Scientific Forecaster Discussion
fxus61 kpbz 250108
Area forecast discussion
National Weather Service Pittsburgh PA
908 PM EDT Sat Jun 24 2017
sunshine and lower humidity are the main headlines this
weekend. Scattered showers are possible Sunday afternoon with a
passing upper level system. Widespread 60s are forecast highs
Monday and Tuesday, not the best pool day.
Near term /through Sunday/...
as surface temperatures have likely seen their afternoon apex
and have begun to come down, cumulus buildups are already
beginning to fade across the area. This has allowed for the few
showers generated along the 500 mb cold front to likewise fade
as the front has begun to exit to the east. Enhanced lapse rates
in its wake do remain, which combined with weak surface
convergence along the lake breeze interface are allowing for a
few showers to move into Mercer County. These are already
weakening a bit, and they should continue to rapidly weaken now
that the sun has set. A clear and cool overnight is on tap for
the whole area with cold advection well underway. Fries
Isolated showers and perhaps a thunderstorm are possible Sunday
afternoon during peak heating with the passing pocket of cooler
mid level temps. Any shower or storm will be brief Sunday.
Temps and humidity levels will be a welcome relief with highs
slightly below normal and dewpoint in the 40s to lower 50s.
Short term /Sunday night through Monday night/...
Monday will follow a similar pattern as Sunday, with a
shortwave trough digging into the Great Lakes. Models continue
to show this trough sliding further south than the previous
shortwave. Again, bolstered by steepening lapse rates, showers
and thunderstorms are expected to spread southward through the
afternoon and evening. Rain chances will continue into Monday
night as the main upper-level trough axis passes overhead.
Temperatures will continue to cool through the early part of the
week, dropping around 3-5f off the daily highs and lows from today's
expected numbers. By Monday, temperatures will be about 10 degrees
Long term /Tuesday through Saturday/...
the middle of the week will feature cool temperatures, left over
from persistent northwest flow from the broad upper trough.
Despite building high pressure at the surface, rain chances will
exist Tuesday before the axis of the main trough finally shifts
east of the area.
High pressure will take firm hold of the area Wednesday into
Thursday, restoring dry conditions areawide and allowing
temperatures to begin moderation. By the latter part of the
week, the center of the high shifts to just off the mid-
Atlantic coast. This will will establish a return to a warm and
humid airmass that will fuel showers and thunderstorms by the
early weekend. Currently, the best chance of precipitation
exists on Saturday, as low pressure returns to the Great Lakes.
Aviation /01z Sunday through Thursday/...
high confidence forecast. VFR conditions will continue through
the period. Diurnal cumulus will return on Sunday with
occasional wind gusts yet again.
chance for restrictions will come with afternoon convection on
Sunday and Monday as an upper trough settles over the region.