Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 112310
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
610 PM EST Mon Dec 11 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 WEDNESDAY/...
Have issued a Winter Weather Advisories and Lake Effect Snow
Warnings that will run through Wednesday evening.

A clipper will track across northern Ohio and the east end of
the lake tonight into Tuesday morning. A good frontogenetic band
will extend light snow into far northeast OH/northwest PA this
evening (in addition to the flurries around). But as the low
tracks across the state, banding of snow will increase north of
the low beginning after midnight, with accumulations of 1 to 3
inches by the end of the morning rush. Amounts will be under an
inch outside of north-central, northeast OH and NW PA, but all
should see some snow. 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.

Temperatures will hold fairly steady for a big chunk of the
night. 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.

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.

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

&&

.SHORT TERM /TUESDAY NIGHT 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 NIGHT 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 /00Z Tuesday THROUGH Saturday/...
An elongated area of low pressure over LMIC will move east across
the area tonight and Tue morning leaving a trough lingering back
into the Eastern Lakes into Tue night. Widespread light to locally
moderate snow will develop ESE across the area tonight then shift
into mainly NE OH and NW PA for Tue into Tue night. Locally heavy
bands of lake enhanced snow showers are expected Tue and Tue night
around ERI with a lesser threat at YNG and CLE.

Southerly winds will shift to the west and northwest behind the low
and increase to 15-20 knots with gusts to 30 knots into Tuesday
which will produce some blowing of the snow.

Expect conditions to drop to a mix of low MVFR/IFR in the snow
tonight then improve at TOL, FDY and maybe MFD Tue morning to mix of
VFR or high end MVFR.

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 from 7 PM this evening to midnight EST
     Wednesday night for OHZ011-012-023-089.
     Lake Effect Snow Warning from 7 PM this evening to midnight
     EST Wednesday night for OHZ013-014.
PA...Winter Weather Advisory from 7 PM this evening to midnight EST
     Wednesday night for PAZ001.
     Lake Effect Snow Warning from 7 PM this evening to midnight
     EST Wednesday night for PAZ002-003.
MARINE...Small Craft Advisory from 3 AM Tuesday to 4 AM EST Wednesday
     for LEZ142>144.
     Gale Warning from 7 AM to 10 PM EST Tuesday for LEZ145>149-
     165>169.

&&

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



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