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181
FXUS61 KPBZ 120002 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
802 PM EDT Sat May 11 2024

.SYNOPSIS...
Rain showers and scattered thunderstorms are likely through
tonight with passage of a cold front. Dry and more seasonable
weather will develop through Monday before the next round of
upper level disturbances increase precipitation chances midweek.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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KEY MESSAGES:

- Severe weather potential ending this evening
- Scattered showers remain
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The latest mesoanalysis shows shows an area of sfc based CAPE at
500 j/kg across Westmoreland and Fayette counties. Efective
0-6km shear remains at 35-40kt in this same area. A veering
profile had also been supporting rotation and isolated tornadoes
across portions of the region. The CAPE and shear will be
diminishing through 830 PM, with the severe weather potential
exiting the forecast area with the passage of a cold front.

An upper low across southern Ontario and the Lower Great Lakes
region will drop southeward overnight. This should maintain
scattered showers across the region.
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&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Dry weather likely, saving for passing disturbances near far
  northwest PA.
- Above normal temperature likely by Monday.
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Shortwave ridging ahead of a deepening central CONUS upper
trough will promote dry weather and rising temperature through
Monday. Residual NW flow Sunday with the surface high just to
the west will limit the degree of temperature rebound. But as
heights further increase Monday and the surface high positions
along the eastern coast, warm advection in southwest flow will
drive temperature to about 5 degrees above the daily average.

Any precipitation chances during this period will be tied to
shortwave movement well to the north and the positioning of a
developing warm front near the region. Latest trends lift the
warm front and upper wave north of the region, but will
maintain low probability chances in northwest PA in case those
trends change.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Midweek showers and thunderstorms likely, with limited severe
  and flooding threats.
- Dry conditions likely to end the week.
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The sagging central plains trough will meander eastward across
the TN River Valley Tuesday into Wednesday, with weak shortwaves
likely traversing the Upper Ohio River Valley ahead of the wave.
Showers and thunderstorms are likely through the
afternoon/evening Tuesday, though positioning of forcing and
potential influence of shortwave ridging in the mid-Atlantic
could alter the areal coverage/probabilities. Early analysis
suggests that the instability/shear parameters are unlikely to
promote much severe threat, while forcing/deep moisture should
remain south of region and limit a flooding threat (only 20%
probability of seeing greater than 1" of rain over 24 hours at
any location).

The trough will progress towards the eastern coast Wednesday,
with low positioning and depth dictating how long precipitation
will linger in the Upper Ohio River Valley. Ensembles are
confident in ridging developing over the lower Ohio River
Valley late week that should promote a few day period of dry
weather and above normal temperature.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
After the exit of a mid-level warm frontal rain band, dry
advection aloft may create a window of drier weather at TAF
onset before scattered to numerous showers and thunderstorms
develop along the cold front. Upper level support and greater
moisture depth will favor northwest PA for this convective
activity, with decreasing probabilities moving towards KZZV.
Sufficient wind flow aloft, and a low freezing level, should
result in gusty wind and small hail in some of the storms.

Shower activity will slowly dissipate overnight (ending later in
NW PA) with the exit of the surface cold front and upper level
trough axis. Cold advection by Sunday morning should return MVFR
to localized IFR stratocu to most terminals before high pressure
and subsidence lift area cigs to VFR levels.

.Outlook...
VFR favoring through Monday under the influence of high
pressure.  Slow progression of the next upper level trough
system means increases precipitation and restriction potential
Monday night through Wednesday night, peaking Tuesday night into
Wednesday.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...WM
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Frazier