063
FXUS61 KPBZ 221949
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
249 PM EST Wed Jan 22 2025

.SYNOPSIS...
Wind chills on either side of zero continue today and tonight
but are expected to remain above headline criteria outside
of Eastern Tucker County. Dry weather otherwise today with
light snow returning Thursday night and some modification to
temperatures for the weekend ahead.

&&

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

- Dry with increasing mid/upper cloud coverage.
- Cold overnight lows, but not as cold as recent nights.
-----------------------------------------------------------------

Some high clouds are sliding through the area downstream of an
approaching upper wave, but strong 1036 mb high pressure
centered overhead will maintain a dry period through tonight.
Southerly flow will usher in some weak "warm" advection as 850
mb temperatures increase to -12 to -13C and NBM suggests a good
chance for highs to reach into the teens south of I-80 whereas
up that way we`ll likely hold in the upper single digits. Wind
chills this afternoon under a 5-10 mph wind will still remain in
the upper negative to positive single digits.

Headed into tonight, low temperatures will be some 15-20 degrees
warmer than Wednesday night thanks to modest warm advection and
increased cloud cover, though that still only puts the area
into the low to mid single digits with a <20% chance of
remaining above 10 degrees. Light southerly wind will drop
apparent temperatures into the negative single digits and are
likely to remain above headline criteria, but it will still be
quite cold. The exception will be Eastern Tucker County where
colder overnight lows, more elevated wind, and the potential for
some periods of breaks in the clouds will result in wind chills
dipping below -10F. The best chance for this will be the
highest elevations, and for that reason, have issued a new Cold
Weather Advisory covering 7PM tonight - 10AM Thursday.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Temperatures will begin to moderate Thursday.
- Light snow returns Thursday evening with minimal accumulation.
- Mostly dry Friday with temperatures slightly colder.
--------------------------------------------------------------------

The aforementioned shortwave will struggle to bring much snow to the
ground early in the morning Thursday with dry air to overcome.
Ensemble soundings show some mid-level moisture advection, but still
dry low levels from ~800 mb down. For most, the day will be dry as
establishing southerly flow modifies the airmass with a 60+% chance
of >25F for highs extending up to Pittsburgh. The best chance
for some snow showers will come later Thursday into the
overnight hours when better moisture works in and a decaying
boundary passes through. Displacement of upper support moving
through just ahead of the boundary won`t help our snow chances.
The NAM is a bit more aggressive with saturation occurring
quicker and suggests a couple tenths of an inch possible, though
this is likely more representative of the worst case scenario.
As a whole, HREF probability for a half an inch of snow through
Thursday night is up to ~40% in the ridges where orographic
ascent may aid in enhanced forcing, though the moisture issue
still remains. Elsewhere, chances are low and the nature likely
remains light and scattered.

Snow chances taper off on Friday as surface ridging re-
establishes from the southwest and we`re sandwiched between two
mid-level waves. Highs will take a hit back down a few degrees
as some colder air works in in west-northwest flow. A shallow,
near dry-adiabatic layer with cold advection at the 850 mb level
will steepen lapse rates and tap into elevated flow aloft.
Momentum transfer isn`t all that impressive with only 15-20 knot
flow, so wind may take on more of a 5-10 mph sustained nature
with sporadic gusts.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
KEY MESSAGES:

- Below average temps are expected to linger through early next
  week.
- Rounds of weak disturbances will produce scattered snow
  chances.
--------------------------------------------------------------------

A lead shortwave will slide through zonal flow locally on Saturday
with relatively good agreement among the ensembles. Surface high
pressure progged across the Carolinas is favored to keep us dry,
though can`t entirely rule out very low-end snow shower chances
confined north of I-80 in the evening as a warm front lifts through.
The better chance, albeit with low accumulation potential, will come
on Sunday. Ensembles bring a second wave with minor disagreement on
its depth, as surface low pressure drags a cold front through. One
ensemble cluster with a deeper shortwave suggests slightly higher
probability of >0.5" extending down off of the lake, but even in
this scenario, the chance of reaching 1" is less than 20%. The
primary issue looks to be available moisture as the lack of
amplification with westerly mid-level flow isn`t pulling from a
great moisture source region.

Weekend temperatures will moderate in comparison to the past
week, but continue to remain below average with afternoon highs
in the upper 20s/low 30s and overnight lows in the low 20s
through Sunday. Probabilities to eclipse the freezing mark for
highs are better on Sunday extending a 50-70% chance as far
north as Pittsburgh.

Ensembles eject yet another shortwave on Monday through the still
established westerly zonal flow. Noted disagreement comes into play
at this point with the progression of the upper levels as some
clusters exhibit a potentially phased solution with a southern
stream and northern stream shortwave. Others keep them unphased and
weaker with quick progression through the area. Most of the guidance
is not bullish on much with this disturbance either as we again lack
sufficient deep layer moisture. The mean QPF from 3/4 clusters
through Monday night is generally <0.10" areawide, with the 90th
percentile as high as 0.15", which would suggest low-end snow
accumulation potential. The outlier at this point is one cluster
that suggests a much deeper, phased, and slower trough. This
solution points toward more QPF and more representative of the
current NBM 90th percentile suggesting 1-2 inches or so in the
ridges. Overall confidence is low, but the trend points toward
a lesser impact event.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
VFR conditions are forecast through at least 12Z with high
confidence. Mid and upper level cloud cover will continue to
advance across the region hours as (welcome) warm advection
take place. Light wind with a southerly direction can also be
expected.

Ceilings will begin to drop after 12Z ahead of an approaching
shortwave trough. For now, kept MVFR ceilings out of the TAFs
for FKL/ZZV, but HREF probabilities of MVFR ceilings approach
the 50-60 percent range right at 18Z.

Outlook... Restriction and precipitation chances increase
Thursday afternoon with the likely approach/passage of the next
upper level trough. Periods of lower cloud cover may then
linger into the weekend.

&&

.CLIMATE...
Anomalously cold weather continues today with some locations
approaching record values. 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 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. 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.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...Cold Weather Advisory from 7 PM this evening to 10 AM EST
     Thursday for WVZ514.

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...CL
CLIMATE...Milcarek