Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
238 PM EDT Thursday Jul 30 2015
seasonal temperatures and lower humidity are expected through the
Near term /through tonight/...
nearly all clouds associated with the cold front that moved through
the region have shifted to the east. In addition...drier air moving
into the region has dropped dewpoints into the 50s. It has been 5
days since dewpoints were lower than 60 at many locations. Along
those lines...it has also been several days since temperatures have
fallen as low as the forecast calls for tonight...with values
reaching the upper 50s and lower 60s. Considering skies will be
clear...if winds go calm overnight...the temperature could drop
another few degrees from that forecast.
A cold front will move across the western Great Lakes on
Friday...but will remain well west of the region through the
afternoon. Nevertheless...some high clouds should begin to move into
the region late in the day. High temperatures should be similar to
values from Thursday...which are a couple of degrees above normal.
Short term /Friday through Sunday/...
the cold front will cross the region late Friday night into Saturday
morning. Ensemble models are definitely indicating more
precipitation than deterministic models are at this point...but
considering the dry air that will be in place as well as little
moisture along the front itself...hard to go high with chances for
precipitation. Have brought chances for rain slightly farther south
Friday night...but have backed off to slight chance probability of precipitation for many
locations on Saturday. Another shortwave will approach later Sunday
afternoon...with several models showing showers moving into the
northern portions of the forecast area by sunset. Considering
previous forecast noted timing uncertainty with
precipitation...have only added slight chances probability of precipitation at this time.
Little change in diurnal temperature trends through the
weekend...with temperatures generally going between lower 60s and
Long term /Sunday night through Thursday/...
broad eastern Continental U.S. Upper troughing is prognosticated to persist through
the period. Surface ridging should allow for dry weather and
seasonal temperatures much of the time...though a couple of shortwaves
advancing through the main upper trough could provide rain chances
mainly Monday night...and again toward middle week. Made downward
adjustments to wpc temperatures and probability of precipitation to nudge the ensemble based
forecast solution closer to the latest operational models.
Aviation /19z Thursday through Tuesday/...
high pressure will result in VFR conditions with minimal cloud
coverage through Friday. Gusty west-northwest winds will decrease this
evening as the pressure gradient relaxes. Light westerly winds
Outlook...Friday through Tuesday...
restrictions are possible with a Saturday cold front.