Area Forecast Discussion
Issued by NWS Cleveland, OH

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242
FXUS61 KCLE 130039
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
739 PM EST Tue Dec 12 2017

.SYNOPSIS...
Arctic air will continue spilling in across the area into
Wednesday. Lake effect snow will continue across the snowbelt
tonight through Wednesday. Another clipper system will track
across the forecast area Wednesday through Wednesday night
producing widespread accumulating snow.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Not many changes to the forecast grids with this update, with
the lake effect still on track with the forecast. Several bands
continue to impact NE OH and NW PA this evening, although
expecting somewhat of a downtrend as we head into the overnight
hours for the band from Lorain to Akron/Canton. Several snowfall
reports of 2 to 4 inches with this band that fell from this
afternoon through now. Will hold off on an advisory for this
band, as the majority of the snow has already fallen, and hi-
res guidance continues to show the band losing upstream
connection and becoming weaker and disorganized starting around
03Z and . Another 1 to 3 inches cannot be ruled out in the
meantime.

Focus for the overnight will be a strong lake effect band
swinging down into Erie/Crawford PA. Confidence remains high
with this band, and forecast thinking remains the same from the
previous forecast discussion.

Original discussion...
Lake effect snow continues across central and eastern Ohio with
the heaviest falling across northwest PA as of 3:30 PM. Expect
the lake effect to intensify as the evening progresses into
night with several bands taking shape. One band will form across
the Lorain/Medina/Summit county area and this can already be
seen in its beginning stages on radar. This band will likely
produce a swath of 2 to 4 inches of snow with locally higher
amounts possible. Will hold off on an advisory for now, but will
have to monitor this area closely for a potential upgrade to an
advisory this evening.

Additional bands will affect the Primary Snowbelt in northeast
OH overnight with another 3 to 6 inches of snow expected in the
typically favored locations. Expect lesser amounts near the
lakeshore. Northwest PA will see the heaviest snow tonight
through Wednesday midday where a Lake Huron connection will
likely develop tonight. Wherever this band sets up is where the
most snowfall can be expected. We are looking at another 5 to 10
inches of snow across inland northwest PA tonight with up to
another 2 to 4 inches through midday tomorrow before the lake-
effect begins to taper off as the winds switch around to the
west and eventually south by late afternoon. Around 4 to 7
inches of snow can be expected along the Erie PA lakeshore,
though isolated higher totals cannot be ruled out if a good Lake
Huron fetch develops.

No changes have been made to the Lake Effect Snow Warnings and
Winter Weather Advisories currently in effect, though these may
be able to be cancelled a few hours early.

As the lake-effect comes to an end Wednesday afternoon the next
system will be moving in. A clipper will cut southeast across
the area with a surface low moving across northern or north-
central Ohio. Warm air advection snow will first affect areas
from west to east from early afternoon along the I-75 corridor
to mid/late-afternoon across northwest PA. As the low moves
southeast across the area winds will turn to the north behind
the low Wednesday night leading to lake-enhanced snow across
northern areas. By late Wednesday night the remaining snow will
mostly be lighter lake-effect occurring from near Cleveland
eastward. Look for total snow accumulations of 3 to 6 inches
area wide with the lower amounts farther south and the higher
amounts in areas affected by the lake-enhanced snow. A winter
weather advisory will be needed for most, but will wait until
later shifts to issue these headlines as we still have many
headlines currently in effect for the lake-effect snow. Can`t
rule out that some areas from Lorain to Medina county and points
east may receive warning criteria snow (6+ inches in 12 hours),
but the current forecast calls for amounts just below this.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Snow will be diminishing Thursday morning as the system pulls away.
The airmass dries out quickly so any residual lake effect will be
light with shifting flow in the column. A brief ridge builds in at
the surface on Thursday night and a window of light winds will allow
temps to drop off into the lower teens. Another piece of energy
diving south from the arctic will move through the trough aloft on
Friday bringing scattered light snow showers. Best chances for
any accumulation will be focused downwind of Lake Erie with
westerly flow but any accumulation should be light. Slowed the
warm up heading into Saturday as low level warm advection will
be slow to develop.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The models have changed from yesterday but are at least in
better agreement today. Low pressure no longer is expected to
move up the Oh Valley. Instead the models are showing low
pressure moving across southern Canada with another system
moving up the East Coast. Some precip is likely ahead of the
cold front trailing the Canadian low. Best chances will be in
the east. Moisture from the east coast storm could reach that
area and help things along. The precip threat will wind down
from west to east Sunday night. NW Ohio probably won`t see much
in the way of QPF from this system. Farther east it could be a
blend of rain or snow or rain changing to snow. Hopefully later
model runs will allow us to add some details. Some lake effect
could linger through Monday but will try to dry things out for
Monday night and Tuesday. Temperatures will be seasonable during
the period.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
Lake effect snow will continue to bring periods of snow showers,
and possible IFR/MVFR conditions, to KCAK, KYNG and KERI through
the overnight hours. Elsewhere, VFR conditions are expected
through the overnight. A strong low pressure system will track
into the region late in the period, with widespread snow
expected to impact the terminals. Reductions to MVFR seem
likely, with possible IFR as well through the end of the period.
Northwest winds will subside a bit through the overnight,
becoming more westerly/southwesterly as the low approaches the
region.

OUTLOOK...Snow and MVFR conditions expected across the snow belt
Thursday morning. Snow and MVFR conditions possible Friday and
Friday night as a cold front moves into the region.

&&

.MARINE...
A Gale Warning remains in effect for the eastern two thirds of Lake
Erie through 4 AM. Winds were sub gale this afternoon but are
expected to increase this evening as a surface trough over Lake
Huron sinks south. A Small Craft Advisory will be needed after the
warning ends through the day on Wednesday. After that the flow backs
to the south then continues to back to the north by Thursday as an
area of low pressure moves across central Ohio.

Water levels have dropped to within a half foot of the critical
mark for safe navigation on the western basin of Lake Erie.
Water levels are forecast to remain fairly steady through
midnight then start to rise so a Low Water Advisory is not
expected.

&&

.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 9 AM EST Wednesday for LEZ142>144.
     Gale Warning until 4 AM EST Wednesday for LEZ145>149-165>169.

&&

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



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