PBZ issues Area Forecast Discussion (AFD) at Jan 6, 1:19 PM EST995
FXUS61 KPBZ 061819
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
119 PM EST Mon Jan 6 2025
.SYNOPSIS...
A winter system will continue to impact the region through late
this evening and overnight. The highest snowfall amounts will
be south of Pittsburgh where a Winter Storm Warning is in
effect. Snow will end from north to south through tonight. Cold
weather continue throughout the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Lowland Winter Storm Warning/Winter Weather Advisory in effect
through 7pm Monday.
- Winter Storm Warning continues until tomorrow 7am for preston
and Tucker counties.
- Another 1 to 3 inches expected across the lower elevations and
PA ridges, another 2 to 5 inches in the higher terrain.
- Snow showers activity will be focused along the ridges late
tonight
--------------------------------------------------------------------
Current conditions across the forecast area feature a northern
swath of snowfall beginning to dissipate as a new southern band
of snow begins to develop and move into southeast OH and SW PA.
Even with this band not looking as impressive as the northern
one was, still there could be 0.5 inch/hour snowfall rates with
this. In fact, the probs from the HREF for 3 inches of snow or
more is 40% to 50% in the lower elevations and near 90% in the
higher terrain. This band will mean that another 2 to 5 inches
is possible through dawn on Tuesday morning for the impacted
regions. As much of the energy has transitioned to the parent
low now developing over south central VA and beginning to shift
to the coast. This will bring the back end of the deformation
zone through the forecast area, effectively ending the synoptic
snowfall event this evening or early overnight. The wind will
shift to the northwest tonight just after 00Z as the focus
shifts back to a more lake effect to the area and mainly the
higher terrain as snow showers are expected.
An additional 1-3 inches of snow could accumulate along the
West Virginia ridges/Laurel Highlands due to upsloping tonight
into early Tues morning, hence the Winter Storm Warning in the
higher terrain continuing through 12Z Tuesday.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:
- Lake effect snow showers expected to begin early Tues and
continue through Tues night
--------------------------------------------------------------------
As low-lvl winds shift from north to northwest, lingering bands
of snow from lake effect will evolve in isolated areas. These
snow showers will likely continue through Tues night in areas of
weak convergence within the boundary layer with available
moisture from the sfc to 800mb.
Below average temperatures will continue in this forecast
period.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Confidence is high that lake enhanced snow showers will
continue Wed
- Dry but cold conditions expected Friday under ridging
- There is the potential for a large-scale weather disturbance
to impact portions of the region Saturday.
--------------------------------------------------------------------.
The grand ensemble of long range models are in agreement that
troughing over the Great Lakes will persist Wednesday and
Thursday. This overall means that lake enhanced snow showers
will continue across the region. The snow squall parameter is
considered low for bursts intense snow bands so travel impacts
are expected to remain low.
For Friday, models are in agreement that a ridge axis will build
across the Great Lakes in the morning. With winds shifting from
the west, snow showers activity will dissolve and clearing is
likely. With radiational cooling under a clear sky,
temperatures will very cold early Friday. Single digits to near
zero temperatures are likely in a large portion of the region.
Models start to vary in the timing of a trough axis ejecting out
of the west late Friday into Saturday. About 40% of the variable
with models is based on timing. This is important disturbance to
keep an eye. If the trough phasing with a cut- off low in
southern California, a new low pressure system could form and
track towards the East Coast. With high confidence in cold
temperatures throughout this period, this low could create
winter weather impacts Saturday.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Another period of steady snow and IFR conditions are unfolding
across our southern terminals as an upper trough axis crosses.
These steadier snow showers are largely confined south of PIT
and PIT looks to ride the line of MVFR snow to the north and IFR
snow to the south. Improvement to MVFR is expected by evening
as steady snow ends with the passage of the upper trough, though
scattered snow showers are then expected in cold NW flow off of
the Great Lakes.
A tight surface pressure gradient will result in NE wind gusts
to around 20 kt, with a WSHFT to the NNW this evening after the
passage of the upper trough.
Several high-res models are trying to paint a possible huron
connection lake-effect band moving through the region between
08-12z Tuesday. This band could bring the return of IFR snow to
terminals in its way. Confidence in timing and placement of this
band remains low at this time and it has been kept out of the
18z TAFs.
High pressure and drier air begins to filter into the area
tomorrow. However, with NW flow and moisture trapped beneath the
subsidence inversion it looks likely that MVFR CIGs remain at
terminals through the remainder of the 24hr TAF period.
Outlook...
The Upper OH Valley region will remain in a cold NW flow
pattern, under broad upper troughing through much of the week.
Scattered snow showers and periodic restrictions are expected.
Improvement is expected Friday as high pressure builds in.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 7 PM EST this evening for PAZ021-
077-078.
Winter Storm Warning until 7 PM EST this evening for PAZ029-
031-073>076.
OH...Winter Weather Advisory until 7 PM EST this evening for OHZ039-
048>050.
Winter Storm Warning until 7 PM EST this evening for
OHZ057>059-068-069.
WV...Winter Weather Advisory until 7 PM EST this evening for WVZ001-
002.
Winter Storm Warning until 7 PM EST this evening for WVZ003-
004-012-021-509>511.
Winter Storm Warning until 7 AM EST Tuesday for WVZ512>514.
&&
$$
SYNOPSIS...Shallenberger
NEAR TERM...Shallenberger
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...AK
Source:
PBZ issues Area Forecast Discussion (AFD) at Jan 6, 1:19 PM EST---------------
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