PBZ issues Area Forecast Discussion (AFD) at Oct 16, 2:10 PM EDT280
FXUS61 KPBZ 161810
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
210 PM EDT Wed Oct 16 2024
.SYNOPSIS...
Showers taper overnight tonight. Additional frost/freeze
concerns for tonight and tomorrow night with below average
temperature. A warming and drying trend is expected into the
weekend, with high confidence in warm and dry conditions next
week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Scattered showers today.
- Another night of frost/freeze concerns tonight.
-------------------------------------------------------------------
The main axis for showers today has set up slightly of the east
of the prior forecast, further, PoPs have been adjusted slightly
to match observations. As mentioned before, this axis is
utilizing the largest moisture fetch from Lake Huron and Lake
Erie. As noted on the 12Z sounding, this moisture is much more
shallow than yesterday, however, surface heating is allowing
enough instability to continue the shower trend. Instability
maintenance if forecast slightly into the overnight period, but
the trend is towards stabilization as high pressure, and
subsidence encroaches from the west.
And so, with cold air in the low levels, another night of frost
and freeze concerns prevails. As we get back into the winter
pattern, we will see a common sight: lake moisture trapped
underneath a subsidence inversion. This climatologically favors
more bullish cloud cover as temperatures cool overnight,
enforcing saturation. Probabilities of greater than 50% cloud
cover prevail across the whole area save parts of Coshocton and
Muskingum Counties. There, efficient cooling is expected and a
freeze headline has been hoisted accordingly. Uncertainty in
where this cloud gradient sets up extends into Tuscarawas,
Guernsey, and Noble Counties, where a frost advisory has been
hoisted for now. There is uncertainty here. In a clearer
scenario, temperature may cool to around freezing in isolated
cold spots. In a cloudier scenario, even frost formation may be
difficult. This will bear watching into tonight. For other
areas, clouds are favored, but despite this, freezing pockets
with greater than 50% probability prevail for Jefferson County
(PA) and Forrest County.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
KEY MESSAGES:
- Overall warming trend with dry weather returning.
- Frost/freeze concerns continue through Thursday night.
-------------------------------------------------------------------
Ensembles build upper level ridging with the axis extending from
Southern Quebec southwestward to the Kentucky on Thursday as
the upper low/trough departs. Regardless of whether it closes
off, all solutions push it east late on Thursday with the more
amplified ones exhibiting a slower departure. This may have some
effect on minimum temperatures depending on how quickly the
clouds dissipate.
Lows Thursday night look to be the coldest of the week as high
pressure centers overhead with high confidence allowing for clearing
skies with light wind; probabilities for <32F range from 50-80%
outside of the immediate urban areas. This will support perhaps the
best frost/freeze chance of the week. Friday morning there is a
chance for river valley fog with the cool air over the warm rivers.
Highs will continue to moderate with a return to the mid 60s come
Friday under high pressure as the upper level ridge axis
establishes overhead. Light northerly wind will keep dew points
low and allow for another notable ~30 degree diurnal swing with
lows dipping back into the low to mid 30s, though not quite as
cold as Thursday night, but frost/freeze potential is still
there provided the growing season doesn't end in prior nights.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
KEY MESSAGES:
- Clear, dry, and warm under high pressure.
-------------------------------------------------------------------
There is now high confidence that a cut-off low drops into the
desert southwest by Friday evening, though there are still some
questions in the exact position of the low, though this
uncertainty will have little effect on downstream
predictability.
This digging cut-off low will provoke a stout response of
eastern ridging through the weekend and most of next week.
Remarkably, all clusters indicate a 880dm height over
Pittsburgh come Friday night, hanging around through at least
Saturday night with some uncertainties in local heights tied to
the presence or lack of a weak wave in the flow overtopping the
ridge. This will do little to affect daytime highs. Given the
pattern, temperatures are expected to return to well above
average. Though 880dm heights may suggest 80s, low-level cool
air may hang around and only allow 70s for most. Nonetheless,
with clear skies, anomalous ridging, and subsidence,
temperatures were nudged up slightly and dew points down
slightly during daytime hours. This may allow relative
humidities in the 30s or even upper 20s for parts of the area.
From a fire- weather perspective, this will allow fuels to dry.
Again, there is notable consistency in picking up the western
low into the mean flow sometime on Monday, with only small
variations in the speed to which the low rejoins. Late Monday
through next Tuesday, what is left of the trough axis is
forecast to pass, potentially allowing a slight cool down and
the next (albeit low) chances of precipitation. An acceleration
of winds combined with the warm, dry conditions and leaf-fall
may warrant watching for continued fire-weather concerns.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Northwest flow will continue to produce scattered lake-effect clouds
and snow showers into the evening hours. Expect ceilings to
fluctuate between low-end VFR and MVFR for the most part with these
showers, with a modest visibility restriction possible in the more
robust precipitation. The low-level instability that is promoting
these showers will also support gusty wind as well. Wind direction
will vary from northwest to north, with some gusts of up to 20
knots.
The showers will largely fade by midnight with the loss of
instability and with approaching high pressure from the west.
However, clouds will continue to linger as moisture remains trapped
under an inversion aloft. Low-end VFR/high MVFR ceilings should be
maintained at most terminals overnight. Confidence in
location/timing of MVFR ceilings is moderate at best, although areas
north of I-80 and upslope-prone locations have the best chance of
sub-3000 foot ceilings.
Past sunrise, the onset of mixing will allow clouds to finally
scatter out areawide, leading to VFR conditions by midday, with a
lighter northwest wind as the surface high center approaches.
.Outlook...
High pressure is expected to filter in on Thursday, though a
continued northwesterly flow may allow at least scattered lake-
effect clouds to linger through much of the day. Height rises and
dry air advection bring prolonged VFR conditions and dry weather
back to the area by Friday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Warning from 2 AM to 9 AM EDT Thursday for PAZ009-016.
OH...Frost Advisory from 2 AM to 9 AM EDT Thursday for OHZ039-058-
068.
Freeze Warning from 2 AM to 9 AM EDT Thursday for OHZ048-057.
WV...None.
&&
$$
SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...Milcarek/Lupo
LONG TERM...Milcarek
AVIATION...CL
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 16, 2:10 PM EDT---------------
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