110
FXUS61 KPBZ 092139
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
539 PM EDT Sun Jun 9 2024

.SYNOPSIS...
Generally dry and seasonably cool weather is expected through
Tuesday under the influence of an upper trough. Rising
temperatures and dry weather will characterize the mid to late
week period. Heat index vales Thursday and Friday will be well
into the 80s.

&&

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

- Seasonably cool temperature will persist despite increasing
  overnight cloud cover ahead of the next system.

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

The only change to the late afternoon - supper time update was
to tweak clouds upward overnight given latest NCEP suite. This
aligns well with the NBM on mostly cloudy conditions especially
north of I70 arriving overnight. The rest is in fine shape with
no changes.  Previous discussion follows.

Dry air and subsidence between upper level shortwaves will
foster scattered cumulus and slightly below average temperature
this afternoon. The next shortwave within the broad New
England trough may combine with weak destabilization to generate
isolated late afternoon to evening showers across northwest PA.

Cloud coverage will increase overnight into Monday morning ahead
of another upper level perturbation, which should mitigate
further temperature falls and keep low values only 5 degrees
below average.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:

- Shortwave movement and additional cold front will create low
  probability light rain showers Monday.
- Well below average temperature Monday is expected to become
  near normal by Wednesday as dry weather persists.

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

In response to ridge building just west of the upper Mississippi
River Valley, another embedded shortwave will round the New
England trough and cross the region Monday. Isolated light rain
showers may develop along the associated surface cold front, but
weak ascent and moisture origins mainly associated with Lake
Erie should limit activity to the I-80 corridor and (later in
the day) higher terrain. More notably, an uptick in cloud cover
and additional cool advection will keep high temperature 10 to
15 degrees below the daily average while strong radiational
cooling keeps similar temperature transparencies for the
overnight low.

Gradual height rises as the New England trough heads out to sea
and flow out west becomes more zonal will rising temperature
Tuesday into Wednesday. Surface high pressure will cross the
region during this time as well, ensuring plenty of insolation
and dry weather.

&&

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

- Increasing precipitation chances late Thursday into Friday
  with shortwave movement.
- Upstream convective evolution will play role in timing and
  storm mode during that period.

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

The late week period will feature embedded shortwaves within
fairly progressive zonal flow across the north central CONUS
that will shirt towards the Great Lake region late Thursday into
Friday. Ahead of it, confidence if high for above normal
temperature with an uptick in warm, moist surface flow as the
surface high shifts east. With it, the expectation is for an
increased precipitation chances that generally favor northwest
PA.

There remains notable variation in timing/strength of the upper
shortwave, with potential the prior convective evolution near
the western Great Lakes may dictate the quickness of its
eastward progression. Storm timing and strength of the upper
trough will be key in accurately assessing any lightning
potential, but severe weather appears unlikely as the
probability for daytime SBCAPE values to exceed 1000K/kg are
less than 10%.

How quickly the shortwave traverse the area will dictate
weather Saturday, but the general trend is for ridging to
develop over the Ohio River Valley heading into the start of the
next week. There is fairly high confidence in this pattern
which would support dry weather and near to above 90 degree
weather (75% probability of hitting 90+ on Monday 6/17 in
Pittsburgh).

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
A scattered to broken cu field with VFR cigs is ongoing across
the area under cool northwesterly flow in the wake of this
morning`s cold front passage. This cu field will gradually
diminish by 00Z with the loss of daytime heating and mixing,
though models suggest a broken band of mid-level clouds from
upstream convection passes overhead within that window. VFR
conditions prevail through the remainder of the evening with
winds settling after dark. Restrictions return overnight into
early Monday morning as another weak cold front pushes through
the area. Expect MVFR cigs to creep in from the north, first
starting at FKL/DUJ around 06Z and reaching the I-70 corridor by
12Z. MGW may be the only terminal spared from MVFR as current
guidance suggests cigs bottom out at low-end VFR that far south.

Unfortunately, low cigs remain in place longer this time as
the weak cold front brings a reinforcing shot of cold air that
helps maintain the stratocu deck. Ceilings don`t lift and scatter
until beyond the current 24hr TAF cycle (though improvement is
reflected in the PIT 30hr TAF). There may be a brief, isolated
shower or two up around FKL/DUJ in the 09Z-15Z timeframe, but
confidence in that occurring is low and impacts (in addition to
the ongoing MVFR cigs) would be minimal, so left mention out of
the TAFs for now. Northwest winds will see a slight uptick from
west around 4-7 kts ahead of the front to northwest around 7-10
knots with occasional gusts 15-20 kts behind the front.

.Outlook...
Ceiling restrictions linger through Monday afternoon before
lifting and scattering Monday evening, giving way to VFR
conditions under building high pressure Tuesday through
Thursday. Showers and thunderstorms (and their associated
restrictions) return Thursday night and Friday with another
passing disturbance.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier/McMullen
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Cermak