Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
1052 am EDT Friday Jul 29 2016
a series of weather disturbances will keep showers in the
forecast through the weekend.
Near term /until 6 PM this evening/...
fog has slowly been lifting into stratus this morning south of a
boundary that is laying basically along I-80. Abundant moisture to
the south of this boundary in the low levels with exceedingly
little mixing has allowed for fog and stratus to perpetuate deep
into the late morning hours. A few breaks in the stratus are being
noticed along the Mason-Dixon line as well as along the western
and northeastern periphery of the field on visible imagery late
this morning, and these will likely expand as differential heating
along the cloudy/clearing interface induces turbulent mixing.
However, due to the moisture content of the boundary layer,
clearing stratus will likely turn virtually directly into cumulus
through the day. Thus, a mostly cloudy morning will improve no
more than to a partly sunny afternoon.
A weak wave will shift to the southeast toward evening. Hi-
res/hrrr guidance all develop convection in Southeast Michigan by
afternoon and intensify it a bit as it interacts with the lake
breeze along Lake Erie by later afternoon. It continues southeast
toward our area during the evening, likely weakening as it does
Short term /6 PM this evening through Sunday/...
very little change to the overall pattern, with zonal flow aloft
and shortwaves riding eastward in the flow. The risk for showers
and storms will continue through the entire weekend, with best
timing linked to the passage of aforementioned waves. Continued
humid with near seasonal daytime temperatures.
Long term /Sunday night through Thursday/...
appears to be enough low level moisture for low chance pops in the
ridges Monday, otherwise a weak bubble of surface high pressure
looks to bring warm temperatures with little chance for showers
Tuesday and Wednesday. A frontal boundary may get close enough for
chance pops on Thursday. A modified superblend was used for the
Aviation /15z Friday through Tuesday/...
IFR fog and stratus will impact terminals through mid-morning
until increased mixing helps dissipate fog and lift the stratus
deck. VFR conditions will return by the afternoon with minimal
shower chances as forecast soundings show largely stable
conditions. Precipitation chances will increase tonight ahead of
an approaching shortwave.
Outlook /Friday night through Tuesday/...
broad upper troughing should maintain periodic shower and
thunderstorm restriction potential through Monday.