CLE issues Area Forecast Discussion (AFD) at Dec 16, 1:21 AM EST678
FXUS61 KCLE 160701
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
121 AM EST Mon Dec 16 2024
.SYNOPSIS...
A warm front will continue across the region tonight, followed
by another one on Monday. A cold front will cross the region on
Monday night. High pressure will build into the Ohio Valley for
Tuesday.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
1:21 AM EST Update...
Most of forecast remains valid per latest trends in obs and
model guidance. The Dense Fog Advisory has been expanded to much
of northern OH based on latest trends in observations and
00Z/Mon HREF probabilities of at least 60% for fog with surface
visibility of 1/4 mile or less. Limited nocturnal cooling, abundant
low-level moisture from recent rainfall, and moisture advection
from the Gulf of Mexico have allowed stratus to expand downward
to the surface and form areas of fog. Expect this trend to
continue through daybreak. Will monitor trends in obs and model
guidance closely for potential further expansion of the Dense
Fog Advisory. Fog is expected to dissipate late this morning,
following the onset of weak diurnal convective mixing of the
boundary layer and via warm front-related precip that will
overspread our region from the southwest, which will also
induce mixing of the low-level atmospheric column.
Previous Discussion...
The main freezing rain threat across the region has ended, as
temperatures and road/surface temperatures have largely risen
above freezing and any precipitation should fall as all rain and
not freeze to any surfaces. Therefore, have allowed for the
Winter Weather Advisory to expire at Noon. Some sheltered areas
of Northwest Pennsylvania could see another hour or so of
possible freezing rain, but impacts would be extremely marginal.
A batch of showers is starting to reenter the forecast area this
afternoon as the upper trough axis enters the region. Overall,
the rain pattern will be more showery with hit and miss rain
showers expected through the first part of tonight, mainly along
and right ahead of the trough. Will continue to highlight these
chances with a mix of likely and low categorical PoPs.
With a break in the rain tonight and with some low level warm
air advection, suspect that there will be some lower clouds and
fog that will form. Especially over area that will stay a little
cooler this afternoon and evening and still have some stray snow
remaining on the ground. Will have an area of fog mentioned in
the forecast for these areas and could see the need for a Dense
Fog Advisory, depending on how conditions deteriorate overnight.
The atmosphere isn't expected to completely decouple with clouds
overhead and southerly winds to 10 kt, but the warm advection
should overcome these elements to generate some fog and travel
issues for the Monday morning commute.
The next warm front and quickly approaching cold front
combination will be on deck for Monday and have PoPs ramping
back up to 100 percent as a swath of rain will fill in across
the area with this system. There will be some stronger warm air
advection with this warm front and temperatures may surge into
the mid 50s even with the clouds and rain across the region.
Unfortunately, the cold front is close behind and will clear out
the bulk of the rain and cool temperatures back down into the
30s for overnight lows. There will be flow off Lake Erie to
perhaps allow for some lingering rain showers in NE OH and NW
PA at the end of the period. Unfortunately, the cold air mass
with the front isn't very strong and the lake has cooled
significantly over the last couple of weeks, so the overall
lake instability will be lacking and the impact will be marginal
at best. Therefore, will only have some low chance PoPs to end
the period.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Quiet weather is anticipated for Tuesday and most of Tuesday night
as modest high pressure slides through the region. Expect a mix of
sun and clouds (more sun south) with highs in the low to mid 40s.
Clouds increase overnight Tuesday night with a small risk (20-30%)
for some light rain or rain/snow to spread in from the southwest
during the pre-dawn Wednesday. Lows Tuesday night will be in the
upper 20s and lower 30s.
A somewhat complex weather system will impact the region Wednesday
into Wednesday night. A frontal boundary will be draped across the
Ohio Valley Wednesday morning, and a flat shortwave zipping through
the Ohio Valley on Wednesday will attempt to spark a modest wave of
low pressure along that front. At the same time, another more potent
shortwave will dive into the Great Lakes on Wednesday, pushing a
cold front with a stronger airmass change will cross the area
Wednesday afternoon and evening. Models show some disagreement on
how the stronger shortwave and front diving in from the north will
interact with the flat shortwave and area of low pressure developing
over the Ohio Valley on Wednesday. This afternoon's run of the ECMWF
has enough spacing between the two features to allow the wave of low
pressure to develop quicker and track farther north, bringing a
solid period of cold rain and/or wet snow to the area on Wednesday.
The GFS and Canadian are both a bit quicker to drop in the polar
shortwave, shunning the developing Ohio Valley low pressure a bit
farther to the south and east. This yields less precipitation across
the local area on Wednesday along with less dynamic cooling, meaning
little to no snow during the day Wednesday and just some rain
showers. The current forecast has a 50-80% chance of precipitation
(lowest in Northwest OH, highest from far eastern OH into PA) for
Wednesday in the form of rain or a rain/snow mix, with little to no
accumulation. The ECMWF solution is a bit of an outlier among
ensembles though can't be discounted. However, even a more amplified
solution like the ECMWF wouldn't be a huge snow producer given the
quick-hitting nature of the system, flat nature of the low pressure,
and very marginal low-level thermal profiles for snow, with ensemble
odds of even 3" of snow coming in at under 10%. Currently have
forecast highs in the upper 30s and lower 40s on Wednesday, though
there is a few degrees of uncertainty in either direction.
