CLE issues Area Forecast Discussion (AFD) at Jan 8, 7:33 PM EST881
FXUS61 KCLE 090033
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
733 PM EST Wed Jan 8 2025
.SYNOPSIS...
A trough will swing south across the area this evening followed by
high pressure expanding east across the region Thursday and Thursday
night. A broad area of low pressure will cross the region Friday
night followed by high pressure expanding north through the Ohio
Valley over the weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
630 PM...
Bursts of snow, aided through both synoptic and lake effect
processes, continue across portions of northern Ohio this
evening. The most organized band of snow currently exists along
a NW to SE axis extending from Sandusky County to southern Wayne
County, tied to low-level convergence from an approaching
shortwave to the west. Could see an additional 1 to 3 inches of
snow with this narrow band over the next several hours, mainly
impacting a small area of I-71 just north of Mansfield.
Heading to Northwest Pennsylvania where headlines remain in
effect, recent satellite reveals the Lake Huron band beginning
to shift eastwards into western NY, with substantial dry air
trying to filter in southwards across southern Ontario and Lake
Erie. Models do indicate that the band may shift back towards
the west as the aforementioned shortwave arrives later this
evening and overnight. Will likely be able to remove inland
Ashtabula from the Advisory with the next update.
Previous Discussion...
An upper level shortwave trough will swing southeast across the area
tonight. With that feature we will see increasing mid-level moisture
moving from Michigan across especially Northwest and North Central
Ohio. A 500mb cold pool of -38C will move overhead this evening and
expect to see an increase in snow shower activity for nearly all
areas. Upstream radar show a good amount of snow showers coming off
Lake Michigan. Low level northwesterly flow will focus this moisture
towards Northwest Ohio and convergence is expected to increase
between troughiness across Lake Erie and surface ridging
extending into southwest Ohio. Snow showers will produce light
accumulations across most of the area and a swath of 1-2 inches
in our southwestern tier of counties looks likely.
Bands of lake effect snow with moisture coming from as far away as
Lake Superior have been contributing to snow showers across the
region today. The surface trough will tighten up across Lake Erie
this evening and will also contribute to moisture and snow bands.
Models are highlighting that one of these could set up west of
Cleveland across Erie, Lorain, and Medina Counties. The general
flavor of the forecast through the overnight hours is for many areas
to see a light coating of snow with steepening low level lapse rates
and a dendritic growth zone that is within the lowest 5K feet. Snow
ratios remain high at around 20:1 and snow will stick more
efficiently as we move past sunset.
In the east, have upgraded inland Erie and Crawford Counties to Lake
Effect Snow Warnings. A connection to Lake Huron has been enhancing
snow in these counties since last night and is expected to continue.
While the band has shifted west with time and therefore had an
impact on different portions of the county, it seems enough areas
are seeing 2-5 inches each period and this will continue overnight
with more of a multi-banded set up through at least Thursday
morning. Drying does approach from the north towards 18Z the
northwest flow off the lake continues even into the afternoon. Most
high resolution models continue to focus the Lake Huron moisture
into primarily NW Pennsylvania. While the moisture depth of 6-8K
feet this afternoon is expected to gradually decline below 5K feet
on Thursday, low level lift continues with upslope flow and
convergence downwind of Lake Erie. With several areas already seeing
3-6 inches of snow and potentially another 4-8 to come, went ahead
with the upgrade to a warning.
As the snow starts to taper off on Thursday, high pressure builds
west to east and the cold is expected to continue. Temperatures will
be in the teens again on Thursday and lows on Thursday night will
dip into the single digits in many locations with partial clearing
and light winds. Wind chills values are forecast to dip into the
lower single digits or approach zero.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The cold and active winter pattern will continue to end the week and
move into the weekend as we continue to nickel and dime snowfall
this month.
In terms of the details, a strong southern stream mid/upper trough
and associated cold low will finally eject out of the Desert SW into
the Plains Friday. At the same time, weak mid/upper shortwave
ridging across the eastern Great Lakes will break down as the deep
northern stream mid/upper longwave trough that has dominated so far
this month reloads across the eastern CONUS. This will lead to
phasing of the northern stream deepening trough with the ejecting
southern stream trough, resulting in surface cyclogenesis near the
Louisiana Delta on Friday. Deterministic and ensemble guidance is
coming into decent agreement that this surface low will pass well to
our south across the SE U.S. and Mid Atlantic Friday night into
Saturday. This rapid, suppressed movement makes sense since the
northern stream longwave trough looks to outpace the southern stream
shortwave trough. This will keep the bulk of the impacts well to our
south, however, synoptic support from the mid/upper trough axis
swinging across the region late Friday into early Saturday and the
left exit of a 150-170+ knot H3 jet streak will lead to a shield of
light snow areawide Friday night into Saturday morning.
