Area Forecast Discussion
Issued by NWS Cleveland, OH

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806
FXUS61 KCLE 081735
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1235 PM EST Thu Dec 8 2016

.SYNOPSIS...
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 tonight. Saturday high pressure will build into the region
from the central plains.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...Minor adjustments for the afternoon.

Previous Discussion... Surface trough was located over the upper
great lakes this morning as deep low pressure continues a slow
move across northern Quebec. 8H temperatures already down to about
-8C this morning and should slowly chill from here. So this is
already cold enough to get all snow where lift and convergence are
the strongest. This will occur over Lake Erie through the morning
with it being directed into Western NY on a southwesterly wind.
This band of snow will slowly edge toward the lakeshore through
the afternoon and will likely get into Erie PA by mid afternoon.
As the surface trough passes late afternoon/early this evening the
snow will move inland. This is when the significant accumulations
will begin.

It will become very cold aloft through this afternoon. So with
the steep lapse rates over the warm waters of Lake Erie there
could be some thunder. This will of course increase snowfall rates
and may produce snowfall rates in excess of 2 inches per hour.

Highs today will generally be in the upper 20s to around 30 but it
will feel colder as the day progresses. Gusty west winds will
make it feel like it is in the teens.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Moderate to high instability over the warm waters of Lake Erie
will develop quickly this evening as the surface trough passes. As
the winds turn more to the northwest this will push the snowfall
inland. Have decided to grab a couple more counties for the LES
warning where the higher terrain will assist in significant
accumulations. So with that said we have added Geauga and Inland
Ashtabula counties beginning at 6 pm. Heaviest accumulations will
likely occur after midnight tonight into Friday. Refer to our
snowfall graphic on our webpage and on facebook/twitter.

We will need to monitor the remainder of the watch very closely
and will at least need an LES advisory. While we do expect to see
some thunder snow develop we are reluctant to add the lakeshore to
the warnings. Want to see the thunder develop over the lake this
afternoon to build our confidence.

The lake effect snows will continue through Friday on a
northwesterly flow. However these steering winds will shift back
to the west Friday night into Saturday with the lake effect snow
shifting back up the shoreline. The remaining bands of snow will
likely shift back into western NY at some point on Saturday.

Warm advection develops Saturday night ahead of the next area of
low pressure and will likely produce some light snow for the
entire region. Looks like light amounts but could be a couple
inches.

It will feel winterlike into the weekend. Highs will be in the 20
to around 30. A few teens will be possible each night...especially where
any breaks in the cloud cover can occur. Winds will make it feel
even colder.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The models show a low moving ne across the area sun night thru
monday with widespread but generally light precip with the type of
precip being the issue. Will stay with likely or better pops and
mainly snow but by sometime monday at least the se half of the cwa
could see chg to rain if the low does take a more nw track.

Another push of arctic air is expected to arrive about tue night and
this batch will likely be even colder than the current one. More
lake effect snow showers will occur.

&&

.AVIATION /18Z Thursday THROUGH Tuesday/...
Bands of lake effect snow showers over Lake Erie will push inland
tonight as the 850mb winds turn to the NW. Could see a widespread
couple of inches overnight...with higher amounts in the snowbelt.

Westerly winds will gradually increase into midday with gusts to 30
knots then diminish some tonight.

OUTLOOK...Mainly mvfr cigs thru monday with areas of ifr in lake
effect snow showers into saturday then widespread snow sunday into
monday.

&&

.MARINE...
SCA conditions expected into fri morning for all of the lake then
continuing east 2/3 into saturday until high pressure moves up the
ohio valley to lessen the flow. Winds back to the south by sunday
then more in question from sunday evening thru monday do to model
differences so will stay with superblend progs for this time period
as a low should track ne near the lake monday.

The moderate west winds could push water levels in the western basin
down near the critical mark for safe navigation later today into
tonight.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Lake Effect Snow Watch through Saturday morning for OHZ012-089.
     Lake Effect Snow Warning from 6 PM this evening to 4 PM EST
     Saturday for OHZ013-014.
     Lake Effect Snow Watch from 7 PM EST this evening through
     Saturday morning for OHZ011.
PA...Lake Effect Snow Warning until 4 PM EST Saturday for
     PAZ001>003.
MARINE...Small Craft Advisory until 4 PM EST Saturday for LEZ146>149.
     Small Craft Advisory until 4 PM EST Friday for LEZ142>145.

&&

$$
SYNOPSIS...Mullen
NEAR TERM...TK/Mullen
SHORT TERM...Mullen
LONG TERM...Adams
AVIATION...DJB
MARINE...Adams



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