Area Forecast Discussion
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FXUS61 KPBZ 310107
Area Forecast Discussion
National Weather Service Pittsburgh PA
907 PM EDT Tue Aug 30 2016
Dry and warm weather continues through tonight and into
Wednesday. A cold front will bring scattered showers and
thunderstorms later Wednesday and Wednesday night. A cooler
pattern will follow for the remainder of the week.
.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --Some cirrus is beginning to filter into the northern half of the
CWA while upstream convection straddles the Indiana/Ohio border.
HRRR guidance as well as most synoptic guidance suggest this
activity should fall apart very rapidly in the next few hours and
cross our area as nothing but debris. Additionally, substantial
dry air has become established in the column across our area such
that any activity that would even approach our area should result
exclusively in virga.
Larger scale ascent looks to hold off until Wednesday as dry air
will rule the day until deeper moisture and ascent approach with
the late afternoon encroachment of a frontal boundary. Fries
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.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
The main event will be the cold frontal passage late Wednesday and
Wednesday night. The best support for lift will lie across the
northern counties, closer to the crossing shortwave. Have
increased PoPs to likely in this area while keeping lower values
to the south. Moisture increases after 18Z, with precipitable
water increasing back into the 1.75 to 2.0 inch range. Some model
soundings take on a moist adiabatic look late Wednesday and
Wednesday evening. Given the relatively low instability, this
should keep severe probabilities quite low and in agreement with
the SPC Day 2 outlook. However, we cannot rule out some at least
briefly heavier rainfall rates, given the high moisture content
and sufficient warm cloud depths. Still, flooding does not appear
to be a threat at this time.
Kept some low PoPs southeast of PIT early on Thursday as the front
crosses the ridges. Surface high pressure builds in later
Thursday with a trough in the mid levels. This brings in a drier
and cooler air mass through Friday, with temperatures below
climatology both Thursday and Friday afternoons.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The extended forecast will be very quiet through the holiday
weekend. Ridging is progged across much of the eastern CONUS
through Labor Day, with dry weather and gradually warming
temperatures expected. Clouds may be on the increase on Tuesday,
but precipitation should still remain west of the area.
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected through the bulk of the TAF period.
Cloud cover will begin to increase by Wednesday morning, but
precipitation chances will be rather slow to spread eastward.
Expecting scattered showers and thunderstorms through the
afternoon/evening hours with temporary restrictions possible in
any stronger thunderstorm.
.OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...
After the Wednesday night cold front, VFR conditions will be
expected through the weekend.