Area Forecast Discussion
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FXUS61 KPBZ 240735

Area Forecast Discussion
National Weather Service Pittsburgh PA
335 AM EDT SUN JUL 24 2016

Hot and humid conditions will continue. The best chance for
showers and thunderstorms will return on Monday with the passage
of a weak cold front.


Quite the dewpoint discontinuity remains over the area early this
morning as the weak surface boundary has sagged southward.
Regardless of where that boundary is this morning, low level flow
looks to quickly turn west-southwesterly after sunrise. This will
bring the air currently residing over southwestern Ohio toward our
CWA. As a result, dewpoints should climb rapidly into the daytime
on as the boundary lifts back north of the area.

A convective complex currently decaying while slowly trudging
eastward near the southern end of Lake Michigan will manage to
spread high clouds toward the area for portions of the day on
as model RH projections do surge above 500 mb through the morning.
However, even in the upper levels, flow does manage to back a bit
more southwesterly through the day, which should shunt a bit of
that moisture northward by afternoon. However, to be complete,
some of the hi-res guidance does sag the remnants of the complex
southeastward toward the CWA by afternoon. Satellite trends would
suggest that even if this were to occur, there would likely be
scant activity remaining with it.

What was particularly unusual on Saturday was the spread of 90F+
temperatures across the area with 850 mb temperatures that really
didn`t even manage to meet 20C. That said, the drier boundary
layer present in some areas on Saturday will not be readily
apparent on today with dewpoints surging toward and above 70F.
However, consensus 850 mb temperatures manage 22C with 23C likely
toward Morgantown. This should put the majority of the area into
the 90s for highs...and even well into the 90s over Ohio. Thus
with dewpoints increasing and high temperatures at least as high
as Saturday even with more high clouds, a heat advisory has been
coordinated for all Ohio, non-mountainous West Virginia, and
southwestern Pennsylvania counties generally south of the

Yet another warm front does start to move through the area by
late Sunday, increasing the chances of showers and thunderstorms
as it does. This will bring increasing clouds and dewpoints into
tonight, which will likely keep low temperatures well above 70 in
most spots. The associated cold front looks poised to advance
southeastward by Monday afternoon and evening. However, strong
mixing and warm advection with a very humid air mass ahead of it
will again mean a day with heat index values possibly reaching 100
degrees again on Monday. Fries


A sweeping cold front will bisect the forecast area Monday night,
as the parent upper-level low shifts into the eastern Great Lakes.
The boundary will be slow to sag south of the area, prolonging
shower and thunderstorm chances into midday Tuesday. By Tuesday
afternoon, surface high pressure and drier air will invade from
the north and quell rain chances north of I-70. Wednesday is
expected to be mostly dry, with the exception coming in the ridges
where the elevated heat source could generate a few showers or

Relief from the recent high dewpoints will finally come with
fresh air behind the front. Dewpoints will drop precipitously into
the low to mid 60s by Tuesday afternoon, and upper 50s to low 60s
by Wednesday. Despite temperatures holding above average, the
lower dewpoints will feel much more comfortable than the current
air mass.


A bit of a pattern shift expected later this weekend carrying into
the weekend. High pressure that has led to the current heat wave
will gradually retrograde back to the four corners region of the
southwest CONUS. This will allow a broad trough to replace the
zonal flow over our region by Thursday. Several shortwaves
will pass through the upper-level flow pattern, bringing periodic
rain chances through the weekend. With the broad upper-level
trough firmly in place, temperatures will return to near-normal
by the weekend.


Some high clouds are moving over the area as of 06z. This is
slowing radiational cooling and also likely slowing the onset of
visibility restrictions. Due to ample low level moisture and
recent rain, it still seems fairly likely some amount of fog will
be present by morning generally from KPIT southward. Otherwise,
some increase in mid-level clouds will be apparent through the day
from NW-SE as the next system to affect our region approaches for
this evening. Otherwise, VFR conditions will be common after some
morning fog. Fries

Restrictions will be possible late Sunday and Monday with the
approach and passage of a weak cold front.


OH...Heat Advisory from noon today to 8 PM EDT this evening FOR
PA...Heat Advisory from noon today to 8 PM EDT this evening FOR
WV...Heat Advisory from noon today to 8 PM EDT this evening FOR


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