PBZ issues Area Forecast Discussion (AFD) at Jan 16, 1:16 PM EST114
FXUS61 KPBZ 161816
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
116 PM EST Thu Jan 16 2025
.SYNOPSIS...
More widespread snowfall is expected Thursday and Thursday
night with heavy snow possible in the Allegheny Mountains.
Another system will cross this weekend before a significant
arctic outbreak and very cold temperatures next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Heavy snow possible in the higher terrain through tonight with
1 to 3 inches possible elsewhere (locally higher possible).
- Cold surface temperatures may increase the potential for
hazardous travel conditions similar to Tuesday.
--------------------------------------------------------------------
Mid-morning update:
Light to moderate high-ratio snow continues to press southeast
across the region this morning. Dry air can be noted on
satellite working through central Ohio brining and end to
stratiform snow. More scattered banded snow showers are expected
to pick up as we move into the midday and afternoon hours.
Road temperatures currently in the low to mid 20s will continue
to support accumulating snow on untreated surfaces. A coating
remains possible on treated surfaces and extra caution is
advised for those out on the roads.
A couple of updates were made to the overnight period to raise
POPs in NW flow on the backside of our departing shortwave. This
change also lightly raised snow totals across NW PA Thursday
night. The rest of the forecast remains on track.
.. Previous Discussion..
A quick-moving shortwave will cross the region today, bringing
widespread light and high-ratio snowfall to the lowlands and
heavy snowfall across the higher elevations.
Thermal profiles remain supportive of efficient dendritic growth
through the day, with initial snow ratios likely around 20:1.
These may become gradually lower through the afternoon as
surface temperatures warm slightly. Initial snowfall will be
stratiform in nature, possibly becoming banded as more scattered
showers develop this afternoon.
Snowfall totals across the lower elevations will remain
generally in the 1 to 3 inch range through this evening, with
locally higher amounts possible with afternoon banding. Much of
the area may end up with lower than the typical 3" Advisory
threshold, but given very cold surface and road temperatures,
impacts from Tuesday's 1-2" snowfall, and the potential for
locally higher amounts under snow bands, the Advisory feels
appropriate. The highest snowfall rates are expected during the
work day (up to 0.25"/hr), with accumulations tapering by the
evening commute; nonetheless, evening impacts are still
possible.
Moderate to heavy snowfall will ramp up in the higher terrain
this afternoon as flow becomes more westerly, enabling enhanced
orographic lift in combination with synoptic forcing. Moderate
snowfall is likely to persist through the evening, eventually
diminishing through the early morning hours. Snowfall in the
higher terrain is likely to total between 4 and 10 inches, with
the highest amounts falling across the highest peaks. Confidence
in warning criteria is high (>90%) and a Winter Storm Warning
remains in effect through tonight.
Light snow and snow showers will likely linger in northwest
flow tonight, clearing early Friday morning.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Gradually warming temperatures into the weekend.
- Dry on Friday with snow, rain, and mixed precipitation
returning Saturday.
--------------------------------------------------------------------
Lingering light snow is possible in northwest flow early Friday,
but this should end shortly after sunrise as ridging aloft
quickly builds across the region. A dry and closer to average
temperature day is expected with highs above freezing for the
southern half of the forecast area.
The northern and southern streams will phase Friday into
Saturday as a deepening trough digs across the eastern US while
surface low pressure crosses to our north. Positioning of the
low will help drive strong warm advection across the region late
Friday into Saturday while pulling in Gulf moisture.
Precipitation chances will return Saturday morning -- initially
as snow in some locations, or low-probability freezing rain --
but quickly transitioning to rain/snow and rain as temperatures
warm. Afternoon temperatures will be near 40F for much of the
region.
Impacts are expected to be minimal unless chances of freezing
rain increase. In the event of freezing rain, ground
temperatures will be quite cold given recent temperatures. A
gradual transition to snow showers is possible on the back side
of the low Saturday night in cold advection and lake-influence,
but the coverage of snow will also depend on the coverage of
Lake ice (more lake ice means less moisture transfer and less
snow). Temperatures will drop into the teens to lower 20s
Saturday night, which may lead to icy conditions anywhere
daytime rain pools.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Snow showers continue on Sunday and Monday in northwest flow.
- Arctic outbreak with dangerously cold temperatures and wind
chills likely next week.
--------------------------------------------------------------------
Light snow showers may continue with northwest flow on Sunday
and Monday, but this will largely depend on ice-free lake
surfaces. As Lake Erie nears full ice coverage, moisture
availability may be limited.
High temperatures on Sunday will drop back into the 20s, with
colder weather still to come.
.. EXTREME COLD MONDAY THROUGH WEDNESDAY ..
Confidence continues to grow in a significant arctic outbreak
early next week, with high confidence in extreme cold
temperatures impacting the area Monday through Wednesday.
The time to begin preparing is now. Frozen pipes are likely.
Rescheduling any events, especially outdoor events, is
encouraged. Once the cold air sets in, avoiding prolonged
exposure to the cold is advised as it may lead to hypothermia.
Frostbite may occur in as little as 30 minutes for exposed skin.
