Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
941 PM EDT Friday Jul 31 2015
mainly dry weather and seasonal temperatures will continue through
Near term /through Saturday/...
frontal boundary is still back in Northwest Ohio. Minor ripples in the
passing shallow midlevel trough have managed to support a few
isolated rain showers in the relatively dry airmass ahead of the front.
Pit/iln soundings showing very little moisture above 12k
feet...and thus expect precipitation to remain isolated and weak
for the most part. A couple of heavier showers could skirt
Mercer/Venango over the next hour or two. Maintained slight
chance probability of precipitation ahead of the boundary...and also updated the sky cover
forecast. Removed thunder chances given the shallow moisture and
lack of instability. Temperatures were more or less on track and
updated these slightly with lamp guidance.
Short term /Saturday night through Monday/...
expect dry weather Saturday night. A cold front will approach the
area Sunday and cross the region late Sunday night into Monday.
Model continue to struggle with the timing of the front...and have
not been consistent from day to day. Considering yesterdays 12z
models sped up frontal timing while last nights 00z models delayed
the frontal timing...will not make much changes to precipitation timing
even though todays 12z models show some consistency with 00z models.
At this point...sref certainly seems to be the fast outlier compared
to deterministic models. Depending on when the front passes on
Monday...it appears that modest values of instability and wind shear
could allow for stronger thunderstorms during the afternoon.
Temperature trends should change little with seasonal values for
Long term /Monday night through Friday/...
a broad eastern Continental U.S. Upper trough is prognosticated to persist through the
period with slightly cooler than average temperatures. Much of the
time should be dry...though a few shortwaves advancing through the
trough should bring periodic shower chances. Followed close to wpc
ensemble based guidance to smooth out individual model
differences...though did adjust guidance probability of precipitation downward with
shortwave timing and available moisture in question.
Aviation /02z Saturday through Wednesday/...
VFR conditions are expected with broken clouds overnight associated
with a weak shortwave and increased moisture. Little if any
precipitation is expected through the period...with the greatest
chance near zzv. Tomorrow...expect VFR conditions with broken diurnal
cumulus and west-northwest winds generally 10 knts gusting to 15 knts.
Outlook...Saturday through Wednesday...
restriction potential returns early next week with crossing