Area Forecast Discussion
Issued by NWS
FXUS61 KPBZ 251826
Area Forecast Discussion
National Weather Service Pittsburgh PA
226 PM EDT Thu Aug 25 2016
Showers and thunderstorms will move through the area this evening
and tonight with very warm conditions continuing through the
.NEAR TERM /THROUGH TONIGHT/...
Scattered to broken cumulus remains over the area late this
afternoon with dewpoints generally in the 70s across the board.
Convection is starting to develop from Indiana into lower Michigan
and southwest Ontario ahead of an eastward moving short wave
trough. The vast majority of large scale ascent associated with
this wave will move to the north of the area, however the trailing
edge of the wave combined with an uptick in shear late this
evening and CAPEs still elevated due to very high dewpoints will
mean a pretty good chance of showers and thunderstorms traversing
especially the northern reaches of the CWA late this evening. SPC
maintains a slight risk for severe thunderstorms with damaging
wind gusts and isolated tornadoes as the predominant threats.
In examining the 12z raob, PWATs were already 1.6 inches at that
time and KILN revealed 1.9 inches. As soupier air moves in, this
will mean that any storms that do develop will likely be copious
rainfall producers due to warm rain processes and a very high
freezing level. Likewise, this means hail will be a minimal threat
as the system moves through. Fries
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
Upper ridge of high pressure centered over the Mid-Atlantic will
continue to build through the weekend. This, and a broad area of
surface high pressure drifting across our north will keep our
area dry through a majority of the weekend with a warming trend.
Dewpoint temperatures will drop back down to around 60 by Friday
night, but will slowly creep back up through Saturday and into
By Sunday, the very humid air mass will return with dewpoints in
the mid to upper 60s common. This, and a draw of warmer air from
the south will combine for high heat indices that may near 100
degrees. How warm we get Sunday may largely depend on the arrival
of clouds associated with a disturbance passing well to our
north. Model guidance indicates the potential for
afternoon/evening showers and thunderstorms as a mid-level wave
tries to flatten the upper ridge. With the best forcing riding
over the ridge and staying to our north, coverage of showers may
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Little change in pattern is indicated through the first half of
next week with the southern U.S. upper high maintaining grip, but
with tropical system encroachment toward the Southeastern Coast. Shortwaves
with the zonal flow over the immediate area would support periodic,
and diurnally-supported precip chances for the long term. Low-confidence
slight to chance POPs were maintained for that eventuality as per
the latest Superblend guidance. Warm temperature can be expected
given the lack of any significant airmass alteration.
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Showers and a few thunderstorms will encroach from the west
during the early portions of the forecast. Expect coverage and
intensity to continue to decrease overnight, so have only included
restrictions in a tempo group. Shortwave that has sparked the activity
will clear the area quickly this morning. Expect a quick return to
vfr conditions after sunrise.
.OUTLOOK /FRIDAY THROUGH MONDAY/...
Periodic restriction chances should persist through Friday with
the approach and passage of a cold front.