Area Forecast Discussion

Pittsburgh, PA

Forecast Discussion for PBZ NWS Office
000
FXUS61 KPBZ 032043
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
443 PM EDT Fri Jul 3 2020

.SYNOPSIS...
Above-average temperature will persist through much of the coming
week. A generally dry forecast is expected outside of the ridges
until mid-week, when upper-level high pressure weakens its hold on
the region.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Not much change was needed to the evening forecast at this time.
Cumulus are scattered in most cases across the CWA, with some of them
collecting along a lake breeze boundary evident near I-80. The strong
mid-level capping in place over the region is keeping the clouds
from achieving much in the way of vertical extent. A few showers did
manage to pop along the boundary in Elk County, just to the
northeast of our forecast area, but am still expecting locations in
Forest/Clarion/Jefferson Counties to remain dry.

Only minor adjustments were made to temperatures during the late
afternoon/evening. PIT has already reached 91 degrees, the warmest
temperature at Pitt International since September 5th 2018 (when the
high reached 94).

Previous discussion...

The upper OH Valley will be located on the nern flank of a strong
upper ridge, with weak nly flow aloft and increasing sfc high
pressure. 12Z KPBZ RAOB reveals a well-mixed low-level airmass
beneath a stout inversion at H7-H6. With the morning inversion now mixed
out and temps in the mid 80s at 11am, the temperature climb into the
low 90s will be slower for the remainder of the day.

Although the dewpoint temperature will increase slowly today,
moisture will be insufficient for buoyant parcels to circumnavigate
the strong inversion/cap, with chances non-existent for deep
convection today. At best, a modest cu field at 6-7kft will be
possible by noon for a few hours.

Dewpoint temperature will continue to rise overnight amid generally
clear sky and light wind, which may support spotty river valley fog
development late tonight.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Little change in the weather pattern is expected through the weekend
as the strong upper ridge in the Midwest remains entrenched. Modestly
higher moisture content and signals of a ripple in the weak flow
aloft may aid in convective development along the sern ridges where
terrain circulations will enhance convergence Sat and Sun afternoons.

Outside of the higher terrain, a continued mid-level inversion and
lack of low-level convergence will suppress convective storm development
through the weekend. Maxima will hover around the low 90s both days,
with overnight minima generally in the 60s (driven in large part by
moisture content of the low-level airmass).

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
The prolonged upper ridge in the Midwest will flatten early next
week, leaving the door open for disturbances to move through the
upper OH Valley region.

Some models suggest a weak disturbance on Monday could generate
scattered showers and storms, although confidence is low that the
capping inversion will be eroded by then. Better chances may not
arrive until later in the week, closer to Wed. Even then, weak mid-
level flow and a nebulous sfc pattern will support little in the way
of storm organization.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
High pressure centered across the greater Great Lakes region will
continue to provide dry, tranquil weather through the TAF period. VFR
will prevail with a light northerly wind and diurnal cu field. Some
isolated instances of valley fog may be possible toward dawn
Saturday, but nothing that warrants inclusion in the TAF set at this
point.

.Outlook...
No widespread restrictions expected for the next week as VFR is
expected to prevail with persistent ridging in place.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$

NWS PBZ Office Area Forecast Discussion