PBZ issues Area Forecast Discussion (AFD) at Aug 18, 1:19 PM EDT297
FXUS61 KPBZ 181719
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
119 PM EDT Sun Aug 18 2024
.SYNOPSIS...
Scattered showers along with some isolated afternoon thunderstorms
will continue through Monday, followed by dry, seasonably cool
conditions the remainder of the week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Isolated to scattered showers through the day.
- Isolated thunder, no severe.
-------------------------------------------------------------------
A slow-moving upper low north of the area will continue to
transition east as a weak cold front currently moving into
western PA crosses the region. Isolated to scattered showers
and possibly a few non-severe storms are expected through the
afternoon given limited instability and shear. Additionally,
coverage should limit the potential for diurnally driven
thunderstorms during the afternoon. PWATs remain near the 90th
percentile (1.6"), but storm motion and weak instability are
likely to preclude more than an isolated flash flooding threat.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
KEY MESSAGES:
- Residual showers with cooler temperatures are likely on
Monday, diminishing Monday evening.
-------------------------------------------------------------------
The trough will shift east overnight, with the axis crossing
Pittsburgh early Monday morning. This will leave the region
under cool northwest flow. Residual diurnally-driven showers
are possible on Monday with some lake enhancement possible
north of I-80. These will eventually diminish Monday evening.
Area temperatures will drop well below the daily average,
resulting in daily highs in the 60s and lower 70s. Overnight
lows will fall back into the 50s...with lows dropping down to
values not seen since early June.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
KEY MESSAGES:
- Long range ensembles support dry weather with seasonally cool-
to-near-normal temperature through the week.
-------------------------------------------------------------------
Long range ensembles indicate that upper low pressure will
slowly meander across the Northeast through much of the week
while fairly amplified ridging continues over the Rockies. This
puts us squarely under northwest flow for the first half of the
week, favoring dry conditions with any precipitation reliant on
strong shortwaves. Tuesday will feature cool conditions similar
to Monday (~10 degrees below average), but temperatures should
slowly climb through the week with building surface high
pressure and eventual return flow by late week.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
Low stratocumulus coverage has overspread the area this morning
resulting in restrictions to IFR/LIFR at most sites.
Probabilistic guidance indicates a slow recovery through the
early afternoon hours as the low-levels remain saturated with no
distinct intrusion of drier air to speak of. Daytime mixing is
favored to eventually return VFR after 18-19z (a bit later for
FKL/DUJ), but morning cloud coverage will delay the mixing
process.
An uptick in showers and thunderstorms is anticipated again with
afternoon heating beneath the exiting system, but with limited
instability to work with, coverage is expected to be less
organized. Owing to spatial and temporal uncertainty of the
precipitation, carried VCTS at all sites during the most
favorable time period this afternoon, but confidence in TS at
any site is low. A brief period of VIS restrictions is possible
in any shower. Expect southwest wind generally 5-10 knots on
Sunday but could fluctuate as surface troughs cross and even
freshen a bit with a few gusts at times.
Guidance then favors a 50-70% chance of IFR restrictions
returning overnight Sunday night with remnant boundary layer
moisture. Given a light gradient wind still in place,
restrictions should come from lowering CIGs.
.Outlook...
Periodic restrictions and showers and thunderstorms are possible
through early Monday as low pressure slowly crosses the region.
VFR conditions return by Tuesday under high pressure.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...Rackley/88
LONG TERM...Rackley
AVIATION...MLB/Shallenberger
Source:
PBZ issues Area Forecast Discussion (AFD) at Aug 18, 1:19 PM EDT---------------
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