132
FXUS61 KPBZ 080030
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
730 PM EST Fri Feb 7 2025

.SYNOPSIS...
Dry weather is expected through tonight as high pressure moves
across the region. Crossing low pressure returns a wintry mix to
the area Saturday and Saturday night. Dry weather returns Sunday
under high pressure.

&&

.NEAR TERM /THROUGH SATURDAY/...
KEY MESSAGES:

- Dry weather continues most of tonight with a slight chance of
  winter weather by daybreak south of I-70.

-----------------------------------------------------------------

Evening satellite completely cleared out for much of the area,
but high to mid clouds will progress in overnight with the next
incoming low. Clearing has allowed temperatures to cool
effective in the early overnight, with a nearly 100% chance of
sub-freezing lows to start the day. The only question remains
how fast will precipitation move in? Current guidance has at
least a light freezing rain or snow by daybreak in the higher
terrain of West Virginia with more uncertainty for the lowlands.
Should precipitation arrive earlier, it may be able to more
effective utilize the overnight cool temperatures and wet-bulb
effects. At this time this remains lower probability (less than
20% or so and confined to West Virginia). More on snow and ice
tomorrow are included in the short term.


&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Wintry mix returns for portions of the region
- Winter Weather Advisories for the WV and PA higher terrain,
  and areas north of PIT
- Dry weather Sunday

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A shortwave trough will advance eastward from the Midwest on
Saturday, as surface low pressure develops and tracks along the
OH River. Increase ascent in warm advection, and jet support
aloft, should result in precipitation overspreading the region
through the day. Precipitation approaching the area in the
morning should run into dry air in place. Some of this precip
could reach the ground as light snow or freezing rain, though
POPs/confidence of this occuring are low.

Precipitation coverage should increase especially in the
afternoon and evening as the surface low approaches, and pulls a
warm front into SW PA. Warm advection will occur on the eastern
side of the low, with sounding, 850mb temperatures, and critical
thicknesses indicating precipitation should be in the form of
rain for much of the area south of Rt 422. Areas to the north
and in the ridges are likely to see mainly freezing rain. Some
snow could persist in colder air aloft north of I 80, though
even these areas should transition to freezing rain by late
afternoon/evening.

A Winter Weather Advisory has been issued for the ridges and for
areas generally north of Pittsburgh. The highest confidence
exists in these areas for prolonged freezing rain, which will
cause primarily hazardous travel. Areas just to the south of the
advisory could see a brief period of freezing rain, though
confidence was too low to include in the advisory at this time.
Will mention this in the Hazardous Weather Outlook, indicating
an expansion of the advisory is possible.

The low is progged to cross SW PA Saturday evening, exiting the
region overnight. Precipitation should quickly end from west to
east as the low exits, though the ridges could see low chances
for drizzle, freezing drizzle, or flurries into early Sunday
morning.

Generally dry weather returns Sunday and Sunday night as high
pressure builds across the Upper Ohio Valley region.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Dry Monday with residual cloud cover.
- Early week disturbance returns accumulating snow chances but with
  low to moderate confidence at this time.
- Continued unsettled pattern through the week with a second
  system expected to bring precipitation by Thursday.
-------------------------------------------------------------------

On Monday, a surface high pressure across the Midwest extends
ridging into our area. A stalled boundary from the weekend system
will park off to our south across the Carolinas with residual
moisture locally providing some cloud coverage that should dwindle
some as the day progresses with highs just a couple degrees below
normal.

The pattern then becomes more active headed into Tuesday as
ensembles develop surface low pressure along the aforementioned
stalled boundary and lift it back north. The track and strength of
the low will be of importance for what kind of potential winter
weather impacts we see locally. Ensembles are in relatively good
agreement that the low tracks up the East Coast but differ on exact
track. A strong surface high pressure across the Dakotas will slide
toward the Great Lakes and its positioning will be a primary driver
of said path. Latest ensemble runs have all taken a south and
eastward shift in QPF footprint suggesting the area with the higher
probability for accumulations for our area will be in northern West
Virginia (Preston and Tucker counties) with a 45-55% chance of
advisory criteria (3 inches). Will have to await better agreement
before honing in on totals.

The unsettled pattern continues through the week as ensembles eject
a deeper trough out of the Four Corners region with uncertainty on
its depth and speed. The grand ensemble mean brings another round of
low pressure moving up the eastern seaboard similar to the Tuesday
one and ramps up precip chances Wednesday night into Thursday. The
track and strength is going to be of importance for local effects
and brings a chance for mixed precipitation.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Widespread VFR conditions are likely through 12Z under high
pressure; mid and high level clouds will continue to increase
from the southwest during the overnight hours with variable
winds.

A new low pressure system is expected to enter the region late
tomorrow morning, cig and vis restrictions are likely for all
sites. Cigs will likely fall rapidly to IFR between 17Z and 20Z
(from south to north) with increasing low-lvl moisture and warm
air aloft. Precip type for areas south of PIT will likely be
rain (MGW/ZZV/HLG), FKL/DUJ will likely experience freezing rain
after 19Z through at least 00Z with cold sfc under southeast
flow. For AGC, PIT, LBE, and BVI there is a 3 to 4 degree spread
in temps late morning/early afternoon that could prompt either
rain or freezing rain; PROB30 -FZRA was added with this latest
forecast package.

The heaviest precip is expected between 22Z to 01Z, as the
center of the low ventures over western Pennsylvania. Low-lvl
wind shear (35kt to 40kts) is expected briefly in northern West
Virginia.

There is also the potential for lightning for the following TAF
sites during this period: HLG/AGC/MGW. Hi- Res model soundings
suggest elevated instability and strong vertical velocity could
prompt -TSRA. TEMPOS were added to several sites to cover the
potential of low vis due to heavier convection. However, -TSRA
was NOT added to the forecast with this latest package until
confidence increases on the timing and occurrence.


Outlook...

Widespread IFR conditions are likely between 00Z to 12Z Sunday
with high amounts of low-lvl saturation. However, precip chances
will likely diminish between 03Z to 05Z from west to east with
increase mid-lvl subsidence.

VFR returns between 18Z to 21Z Sunday under building high
pressure.

Increase cold, northwest flow early Monday morning may return
MVFR status to sites north of PIT before returning to VFR.

Restrictions and snow are likely Tuesday with crossing
low pressure. Another in a series of low pressure systems will
maintain restriction and snow chances through Wednesday.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory from 1 PM Saturday to 1 AM EST Sunday
     for PAZ007>009-013>016-022-074-076>078.
OH...None.
WV...Winter Weather Advisory from 7 AM to 7 PM EST Saturday for
     WVZ512-514.

&&

$$

SYNOPSIS...WM
NEAR TERM...Milcarek
SHORT TERM...WM
LONG TERM...MLB/Lupo
AVIATION...Hefferan