615
FXUS61 KPBZ 200713
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
313 AM EDT Sat Jul 20 2024

.SYNOPSIS...
Dry weather is expected through Monday apart from shower chances
southeast of Pittsburgh Saturday. A wetter and more unsettled
pattern is favored for next week.

&&

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

- Increasing clouds overnight
- Seasonably cool temperatures

__________________________________________________________________

High clouds will continue to increase overnight ahead of an
approaching shortwave in southwest flow aloft across the TN
Valley/Carolinas. Otherwise, dry weather will continue overnight
under surface high pressure. THe high clouds, and dry daytime
mixing on Friday, should limit any fog potential. Lows are
expected to be near seasonable levels.

&&

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

- Dry weather is expected through Monday, save shower and storm
  chances south and east of Pittsburgh Saturday.

_________________________________________________________________

The vorticity maximum embedded in southwest flow will encroach
the area early Saturday morning. Around 10kts to 20kts of
southwest flow in the 850mb layer will act to saturate and warm
the low levels. With daytime heating, this will come together
to allow convective temperatures to be reached in roughly 500
J/kg CAPE. Spotty showers and storms are expected in the ridges,
with chances dropping of to the northwest. Severe weather is not
expected. For Pittsburgh and points north and west, remnant dry
air is favored to keep the rain away. A low-probability camp of
NAM guidance has precipitation focused farther northwest and
shows much higher totals than other guidance with moisture
pooling and stagnant convection, but this solution remains an
outlier.

This surge of southwest flow will bring temperatures a few
degrees higher than the day prior, with a fairly sharp dew point
gradient setting up between the Pittsburgh and Morgantown area,
with more humidity favored for the latter.

The wave is expected to clear overnight and allow for radiative
cooling to drop temperatures near-normal. Fog is most likely for
locations that experienced rain the day prior and typical valley
locations. Seasonably warm temperatures and passing high clouds
with dry conditions are favored Sunday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Periodic shower and thunderstorm chances increase through the
  week
- Above average temperatures expected

________________________________________________________________

Model ensembles indicate a trough will deepen across the Central
CONUS early next week, before drifting eastward by mid to late
week. This trough should approach the Upper Ohio Valley region
by Thursday. Southwest flow ahead of this persistent trough
will result in warm, moist advection across the region.

A series of shortwaves embedded in the southwest flow, and
diurnal instability, will lead to periodic shower and
thunderstorm chances across the area. At this time, it appears
the more significant shortwave passages will be mid-week where
highest POPs are focused in the forecast. Uncertainty still
exists though in the exact timing and coverage of the rain.

Above average temperatures are expected through the period, with
increased humidity levels as well.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
VFR expected through the TAF period with light to variable
winds. With mid to upper-level clouds advancing across the
region from a shortwave to our south, probability of river
valley fog developing is less than 10%.

As the shortwave tracks across the West Virginia ridges,
isolated shower and thunderstorms may be observed south of PIT
after 18Z. With the 06Z TAF update, adjusted MGW to PROB30 for
shower activity.

.Outlook...
VFR is expected through the Monday under the influence of high
pressure.

A series of shortwave troughs lifting NE from the Tennessee
River Valley will support increased shower/tstm chances along
with area restrictions mid-week.

&&

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

&&

$$

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