Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
608 PM EDT Monday Aug 31 2015
warm and humid conditions will continue through the week with
isolated daytime showers and thunderstorms possible.
Near term /through Tuesday/...
showers and isolated thunderstorms have limited themselves well
south along a weak convergence zone and thus have made cosmetic
changes to probability of precipitation for the evening update. With very weak shear and
forcing...precipitation is expected to diminish as the evening
progresses with loss of heating.
A clear sky and light to calm winds should help promote fog tonight...especially
in the river valleys. Temperatures tonight will be warmer than
average based on a blend of model guidance.
Short term /Tuesday night through Thursday/...
the models continue to build the upper ridge Tuesday before the
weak upper shortwave over the Ohio Valley finally gets absorbed
back into the upper level flow Wednesday. Thus...probability of precipitation were
constructed with the best chance for showers and thunderstorms
across the entire region Wednesday afternoon. Working against any
probability of precipitation higher than chance values are the warm temperatures in the
middle-levels both days. Generally expect coverage to be mainly
Summer airmass/diurnal convection that will dissipate each evening
with the loss of heating.
Another weaker disturbance will pass across the region on
Thursday as the ridge rebuilds. Again...will keep probability of precipitation rather low
at this time.
The warm air in the middle-levels will translate to very warm
temperatures at the surface with highs expected to get very close
to 90 through the entire time period.
Long term /Thursday night through Monday/...
no major changes to the extended period as the impressive eastern
Continental U.S. Ridge further amplifies reaching into eastern Canada. Cannot
rule out diurnal rain chances...especially in the higher terrain
as the center of the upper high moves north of the area and return
flow establishes a moisture feed from the mid-Atlantic.
Still...largely dry conditions will persist into and through the
weekend. Temperatures will stay several degrees above average
through the period.
Aviation /22z Monday through Saturday/...
VFR conditions will persist through early tonight before patchy
MVFR to IFR fog occurs over the terminals by dawn as the sky
clears and winds become light to calm. Fog should burn off by
approximately 14z...returning conditions to VFR through the day.
Outlook...Tuesday night through Saturday...
general VFR is expected through the period with some restrictions
possible during morning fog and isolated diurnal thunderstorms
possible later in the week.