PBZ issues Area Forecast Discussion (AFD) at Dec 9, 2:01 PM EST632
FXUS61 KPBZ 091901
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
201 PM EST Mon Dec 9 2024
.SYNOPSIS...
Light rain and drizzle chances persist tonight until a
more notable rain chances Tuesday afternoon through Wednesday.
A transition to snow is expected Wednesday afternoon before the
system departs. Cold air with wind chills in the single digits
expected Thursday through Friday morning.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Light rain and drizzle chances persist with temperatures well
above average.
-------------------------------------------------------------
The heaviest and highest chances of rain have lifted northeast with
a passing warm front. The ares will remain embedded in the warm
sector through the near term, with saturated, moist adiabatic low-
level profiles. This will allow low chances of light rain and
drizzle through the rest of the overnight with weak forcing in the
low pressure trough.
Accordingly, temperatures are expected to remain well above normal.
High temperatures today will top out around 10 to 15 degrees above
average, while nighttime lows may even be around 5 degrees
above normal highs for early December thanks to saturation
hurting efficient radiative cooling and low-level warm
advection.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:
- Widespread rain Tuesday afternoon through Wednesday morning.
- Rain transitions to snow by Wednesday afternoon with a drastic
cooldown overnight.
-------------------------------------------------------------------
A series of low pressure disturbances are expected to ride up
the surface trough axis Tuesday afternoon through Wednesday. The
strongest of which is expected to arrive and deepen early
Wednesday morning as a longwave trough axis sweeps across the
central CONUS, enhancing convergence and accelerating moisture
advection into the day Wednesday.
At this time, the best forcing in the warm sector is expected
after the cold front clears the area to the east, but before the
front departs mid-day Wednesday, 0.5" to 1" is most likely east
of Pittsburgh, while 0.1" to 0.5" is expected in Pittsburgh and
points east. Should the front be slower to clear, totals could
be as high as 1" to 2.5" east of Pittsburgh, but this scenario
remains low probability (25% chance) for now.
Behind the cold front, temperatures will cool. Because of this,
high temperatures are likely in the early morning and a sharp
temperature gradient could set up between east OH (behind the
front) and western PA/ northern WV (ahead of the front). Low-
level cold advection and weak mid-level lift on the back side of
the departing low is expected to transition rain to snow
throughout the day. Accumulations will be challenged with warm
surface temperatures and limited QPF. Low end scenarios have a
dusting for most with an 1" in the ridges, while higher end
scenarios have as much as advisory criteria snow for the high-
terrain. This will need to be monitored for additional updates.
Behind the cold front, a drastic cool down is expected with low
temperatures Thursday morning forecast in the mid 10s to lower
20s with wind chills in the single digits to near zero. Should
any ponding water of slush be left on roads overnight, a freeze
is possible and cold result in some slick spots.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Single digit to near-zero wind chills Thursday morning
through Friday morning.
- Warm up into the weekend.
-------------------------------------------------------------------
The main story for Thursday and Friday will be the cold, with
single digit wind chills forecast between Thursday morning and
Friday morning. There is a 50% to 75% chance of maximum wind
gusts Thursday above 30mph in a strong pressure gradient behind
the Wednesday system. This remains fairly high confidence.
Temperatures are expected to moderate some Friday with warm
advection, and winds are likely to subside a bit as surface
high pressure builds across the region.
The rest of the long term will be defined by subtle shortwaves
embedded in low-amplitude flow with a general trend towards
riding to start off the week. This means timing predictability
remains low in any passing disturbance; but here is what's most
likely:
Another shortwave trough moves east from the central CONUS on
Saturday, crossing our region on Sunday. Rain chances are
return with the approach and passage of the trough over the
weekend. Some mixed precip is possible north of PIT Saturday
night, though confidence in this occurrence is low.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
As expected organized rain has tapered across much of the region,
with FKL/DUJ being the last terminals in steady rain. Rain is
expected to wind down for these terminals over the next couple
hours.
Area-wide MVFR with pockets of IFR are observed at this time. With
rain moving out a gradual improvement to MVFR is expected for most
IFR terminals besides DUJ. CIGs are expected to bounce around within
MVFR itself for much of the TAF period but the take home message is
this: The probability of MVFR remaining locked in region-wide
remains largely greater than 80% for the entire TAF period with only
small pockets of lower probabilities moving through. Probabilities
for IFR CIGs degrade as we approach 00z tonight (lingering longest
in DUJ) and remain rather low (<40%) for all terminals except
ZZV/FKL/DUJ through 18z tomorrow.
Outlook...
Low level moisture should maintain restrictions and rain
chances late Tuesday/Tuesday night with the approach and passage of
a cold front. Restrictions and rain transitioning to snow are
expected Wednesday under subsequent upper troughing and cold
advection. Dry air is expected to begin filtering in by Thursday and
can bring a return to VFR conditions as clouds erode.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...AK
Source:
PBZ issues Area Forecast Discussion (AFD) at Dec 9, 2:01 PM EST---------------
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