PBZ issues Area Forecast Discussion (AFD) at Dec 30, 5:04 AM EST
845
FXUS61 KPBZ 301004
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
504 AM EST Mon Dec 30 2024
.SYNOPSIS...
Low pressure tracking across the eastern Great Lakes tonight
will bring additional rainfall and strong winds. A second
disturbance will track across the area on Tuesday, with
additional rainfall. A pattern change to colder conditions will
occur during the second half of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Rain tapers off overnight tonight.
- Showers across the north this afternoon.
- A brief break in the active weather tonight.
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The winds have subsided quite a bit, even on the ridges. A few
places may still see some gusts into the 40 to 45 mph mainly on
the highest ridges in eastern Tucker County, but the threat is
mainly over and as such the advisory was allowed to expire.
Expect continued shower activity through day break as the
trough passing to the north will continue to spawn some shower
activity.
Showers will continue to track north of Pittsburgh this morning and
into the afternoon due to the previously mentioned shortwave,
with perhaps some modest lake enhancement. These will likely end
by sunset as mid-level riding pays a brief visit to the region.
Cloud cover will be slow to scatter out through the day, but a
brief period of clearing is possible during the evening hours.
Dry weather is expected tonight amid drier northwest flow and
influence of surface ridging centered over the Carolinas.
Temperatures will remain roughly 10 degrees above climatologic
norms through the period.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Another period of rain likely Tuesday/Tuesday night with
another low pressure system.
- Snow showers expected Wednesday/Wednesday night, with the
ridges most favored for accumulation.
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Ensembles still advertise that the next surface low pressure
system will likely advance from the Lower Ohio Valley Tuesday
morning, crossing our region and reaching the Middle
Atlantic/southern New England area by 12Z Wednesday. Another
period of steady rain is expected with this system lasting into
Tuesday night, before colder air arrives and starts to change
precipitation over to snow and this would seem more likely to
occur a couple hours before or over day break on Wednesday
morning. Snow showers will continue behind the departing low on Wednesday
and into Wednesday night, aided by lake enhancement and/or
upslope flow. The higher terrain is most favored for
accumulation. The NBM has come in with probs for 3 inches or
more at 70% to 80% in Tucker and Preston Counties. The
probabilities in the PA ridges is more closer to 50% for 3
inches or more. The northern counties along I-80 will get in on
some snow with their probs ranging about 30% for 3 inches. Have
included this into the HWO. Cold air advection will bring the
coldest air to the region on Thursday as the lows on Thursday
morning will be right around normal if not a few degrees below
normal. During the day on Thursday, high pressure will be more
centered over the southeast CONUS giving a westerly direction to
the winds. This will confine any snow accumulation on Thursday
to the northern counties and this will persist through the day.
High temperatures will be a bit below normal during the day on
Thursday on the order of 3 to 5 degrees.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
KEY MESSAGES:
- Late week pattern shift will favor below normal temperature,
periodic snow, and high terrain gusty wind.
--------------------------------------------------------------------
The extended period will feature the 500MB broad trough over
the forecast area for the entire period just about. The
ensembles are showing quite a bit of confidence for normal
temperatures or slightly below normal through the Thursday night
to Sunday period. In fact, the NBM probs are giving a 70% to
90% probability of daytime highs below 32 degrees on Friday
through Sunday. Friday will feature a shortwave passing through
within the northwest flow setup and will bring another round of
snow showers and potentially lake enhanced snow showers. At this
time, the NBM probs this far out only highlight the ridges and
as such will be the case for the behind this disturbance and
also another round on Saturday and into Sunday to finish out the
forecast period. The jet streak aloft takes shape with the
shortwaves on Saturday and into Sunday as the NBM does not
highlight the lower elevations for criteria gusts but the ridges
show some potential. Will need some better confidence to nail
down the snow and wind potential in the coming days.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
Precipitation (largely north of KPIT) will come to an end by
early afternoon, with gusty winds and widespread MVFR cigs
improving to VFR by late afternoon. Latest ensemble guidance
shows probabilities for MVFR cigs decreasing to 15%-0% by 00Z
this evening.
Outlook...
Periodic restrictions return later Tuesday through Thursday
with crossing low pressure, and subsequent upper troughing. Rain
should also gradually change to snow by mid week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Shallenberger
NEAR TERM...Shallenberger
SHORT TERM...Shallenberger
LONG TERM...Shallenberger
AVIATION...88
Source: PBZ issues Area Forecast Discussion (AFD) at Dec 30, 5:04 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412301004-KPBZ-FXUS61-AFDPBZ)
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