-- Discussion containing changed information from previous version are highlighted. --
370
FXUS61 KPBZ 181733
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
133 PM EDT Wed Sep 18 2024

.SYNOPSIS...
Limited, light rain chances persist today, primarily southeast
of Pittsburgh. A warmer and drier patter returns late week
through the weekend.

&&

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

- Light rain chances, mainly southeast of Pittsburgh today.
-------------------------------------------------------------------

East-west oriented troughing extending into the Mid-Atlantic
region, along with slow-moving stacked low pressure over the
western Carolinas, will continue to promote moist easterly flow
into the Upper Ohio Valley today. Forcing for ascent is rather
weak, limited mainly to spokes of vorticity. Also, the easterly
flow adds a downslope influence to some areas, which will also
act to keep any rainfall amounts low for the most part. East-
facing slopes will get the opposite effect, with a slight
enhancement to rain totals. In any case, probabilities of more
than 0.25 remain lackluster at best, and mainly confined to the
ridges. In other words, the long-term drought rolls on.
Temperatures will be held in check by cloud cover, although
eastern Ohio will get a bit warmer with a thinner layer.

Precipitation chances taper overnight with weakening upper flow,
the eventually dry, northerly flow. The amount of lingering
cloud cover will largely influence fog potential.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
KEY MESSAGES:

- Dry weather returns by Thursday
-------------------------------------------------------------------

A quiet, moderating day is expected Thursday as the
aforementioned surface low pulls out into the Atlantic, and the
area maintains dry north to northeast flow. Clearing clouds
will allow temperatures to top out slightly above normal, and
elevated dew points at nighttime will keep lows a tad warm as
well. Nighttime fog is possible once again. This is the most
likely scenario for Thursday.

There is a lower probability scenario, whereby the Atlantic
trough axis elongates and accelerates easterly flow, pulling
more moisture and perhaps some rain chances in while keeping
temperatures cooler. Even then, chances of notable rain are
quite low. This is not reflected in the current forecast given
it`s low (less than 20% probability), but will warrant watching.

&&

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

- Dry weather through the weekend, very low rain chances early
  next week
- Above average temperatures through early next week
-------------------------------------------------------------------

Little change to the long term forecast. Model ensembles are in
good agreement that the developing ridge to our west will
slowly build eastward, extending from the Texas Gulf coast into
eastern Canada by Saturday. This will also push the East Coast
trough further offshore with time. As a result, dry weather and
above- normal temperatures are forecast for Friday through
Sunday with high confidence.

Uncertainty ticks up a bit with the new work week.  A new trough
approaching from the Northern Plains/Upper Midwest has at least some
potential to weaken the ridge during the Monday/Tuesday period,
which would lead to cooler temperatures and an uptick in rain
chances.  However, cluster analysis shows that the majority of
ensemble members largely maintain the ridge over our region, which
would tend to keep the dry and warmer-than-normal pattern going. For
now, the forecast for early next week will lean towards this latter
scenario, pending future model runs.

Both the 6-10 day, 8-14 day, and 3-4 week outlooks all favor
above average temperatures, but precipitation will remain more
of a toss up with a potential pattern break down by the end of
the month.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
With an upper-level low drifting lingering across the region
today, moisture and weak ascent will continue the chances of
drizzle/light rain for areas east and south of PIT. Expect a
MVFR to IFR conditions for LBE/MGW; AGC/DUJ may bounce between
MVFR to VFR into the evening. However, confidence in prevailing
MVFR for DUJ/AGC is considered low.

Hi-Res model guidance suggests restrictions returning early
Thursday morning for a number of sites with lingering low-level
boundary moisture. Foggy conditions for ZZV, HLG, and BVI may
develop with clearing. MVFR to IFR stratus may also redevelop
near the ridges and impact MGW/LBE/DUJ.

.Outlook...

There is the potential for some early morning fog again Friday
morning.

VFR is then expected through Sunday as high pressure builds in.
-- End Changed Discussion --

&&

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

&&

$$

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