Great Lakes and surface high will move southward
through the western Great Lakes. This will shove the clouds and
precipitation further south...again differences in model solutions here
make for a difficult forecast. Will lean toward the drier solution
but with low confidence.
On Monday...high pressure moves through the Great Lakes. Sunday's
front will have stalled over the middle-Atlantic and a surface wave
will move through the southeastern US. A large portion of the
cloud cover should be confined to the far south Monday. The wrench
in the forecast will arrive Monday afternoon as a jet streak will
move through the far south increasing the lift and moisture. Models
are spitting out some light precipitation...mainly over the southeastern
ridges...Monday afternoon. This is when temperatures aloft and at the
surface will become crucial. Will use a blend of model solutions
here and leave in chance/schc probability of precipitation with this feature.
Long term /Monday night through Friday/...
the extended will largely be dry with a decreasing trend in
temperatures as a broad trough in the longwave pattern slowly sags
south across the eastern Continental U.S..
Aviation /18z Saturday through Thursday/...
condition deterioration to genl MVFR can be expected aftr dark as
cold front draws near the region. Lower MVFR and some IFR ceilings are expected
tonight as moisture increases and showers more widespread. Rain
will end Sunday morning but ceilings will remain MVFR during the
Outlook.../Saturday night through Wednesday/...
periodic MVFR restrictions can be expected for the first half of