PBZ issues Area Forecast Discussion (AFD) at Aug 2, 3:21 AM EDT197
FXUS61 KPBZ 020721
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
321 AM EDT Fri Aug 2 2024
.SYNOPSIS...
Showers and thunderstorms will continue at times through
Saturday as a slow moving trough of low pressure crosses the
region. Some of the storms could contain locally heavy rainfall
and gusty wind. Mainly dry weather returns Sunday.
&&
.NEAR TERM /THROUGH TODAY/...
KEY MESSAGES:
- Showers and thunderstorms this morning
- Locally heavy rainfall possible
- Scattered showers and thunderstorms this afternoon, some with
gusty wind
-------------------------------------------------------------------
A shortwave trough will continue to cross the Upper Ohio Valley
region this morning. Clusters of showers and thunderstorms will
continue until the passage of the trough. The latest
mesoanalysis MU CAPE from 500-1000 j/kg. Instability should
continue to gradually wane through sunrise, though will still be
sufficient to maintain thunderstorms. Some of the stronger
storms have produced wind gusts to 30 mph and heavy rainfall.
The shortwave will complete its passage by mid-late morning.
Subsidence behind the wave should result in a lull in the
precipitation from late morning through early afternoon.
Building diurnal instability, and low convective temperatures,
should result in additional scattered showers and thunderstorms
developing through the afternoon. Coverage is expected to be
highest near a surface boundary north of I 80, and across Ohio
where another shortwave trough will approach later in the day.
Locally heavy rain is possible this afternoon, though any flood
potential would likely be due to training. The Storm Prediction
Center has included the area in a marginal risk for severe
storms this afternoon, mainly due to a damaging wind potential
with dry mid level air in place. Will continue to mention these
potential impacts in the Hazardous Weather Outlook.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Scattered showers and thunderstorms continue tonight
- Periodic showers and thunderstorms continue Saturday
- Mainly dry Sunday, outside of the higher terrain areas
-------------------------------------------------------------------
The next, stronger shortwave trough will slowly approach the
Upper Ohio Valley region tonight. Scattered showers and
thunderstorms are expected to continue, though instability
should wane overnight. HREF output indicates a MU CAPE around
500 j/kg overnight tonight. Any severe potential should quickly
diminish this evening.
The trough will then slowly cross the Upper Ohio Valley region
on Saturday, with more widespread showers and thunderstorms
expected. The greatest coverage should be in the afternoon with
diurnal instability. Locally heavy rainfall will also remain
possible on Saturday.
The trough axis is expected to be across the Laurel Highlands
and the WV higher terrain by Sunday morning. While dry weather
is expected to the west of the trough, shower and thunderstorm
chances will continue especially for the higher terrain areas of
WV until the trough exits Sunday night.
Temperatures are expected to average above seasonable levels,
especially on Sunday as highs return to the mid 80s to near 90.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Shower and thunderstorm chances Tuesday
- Mainly dry for the remainder of the period
-------------------------------------------------------------------
Model ensembles indicate the Upper Ohio Valley region will be
under a broad upper trough from the early to middle part of the
week. A shortwave embedded in the trough will result in shower
and thunderstorm chances Tuesday into early Wednesday as it
crosses the region. Otherwise, surface high pressure should
maintain mainly dry weather through the long term period.
Temperatures are expected to be above average to start the week,
returning to more seasonable levels by mid week.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Through 12z, persistence with some blend of model guidance used
to best track timing of showers and isolated thunderstorms
moving roughly ENE through the region ahead of an upper level
shortwave. Anticipate gusts generally less than 30kts while the
heavier rain cores reduce cigs/vsby toward MVFR levels.
A boost of boundary layer moisture along with a cooler
temperature profile should result in a period of MVFR (localized
IFR) cigs post-convective movement during the 12z-18z time
frame. Diurnal heating/mixing combined with subsidence behind
the wave should return widespread VFR heights to all terminals
while any additional convection remains isolated (probability
too low for mention).
Ensembles favor additional shortwave movement leading to another
round of convection near or just after the end of the TAF period
while lifting NE through the region.
.Outlook...
Approach of a closed upper level low should increase moisture
into the region Friday night into Saturday, leading to periodic
showers/thunderstorms and patchy morning cig/vsby restrictions.
Expect lowering precipitation chances Sunday into Monday as the
upper low exits east.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...Frazier
Source:
PBZ issues Area Forecast Discussion (AFD) at Aug 2, 3:21 AM EDT---------------
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