PBZ issues Area Forecast Discussion (AFD) at Oct 28, 1:53 AM EDT030
FXUS61 KPBZ 280553
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
153 AM EDT Tue Oct 28 2025
.SYNOPSIS...
Dry, seasonable weather today will give way to widespread rain
and below average temperature starting Wednesday evening
through the end of the week. Periodic precipitation chances and
below normal temperature is favored to continue into next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Dry and seasonable weather today with some high clouds to the
south.
---------------------------------------------------------------
As deepening of an upper level closed low and surface
cyclogenesis occurs near the western TN River basin, the Upper
Ohio River Valley will remain under influence of high pressure
to the northeast. Lower heights and cooler air aloft will cap
diurnal heating potential today despite mostly sunny skies (save
for high cirrus south of I-70). The near average high
temperature may end up feeling a bit cooler due to breezy
easterly flow that may occasionally gust 20-25 mph (up to 35 mph
along WV higher terrain).
Little change in pattern dynamics is expected overnight, meaning
mostly clear skies with a mixed boundary layer featuring steady
easterly surface wind. Areas of frost may develop (favoring
northwest PA) but occurrence may be more in valley locations
that are able to have the surface wind decouple.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
KEY MESSAGES:
- Dry start to Wednesday turns wet by the night.
- Widespread rain favored thereafter, with below normal
temperature and periods of gusty wind.
----------------------------------------------------------------
The upper Ohio River Valley will see the phasing of two upper
level troughs that will draw surface low pressure northward to
the Mason-Dixon line Thursday before transitioning to a
weakening, negatively tilted trough/surface low combo entering
the New England region. The basic result is a multi-day rain
event with below normal temperature through this period.
For Wednesday, high pressure and positioning of the low farther
south will allow for a dry start to the day but see an expanding
cloud shield that will inhibit diurnal heating (resulting in
slightly cooler high temperature readings). Primarily driven by
upper jet dynamics but with some orographic convergence along
the WV higher terrain, rain is favored to overspread the region
starting Wednesday evening through Thursday morning. Subtle
variances in low positioning exist that puts some doubt in
location of a banded axis of heavy rain but ensembles favor its
positioning SE of the region. By Thursday morning, there is only
a 20-30% chance for a location to have received greater than 1"
of rain as the lack of instability will limit rainfall rates
despite PWATs near the 90th percentile. The one potential impact
item will be downslope wind early Thursday morning if a low-
level inversion can setup at the ideal height AND a subsequent
low-level jet creates enhanced downslope wind; probability of
occurrence appears low at this time given variability on
positioning of these features.
For Thursday, the upper trough will begin to weaken and slowly
tilt negatively as it translates of the upper Ohio River Valley;
the surface low positioning may vary but should see a late-day
transition to coastal low. Widespread light to occasionally
moderate rain is likely that generally is an all-day type rain
but there is potential for some dry intrusion works in from the
south to create pockets that experience precipitation-free
periods. As the low exits Thursday night, TROWAL-like moisture
near the occluded low favors maintenance of precipitation
chances favoring west-facing upslope locations as boundary layer
wind rotates to the NW.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
KEY MESSAGES:
- Residual cool advection in NW flow maintains areas of showers
with low probability snow accumulation
- Active pattern favored that would create periodic
precipitation chances
-------------------------------------------------------------------
Ensemble models favor troughing of some depth lingering over the
region as the prior low pressure systems moves through New
England. Weak cold advection within the WNW flow may maintain
showers for northwest PA and the higher terrain with an
occasional sprinkle elsewhere. 850mb temperatures a likely to be
near or just under 0 degrees C, meaning any precipitation that
falls during the early morning/late evening in the high terrain
offers some chance to mix with or be snow; but there is less
than 10% probability of accumulating snow (due to wet grounds
and lack of colder air).
Saturday may feature brief shortwave ridging as the next upper
trough aims to traverse the region, meaning brief dry weather
with moderating temperature is possible. However, long range
analysis suggests that trough (and other shortwaves) may
potential continue the active pattern that features periodic
precipitation chances and near to below average temperature
into early next week.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR conditions are projected to continue through tomorrow night,
with only high clouds at times. A continuing pressure gradient
will keep easterly wind up to around 10 knots overnight. This,
plus dry low-level air, will negate fog potential. Once mixing
commences by midday Tuesday, wind should become gustier, with
15-20 knot peak values during the afternoon that should subside
by sunset.
.OUTLOOK...
The next system could return rain and restriction chances from
the south by late Wednesday, with restrictions appearing
increasingly likely for Thursday and Friday. Breezy conditions
also return during the latter half of the week as a surface low
pressure passes south of the area.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...CL
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 28, 1:53 AM EDT---------------
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