046
FXUS61 KPBZ 190319
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1119 PM EDT Thu Jul 18 2024

.SYNOPSIS...
Dry conditions with near-normal temperatures persist through
Saturday, when rain chances increase southeast of Pittsburgh
and temperatures nudge above normal. Next week, a wet pattern is
favored.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
KEY MESSAGES:

- Mainly dry and less humid weather after the passage of a cold
  front.
__________________________________________________________________

Update...
Made only minor changes to the overnight forecast based on the
latest surface observations and near term model data.

Previous discussion...
Valley fog is likely tonight with water temperatures warmer
than air temperatures. Patchy fog may also extend outside of
valleys tonight as air temperatures approach dew points in calm
winds.

The most recent drought updated expanded drought mentions across
the entire area. Even with yesterdays rainfall, the area still
has a ways to make up it`s short term deficit. In addition to
the D2 expansion into eastern Ohio, D3 was actually introduced
in Tucker County. Flows on all rivers, particularly the Mon,
remain low.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- Dry conditions favored in Pittsburgh and points north and
  west; shower and storm changes return southeast of Pittsburgh
  Saturday.

_________________________________________________________________

Valley fog is expected to burn off rapidly into the morning
while surface high pressure builds in from the west. Subsidence
will bring back dry air throughout the atmospheric column.
Mixing will tap into this which may suggest a cu field develops
in the morning that will gradually erode and lift through the
day. High clouds will encroach from the south ahead of a
shortwave that will ride up the Blue Ridge Mountains. With a
high cloud deck, valley fog probabilities will tend lower on
Saturday morning.

During the day on Saturday, shortwave forcing and orographic
influences may allow a chance of showers and storms in the
ridges, with chances dropping off into the lowlands with weaker
forcing. The best chances of rain will reside in Tucker County,
but even then, chances of 0.5" or greater are only around 30% to
40%. This will do little to help with drought concerns.

Elsewhere on Saturday, high pressure will continue to dominate
with temperatures just a hair above normal with just a few high
clouds decreasing through the day. Temperatures will drop to
near-normal Saturday night with valley fog chances returning.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:

- Dry weather to start the week will transition to a wetter
  pattern.

________________________________________________________________

Model clusters maintain high consistency in the 500mb pattern
through next Wednesday. This will start as quali-zonal flow
under a weak eastern trough and transition to warm, moist,
southwest flow for much of the latter half of the week as the
main trough axis retrogrades slightly into the midwest.

A parade of shortwave passages within this pattern suggest that
rain will be favored and should help alleviate some of the
drought concerns. Machine learning maintains daily marginal
risks of excessive rainfall with this, but NBM probabilistic
guidance is generally less than 50% for exceeding 0.5" of
rainfall in any 24 hour period, but this may be a result of
large ensemble spread in shortwave strength and timing.

Towards the end of next week and into next weekend, the trough
is favored to migrate back east, but there are large
uncertainties in the strength and timing.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
General VFR through the forecast period will be interrupted
late tonight and through dawn on Friday as IFR/MVFR fog is
expected to develop once again. The lower restrictions are
anticipated at ports nearest the river valleys.

Fog will quickly burn off after sunrise with scattered cu
developing by late morning.

.Outlook...
VFR conditions are expected through the weekend as a ridge axis
builds over the Great Lakes.

&&

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

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...WM/CL/Milcarek
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...22