-- Discussion containing changed information from previous version are highlighted. --
233
FXUS61 KPBZ 070512
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
112 AM EDT Fri Jun 7 2024

.SYNOPSIS...
Probability of rain showers will be elevated on Friday north of
Pittsburgh with passing shortwave. Below average temperatures
are also expected into late Saturday.

&&

.NEAR TERM /THROUGH TODAY/...
KEY MESSAGES:

- Pockets of river valley fog will continue to develop early
  this morning east of Pittsburgh.
- Probability of rain shower activity increases after day break
  north of Pittsburgh with a passing shortwave.
- Areas north of I-80 may observe a few thunderstorms; small
  hail may develop.
- Confidence is high that rainfall total amounts through Friday
  evening will be less than 0.25 inches.

--------------------------------------------------------------


A passing surface trough is created enough lift early this
morning to create a few stray showers across the region.
Probability of precipitation decreases below 10 percent just
before 3am.

With noted remnant moisture, light winds, and some breaks in the
clouds, river valley fog is noted northeast of Pittsburgh on
Nighttime Microphysics GOES-16 satellite. However, confidence is
high that fog will not be an issue during the early morning
commute with passing clouds from the northeast with a new
shortwave.

Rain showers probabilities increase after 10am north of
Pittsburgh with a passing shortwave and will likely continue
into the late evening. Hi-Res model soundings suggest pockets
of 50J/kg to 150J/kg low-level instability during peak heating.
Therefore, a few updrafts may lead to thunderstorm activity.
With a low freezing level (7kft to 8kft) and storm tops
projected near 10kft to 11kft, a few cell may produce small
hail. With rainfall activity being sporadic, low PWATs, and the
loss of a well- defined warm cloud layer, rainfall totals will
be range between a trace to 0.25 inches across the region;
higher amounts mainly focused near I-80.

High temperatures will range from mid-70s to mid-60s Friday
afternoon. The probability of higher temperatures will likely be
south of I-70, where clouds and precipitation will be heavily
absent for a large portion of the day.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- Persistent upper trough maintains an unsettled pattern
- Cooler temperatures expected

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An upper low will drift across southeastern Canada and the
Great Lakes region Friday through Saturday night. Individual
shortwaves rotating around the low will keep an unsettled
pattern across the Upper Ohio Valley region through the
remainder of the period.

A diurnal trend to the cloud cover is expected, with low
convective temperatures in place and cool air aloft. One of
these shortwaves is expected to cross the Upper Ohio Valley
region on Friday, with isolated to scattered showers. Another
is expected for Saturday, though the best upper support for any
showers is expected to be mainly north of PGH.

A stronger shortwave rotating around the low is expected to
cross the region Saturday night, with scattered showers across
much of the area. Temperatures are generally expected to average
around 5 degrees below seasonable levels through the period.

&&

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

- Unsettled pattern through mid week under a series of upper
  troughs
- Cool temperatures to start should warm next week

-------------------------------------------------------------------

Shortwave troughs rotating around the upper low, mentioned in
the short term section of the discussion, will maintain
scattered showers on Sunday and Monday, though much of the time
in any one location will be dry.

Mainly dry weather is expected on Tuesday as the upper low exits
the New England coast, and ridging briefly builds in. A
shortwave trough is expected to advance eastward from the Plains
region Tuesday night, crossing the Upper Ohio Valley region on
Wednesday. Scattered showers are expected with the approach and
passage of the trough.

Temperatures should start out a few degrees below average
Sunday and Monday, before returning to near, or above average
readings by mid week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
VFR conditions are expected through the TAF period. Areas of mid
level clouds will cross the region tonight, around an upper low
centered across Ontario and the Great Lakes region. Model
soundings and the CU rule indicate a broken diurnal cumulus
layer will develop Friday morning as convective temperatures are
reached, and continue through the day. Scattered showers are
expected, mainly north of PIT, with that area in closer
proximity to the low, and more favorable moisture. An isolated
thunderstorm is also possible, though chances remain too low for
inclusion in the TAF at this time.

A sufficiently tight pressure gradient, and mixing, will result
in west wind gusting to 25kt during the daylight hours on
Friday. Clouds should gradually decrease Friday evening as
temperatures fall below convective thresholds. Wind will also
diminish with decreased mixing.

.Outlook...
Periodic restrictions and scattered showers are then expected
through Monday as a slow moving upper low persists across the
Great Lakes region. VFR should return Tuesday under high
pressure.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...WM/88
LONG TERM...WM/88
AVIATION...WM