PBZ issues Area Forecast Discussion (AFD) at Feb 23, 8:16 AM EST853
FXUS61 KPBZ 231316
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
816 AM EST Sun Feb 23 2025
.SYNOPSIS...
Above normal temperatures will prevail this week, with a slight
chance of light showers on Tuesday, and more widespread
precipitation later Wednesday through Thursday with crossing
low pressure.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Dry weather and rising temperature continue
- Timing and degree of cloud cover this afternoon may limit warming
for northern zones.
----------------------------------------------------------------
Surface high pressure centered south of the region will continue
to promote dry weather as the combination of insolation and weak
warm advection in southerly flow raises temperature a few more
degrees from Saturday's readings. There is some uncertainty in
the degree of that rise, as shortwave movement to the north will
increase mid and high level cloud cover during the afternoon
and evening. The timing and thickness of this cloud cover is
expected to greatly impact this trend for locations generally
north of I-70. The lack of lift or surface forcing will ensure
no precipitation occurs as the shortwave crosses.
Dry weather will persist overnight as southerly flow begins to
increase as a surface low traverses north of Michigan. Clear
skies should allow for strong radiational cooling that fosters
near normal low temperature, but higher terrain or areas that
can stay mix may see lesser temperature drops than forecasted.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:
- Above average temperature favored Monday/Tuesday
- Precipitation chances favor northwest PA Tuesday with light
accumulations
------------------------------------------------------------------
There is high confidence in dry weather persisting Monday as
southern ridging helps shunt the low north of Michigan due east.
Strengthening southwesterly flow through the day will aide in a
high probability (near 100%) in above normal temperature but
late date high level cloudiness may act to soften potential
rises.
A lobe of shortwave activity will develop SE of Wisconsin Monday
night and swiftly move east through the lower Great Lakes
Tuesday morning. Weak moisture depth and little surface lift
means associated precipitation is driven by jet ascent and
generally light (only 20% probability for total accumulations
exceeding 0.10 inches), with jet positioning favoring
precipitation chances over northwest PA. Though early timing may
lead to initial precipitation falling as snow, the favored
precipitation type for the event is rain as 850mb temperature
(60% likelihood) and surface temperature (90% likelihood) are
favored to be above freezing. The shortwave will exit by Tuesday
afternoon and allow surface high pressure to support dry
weather by Tuesday night. Temperature should be near seasonal
averages, with quicker than forecasted west to east cloud
clearing offering potential for slightly higher temperature.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
KEY MESSAGES:
- High confidence in dry weather and above normal temperature
for the majority of the day Wednesday.
- A more active weather pattern develops into the weekend that
suggests periodic precipitation chances and falling
temperature.
-------------------------------------------------------------------
Ensembles exhibit high confidence in dry weather continuing for
a majority of the day Wednesday as the region sits underneath
shortwave ridging and of the first in a series of upper level
troughs. Increasing southwesterly flow ahead of that trough is
expected to aide in creating the warmest temperature and the
highest readings since February 4th. Using 50 degrees as an
arbitrary "warmth" indicator, areas along and south of I-70
currently have 80-90% probability of meeting/exceeding that high
temperature values. Areas generally between I-76 and I-80 show
a 50-70% probability of meeting/exceeding that value.
Shortwave movement through the Ohio River Valley will occur
Wednesday night into Thursday with the surface low tracking
north of the forecast region. There is some variability in the
timing/depth of the initial shortwave that may alter
precipitation onset and progression, but confidence is high on
initial precipitation being rain and fairly widespread (near
100% probability 24 hour total accumulations being less than
0.5 inches).
Uncertainty significantly increases in 500mb pattern evolution
starting Thursday afternoon into the following weekend. Degree
of trough depth, timing of additional shortwaves, and ability to
develop height rises between systems all contribute to an
uncertain long range assessment. Ensemble means currently favor
an active weather pattern with multiple shortwaves moving
through eastern CONUS troughing that would support periodic
precipitation chances and temperature falling below normal once
again.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
VFR conditions and relatively light southwesterly winds will
prevail through the period with sfc high pressure in control.
Increased mid and upper level cloud coverage is expected later
this afternoon and this evening with a crossing shortwave.
Outlook...
A series of shortwaves are expected to drop out of the Great
Lakes next week, bringing periodic restrictions and
precipitation chances throughout the week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...88
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...88
Source:
PBZ issues Area Forecast Discussion (AFD) at Feb 23, 8:16 AM EST---------------
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