CLE issues Area Forecast Discussion (AFD) at Dec 2, 4:49 PM EST331
FXUS61 KCLE 022149
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
449 PM EST Mon Dec 2 2024
.SYNOPSIS...
A trough lingers across the Great Lakes through Tuesday. High
pressure quickly slides through the Ohio Valley Tuesday night. A
potent low pressure drops through the eastern Great Lakes Wednesday
night into Thursday, pushing an arctic cold front across the local
area Wednesday night.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Lake effect snow continues in the "primary snowbelt" east of
Cleveland across far northeastern Ohio and northwestern Pennsylvania
as we head towards this evening. However, we are past the peak of
the event and are now into the slow, agonizing ramp down where it
keeps snowing just enough to be annoying while recovery and digging
out continue where feet of snow have fallen over recent days.
Thermodynamics remain fairly conducive for lake effect snow with
relatively efficient snow ratios, though a fair amount of wind
shear, diminishing synoptic support as the deep trough starts
lifting out and as surface high pressure starts building in from the
southwest, and some drier continental air continuing to advect in
from the west-southwest are all acting to keep bands relatively
less organized and not as intense as they were through Sunday.
We still have two relatively more intense and organized bands
wavering across parts of the snowbelt...one connected to Lake
Huron, which is largely going into western NY at the moment but has
been grazing northeastern Erie County at times. Another band, which
hasn't been quite as intense at times but is flaring as of this
writing (4 PM), is a more W-E oriented band from Lake County into
northern Geauga County and Ashtabula County. A combination of broad
convergence and uplift from the shoreline into the higher terrain is
causing less-organized snow showers across the remainder of the
primary snowbelt. Activity is currently intensifying and has focused
a bit farther north ahead of a subtle trough axis that will swing
through this evening. Winds veer more northwesterly over the lake
behind the trough into tonight, which will likely push activity a
bit farther inland and southwest. However, this will also increase
shear, which along with weak subsidence behind the trough should
cause activity to become less intense and disorganized for several
hours late this evening into the overnight. The exception will be
the Lake Huron-connected band, which should swing a bit farther west
behind the trough and could again impact northeastern Erie County.
Another shortwave will move through during the morning to midday
timeframe on Tuesday, likely again causing activity to focus closer
to the lakeshore while becoming a bit more organized/intense. Behind
this shortwave high pressure will start quickly building in towards
Tuesday night, which will (finally) cause the lake effect to begin
shifting northeast up the shoreline. Lake effect may continue across
far Northeast OH through most of the day Tuesday, and probably
won't completely end in Erie County until Tuesday night.
In terms of additional accumulations through Tuesday evening, have
an additional 4 to 10" across most of Erie County, highest in the
higher terrain just south of I-90. This increases to 12 to locally
18" across far eastern Erie County due to influence from Lake Huron.
Amounts drop off to about 2 to 6" in Crawford County, highest near
the Erie County border. Into the Ohio snowbelt, generally have 2 to
5" of additional snowfall in the forecast from far northeast
Cuyahoga County points east. Amounts quickly drop off to 1" or less
across the rest of Cuyahoga County. Have a small bullseye of 4 to
7" additional focused on the Lake, northern Geauga, and western
Ashtabula County area due to the more organized band that has been
impacting this area at times since Sunday and will continue to do so
(intermittently) through at least midday Tuesday. Given how
efficient snow growth aloft will be, if this band can focus on an
area for a long enough period of time there could still be a
localized higher amount somewhere in Lake or far northern Geauga.
Behind the trough passage this evening we'll see activity shift
inland towards Trumbull and northeastern Portage County, where 1 to
3 inches is possible through the day Tuesday.
For headlines, maintained all warnings and end times as is for Lake,
Geauga, Ashtabula, Erie, and Crawford Counties. Additional amounts
are marginal for a warning outside of Erie County, though suspect a
small area in parts of Lake and northern Geauga may still see
additional warning amounts, and given that parts of these areas are
digging out from a massive dump of snow don't see much gain in
getting cute and downgrading a county or two to an advisory. Snow
will continue across parts of Lake, northern Geauga, Ashtabula, and
perhaps northern Crawford after the 7 AM Tuesday expiration, though
it generally won't be significant. Future shifts can take another
look at those expiration times, however. For now will maintain the
Advisory for Cuyahoga, as despite best efforts to hedge low on the
southwestern fringe of things we still have up to a few inches of
snow in the forecast for the Euclid/Richmond Heights/Mayfield area.
This is not of high confidence. It is possible the band currently
coming into Lake/northern Geauga Counties shifts southwest into
tonight behind the trough passage and drops snow on northeastern
Cuyahoga County. However, there is likely room for the Advisory to
be canceled later this evening if that isn't coming to fruition.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Strong upper-level trough and low pressure system move southeast
across the Great Lakes region Wednesday through Thursday with latest
12Z model guidance continuing to trend toward a deeper and more
amplified upper-level trough. Various impacts from this low pressure
system are expected through the duration of the short term forecast,
starting with strong southwest wind gusts of 35-45 mph as a strong
low-level jet (model mean of 50-55 kts at 850mb) moves within the
"warm sector" of the low pressure system. There is a low chance that
a wind advisory is need Wednesday afternoon, mainly for the western
portion of the forecast area west of I-71 but it depends if we are
able to develop a deep enough boundary layer to tap into those very
strong winds aloft. It's uncertain if this happens because most
models have overcast skies with rain/snow showers developing during
the afternoon/evening hours, which is prohibitive to deep boundary
layer mixing.
