Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
253 PM EDT Thursday Jul 31 2014
temperatures will move to near average with daily chances for
showers and thunderstorms Friday through Sunday. Dry and mild
conditions to return by the beginning of next week.
Near term /through Friday/...
shortwave is exiting east but enough low level instability and
differential heating to pop isolated showers this evening.
Otherwise a bit of drying in the column overnight with
temperatures still a few degrees below average by morning. After
patchy morning fog expect clouds to be on the increase Friday as
moisture streams up the west slopes of the Appalachians as flow
becomes more southwesterly aloft. Chance probability of precipitation for showers and
scattered thunderstorms becoming likely in the southeast ridges
closest to best deep moisture. Temperatures approaching seasonal norms.
Short term /Friday night through Sunday/...
southwest upper flow will continue with deep moisture
overspreading the region as weak trough axis shifts west while a
ridge builds into the western Atlantic. Will be tough to time any
significant upper impulse so have gone with a broad brush for
chance shower probability of precipitation with higher probability of precipitation in the ridges. A diurnal
trend for thunderstorm chances with afternoon heating. Little
change to temperatures to average a bit below normal.
Long term /Sunday night through Thursday/...
mainly dry and mild conditions can be expected through the first
half of the week as the long wave pattern becomes more zonal and dry
west/northwest flow sets up across the region. Operational models
vary greatly on the idea of showers/thunderstorms returning by
midweek so have included a slight chance on Wednesday...increasing
on Thursday based on ensemble guidance.
Aviation /19z Thursday through Tuesday/...
MVFR into early afternoon at northern ports will mix out to VFR.
Light southwest flow with mfvr fog in spots overnight.
Outlook.../Friday night through Tuesday/...
a low pressure system over the weekend could bring restrictions.