Mount Lebanon, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

348
FXUS61 KPBZ 140518
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1218 AM EST Thu Nov 14 2024

.SYNOPSIS...
A front will approach late tonight bringing showers to the
region on Thursday. A drying trend begins Friday and continues
through Saturday.

&&

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

- Dry weather continues through this evening.
- Chances for showers increase late tonight over Ohio.
- Beneficial showers on Thursday.

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

A very dry 00Z sounding at PIT has prompted the slowing of PoPs
late tonight. This is also supported by a later onset of
measurable rainfall in the latest run of the hires models. Have
updated the overnight PoPs to reflect this. Overnight QPF has
also been trimmed back. Rest of the forecast is in good shape.

Previous discussion...

Low pressure will gradually approach from the west on Thursday
with precipitation (rain) ongoing across much of the region. In
terms of QPF amounts...most area basins will see between 0.25 to
0.50 of an inch, with up to 0.75 in spots. Otherwise...expect
breezy conditions with gusts up to 30 mph and temps in the 40s
to low 50s.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/...
KEY MESSAGES:

- Widespread showers taper off Thursday night.
- Drying trend begins Friday and last into this weekend.
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Lingering rain showers will persist into Thursday night as the mid-
level low moves overhead and eventually southeast of the area into
the Mid-Atlantic by Friday morning. 500mb height rises are expected
in the wake of this system Friday with drier weather expected as
surface high pressure builds across the Great Lakes and Ohio River
valley into Friday night. Temperatures Friday afternoon will recover
to slightly above normal for mid-November with highs mainly in the
50s. However, with northwest flow aloft and lingering low-level
moisture, could see a few lake showers remain across western PA
Friday night before drier air arrives. Little accumulation is
expected with latest NBM probability of exceeding a tenth of
accumulation remaining >5%.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
KEY MESSAGES:

- Highs a few degrees above normal for the weekend.
-------------------------------------------------------------------

A high amplitude pattern is shown to continue over the weekend
into early next week. Ensemble cluster analysis indicates that
the primary issue will be timing of the upper ridge spreading
east into Great Lakes and Ohio Valley Saturday due to a low
moving and deep low near Nova Scotia. Readings may well be near
normal on Saturday if the trough hangs on a bit longer to the
east.

Most of the ensemble guidance has the upper ridge overhead by
Sunday, suggesting highs about 5F above normal. Primary
uncertainty is related to the details of a trough lifting
northeast out of the northern Plains towards the Great Lakes,
and a potential short wave trough digging into base of western
Atlantic trough near New England. Neither of these features
would impact our area much other then minor differences in
temperatures.

Uncertainty begins to increase significantly by Monday and
Tuesday. While many of the global ensemble members keep a
somewhat flattened ridge overhead with mild weather continuing,
a significant number of ECMWFE members dig the Great Lakes
trough southeast and lower the heights across area. The NBM 10th
to 90th percentiles show this range of possibilities well,
ranging from middle 60s/10F above normal with the ridge
remaining in place, and near normal and lower 50s if the trough
digs southeast per subset of ECMWFE members.

Potential exits for a short wave trough to eject out of the
central US long wave trough position on Monday and potentially
be in the Middle Mississippi River Valley. Ensembles have
tendency to build the ridge downstream of this feature into the
Great Lakes and Ohio River Valley, which would keep readings
above normal (per the NBM 90th percentile MaxT in the mid to upper
60s Monday and Tuesday). While the ejecting and weakening trough
could bring showers around Tuesday to the area, it appears that
significant rain chances will be slow to move east from the
central US as the ensembles hint at a blocking pattern with long
wave trough remaining anchored somewhere near NM to TX area.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
Rain (moderate at times) will overspread the region ahead of a
warm front today, reaching ZZV by 08z and western PA terminals
by 14z. Initial restrictions will be tethered to visibility
reductions with pockets of heavier rain, as residual dry air
will delay ceiling drops. Between 14z-19z, MVFR to IFR ceilings
develop areawide amid top-down moistening with probabilities
favoring greater reductions at ZZV/FKL/DUJ/BVI. The influx of
dry air in near-surface southeast flow is expected to
slow/delay cig restrictions along the Laurel Highlands and
terminals just west (PIT/AGC/LBE/MGW). Surface wind will remain
ESE through 00z and occasionally gusty to 20-25kts.

As the upper trough shifts southeast of the region after 00z,
area rainfall will gradually end with only pockets of light
rain/drizzle remaining and surface wind becomes light/variable.
Settling of boundary layer moisture and the near onset of cold
advection should aid higher confidence in widespread MVFR and
localized IFR ceilings after 06z (50-90% probabilities).

Outlook...
Passage of the cold front initiating cold advection and NW flow
are factors that are likely to maintain MVFR conditions with low
probability rain chances through the day Friday, favoring
eastern OH and northwest PA.

VFR is more likely to return Saturday under greater influence of
high pressure with stronger subsidence as ridging develops
aloft. The next potential shortwave disturbance could cross
Monday and offer increased rain/MVFR cig chances.

&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22/Shallenberger
SHORT TERM...Shallenberger
LONG TERM...Craven/Shallenberger
AVIATION...Frazier