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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCLE 181443
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
943 AM EST Sat Jan 18 2020

.SYNOPSIS...
Low pressure will move east across the central Great Lakes
today. High pressure from the northern Great Plains and upper
Midwest will build southeast to the Ohio Valley Monday through
Wednesday, lingering over the mid-Atlantic Thursday and Friday.
Low pressure will move northeast toward the central Great Lakes
Friday night. A warm front will lift north across the area
Friday night followed by a cold front Saturday.

&&

.NEAR TERM /THROUGH SUNDAY/...
Precipitation continues to transition over from snow to sleet
and freezing rain, and to rain once surface temperatures rise
to above freezing. Will be looking to expire the Winter Weather
Advisory as we transition to all rain. Once most of the current
Winter Weather Advisory goes, we will be looking to address the
expected lake effect snow tonight and tomorrow.

Previous Discussion...
Mixed bag of precipitation continues across the local area at
this time. Biggest surge of precipitation appears to be with the
warm front as it lifts northeast. Latest observations indicate
freezing line is across the central portions of Ohio and is
showing signs of beginning to lift north and northeast at this
time. Timing of the warmer air and the freezing line appears it
will begin to move into the local area around sunrise and lift
northeast across the area during the morning as the 850 MB jet
maximum pushes into the area. This will help to warm
temperatures at the surface today into the 40s for highs. Snow
amounts are expected to be on the lighter side due to the mixed
precipitation this morning. Then, as whole package of
precipitation (rain) moves northeast across the area, expecting
back edge to move east of the area overnight tonight. As cold
air advection returns behind the cold front tonight, the rain
will transition over to snow mainly in the eastern portions of
the forecast area. A return back to fair weather will result in
the west later tonight into Sunday. Cold air advection overnight
tonight will cause surface temperatures to drop into the teens
and begin to set-up some lake effect snow heading into Sunday.
Lake effect snow potential looks good but a lot of factors have
the potential to prevent widespread areas from reaching warning
criteria for snow. First is the best flow with the longest Lake
Erie fetch occurs during the day Sunday when the inversion is
relatively low and instability is conditional at best. As the
instability becomes a bit more favorable, wind flow becomes less
favorable in direction and becomes more northwest to northerly
by evening. The firehose effect of spreading the snow across a
larger area rather than a concentrated area will likely keep
widespread areas from seeing significant snow accumulations.
Therefore, since confidence is low in reaching warning criteria
at this time, will hold off on issuing a watch for the lake
effect snow. We may wind up with just advisory criteria when it
is all said and done. Highs on Sunday will only max out in the
lower to middle 20s in the cold air advection.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
A secondary push of Arctic air with a surface trough will move
across the area Sunday evening which will shift the surface flow
from westerly to more northwesterly Sunday night and eventually
more northerly by Monday morning. 850 mb temperatures will be
around -12C to -15C if not a little colder. The surface trough
and wind shift Sunday evening will have some convergence along
that boundary and will likely see a band of snow with the wind
shift push across much of the area early evening. The Lake
Effect snow will be in prime time mode Sunday night and will
become more oriented with the northwest to northerly flow
impacting both the primary and secondary Snowbelt areas as well
as the higher terrain areas. We will need to monitor a potential
Lake Huron connection Sunday night into Monday morning possibly
impacting the Monday morning rush hour for the Cleveland metro
area.

The surface flow shifts again to more west-northwest by late Monday
afternoon and night with the primary focus shifting back to the
primary Snowbelt areas. Another weak surface convergence feature
showing up in some of the models may have another slight uptick in
the lake effect bands Monday evening. The lake effect will slowly
begin to decrease by midday or the afternoon on Tuesday as winds
become westerly late on Tuesday. A light southwest surface flow
returns by Tuesday night. Overall, there will be the potential for
moderate to locally significant snowfall amounts in the Snowbelt
over the 2 to 3 day lake effect event. There still remains
uncertainty on which areas may see the highest totals and exact
amounts with the possible "firehose" effect of the movement of the
bands and squalls.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
Southerly winds will bring a moderation in temperatures by Wednesday
through the end of the week. Temperatures will be back to above
average for the end of next week with 40s returning. The next storm
system to impact the region will be towards the end of next week
with widespread rainfall this time around.

&&

.AVIATION /12Z Saturday THROUGH Wednesday/...
Low pressure and associated warm front will continue to move
northeast and then east this morning. A mixed bag of
precipitation can be expected through this morning and then
warmer air will move northeast into the region and change the
precipitation over to all rain. Deteriorated ceilings and
visibilities will continue across the area over the next
several hours with improvement taking place into tonight.
Lingering lake effect snow will begin to develop later tonight
in the northeast.

.OUTLOOK...Widespread non-VFR returns over the weekend with
rain and snow.

&&

.MARINE...
Conditions will deteriorate today and tonight on the lake with
southerly winds and waves increasing this morning through the
afternoon. Southerly winds will increase to 15 to 25 knots and gusts
up to 35 knots by midday and afternoon. A deepening area of low
pressure will move across the Great Lakes into southern Ontario this
evening and overnight. Southwesterly Gales of 35 to 40 knots with
gusts to up 50 knots will be likely on the lake late this afternoon
through Sunday morning. As the low pressure system moves away from
the area Sunday, cold air advection will come across the lake on
westerly winds 20 to 30 knots on Sunday and higher waves. Critical
low water levels will be likely on the western basin of the lake
tonight into Sunday and an advisory will likely be needed in future
forecast updates. With much colder air moving in late tonight
through early next week, freezing spray will be a concern as well.
With strong westerly winds, there will be some concern for higher
waves and erosion along the lakeshore later today through Sunday. A
surface trough will shift the winds to more northwesterly 15 to 25
knots Sunday evening through Monday. Winds start to decrease and
become westerly to southwesterly by Tuesday into Wednesday with
lower wave heights.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until 3 PM EST this afternoon for
     OHZ009>014-019>023-028>033-036>038-047-089.
     Wind Advisory from 6 PM this evening to 10 AM EST Sunday for
     OHZ012-089.
     Wind Advisory from 3 PM this afternoon to 7 AM EST Sunday for
     OHZ007>010.
     Wind Advisory from 3 PM this afternoon to 10 AM EST Sunday for
     OHZ011.
     Winter Weather Advisory until 1 PM EST this afternoon for
     OHZ003-006>008-017-018-027.
PA...Wind Advisory from 6 PM this evening to 10 AM EST Sunday for
     PAZ001.
     Winter Weather Advisory until 10 PM EST this evening for
     PAZ001>003.
MARINE...Small Craft Advisory until 3 PM EST this afternoon for
     LEZ142>146.
     Gale Warning from 3 PM this afternoon to 7 AM EST Sunday for
     LEZ142>145-162>165.
     Small Craft Advisory until 6 PM EST this evening for
     LEZ147>149.
     Gale Warning from 6 PM this evening to 10 AM EST Sunday for
     LEZ147>149-167>169.
     Gale Warning from 3 PM this afternoon to 10 AM EST Sunday for
     LEZ146-166.

&&

$$
SYNOPSIS...Lombardy
NEAR TERM...Lombardy/Saunders
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Lombardy
MARINE...Griffin