Scientific Forecaster Discussion
fxus61 kpbz 172258
Area forecast discussion
National Weather Service Pittsburgh PA
658 PM EDT Tue Sep 17 2019
a strengthening ridge of high pressure will provide dry weather and
above-normal temperatures through the end of the week.
Near term /until 6 am Wednesday morning/...
mostly clear skies and light winds will allow for temperatures to
drop to the mid to low 50s overnight in general. Temperatures will be
locally cooler in valleys with a good radiational cooling setup, but
higher along ridgetops where lower levels winds will remain elevated
overnight and keep things mixed up near the surface. Patchy valley
fog looks likely as there should be a favorable hydrolapse based off
observed dewpoints while mixed this afternoon and lows forecast to
reach crossover thresholds in some locations.
Short term /6 am Wednesday morning through Thursday night/...
not much change to the thinking for this period. The amplifying upper
ridge will continue to slowly trudge eastward, with the axis creeping
into the middle Ohio Valley by Thursday night. A dry and well-capped
column justifies the continued dry forecast. Temperatures will
continue to slowly creep further above normal with time as mid-level
heights rise. Started to go a bit above guidance by Thursday given
the dry ground and the dearth of moisture aloft.
Long term /Friday through Tuesday/...
a trough over the western Continental U.S. Will finally start to make some
eastward progress Friday and into the weekend. This will push the
ridge axis through and east of our region by Saturday. Deepening
southwest flow will finally start to funnel a little more moisture
into our region. Continued the trend of going with higher Max
temperatures than those suggested by superblend through Saturday, by
which time many readings in the lower and mid 80s can be expected.
If anything, the models are a bit slower in bringing the next cold
front eastward, as would be expected when the attempt is made to
dislodge such a strong ridge. The best chance for our next rainfall
still appears to be Sunday night and Monday as the front crosses. A
drier and slightly cooler Tuesday would then follow.
Aviation /00z Wednesday through Sunday/...
VFR conditions is expected to prevail throughout the evening and into
tomorrow for all taf sites as high pressure remains over the Great
Lakes. With clear skies and light winds, fog may form briefly before
sunrise southwest of pit where low-level residual moisture lingers.
However, the confidence is not high enough to mention in the tafs at
No widespread restrictions expected under high pressure.