980
FXUS61 KPBZ 211111
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
711 AM EDT Sun Jul 21 2024

.SYNOPSIS...
Quiet, dry weather is expected for a large portion of the
region today under high pressure. Precipitation chances
increase Monday into Tuesday with an approaching disturbance.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:

- Dry, quiet weather is expected today.
- Patchy river valley fog may form early this morning.

_______________________________________________________________

Quiet, dry conditions are anticipated to continue today under
high pressure. Upper-level clouds from the west continue to
stream into the region, associated with a weak low pressure
centered over Iowa/Illinois. Areas of clearing may prompt
patchy fog near I-80 and south of Morgantown, WV through dawn.

Afternoon high temperatures will be near to slightly above
average, ranging from the mid to upper-80s. With dew points
comfortably in the mid-50s, heat index values will stay below
90F.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
KEY MESSAGES:

- Seasonable temperature return with increasing cloud cover and
  precipitation across the region.

- Probabilities are elevated (above 50%) for areas south and
  east of Pittsburgh to observed t-storm after 12pm.

_________________________________________________________________

Models have been consistent that convective chances return early
Monday morning over central West Virginia and central Ohio, as
new low pressure system forms, before venturing north into our
region.

Diurnal heating and a flux of low-level moisture will increase
buoyancy to prompt thunderstorms (MUCAPE values may range from
800J/kg to 1500J/kg across the region). Effective shear of 30kts
to 35kts may create small hail in stronger storms. However,
confidence is still low on that situation.

Spatially, heavier rainfall amounts will be generally focused
east of Pittsburgh as a mid-lvl jet enters southern Ohio and
tracks east mid-afternoon. Rainfall amounts over a 24 hour
period (ending at 2am Tuesday) will likely range between a
quarter to half inch.

Probability of thunderstorms decreases significantly (from 60%
to 10%) between 11pm Monday to 2am Tuesday under weak
instability and as the center of the low tracks towards New
York. However, remnant showers may linger across the region
through dawn.

Isolated to scattered showers and thunderstorms could continue
into Tuesday afternoon/evening as a disturbance over the
Southeast tracks north. Afternoon high temperatures will range
near-normal given lingering clouds and precipitation in the
region.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:

- Periodic shower and thunderstorm chances increase through the
  week
- Near-normal to slightly above average temperatures are
  expected mid-week.
- Above average temperatures are anticipated over the weekend
  with dry conditions.

________________________________________________________________

Slow progression of an upper-level trough over the Great Lakes
and a building ridge over the New England/Newfoundland region
will encourage strong southwest flow into the Ohio River
Valley. Disturbances developing off the Gulf Coast will likely
track through portions of our region (mostly east of Pittsburgh)
and keep precipitation chances elevated through late Thursday/
early Friday.

Probability of widespread 1 inch of rainfall between Monday and
early Friday morning are between 60% to 65% for the ridges of
West Virginia; Pittsburgh, PA is 45%.

A pattern shift, trough axis exiting to the east and a ridge
building over the Great Lakes, will return warm and dry
conditions to region Saturday into Sunday.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
VFR is expected through Monday morning under a ridge of high
pressure. Increasing moisture and warm advection ahead of an
approaching trough will result in increasing high clouds today,
with mid clouds tonight.

Shortwave movement may foster scattered light showers after 12z
Monday near and south of the I-70 corridor while ushering in
lower VFR cloud decks.

.Outlook...
Scattered showers and thunderstorms and restrictions,
especially during the afternoon and evening hours, are expected
Monday through Wednesday, as shortwaves embedded in southwest
flow cross the region. Showers and thunderstorms are likely on
Thursday with the passage of a cold front.

&&

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

&&

$$

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