Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
556 am EDT Wednesday Oct 7 2015
seasonably warm and dry conditions will remain until a cold front
brings showers and cooler temperatures Thursday night and Friday.
Near term /through tonight/...
early morning update to adjust sky grids to latest observation and Sat
pictures. Quite a few large breaks in clouds across eastern Ohio
working into the northern West Virginia Panhandle. No other
changes and previous discussion follows.
Shortwave crossing the eastern Great Lakes will keep clouds across
much of the region this morning. Deep moisture is lacking so no
precipitation is expected. As high pressure builds into Ontario and
shortwave exits east temperatures will be slightly cooler this
afternoon than Tuesday. As drier air works in clouds will be on
the decrease in the afternoon north to south.
Dry and seasonal overnight as surface ridge shifts south.
Short term /Thursday through Saturday/...
ridging will transition over the region Thursday resulting in
continued dry conditions and a slight increase to temperatures.
Maximum daytime temperatures are forecast to range from 5 to 8 degrees
above climatology norms. Clouds will be on the increase by Thursday
evening as a middle level shortwave and an associated cold front
approach. Shower chances will increase from west to east Thursday
night with likely probability of precipitation west of the ridges daybreak Friday. Cat
probability of precipitation for Friday as front progresses across the region. Middle level
trough will deepen in the southern stream Friday night and slow the
fronts exit Friday evening...with likely probability of precipitation in the southeast
ridges and chance probability of precipitation elsewhere. Showers will end overnight as
surface ridge axis slides across the Ohio Valley into Saturday
with cooler temperatures.
Long term /Saturday night through Tuesday/...
high pressure is expected to bring dry weather through early next
week. Broad upper troughing is prognosticated across the eastern Continental U.S.
Monday night into middle week. A couple of weak shortwaves advancing
through the trough should bring an increase in clouds and only
slight chances for showers. Followed close to wpc ensemble based
guidance through the long term period. Other than above average
temperatures on Monday...seasonally cool temperatures are expected.
Aviation /10z Wednesday through Sunday/...
low level moisture behind a weak shortwave should continue to
bring MVFR/local IFR conditions to most ports this morning. Where
clearing has occurred...patchy IFR fog has developed...though this
should mix out this morning. Ceilings should begin to lift to VFR by
late morning/early afternoon as the wave exits and mixing
begins...with clearing by late afternoon under building high
pressure. IFR fog is expected late tonight.
Outlook...Thursday through Sunday...
restrictions are possible in fog Thursday morning...and with a
crossing cold front Thursday night and Friday.