Air will be sourced from northern Canada, near the north pole,
dipping down across the eastern United States beginning Sunday
night. Long-range guidance (NAEFS) suggests that 700mb to 850mb
temperatures could be near the 1st percentile of all historical
guidance for mid-January (temperatures are warmer this time of
near 99% of the time).
There is still modest variability in the guidance depending on
how deep the western trough digs, but in the last 24 hours, the
western trough looks weaker, allowing deeper troughing in the
east. Even in the warmest scenario at this point, daytime highs
would be in the low 10s with lows around zero. The colder end
(and more likely) end of guidance suggests high temperature in
the single digits for at least Monday and Tuesday with lows
approaching -10 for most Tuesday and Wednesday morning. The take
home message: regardless of the exact, there is high confidence
in extreme cold impacts.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Snow showers continue across the area this afternoon with
conditions generally ranging from MVFR to IFR (locally LIFR in
the heaviest bands). Snow will generally taper from west to east
after 00z, lingering longest over the ridges where light snow
showers may continue into early Friday morning. Low-end MVFR or
IFR ceilings persist overnight into Friday morning before
improving Friday afternoon, though most terminals won't return
to VFR until just beyond the current 24-hr TAF window.
Winds remain generally out of the west or southwest with
occasional gusts to around 20 knots this afternoon then
settling overnight.
Outlook...
Improvement is expected Friday afternoon under a ridge of high
pressure, but another system brings restrictions and rain/snow
back to the area Saturday through the weekend. A strong arctic
front will bring bitter cold temperatures near or below zero to
the area Monday and Tuesday.
&&
.CLIMATE...
A period of anomalously cold weather is expected to pass Monday
through Wednesday that will challenge many standing January
temperature records. Attached below are the standing
climatology for local sites. Pittsburgh has a full record,
while other sites are partial records and may not be fully
reflective of historical temperatures:
January 20th: High Minimum Low Minimum
Pittsburgh, PA 1F (1985) -18F (1985)
Wheeling, WV 13F (1940) -1F (1940)
Morgantown, WV 3F (1985) -17F (1985)
New Philadelphia, OH -3F (1994) -22F (1994)
Zanesville, OH -2F (1985) -17F (1985)
DuBois, PA -2F (1985) -19F (1985)
January 21st: High Minimum Low Minimum
Pittsburgh, PA 5F (1984) -18F (1985)
Wheeling, WV 12F (2000) -2F (1924)
Morgantown, WV 2F (1985) -18F (1985)
New Philadelphia, OH -8F (1985) -19F (1985)
Zanesville, OH 7F (1985) -22F (1984)
DuBois, PA 0F (1985) -22F (1985)
January 22nd: High Minimum Low Minimum
Pittsburgh, PA 10F (1961) -14F (1936)
Wheeling, WV 11F (2014) -4F (2014)
Morgantown, WV 11F (2014) -5F (1984)
New Philadelphia, OH 5F (1984) -15F (1994)
Zanesville, OH 13F (2014) -11F (2011)
DuBois, PA 8F (2013) -11F (1984)
Below is the lowest daily high and daily low temperatures of the
21st century. This encompasses all days of all months running
from January 2000 to present:
High Minimum Low Minimum
Pittsburgh, PA 4F (01/07/2014) -10F (01/17/2009)
(02/20/2015)
Wheeling, WV 5F (01/07/2014) -10F (01/07/2014)
Morgantown, WV 7F (01/07/2014) -9F (01/28/2014)
(01/28/2014) (01/29/2014)
New Philadelphia, OH 6F (01/16/2009) -18F (01/28/2014)
(01/28/2014)
(02/15/2015)
Zanesville, OH 6F (01/28/2014) -20F (01/29/2014)
DuBois, PA 0F (01/07/2014) -17F (02/16/2015)
In addition, Pittsburgh has not seen a daytime high below 4F
since January of 1994. Pittsburgh has also has not seen 2
consecutive days of high temperatures less than 10F since
January of 1997. If you extend this statistic to 3 days, you
would have to go back to February 1899.
The last time Pittsburgh's minimum temperature was less than or
equal to -5F was December 2022. Last time it was below or equal
to -10F was February 2015. For 2 consecutive days of lows less
than or equal -10F, you would have to go back to January of
1994.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 4 AM EST Friday for PAZ007>009-
013>016-020>022-029-031-073-075-077-078.
Winter Storm Warning until 7 AM EST Friday for PAZ074-076.
OH...Winter Weather Advisory until 4 AM EST Friday for OHZ039>041-
049-050-058-059-068-069.
WV...Winter Weather Advisory until 4 AM EST Friday for WVZ001>004-
012-021-509-510.
Winter Storm Warning until 7 AM EST Friday for WVZ511>514.
&&
$$
SYNOPSIS...Rackley
NEAR TERM...Milcarek/AK
SHORT TERM...Rackley
LONG TERM...Rackley/Milcarek
AVIATION...Cermak/Shallenberger
CLIMATE...Milcarek
Source:
PBZ issues Area Forecast Discussion (AFD) at Jan 16, 1:16 PM EST---------------
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