Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 081127
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
627 AM EST Fri Dec 8 2017

.SHORT TERM...(Today and tonight)
Issued at 453 AM EST FRI DEC 8 2017

A band of moderate to heavy lake effect snow associated with the
axis of a slow moving surface trough has pushed onshore east of
Marquette this morning. Across the west, lake effect snow has
begun to diminish in intensity as visibilities have improve
through the early morning hours. The light synoptic driven snow
across the interior portions of Upper Michigan has diminish from
north to south as the main forcing continued to dig southward.

Expect moderate to at times heavy lake effect snow mainly across the
east as the above mentioned band of lake effect snow continues to
push onshore. At times this band of snow may produce 1-2`` per hour
snowfall rates, resulting in reduced visibilities and deteriorating
travel conditions during the morning commute. With flow becoming
northwesterly behind the surface trough, expect this single band to
transition to multiple bands with impacts becoming a bit more
intermittent through the afternoon hours across the east. A few of
these bands may try to sneak into Marquette county, but due to the
northwest flow expect only the far northeast portions of the county
to be impacted, if at all. Out west, expect the light lake effect to
linger through the morning hours before diminishing in intensity.

Late this afternoon into the evening hours, expect the lake effect
snow to linger in the northwest wind snow belts. However, a clipper
system will dig across the region and bring widespread chances for
accumulating snow across the area, along with the potential for
moderate to heavy lake enhanced snow in the northwest to north wind
snowbelts late today through the overnight hours. While this clipper
system will be quick hitting, given the potent shortwave energy and
the left exit region of the northern jet tracking across the area,
ample synoptic-scale lift will be present. Therefore, we could be
looking at a sneaky event across the interior; however it does look
like SLRs will remain fairly high given the extent of the colder air
aloft. Near the shore of Lake Superior, initially we`re looking
across the western half of the area late this afternoon into the
overnight hours for the potential for moderate to heavy lake
enhanced snow, especially after the surface trough pushes through.
Into the overnight hours, flow behind the exiting clipper system
will veer northerly and allow lake enhanced/effect snow to
transition over the north wind snowbelts. This is especially notable
in the 1000-850mb omega fields as strong vertical motions are
present. Forecast soundings show a deep convective layer, with
equilibrium levels climbing to nearly 10k feet and much of the cloud
depth spanning the DGZ. This should be more than sufficient to
produce 2-3`` an hour snowfall rates in some locations, but it is
hard to discern where exactly these stronger bands will setup
tonight. Therefore, especially across the north central and east,
conditions will need to be monitored closely as winter weather
advisories may need to be upgraded to warnings.

.LONG TERM...(Saturday through Thursday)
Issued at 418 AM EST FRI DEC 8 2017

The extended forecast will continue the trend of near to below
normal temperatures along with a very active lake effect snow
pattern through the entire period.

Generally expecting northwesterly flow aloft into the Upper Great
Lakes region, bringing the continued cold air into the area. 850mb
temperatures are expected to be in the -12C to -18C range through
much of the extended, which will be plenty cold enough for continued
lake effect snow downwind of Lake Superior. For the most part, north
to northwest wind favored snow belts will be the favored lake effect
areas; however, there are a couple clipper systems that will drop
850mb temperatures to around -20C and allow winds to shift.

