PBZ issues Area Forecast Discussion (AFD) at Jan 21, 6:41 AM EST699
FXUS61 KPBZ 211141
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
641 AM EST Tue Jan 21 2025
.SYNOPSIS...
Potentially dangerous sub freezing wind chills are expected
through Wednesday; Cold Weather Advisory/Extreme Cold Warnings
remain in effect across the region.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Cold Weather Advisory/Extreme Cold Warning in effect.
- A passing shortwave could impact the afternoon/evening
commute.
-----------------------------------------------------------------
Surface high pressure crossing the Upper Ohio Valley region
has resulted in mainly clear skies and light wind, which has
allowed temperatures to crater overnight to values below zero
in most locations. Current wind chill values across the region
are largely between -10F to -20F, with lower values in the
higher elevations. Clouds will increase over the course of the
day, and along with the very cold weather, a crossing shortwave
will bring another round of snow to the region, but amounts are
expected to largely capped at 1.0" inches in isolated areas,
with a a trace to 0.5 elsewhere.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
KEY MESSAGES:
- Arctic outbreak with dangerously cold temperature and wind
chill continues.
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EXTREME COLD CONTINUES OVERNIGHT AND INTO WEDNESDAY...
The potential for upgrading to a Extreme Cold Warning across the
region remains below 50% for early Wednesday. The spread of the
apparent temperatures for the latest run of the ensembles that
cover the 25th to 75th percentile is 6 degrees (between -17F to
-23F). A potential outcome is that a strong sfc high builds over
the region (potentially as high as 1040mb) and measured temps
could range from -15F to -18F but with very little wind.
Historically, these are the noted impacts across our region with
a cold weather outbreak this severe: Unprotected pipes can
freeze and burst. Prolonged exposure to the cold may lead to
hypothermia. Frostbite can occur in as little as 30 minutes for
exposed skin.
We advise checking in routinely with vulnerable friends and
family. Extreme care is encouraged for the protection of pets
and animals. Rescheduling any events, especially those taking
place outdoors, is also encouraged.
Along with cold weather, a potential shortwave is expected to
cross the region Tuesday afternoon and increase the threat of
hazardous travel due to snow. Snowfall amounts are expected to
stay below Advisory criteria (likely 0.5 to 1.0 inches in
isolated areas; a trace to 0.5 elsewhere). However, brief
periods of low visibility from heavy snow can't be ruled out.
The 0-3km CAPE values range from 25J/kg to 50J/kg along the
trough axis. Hi-Res guidance also has some noted potential
stronger bands (reflectivity on the radar could measure 20DBZ to
30DBZ at times) between 3pm to 6pm (including Pittsburgh). If
models remain consistent with this potential outcome, short-
fused special weather statements and/or snow squall warnings may
be needed to highlight the threat.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
KEY MESSAGES:
- Confidence is high that very extremely cold temperatures will
exit the region Wednesday. However, below average temps are
expected to linger.
- Near normal temps and widespread precip may return Sunday into
Monday
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A ridge axis is expected to drift over the Ohio River Valley
early Wednesday. The return of warm southwest flow will likely end
the threat for extreme cold conditions across portions of the
region by mid-day. Overnight lows/wind chills late Wednesday
into early Thursday may prompt a Cold Weather Advisory for
forecast zones within the ridges (Tucker/Preston), but the
potential of -10F wind chill values for the lower terrain is
low (less than 10% based on numerous long range ensembles).
Models have been consistent that widespread precipitation may
return on Sunday. Probability of measurable precipitation
within a 24 hour time period is 60% to 75%, higher values noted
along the ridges. If temperatures trend colder, there is a 10%
chance of snow amounts along the ridges reach or exceeding the
Winter Weather Advisory criteria. If warm air lingers, snow
ratios could trend down (decreasing snow amounts totals) and a
rain/snow/wintry mix may occur in portions of our region.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR conditions and southwest wind under 10 knots will prevail
during the morning hours as one surface high departs. The main
impact to aviation operations will likely be the bitter cold
that has taken hold across the region.
A shortwave trough is then expected to cross the region during
the late afternoon/evening hours. Scattered snow showers are
forecast to develop as a result, beginning by 19Z or 20Z in
eastern Ohio, and then progressing eastward into the evening,
possibly reaching the higher elevations by 02Z or so. It is
here where HREF probabilities of less than a mile visibility
are highest, on the order of 50 to 60 percent. Nevertheless,
brief drops to IFR visibility are possible areawide in these
snow showers, along with wind gusts of up to 25 knots or so.
General MVFR ceilings should accompany the snow.
Clouds will clear behind the snow showers late this
evening/overnight. VFR conditions, light wind, and even more
bitterly cold temperatures will then take hold through the
remainder of the TAF period.
Outlook...
Development of strong surface high pressure from the west will
return VFR (near 100% probability) to all sites by 12Z Wednesday.
Restriction and precipitation chances increase Friday with the
likely approach/passage of the next upper level trough.
&&
.CLIMATE...
A period of anomalously cold weather is expected to settle in
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 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...Cold Weather Advisory until 1 PM EST Wednesday for PAZ007>009-
013>016-020>022-029-031-073-075-077.
Extreme Cold Warning until 1 PM EST Wednesday for PAZ074-076-
078.
OH...Cold Weather Advisory until 1 PM EST Wednesday for OHZ039>041-
048>050-057>059-068-069.
WV...Cold Weather Advisory until 1 PM EST Wednesday for WVZ001>004-
012-021-509>511.
Extreme Cold Warning until 1 PM EST Wednesday for WVZ512>514.
&&
$$
SYNOPSIS...88
NEAR TERM...WM/88
SHORT TERM...Hefferan/88
LONG TERM...Hefferan
AVIATION...CL/AK
CLIMATE...
Source:
PBZ issues Area Forecast Discussion (AFD) at Jan 21, 6:41 AM EST---------------
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