Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 120516
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1216 AM EST Tue Dec 12 2017

.SYNOPSIS...
A clipper system will track across the lower lakes tonight
sweeping an arctic front across the forecast area early Tuesday
morning. Lake effect snow will develop Tuesday and continue
through Wednesday. Additional clippers will track across the
area Wednesday night and again Friday.

&&

.NEAR TERM /THROUGH TODAY/...
Have issued a Winter Weather Advisories and Lake Effect Snow
Warnings that will run through Wednesday evening.

As expected, little or no snow occurring attm except for some light
snow in NW PA where up to a half an inch possible thru midnight.
Band of synoptic snow with the clipper low over SE MI and Nrn
Indiana will drop southeast across the area the rest of tonight.
Emphasis for better accumulation will be near Lake Erie and over the
rest of the NE half where a general 1 to 2 inches seems to be the
best guess. Elsewhere, accums will taper down to only a dusting for
the far southern edges of the cwa.

There will likely be a relative lull between the exiting of the
synoptic snow and the organization of lake effect snow Tuesday late
morning into the early afternoon.

Lake effect snow will be heavy at times, particularly Tuesday
night. There is some uncertainty as to how long the significant
lake effect will continue and have extended the advisory/warning
into Wednesday evening (beyond the previous watch). Set up for
the lake effect is really good through Wednesday morning, but
concerns of how much dry air will begin encroaching on the west
end of the snowbelt come Wednesday. Northwest PA will likely
have a connection with Lake Huron enhancing the snow. This may
drift into Ashtabula Co. at times. Highest totals will be across
the higher terrain. With the northwest flow, fetch is limited
and so is residence time making the decision for Geauga and
Ashtabula Co a little more difficult. Believe during the the
most intense period, we will be able to get 8 inches in at 24
hour period and have gone with the warning. Lakeshore locations
will be borderline as well and have held with an advisory mainly
because the winds will be relatively strong and we can have a
hard time accumulating the more significant totals. Advisory
areas will need to stay tuned for any changes as the lake
effect begins to take shape. Regarding Wednesday into Wednesday
night, lift is still focused within the dendritic growth zone
with plenty of moisture there. The significant drying comes in
at H7 with a lowering of the inversion. So the potential for a
continuation of moderate to heavy lake effect snow is still a
distinct possibility. Winds will be shifting to the west and
therefore a shift in the lake effect snow bands will be taking
place too. The ridge axis begins to move in late Wednesday
evening to begin the tapering process.

Outside of the snowbelt, some snow may reach into northwest OH
off of Lake MI as the winds back going into Wednesday in
addition to what they receive with the clipper tonight/early
Tuesday.

Temperatures will hold fairly steady for a big chunk of tonight. But
as west and northwest winds pick up after the low/cold front passes
temperatures will begin to fall. By late Tuesday afternoon
temperatures will be getting into the upper teens. Wind chill values
will drop to the single digits.

Highs Wednesday will be near 20 across the snowbelt and mid 20s
elsewhere.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
As the lake effect is winding down, another area of low pressure
will track across southern Ohio, bringing a light snowfall to at
least the southern half of the area. Warm advection precipitation
will develop as lift increases across the tightly packed baroclinic
zone over central Ohio with light accumulations of 1-2" focused
along and south of a line from Toledo to Akron, with lesser amounts
to the northeast.

One more piece of energy will dive south out of Canada across the
western Great Lakes on Friday. There will be a limited amount of
moisture to work with but scattered light snow showers will be
possible, especially downwind of Lake Erie. Temperatures will remain
below normal with highs in the upper 20s and lows in the teens.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
A system will be exiting the region at the start of the period and
will have some left over snow chances into Saturday...especially
downwind of the lake.  After that the models really diverge and
confidence is low.  Will likely see rounds of wintry precipitation
and have gone with chance pops every period.  Both the GFS and ECMWF
bring low pressure up the Ohio Valley on Sunday.  The ECMWF is a
good 12 hours faster than the GFS with the surface low. By Monday
morning the ECMWF has the Oh Valley low long gone with another
clipper approaching from the northwest.  At 12z Monday the GFS still
has the low just east of the area.  These differences are typical of
the entire period.  Will try to use a blend of the guidance for the
period. Hopefully later shifts can fine tune the forecast. Temps
during the period will be within a couple degrees or normal with
Sunday perhaps the warmest of the three day period.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
Low pressure between FDY and MFD will track east overnight and
be east of the forecast area by daybreak. Expect widespread inch
or two as the system tracks east. Gusty NW winds will develop behind
the system with wind gusts increasing to lower 30s along the
Eastern Lakeshore by late morning.

OUTLOOK...Lake effect snow will continue across the snowbelt, mainly
east of CLE into Wednesday evening. Another Alberta Clipper is due
Wed night into Thursday, bringing light snow to most Ohio terminals.

&&

.MARINE...
Low pressure located south of Chicago will track northeast across
Lake Erie tonight pulling an arctic cold front across the area. This
low will deepen considerably as it merges with another low over Lake
Ontario on Tuesday. A Gale Warning has been issued for the central
portion of Lake Erie for Tuesday and Tuesday evening as northwest
gales to 35 knots develop. A Small Craft Advisory is in effect for
the nearshore waters west of Vermilion where winds will increase to
30 knots and may briefly approach gales Tuesday morning. Small
Crafts will need to continue on the east end of the lake through
Wednesday night as winds are waves are slower to subside. Conditions
will improve by Thursday as a weak area of low pressure tracks
through the Ohio Valley.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until midnight EST Wednesday night for
     OHZ011-012-023-089.
     Lake Effect Snow Warning until midnight EST Wednesday night
     for OHZ013-014.
PA...Winter Weather Advisory until midnight EST Wednesday night for
     PAZ001.
     Lake Effect Snow Warning until midnight EST Wednesday night
     for PAZ002-003.
MARINE...Small Craft Advisory until 4 AM EST Wednesday for LEZ142>144.
     Gale Warning from 7 AM this morning to 10 PM EST this evening
     for LEZ145>149-165>169.

&&

$$
SYNOPSIS...Oudeman
NEAR TERM...Oudeman
SHORT TERM...KEC
LONG TERM...Kubina
AVIATION...DJB
MARINE...KEC


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