Saturday: A strong and fairly quick moving clipper systems will
slide through during this time period. This will allow 850mb temps
to drop down near -20C, helping to steepen the overwater
instability. The surface pressure pattern would favor the north to
north-northeast wind favored snowbelts as a surface low shifts off
to the south and east of the U.P. This would give most locations
along Lake Superior a good shot at at least moderate lake effect
snow. Snow ratios look to be a little better during the late Friday
night into Saturday time period as the wave slides through with
fairly light winds through and below the snow growth layer. Good
forcing and instability in the snow growth layer along with
inversion heights reaching close to 10 kft also point to an uptick
in the snowfall intensity into at least Saturday morning. At this
point, blending some hi-res qpf guidance gives several inches of
snow from Friday night into Saturday morning especially for north
wind favored snow belts. The heaviest snowfall totals are expected
over the high terrain of the west and over the high terrain of the
north central U.P. Current thinking is that 4 to 8 inches of fluffy
snow may fall in the aforementioned areas with locally higher totals
possible by early Saturday afternoon. Elsewhere along Lake Superior
will likely see totals around 3 to 6 inches. Again these totals
include the Friday night accumulation. The upslope flow into the
higher terrain of Marquette county, could help to increase totals,
but a lot of this will depend on how much of a northeasterly
direction the wind shifts and where/if a more dominant bands sets
up.

Sunday into Sunday night: Another quick moving, very weak, clipper-
type system is progged to slide through the Upper Peninsula. This
will again act to steepen the lapse rates enough to enhance the lake
effect snow downwind of Lake Superior. This will be a similar type
setup as the Friday night into Saturday setup, except not quiet as
strong and much quicker. Initially the lake effect snow would be
confined to the west wind favored snowbelts Sunday morning; however,
as the low shifts to the east of the U.P., winds are expected to
once again shift to the north and northwest, giving most areas
mainly light to possibly moderate lake effect snowfall along Lake
Superior.

Monday into Tuesday: Yet another strong shortwave, in the active
weather pattern, will slide through the Upper Peninsula Monday
through Tuesday morning. Winds look to be east to northeast Monday
before shifting to the north Monday night into Tuesday, allowing for
yet another period of enhanced lake effect snowfall downwind of Lake
Superior. Again, moderate to heavy lake effect snow is possible for
the north to north-northwest wind favored snow belts and as is
typical, the greatest totals are expected over the higher terrain of
the north central U.P. and over the higher terrain of the west.
Depending on the final wind direction, some location could again see
several inches of snow for this time period. At this point, it looks
like the north to north-northwest wind favored locations would see
the heaviest snowfall totals.

Rest of the Extended: Active cold weather pattern is expected to
continue with another strong shortwave progged to slide through the
area Wednesday night into Thursday. At this point, will stick with a
consensus of the models, giving good chances of lake effect snowfall
along Lake Superior, especially in the north to northwest wind
favored snowbelts.
&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 627 AM EST FRI DEC 8 2017

The intensity of lake effect snow will continue to lessen through
the morning hours, but expect the MVFR ceilings to remain in place.
As a clipper system tracks across the region, snow showers will
intensify across KIWD/KCMX this evening, and then KSAW overnight.
Depending on where the bands of moderate to heavy lake effect snow
set up, KIWD/KSAW may see visibilities drop below 1SM at times. As
the snow intensifies later today/tonight, ceilings will drop down
into at least IFR, if not LIFR, given the deep moisture and enhanced
synoptic and mesoscale lift.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 453 AM EST FRI DEC 8 2017

Winds are expected to remain between 20 to 30 knots through the
weekend. With numerous clipper systems expected to dig south across
the lake, the winds will be in and out of westerly to northerly flow
through the weekend. Sunday night into Monday, a weak surface ridge
will move across the lake and allow winds to briefly drop down to 10
to 15 knots. However, expect the winds to ramp back up to around 20
to 30 knots Monday through Tuesday as another system tracks across
the region. Through the rest of the week, winds look to remain below
25 knots. Occasional freezing spray is likely through early next
week; however, no heavy freezing spray is expected at this time.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 5 PM EST Saturday for MIZ006-007-
     085.

  Winter Weather Advisory until 1 PM EST Saturday for MIZ001>004-
     084.

  Winter Weather Advisory from 10 PM this evening to 1 PM EST
     Saturday for MIZ005.

  Winter Weather Advisory from 3 PM this afternoon to noon CST
     Saturday for MIZ009.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Ritzman
LONG TERM...KEC
AVIATION...Ritzman
MARINE...Ritzman



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