Either way, guidance agrees on a piece of colder air briefly
impacting the local area Wednesday night into Thursday morning with
850mb temperatures briefly dipping to around -10C. With a west-
northwest flow and some lingering moisture, lake effect snow showers
are likely in the primary snowbelt Wednesday night into Thursday.
This does not look like a significant event of any sorts as the
airmass is not that cold and high pressure builds in quickly
Thursday, though some accumulation is possible. Lows Wednesday night
will fall into the mid to upper 20s. Locations outside of any lake
effect snow should dry out Wednesday night behind the cold
front.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
High pressure slides through the Ohio Valley on Thursday, providing
for dry weather across most of the forecast area and resulting in
any lake effect snow showers in the snowbelt tapering and ending.
After a brief break on Thursday, the suggestion remains that a
somewhat active and colder pattern returns for Friday and the
weekend. Guidance agrees that a longwave trough will carve out over
the Great Lakes and Eastern U.S. starting on Friday, with a potent
shortwave/clipper dropping through the Great Lakes or Ohio Valley on
Friday. Have chance POPs (30-50%) area-wide late Thursday night
through Friday to account for potential for some light synoptic snow
or snow showers with any clipper and cold front moving through.
Details become less clear over the weekend, as there's disagreement
on how deep and persistent any troughing will be. We'll likely see a
generally north-northwest flow with colder than average
temperatures, which suggests that lake effect snow of some sort is a
good bet. The GFS solution is on the progressive side, giving us
more of a glancing blow of cold air, leading to temperatures that
aren't as cold and less lake effect snow. The European is on the
other end of the spectrum, showing a deeper, slower-moving trough
resulting in colder temperatures and a potentially notable lake
effect snow event that involves Lake Huron. The Canadian model and
most ensembles generally lean closer to the European's solution,
though there is some spread. Either way, POPs for snow showers
diminish Friday night into Saturday outside of the snowbelt, with
likely POPs in the snowbelt through Saturday night that begin
gradually tapering into Sunday (lower confidence that far out).
Temperatures will be near or slightly below average for Thursday and
Friday, with lows in the 20s and highs in the 30s. It will trend
colder over the weekend, with highs likely staying in the 20s and
lows in the 10s quite possible.
&&
.AVIATION /06Z Monday THROUGH Friday/...
At the surface, a ridge continues to exit E'ward before a warm
front sweeps N'ward through our region late Mon morning through
early evening. In addition, a cold front is expected to enter
our region from the west around 00Z/Tues and near the longitude
of KYNG by 06Z/Tues. Behind the cold front, another ridge
builds from the Lower OH Valley and vicinity. Our regional
surface winds will be around 10 to 20 knots. These winds will gust
up to 20 to 30 knots at times, especially during the late
morning through afternoon hours of Mon. Winds veer from SSE'erly
to S'erly with the warm front passage. The cold front passage
will cause S'erly to SW'erly winds to veer toward W'erly.
Widespread low clouds persist through the TAF period. Resulting
ceilings will vary between MVFR and LIFR. Areas of fog with
visibility of 1/2SM or less and drizzle are expected through
~15Z/Mon, especially in interior northern OH. Scattered to
widespread rain, steady to heavy at times, is expected to
overspread our region generally from the southwest between ~13Z
and ~19Z/Mon in association with the warm front and then persist
along and ahead of the cold front. Rain and associated mixing
of the low-level atmosphere are expected to scour-out any
lingering fog. However, visibility is expected to vary between
VFR and IFR in precip. Rain is expected to end quickly behind
the cold front, due to the aforementioned second ridge.
Outlook...Non-VFR expected in periodic rain and/or snow Tuesday
through Friday.
&&
.MARINE...
10 to 20 knot south-southeast flow continues this evening over the
lake (a bit lighter out west, locally 20-25 knots along the eastern
lakeshore). A wind-driven Small Craft Advisory continues from
Geneva, OH points east, though it is on the marginal side. There is
some potential for winds to ramp up a bit more for a few hours this
evening. Either way, winds lull a bit tonight before increasing to
15-25 knots out of the south Monday afternoon ahead of an
approaching cold front. Winds veer southwesterly behind the front
Monday evening and increase a bit more, with up to 30 knots
sustained (and gusts 35-40 knots) possible over the eastern basin.
Winds stay brisk into Tuesday before subsiding Tuesday afternoon and
evening as high pressure builds. Will let the current Small Craft
Advisory for the eastern zones come off the board before considering
future headlines, though we will need new advisories for most or all
nearshore waters Monday afternoon into Tuesday. The potential for
gales still appears to be rather low for most of the lake, though
the HRRR and ARW show a few hours of 30-35 knot sustained winds off
of PA and NY late Monday night into Tuesday morning. The current
impression remains that we'll likely hold just below a gale, though
along with the expected Small Craft Advisory we will also monitor
for potential low water issues in the western basin Monday night.
A cold front will drop across the lake Wednesday evening. Another
front likely crosses on Friday. As colder air returns behind each
front periods of elevated northwest winds will be possible.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Dense Fog Advisory until 10 AM EST this morning for OHZ013-014-
020>023-028>033-036>038-047.
PA...None.
MARINE...Small Craft Advisory until 4 AM EST early this morning for
LEZ148-149.
&&
$$
SYNOPSIS...Sefcovic
NEAR TERM...KEC/Jaszka/Sefcovic
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...Jaszka
MARINE...Sullivan
Source:
CLE issues Area Forecast Discussion (AFD) at Dec 16, 1:21 AM EST---------------
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