CLE issues Area Forecast Discussion (AFD) at Dec 15, 7:36 PM EST
559
FXUS61 KCLE 160036
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
736 PM EST Sun Dec 15 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/...
As rain exits to the east overnight, low clouds and areas of fog
are likely. In addition, models soundings show veering of the
wind with height in a shallow moist layer so have added drizzle
to the forecast. It is a little hard to tell at this point how
dense the fog will get but areas of dense fog are possible. Will
monitor trends in observations and issue a dense fog advisory if
needed.
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 /00Z Monday THROUGH Friday/...
The steadier rain still ongoing across Northeast Ohio and
Northwest Pennsylvania will exit to the east through midnight.
Ceilings will continue to lower overnight and will primarily be
IFR, except perhaps at ERI where downsloping winds may help to
keep ceilings in the MVFR range. In addition, areas of fog and
drizzle are likely to develop. The coverage of dense fog with
1/4 mile visibility is less confident. Think most terminals
except CLE and ERI will at least see IFR visibilities with
dense fog possible as ceilings lower below 400 feet, especially
at TOL/MFD/CAK.
Otherwise, rain will return on Monday morning as a warm front
lifts north, spreading southwest to northeast across the area.
This may initially lead to improvement in visibilities but many
sites will see visibilities remain in the 1-4 miles range
through Monday afternoon. Ceilings are expected to remain IFR.
Winds will be out of the south at less than 10 knots tonight,
except at ERI where conditions will be breezy with gusts to 25
knots. Winds will increase at the other terminals on Monday as a
trough approaches from the west. Gusts to 20-25 knots are
expected Monday afternoon with locally up to 30 knots at ERI.
Outlook...Rain and non-VFR conditions will continue into Monday
night with some non-VFR ceilings continuing into Tuesday. A
pair of weather systems could bring periodic non-VFR in rain
then snow for Wednesday 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...None.
PA...None.
MARINE...Small Craft Advisory until 4 AM EST Monday for LEZ148-149.
&&
$$
SYNOPSIS...Sefcovic
NEAR TERM...KEC/Sefcovic
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...KEC
MARINE...Sullivan
Source: CLE issues Area Forecast Discussion (AFD) at Dec 15, 7:36 PM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412160036-KCLE-FXUS61-AFDCLE)
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