Area Forecast Discussion Issued by NWS Pittsburgh, PA
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000
FXUS61 KPBZ 182306 AAA
AFDPBZ
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
706 PM EDT Thu Apr 18 2024
.SYNOPSIS...
Precipitation chances return early tomorrow with a passing
front, a few thunderstorms may occur. The potential for
frost/freeze impacts increases Sunday and Monday morning.
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.NEAR TERM /THROUGH FRIDAY/...
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KEY MESSAGES:
- Overnight low temperatures will trend above average with
linger low-lvl moisture and cloud coverage increasing with an
approaching disturbance.
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For the evening update...slowed down the onset of the showers
just a bit. A t/td spread of close to 30 degrees this evening
will make it difficult for anything but sprinkles to reach the
ground until surface dewpoints start to rise. 18z model data is
showing an increasing surface southeasterly flow, which will
continue to support the drier air near the surface.
Additionally, as the shortwave associated with the surface from
digs into western Ohio late tonight, minor heights rises are
expected over much of the region, increasing subsidence. Rest of
the forecast in good shape.
The progression of ridging over western Ohio into western PA
this evening will support mainly clear skies this evening.
Clouds will increase overnight amid warm, moist advection ahead
of the next shortwave system set to traverse the Ohio River
Valley Friday. Therefore, above average temperatures will
continue into the overnight hours.-- End Changed Discussion --
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.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Showers and low probability thunderstorms are expected ahead
of a cold front Friday. Lightning will be the main threat.
- Seasonable temperature and dry weather expected through the
weekend.
- Potential for frost and/or freeze impacts each of Saturday and
Sunday mornings.
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An approaching shortwave and cold front will increase the
chances of showers before dawn Friday. There could be a few
isolated thunderstorms south of Pittsburgh will elevated
instability from lingering dry air from the eroding ridge.
Lightning will likely be the only threat early Friday morning.
The probability of precipitation decreases from west to east
with the passage of the cold front late Friday and decreasing
low-lvl moisture.
Confidence is high that an elongated trough over the Great
Lakes will increase cooler conditions over the weekend. For
Saturday and Sunday, temperatures will trend 5 degrees below
average.
With cooling temperatures, the potential for early morning
frost/freeze conditions Saturday night into Sunday will be
elevated in some areas. For our county warning area, all
counties but Tucker County are experiencing active vegetation
growth. Therefore, frost/freeze products may need to be issued
in the 24 to 48 hours.
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.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:
- A building ridge over the Midwest late Monday will increase
the chances of near or above temperatures early next week.
- Next precipitation chances are likely to be Tuesday into
Wednesday with crossing low pressure. The confidence in
thunderstorms is low.
- Ensembles favor dry conditions outside of that period.
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Dry, quiet weather is anticipated Monday as a ridge, that was
over the central CONUS, advances east. Near to above
temperatures are expected to return.
Precipitation chances return late Tuesday into Wednesday as a
shortwave passes through the Great Lakes region. Trough depth
and axis timing remains varied among ensemble members, but they
all favor a shower environment with low to limited lightning
potential.
Long range ensembles favor ridge building over the western Great
Lakes in response to a deepening trough over the western CONUS
for the late week period. The expectation is for area
temperature to once again rise with any passing shortwave posing
greater thunderstorm potential.
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.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
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VFR is expected through tonight as shortwave ridging builds
across the Upper Ohio Valley region. The ridge will slide east
of the area early Friday morning, as a shortwave trough and
surface cold front approach from the west. Showers are expected
to overspread the region with the approach and passage of the
front, along with deteriorating flight conditions to MVFR.
FROPA is expected to occur W-E from late morning through mid
afternoon, with a WSHFT from S to WNW. Improvement back to VFR
is expected by evening under dry advection and a building
surface ridge, though mid level cigs will continue under a broad
upper trough.
.Outlook...
A ridge of high pressure at the surface will maintain VFR
conditions through early Tuesday. Showers and potential
restrictions return late Tuesday with an approaching cold
front.-- End Changed Discussion --
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.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
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SYNOPSIS...Hefferan
NEAR TERM...Hefferan/22
SHORT TERM...Hefferan/Frazier
LONG TERM...Hefferan/Frazier
AVIATION...WM