PBZ issues Area Forecast Discussion (AFD) at Oct 25, 2:58 PM EDT098
FXUS61 KPBZ 251858
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
258 PM EDT Fri Oct 25 2024
.SYNOPSIS...
A cold front brings scattered light rain showers Friday night.
High pressure returns on Saturday bringing dry weather with
moderating temperatures into next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
- Crossing cold front and weak shortwave will return shower chances
this evening into early tomorrow morning
- Rainfall totals are expected to be low (<0.1") for most of the
region
- Winds will ease over night before increasing after sunrise
tomorrow morning
-------------------------------------------------------------------
Latest radar imagery shows light showers in Northern Armstrong and
Southeastern Clarion Counties. For areas north of I-80, expect
clouds to persist and highs remain in the mid to low 60s. Majority
of Southeastern Ohio, Southwestern Pennsylvania, and Northern West
Virginia will see some areas of clearing allowing for additional
warming with highs reaching the mid to upper 60s and some areas in
the low 70s.
A cold front and weak surface low will cross the region starting
this evening around 5pm-6pm. Light and scattered showers expected
across the region with a low probability of accumulation >0.05".
Areas in Northern West Virginia are likely to see closer to around
0.10 inches of rain due to persistent light showers associated with
the northwesterly flow against the Appalachian Mountains.
Showers will diminish before sunrise tomorrow morning. Overnight
temperatures will remain in the 40s given lingering cloud cover and
moisture in addition to persistent light northwesterly wind.
Tomorrow morning, expect wind gusts to strengthen again due to the
high building into the region.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Dry weekend with seasonable temperatures.
- Wind gusts ramp up on Saturday, relax for Sunday.
-------------------------------------------------------------------
High pressure begins to build back in on Saturday in the wake of
Friday night's cold front. The story of the day will be wind
gusts through the afternoon as a northwesterly pressure gradient
tightens. NBM 24 hour max wind gust suggests a 40-60% chance of
>30 mph, highest in the ridges and north of Pittsburgh. BUFKIT
sounding momentum transfer also supports this, although one
limiting factor could be a shallower mixed layer not tapping
into the highest wind aloft and suppressing gusts a little bit.
Either way, it will be a breezy day and the mixing is also going
to help dew points drop in the afternoon in cool, dry northwest
flow. Opted to err toward the lower side of the distribution
for afternoon dews as HREF probabilities for <30F reach 80-90%
south and west of Pittsburgh. The displacement of the higher
wind from the lower dew points may help alleviate more
widespread fire weather concerns, but will still have to monitor
for a low end threat if we really capitalize on the mixing of
dew points and wind gusts. Lows Saturday night are favored to
cool off to below normal with a mostly clear sky and a relaxing
wind as the gradient weakens.
High pressure remains dominant on Sunday with plenty of sun and deep
mixing again supporting a lowering of afternoon dew points. With
weaker flow aloft and little of a gradient with the high positioned
closer overhead, wind will be less of a concern. Will again see low
temperatures dip below normal under a mostly clear sky and light
wind with low dew points.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:
- High confidence dry weather and warming temperatures.
- Next chance for rain comes late week.
-------------------------------------------------------------------
Upper ridging builds into next week as high pressure establishes at
the surface providing high confidence dry weather through mid-week.
There's some ensemble uncertainty on the depth of the departing
trough and how high heights climb into Monday but with minimal
effect on Monday's highs locally; 60+ degrees is favored with
highest probability from Pittsburgh and south regardless of trough
depth while upper 50s are more likely north of Pittsburgh,
especially in a deeper trough solution dominated by the ECMWFE.
Ensembles migrate the high east gradually through mid-week which
should foster some return flow on its backside boosting temperatures
higher each day. Despite clustered ensembles continuing to exhibit
uncertainty in the strength and orientation of the ridge by mid-
week, confidence is very high in the establishment of said ridge
with differences displaced to our north as a wave rides atop it.
Thus impacts locally appear small as we're safely tucked under the
ridge with the most variance in heights displaced to our north and
west; probability for >588 dm into our area is increasing. The
spread in local area temperatures between 25th/75th percentile is
small (2-4 degrees) with probability of 70 degrees at 80+% on
Wednesday and Thursday (80F is not out of the question but less
likely). All that said, confidence in another warmup to above
average temperatures next week is high.
Guidance suggests the next impactful system for our area will arrive
late in the period (Thursday or Friday) as low pressure crosses the
Great Lakes and a cold front crosses the area. Confidence in timing
and rainfall amounts with this system is low for now.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
Predominantly mid and high level clouds continue to fill in
across the region ahead of an approaching cold front. Lowering
cigs (5-6kft) and scattered showers accompany the front as it
moves through the area late this evening. S-SW wind around 10kt
ahead of the front shift to northwesterly after FROPA as cigs
lower to MVFR (IFR possible north of I-80) in a cold advection
regime behind the front.
.Outlook...
VFR is expected to return Saturday through Tuesday as high
pressure builds across the region.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...MLB
NEAR TERM...Lupo
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...Cermak
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 25, 2:58 PM EDT---------------
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