Area Forecast Discussion
Issued by NWS Cleveland, OH

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051
FXUS61 KCLE 080825
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
325 AM EST Fri Dec 8 2017

.SYNOPSIS...
Weak high pressure will extend into the area from the
south today. Tonight the high will move east allowing low
pressure to move through the lower Great Lakes Saturday. Sunday
a weak surface ridge will build over the lower Ohio Valley.

&&

.NEAR TERM /THROUGH SATURDAY/...
Lake effect event ending as winds back to southwest early this
morning. Will continue with chance pops and scattered snow
showers across the Erie lakeshore early but otherwise expect
clearing. Weak high pressure and drier air will build in from
the south today so am looking for a fairly sunny day. Clouds
should be on the increase from evening on in the west and
overnight elsewhere as low pressure dives across the western
lakes overnight to lower MI by 12z Saturday. It will be a close
call as to whether precip gets into Toledo before 12Z. Will
carry a chance pop in the overnight forecast there for precip
towards morning. Saturday the clipper low moves east on a track
just north of the area. Feel there will be a decent chance of
precip across the region and that guidance pops may be a bit too
low. Will stick with our categorical forecast most places.
Amounts should not be excessive however with 1 to 2 inches west
and central and an inch or less east.



&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
The models have come into good agreement with a fairly strong
positive vorticity maximum that will rotate east through the area
Saturday night. As this occurs a low will be developing off the Mid-
Atlantic and Northeast Coasts. While this low doesn`t look like it
will be all that strong it will likely mean that the developing
surface low over the central Great Lakes will not be able to
strengthen much as a portion of the available energy will be
transferred to the coastal low.

Light synoptic snow showers will be ongoing at the start of the
short term across much of the region with snow expected to start
across northwest Pennsylvania by Saturday evening or early Saturday
night. The low levels will be fairly dry ahead of this system, so it
will take a little bit before the boundary layer becomes saturated
enough for meaningful snowfall accumulation begins out east. As we
head into Saturday night and the winds turn out of the northwest
behind a surface cold front we will see some decent lake-enhancement
across the Snowbelt region for a several hour period.

By Sunday morning the synoptic snow will be east of the area but
some lake-effect snow showers will be ongoing. Storm total snowfall
with this event looks to be a widespread 1 to 2 inches for just
about everyone (totals closer to an inch expected across far
southern areas) with higher totals of 3 to 5 inches in the Snowbelt
(most of which will fall Saturday night).

As winds back to the west-southwest by Sunday afternoon the lake-
effect snow showers will be mostly confined to areas closer to the
lakeshore across far northeast Ohio and northwest Pennsylvania, or
they may even push back out over the lake entirely. Another inch or
so of snow is possible through the day Sunday across these areas if
the band doesn`t go entirely off shore. Another shortwave trough
moves through the northeast part of the area Sunday night. This
should briefly bring the winds back around to the west or west-
northwest, which would in turn bring the lake-effect snow back
inland, mainly across Erie County PA. With limited moisture in the
dendritic growth zone and a lowering inversion height (from ~9000
feet in the late evening to 5500 feet overnight) it isn`t likely for
any band to remain organized or overly intense for a long period of
time, so only expecting additional accumulations of around 1 to 3
inches at this time.

A weak ridge of surface high pressure will try to nudge into the
area from the south early Monday. This will help to warm
temperatures up to the lower and perhaps middle 30s during the
afternoon. This will also bring winds back around to the southwest,
bringing an end to the lake-effect snow temporarily.

Another shortwave trough looks to move through the area later Monday
into Monday night, but the exact track is a big question mark. Still
looks like there will be a chance at some accumulating snow for
everyone with the best chances across northeast Ohio and northwest
Pennsylvania, but we won`t have any specific snowfall totals until
we have more confidence in the track of this trough and associated
surface low.



&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The overall pattern will look similar through the long term.
That is, one shortwave trough after another is expected to round
the full latitude trough that will remain in place across the
eastern half of the US. As it stands now it looks like we will
see another potent shortwave swing through Tuesday with some
associated snow, another is expected Thursday and potentially
another shortwave trough on Friday.

Each one will bring the opportunity for snow showers across the
region with some lake-effect snow possibly developing on the back
side of each trough as the winds become favorable.

The coldest air of the season still looks to arrive Tuesday night
into Wednesday. Temperatures will fall into the low teens Tuesday
night with some locations possibly reaching the single digits if the
clouds clear quick enough across western areas. Highs Wednesday only
look to rise into the lower and middle 20s. Highs by Thursday and
Friday look to rise back to near freezing.

&&

.AVIATION /06Z Friday THROUGH Tuesday/...
A patch of low VFR/MVFR cigs moving east across the area roughly east
of a KMFD-KCLE line early today. This will continue to progress
east through the night. Lake effect snow will come to an end
quickly over the next few hours as winds back to southwest
taking snow offshore. to the west clear skies will progress
slowly east through the night. Expect VFR conditions on Friday.

OUTLOOK...Non-VFR developing Saturday from west to east in
general snow across the entire area. Non-VFR at Erie lasting
from Saturday through Sunday in -shsn.

&&

.MARINE...
The Small Craft Advisory remains in effect for the entire lake
through early tonight. The Western Basin continues to look okay to
drop the advisory after 10PM and the winds die down. The rest of the
lake, however, will still see Small Craft Advisory conditions
through Saturday morning. Winds turn southerly and die down Saturday
afternoon ahead of an approaching cold front. As the front moves
through Saturday night Small Craft Advisory conditions will quickly
return to the entire lake with a strong northwest to west flow
continuing into Sunday. Winds will begin to diminish Monday and
there will be a reduced threat for small craft conditions.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 AM EST Saturday for LEZ145>149.
     Small Craft Advisory until 10 PM EST this evening for
     LEZ142>144.

&&

$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...Mottice
LONG TERM...Mottice
AVIATION...TK
MARINE...Mottice



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