FXUS61 KPBZ 201332
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
932 AM EDT Sat Apr 20 2024
.SYNOPSIS...
Seasonably cool temperatures and dry conditions are expected
through the weekend with potential for frost/freezing
conditions both Sunday and Monday morning. Building high
pressure will return above average temperatures mid-week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Dry and relatively cool conditions are expected.
- No Hazardous weather.
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Made adjustments to sky cover this morning based on current
satellite trends. A shield of middle cloud remains in place this
morning, associated with a 300/500mb jet streak and lingering
mid-level moisture, a scenario that was not captured well by the
models. Nevertheless, these clouds should dissipate and/or vacate
the region later this morning with the upper support. For now,
expected the bulk of the NW flow stratocumulus from midday on to
remain north of Pittsburgh, but some scattered clouds will be
possible according to model soundings/cumulus rule guidance.
Elected to add sprinkles in the I-80 region based on model hints
of such and slightly better moisture on model soundings.
However, low-level dry air should largely negate measurable
precipitation. Temperatures appear largely on track for now.
Rest of the discussion...
An upper trough will cross the region today, maintaining cold
advection and resulting in temperatures slightly below average.
Gusty winds will develop during the afternoon as stronger winds
aloft integrate within the boundary layer. NBM probabilities of
wind gusts exceeding 20mph are near 100% with a period of gusts
exceeding 30mph along the timeframe of the trough passage.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Slightly below average temperature and dry weather expected
to continue through the weekend.
- Potential for frost and/or freeze impacts Sunday and Monday
morning.
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High pressure will continue to build in from the west,
maintaining dry conditions through the weekend.
A Freeze Watch was issued for tonight into Sunday morning as
much of the forecast area is now in the growing season and
latest HREF guidance has between a 60% and 80% chance of see
32F or low overnight across the majority of the forecast area.,
Confidence is medium as winds and cloud coverage could be a
limiting factor.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:
- The next low pressure system and associated precipitation
chances is likely for late Tuesday into Wednesday.
- Ridging is favored for the late week period, pointing to
rising temperature heading into the weekend.
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Though ensemble models vary in trough analysis moving across the
southeast U.S. Monday, the outcome remains the same for the
Upper Ohio River Valley: rising heights aloft and the influence
of high pressure will support dry conditions and seasonable
temperature Monday.
There is fairly high consensus on the next upper level trough
and associated surface low to drop from the north central plains
through the Great Lakes late Tuesday into Wednesday. Ahead of
the system, weak warm advection will support above normal
temperature and increasing cloud cover before the system's
arrival. Widespread showers and low probability thunderstorms
are then likely as the system crosses the region. Depth of the
upper trough remains the biggest uncertainty during this period,
which will strongly influence the timing of precipitation
passage and degree of cold advection behind the system.
The late week period will be defined by the progression of the
upper trough through the northeast CONUS and the rapidity of
height rises in its wake. Dry weather will be favored given
high confidence of surface high pressure, with the degree of
temperature recovery in the post-cold front passage environment
dictated by said height rises.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
The forecast remains VFR through tonight. A deck of mid clouds
around 10k feet will continue to cross the region this morning
near/north of PIT, supported by moisture and a jet streak aloft.
From midday on, the passage of a secondary cold front/surface
trough will veer wind to the NW, and an increase in
mixing/surface pressure gradients will promote wind gusts in the
20 to 30 knot range through the afternoon. Scattered to broken
cumulus/stratocumulus are also expected, most numerous north of
I-80, with bases at or above 5k feet. NBM/HREF progs show that
any small chance of MVFR ceilings remains confined to FKL/DUJ.
Wind gusts will diminish this evening, along with daytime
heating-supported clouds, leaving only some cirrus overnight in
westerly flow aloft. These clouds may thicken a bit overnight
while wind goes largely light and variable under surface
ridging.
.Outlook...
High confidence in VFR conditions through a majority of Tuesday
under the influence of high pressure. Passage of a low pressure
system will bring widespread precipitation and restriction late
Tuesday into Wednesday. Ensemble models favor dry weather and
VFR conditions to end the work week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Watch from late tonight through Sunday morning for
PAZ007>009-013>016-020>022-029-031-073>078.
OH...Freeze Watch from late tonight through Sunday morning for
OHZ039>041-048>050-057>059.
WV...Freeze Watch from late tonight through Sunday morning for
WVZ001>004-510>513.
&&
$$
SYNOPSIS...34/88
NEAR TERM...Frazier/CL
SHORT TERM...88
LONG TERM...Frazier
AVIATION...CL