A cold front extending from the ~992 mb low near the Ontario/Quebec
border will move southeast across the forecast area Wednesday
evening into Wednesday night. Temperatures should rapidly drop from
afternoon/evening highs in the mid to upper 30s to around 20 degrees
Wednesday night. Snow showers are expected with and behind the
front, with variable, areawide snowfall accumulations. Most
locations should get at least 0.5" but wherever better snow showers
develop, upwards of 2-3" could be possible. Model data does suggest
a very favorable environment for snow squalls areawide Wednesday
night, with a strong pressure drop/rise with the cold front and high
low-level lapse rates and low-level CAPE behind the front.
Thankfully, the overnight timing will make these snow squalls less
impactful, with most heavy snow squalls done by the Thursday morning
commutes (aside from lake effect).
Within the snowbelt of Northeast Ohio and Northwest Pennsylvania
(including the secondary snowbelt), there will likely be at least
some isolated to scattered snowbelt during the day Wednesday, mainly
during the afternoon ahead of the cold front. Once the cold front
moves southeast across Lake Erie, cold air aloft (characterized by
850 temperatures of -12 to -15 C) will immediately usher in and
result in the develop of lake effect snow Wednesday night. Latest hi-
res model guidance (e.g. NAM Nest) suggests that there could
initially be a rather intense band of snow that develops near the
lakeshore, with lake effect snow continuing within west flow
Wednesday night, becoming northwest by Thursday and Thursday
night. Variable snowfall amounts are expected, but a minimum of
2-4" is expected in the primary/secondary snowbelts, 4-7" in the
area of eastern Cuyahoga, southern Lake, northern Summit, and
then all of Geauga, most of portage/Trumbull. Highs amounts of
6-12" is expected in Ashtabula and all of Northwest
Pennsylvania, with locally higher amounts in southern Erie and
northern Crawford. Very strong winds are expected, which may
carry snowbands further inland that what is usually expected,
and could also limit lakeshore zones, except where the Huron
connection band sets up (which currently should set up
primarily over the PA counties). Strong winds will also result
in blowing snow for any areas that receive at least a couple
inches (mainly in the snowbelt). There is some potential for
blizzard or near-blizzard conditions, particularly for counties
closer to Lake Erie (e.g. Cuyahoga, Lake, Ashtabula, and Erie,
PA) with particularly strong flow off of Lake Erie. It's
possible that the current snow on the ground from the heavy
snow that occurred this past weekend could contribute to
increasing impacts.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Scattered lake effect snow continues mainly in Northwest
Pennsylvania on Friday and Friday night as high pressure dives
to the west and south of the forecast area with temperatures
remaining below average. Another clipper moves southeast across
the Great Lakes region although probably more of a glancing
blow to the snowbelt Saturday and Saturday night before high
builds in briefly. On the backside of the departing high, should
see warmer temperatures on Sunday/Monday with rain chances as
low pressure system moves in.
&&
.AVIATION /18Z Monday THROUGH Saturday/...
A mix of VFR and MVFR ceilings are expected through the TAF
period. Currently most of the area is VFR outside of far
Northeast OH and Northwest PA (including ERI) where MVFR
ceilings are being observed within the lake effect activity. We
should see ceilings bounce above 5,000 feet outside of the lake
effect this evening into tonight, before stratus returns into
Tuesday and brings potential for MVFR across all terminals. As
for the lake effect, the heaviest activity will largely miss the
ERI and YNG terminals, though some periods of more impactful
snow showers with brief IFR or lower visibilities are likely at
ERI through the TAF period. At YNG, some MVFR visibilities are
likely at times with a lower risk for brief IFR. CLE may see
some light snow showers but with few restrictions. Any
restrictions at CLE should only be to MVFR.
West-southwest winds of 6-12 knots are expected through the TAF
period.
Outlook...Non-VFR likely in lake-effect snow bands through
Tuesday. The heaviest and most-persistent lake-effect snow in
our region is expected to impact the primary snowbelt in far
Northeast Ohio and Northwest Pennsylvania.
&&
.MARINE...
Small craft advisory continues east of the islands with west
flow of 15-20 knots through Tuesday night. Southwest winds
strengthen on Wednesday with a gale watch beginning 14Z
Wednesday for the open waters of Lake Erie east of the islands.
A cold front follows, with west to northwest gales developing
Wednesday night, so have the gale watch starting at 04Z
Thursday for the nearshore waters. Winds diminish below gale
force Thursday evening though small craft advisory is likely
needed through the end of the week.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until 7 AM EST Tuesday for OHZ011.
Lake Effect Snow Warning until 7 AM EST Tuesday for OHZ012>014-
089.
PA...Lake Effect Snow Warning until 7 AM EST Tuesday for PAZ003.
Lake Effect Snow Warning until 7 PM EST Tuesday for PAZ001-002.
MARINE...Small Craft Advisory until 7 AM EST Wednesday for LEZ145>149.
&&
$$
SYNOPSIS...Sullivan
NEAR TERM...Sullivan
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Sullivan
MARINE...Saunders
Source:
CLE issues Area Forecast Discussion (AFD) at Dec 2, 4:49 PM EST---------------
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