Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 080251
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
951 PM EST Wed Dec 7 2016

.SYNOPSIS...
A ridge of high pressure across southern Ohio will dissipate
tonight. Meanwhile deep low pressure near James Bay will drift
east to northern Quebec. A trough of low pressure will extend
southwest across the central Great Lakes. The trough will drop
southeast and cross Lake Erie Friday morning. saturday high
pressure will build into the region from the central plains.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A weak ridge of high pressure across the area will dissipate
tonight. Airmass fairly dry at this time but expect clouds to
gradually increase overnight as a 160kt 300mb jet streak along
with a fairly strong shortwave move across the region. Lows
mainly in the mid 20s. Although we are running a few degrees above
where we were forecast this evening...will maintain overnight lows
with cold advection continuing through the night. Pulled more the
precip chances offshore of PA toward morning.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Have adjusted the timing of the Lake Effect Snow Watch for Lake
Geauga and Ashtabula to later Thursday afternoon. Meaningful snow
will likely wait until after dark Thursday late afternoon/evening.
Will continue to monitor new data/guidance and make needed changes
as confidence grows and more specific timing and amounts can be
made.

Previous discussion follows...Models show an upper level low
over James Bay with a surface trough extending southwest across
the central lakes. The low will move east to Quebec Thursday
forcing the trough southeast across the area early Friday before
moving east of the region later in the day. This will drive a
reinforcing shot of cold air across the region. To our west High
pressure will fill the Central and northern Plains States. This
will set up an extended period of west to northwest flow across
the lake. Expect lake effect snow to develop beginning Thursday
morning over the lake moving onshore from Lake county across nrn
Ashtabula county to Erie county PA. This could begin slowly as
synoptic moisture is lacking. By afternoon however the cold air
deepens and moisture increases suggesting significant lake effect
bands could begin developing. Winds in the Cleveland area should
have sufficient shear to slow development but east to Cleveland to
Erie winds will have less shear. Will go with 90-100% pops for the
afternoon Ashtabula county east. Thursday night conditions
continue to look very favorable for NWRN PA with lake induced cape
reaching 11 kft. Winds turn more northwest suggesting highest
totals will be inland. While the lower levels remain sheared
closer to KCLE expect lake effect snow to increase through the
night across NERN OH under moderate instability from the lake to
850mb. Winds line up best Friday for NERN OH with very little
shear. Most favored areas will be eastern Cuyahoga Geauga inland
Ashtabula and possibly southern Lake. Friday night the low pulls
east...heights begin to rise and drier air moves in from the
southwest. Will begin to taper the heavier snow from the west out
of Cuyahoga and southern Geauga as winds back with high pressure
moving into Southern Ohio. Through Saturday...total accums could
exceed 6 inches in eastern Cuyahoga county...reach around a foot
in portions of Geauga and Ashtabula and reach between 1 to locally
2 feet in the higher elevations of eastern Erie and Crawford
counties.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Significant uncertainty remains regarding the forecast for Saturday
night through Monday. The GFS brings a weak low through the central
Great Lakes Sunday with a quick burst of precipitation that would
mostly be in the form of snow. The ECMWF, however, has another
scenario in mind. It brings a deep low up through the central Great
Lakes that originates along the lee of the Rockies. This scenario
would bring both snow and rain to the region from Sunday through
Monday. Hopefully the models will start to come into at least some
semblance of agreeance within the next day or two.

The low will depart to the northeast Monday night, with another
blast of arctic air plunging into the Great Lakes. Surface high
centered south of the region will track along the Ohio valley
through Tuesday, although maintained slight chance to chance pops
Monday night through Tuesday, with persistent lake response in west-
northwest flow.

&&

.AVIATION /00Z Thursday THROUGH Monday/...
Quiet weather will continue overnight but lake effect activity
will ramp up tomorrow. VFR mid level cigs are expected overnight
with lower cigs on Thursday as colder air arrives. Have slowed
down the onset of the lake effect activity at ERI from the earlier
package. Expect no more than flurries through 18z or so with bands
of snow then developing and moving across the ERI area. Will also
include a vicinity mention at CLE and YNG for the end of the taf
period. The remainder of the area should see no more than flurries
through 00z Friday. Cigs outside of the snowbelt will remain VFR.
SW winds will become westerly overnight and increase. Gusts to 25
knots are likely by daybreak with gusts to 30 knots during the
daylight hours.

OUTLOOK...Arctic front will move through tomorrow. Lake Effect
snow becomes more widespread and intense Thursday night and will
continue into Saturday, especially across the snowbelt east of
KCLE.

&&

.MARINE...
Small craft advisory remains in effect until the weekend. Southwest
winds of 15 to 25 knots will continue ahead of an arctic front that
will move through Thursday. There will likely be a little lull in
the winds tonight and they may fall below Small Craft Advisory
conditions for a short time, but will pick back up to 20 to 25 knots
again by Thursday morning as the arctic front moves through. Lake
effect snow will develop Thursday and continue in the snowbelt until
Saturday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Lake Effect Snow Watch from Thursday afternoon through
     Saturday morning for OHZ012>014-089.
     Lake Effect Snow Watch from Thursday evening through Saturday
     morning for OHZ011.
PA...Lake Effect Snow Warning from noon Thursday to 4 PM EST
     Saturday for PAZ001>003.
MARINE...Small Craft Advisory until 3 AM EST Saturday for LEZ146>149.
     Small Craft Advisory until 7 AM EST Friday for LEZ142>145.

&&

$$
SYNOPSIS...TK
NEAR TERM...TK/Oudeman
SHORT TERM...TK/Oudeman
LONG TERM...Greenawalt/Mottice
AVIATION...Kubina
MARINE...Mottice


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