In terms of snow amounts, we still expect the snowfall to stay below
headline criteria, with generally 1 to 3 inches between Friday
evening and early Saturday morning. The latest LREF probabilistic
guidance in DESI suggests the probabilities of exceeding 3 inches of
snow are only 10-20 percent, with much higher probabilities of
exceeding 2 inches. This boosts confidence in the light amounts
forecasted. The snow will rapidly exit Saturday morning giving way
to lake-effect snow showers Saturday afternoon into Saturday night
in a NW boundary layer flow pattern. Instability will be weaker with
marginal 850 mb temps of -12 C, but decent synoptic moisture and
well-aligned flow for a brief period of time Saturday afternoon into
early Saturday night will support multiple bands with a few inches
in the upslope favored areas of north central and NE Ohio into NW PA
(primary and secondary snowbelts). Higher amounts are possible in NW
PA with a Lake Huron feeder.
Highs will modify into the mid/upper 20s Friday and upper 20s to
around 30 Saturday. Lows Friday night will range from the upper
teens to low 20s, with low/mid teens Saturday night.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Lingering lake-effect snow showers will quickly shift into NW PA
before ending by Sunday afternoon as shortwave ridging at the
surface and aloft builds into the region. This drier pattern will
not last long though as guidance continues to suggest a Clipper-type
system slowly crossing the Great Lakes Sunday night through Monday
night. Timing and track is still uncertain, but this system will
have a closed low, so it will probably trend slower. This will lead
to light snow returning gradually to the region Sunday night and
Monday before gradually transitioning to lake-effect snow in the WNW
flow and cold advection behind the low Monday night and Tuesday.
Another shortwave and associated surface trough dropping through the
eastern Great Lakes Wednesday may shift the flow more northwesterly
causing lake-effect snow showers to expand toward the secondary
snowbelt, but at this time, kept the highest PoPs over the primary
snowbelt through mid week. This Clipper and resulting lake-effect
may necessitate headlines early to mid next week, especially for
the snowbelt where significant amounts are possible.
Highs in the upper 20s to low 30s Monday will fall into the low 20s
Tuesday and Wednesday as a fresh batch of cold air drops into the
region.
&&
.AVIATION /00Z Thursday THROUGH Monday/...
Mixed-bag of VFR, MVFR, and IFR across the TAF sites this
evening, with non-VFR conditions mainly tied to lower vsbys from
snow. Snow coverage should gradually decrease later this evening
and overnight, becoming more isolated in nature by early
Thursday morning. Think ceilings will remain in the low-end VFR
range (~3500 ft), though can't rule out brief drops to MVFR late
tonight into Thursday morning. Clearing from west to east should
begin to occur by late in the TAF period.
Winds are variable this evening, with northern TAF sites out of
the north to northwest, 5 to 10 knots, and southern TAF sites
out of the west to southwest ahead of a weakening trough axis,
5 to 10 knots. Winds will favor a westerly direction by Thursday
morning and afternoon, becoming more southwesterly towards the
end of the TAF period.
Outlook... Non-VFR expected in widespread snow Friday afternoon
into early Saturday morning. Lingering non-VFR is possible
across the snowbelt Saturday into Sunday. Non-VFR may return in
snow from a clipper system Sunday night into Monday.
Friday into
Saturday areawide in snow showers.
&&
.MARINE...
NW winds of 15-20 knots will continue into tonight, although they
will gradually diminish a bit. The Small Craft headline is marginal,
but kept it mainly for wave heights occasionally topping 4 feet this
evening. Lighter winds are finally expected Thursday as winds become
W at 5-15 knots before becoming SW at 10-20 knots Thursday night
through Friday night. Another period of strong winds is then
expected behind a cold front Saturday into Saturday night, when W
winds of 15-25 knots are expected, so Small Craft headlines will be
needed at that time. Winds will then diminish Sunday before W winds
increase to 15-25 knots again behind a low pressure system Monday.
Rapid ice growth already occurring on the western basin should
expand east fairly quickly through early next week, and this will
start to mask waves from west to east on the lake.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until 1 PM EST Thursday for OHZ014.
PA...Lake Effect Snow Warning until 4 PM EST Thursday for PAZ002-
003.
MARINE...Small Craft Advisory until midnight EST Thursday night for
LEZ146>149.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/Kahn
SHORT TERM...Garuckas
LONG TERM...Garuckas
AVIATION...Kahn
MARINE...Garuckas
Source:
CLE issues Area Forecast Discussion (AFD) at Jan 8, 7:33 PM EST---------------
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