PBZ issues Area Forecast Discussion (AFD) at Feb 17, 1:00 PM EST839
FXUS61 KPBZ 171800
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
100 PM EST Mon Feb 17 2025
.SYNOPSIS...
Snow and blowing snow continues for some this morning,
with some gusts up to 25 to 35mph lingering today. Wind chills
between 5 and 20 below are expected tonight. Below average
temperatures continue this week with additional snow potential
Wednesday into Thursday. A "warmup" is favored by the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Blizzard conditions linger in the high terrain through midday.
- Wind gusts of up to 25mph to 35mph expected today.
- Wind chills of -5 to -20 overnight; a cold weather advisory is
in effect for portions of the area.
-----------------------------------------------------------------
Snow and blowing snow continues for portions of the area through
midday. The Winter Weather Advisory for the low land areas will
expire at 15Z. As of right now, there appears to be enough
instability for the bands to continue through the mid morning
hours. With the axis of the trough exiting, expect the snow to
start to slow down in the next couple of hours. Drier air
continues to filter into the area as the shallow moisture still
available will finally dry out by the afternoon.
On to the ridges. There is high confidence in maintained wind
gusts throughout the day due to continued cold advection
enforcing adiabatic profiles in a strong gradient between the
low and encroaching high. There is nearly an 80% to 100% chance
the max gusts for exposed hilltops exceeds 30mph, with a 30%
chance of exceeding 40mph. This increases to 100% and 70%
respectively for high terrain. While these are max gusts, is is
forecast the lowlands will gust from 25mph to 35mph for the most
part, while the ridges may be up to 45mph. Wind will combine
with snow on the ground to continue to allow for blowing snow
hazards, particularly for the ridges. With additional snow
chances and blowing snow chances, the blizzard warning for the
high terrain remains through 20Z.
Into tonight, winds are expected to relax with the strongest
winds above the mixed layer, but 15mph to 25mph still seems
reasonable. Combined with the cold temperatures, this will
generate wind chill hazards. A cold weather advisory has been
hoisted accordingly in areas with a >50% chance of -10F "feels-
like" values or below. Forest and Venango were left out due to
their lower (-15F) criteria. Lows are forecast in the single
digits for most.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:
- Dry and cold Tuesday.
------------------------------------------------------------------
Tuesday appears to be likely the coldest day of the week, with
a roughly >50% chance of a max temperature below 20F north of
I-70. For reference, this is nearly 20F below normal for this
time of year. Zonal flow under a strong upper jet should keep
precipitation chances >10%.
Tuesday night, lows return to the low 10s and single digits, but
wind is much less likely surface high pressure overhead. This
would keep wind chill concerns a bit lower than the night prior,
but there is still roughly a 25% chance of hitting cold weather
advisory criteria for parts of the I-80 corridor and the high
terrain.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
KEY MESSAGES:
- Snow chances Wednesday into Thursday
- Higher chances of dry weather and "warming" temperatures into
the weekend.
-------------------------------------------------------------------
Into Wednesday, there is surprisingly high confidence that the
upper level pattern will shape up to be a closed 500mb low or
elongated trough extending from the Canadian Maritimes to the
northern Great Plains. The main, subtle uncertainty, is how the
trough progresses. This trickles into uncertainty on Thursday
in the progression speed and shape of how the trough sweeps through.
This relates to a couple facets of the forecast:
1) There is increasing confidence that the first surface low
developing on the initial trough dipping south, remains
primarily to the south of the forecast area. Through 1am
Thursday, there is only roughly a 15% chance of >1" in
Pittsburgh. This increases to the south, up to a 30% to 50%
chance for eastern Tucker County. The most likely timing of this
snowfall at this point would be between roughly 4am and 4pm
Wednesday.
2) Because of difficulty in resolving how the tough pivots
through there are a couple scenarios. In the first one, the
upper low rejoins the flow as a trough, progresses through
rapidly, and cyclogenesis remains favored in the mid-Atlantic,
south of the area. In the second scenario, the low remains or
becomes closed and progresses a bit slower Thursday, allowing a
bit of convergence ahead of it, and resulting in higher snow
chances. Just how high? Roughly a 30% (<5%) chance of >1" (>3")
in Pittsburgh. Chances increase to the southeast, up to a 50%
(10%) chance of >1" (>3") for the high terrain of West Virginia.
In either scenario, all precipitation will fall as snow.
The main impacts this week appear to likely be the continued
cold, with temperatures remaining in the ballpark of 15F to 20F
below normal from late Monday into early Thursday. The is high
confidence in ridging into the weekend, but the main
uncertainty is how strong embedded troughing may be, which will
correlate to just how "warm" things get. We don't have a >50%
chance of breaking normal until Monday.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Steepened low level lapse rates to near dry adiabatic with cold
advection at the 850 mb level has resulted in streets of cu
development this afternoon. Cloud bases are hovering right
around the 3kft mark and some drier air intrusion from the
southwest has scattered the CIGs out some. This trend is likely
to be the case through the majority of the TAF period as
remnant moisture traps below a sinking subsidence inversion on
the periphery of high pressure. As such, conditions are likely
to bounce around MVFR/VFR at all sites through most of tonight save
ZZV where less cu development lends higher confidence
prevailing VFR.
Wind gusts up to 35 knots are expected to continue through the
daytime hours today with a strong pressure gradient and mixing
heights tapping into the core of a 35-45 knot low level jet. As
subsidence lowers the mixing heights and the jet gradually
weakens through tonight, gusts will lessen.
MVFR probs wane overnight tonight after ~09z with another push
of drier low-level air and VFR probs jump to 70-80% through
daybreak Tuesday. Some uncertainty then arises with how much
residual boundary layer moisture is left and the height at which
diurnally-driven cloud bases sit. HREF probs jump back up to
40-60% for MVFR CIGs after 16z and the cu rule suggests BKN
development with hi res sounding CCLs hovering between 2.5-3kft,
so have opted to carry high-end MVFR CIGs for the daytime hours.
Gusts will be much less in the 10-15 mph range.
Outlook...
By Wednesday, region-wide restrictions are expected to return
as another storm impacts the region. The best chance for snow
will fall south of the Mason-Dixon line and recent trends
continue to shift farther and farther south. Drier weather is
then favored to return to close out the week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Cold Weather Advisory from 10 PM this evening to 10 AM EST
Tuesday for PAZ014>016-022-074-076>078.
Blizzard Warning until 3 PM EST this afternoon for PAZ074-076.
Winter Weather Advisory until 3 PM EST this afternoon for
PAZ078.
OH...None.
WV...Cold Weather Advisory from 10 PM this evening to 10 AM EST
Tuesday for WVZ512-514.
Blizzard Warning until 3 PM EST this afternoon for WVZ512>514.
Winter Weather Advisory until 3 PM EST this afternoon for
WVZ510-511.
&&
$$
SYNOPSIS...Milcarek
NEAR TERM...Shallenberger
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...MLB
Source:
PBZ issues Area Forecast Discussion (AFD) at Feb 17, 1:00 PM EST---------------
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