Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 120930

Area Forecast Discussion
National Weather Service Marquette MI
430 AM EST Thu Jan 12 2017

.SHORT TERM...(Today and tonight)
Issued at 416 AM EST THU JAN 12 2017

LES has lingered primarily across the Keweenaw and eastern portions
of the area this morning and should gradually weaken, if not diminish
in some locations this morning. The next system that will clip the
area later today is evident on water vapor satellite imagery with
energy digging across southern Saskatchewan and Manitoba. This system
is already showing signs of slowing its southward progress as the jet
streak appears to be getting ready to round the base of the
shortwave trough.

As the above mentioned system approaches the area, low-level flow
will back to the southwest across the area providing a brief break
or at least some weakening of LES in the northwest wind snowbelts
through the late morning/early afternoon. However, as this system
clips the region and lifts back north into Ontario, later this
afternoon/evening, an arctic airmass will filter south across the
area with 850mb flow veering to the northwest. This will allow for
LES to redevelop across the northwest wind snowbelts later today and
linger through the overnight hours. The main surface low is progged
to track over northern portions of Lake Superior; however, multiple
things are in play to see gusty winds across the area as this low
tracks north of the area. Not expecting winds to be as strong as we
experienced a few days ago as the stout pressure falls/rises will
remain well north of the area. The strongest winds should be
confined to the Keweenaw Peninsula and along the shoreline of Lake
Superior. Once the LES begins, could see a few hours of moderate to
at times heavy snow, but inversions start to lower through the
overnight hours so currently thinking that snowfall totals will fall
just short of LES advisory criteria. Given the strong winds expected
later this afternoon into Friday morning across the Keweenaw, expect
the blowing and drifting snow be become a problem. Therefore, have
opted to run with a winter weather advisory, primarily for the
impacts of blowing snow on visibilities and drifting of snow already
on the ground, and additional snow expected later today. Upon
collaboration, will let the day shift re-evaluate the potential for
similar impacts across eastern portions of the area as the strong
wind are not expected to arrive there until later tonight. The strong
winds will begin to diminish from west to east across the area
towards daybreak on Friday, but expect a bitter cold start to the day
as wind chills will drop below zero as the arctic airmass moves
overhead. Wind chills Friday morning look to range from -6 to -25,
with the coldest values expected in the interior west.

.LONG TERM...(Friday through Wednesday)
Issued at 308 AM EST THU JAN 12 2017

Nam shows a closed 500 mb low over central Ca 12z Fri with a trough
in the northern Rockies. This closed low heads southeast into the
southern Rockies by 12z Sun. Lake effect snow winds down on Fri and
then relatively quiet into Sat night with very little moisture to
work with. Did not make too many major changes to the going forecast.

In the extended, the GFS and ECMWF show a trough over the southern
Rockies with a closed low over northern Mexico 12z Sun. There is
also an associated trough over the northern plains then. The closed
500 mb low over Northern Mexico heads northeast into KS 12z Mon and
then heads northeast into the upper Great Lakes 12z Tue. Upper
troughing remains over the central and southern plains 12z Wed.
Temperatures warm to above normal this forecast period. Mixed pcpn
also looks to be possible with warm air aloft beginning Mon night
into Tue with majority of moisture staying to the south and our area
is on the northern side of the storm.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1209 AM EST THU JAN 12 2017

MVFR cigs with lake effect clouds and a few light snow showers are
expected to persist overnight until winds back to the southwest
THursday morning. Although conditions will improve to VFR the
southwest winds will become gusty, especially at CMX where some
gusts to around 35 knots are possible which result in blsn with vsby
likely into the MVFR category.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 416 AM EST THU JAN 12 2017

Expect the wind speeds to really ramp up from west to east across
the lake with gales of 40-45 knots through the day and linger into
the overnight hours as low pressure tracks just north of the lake and
veers southwest winds to westerly. A few periodic storm force gusts
are possible, but they do not look persist enough in time and space
to upgrade to a storm warning right now, but definitely looks like a
high end gale warning for later today/tonight. Tonight, as low
pressure lifts into Ontario, west wind will veer to the northwest and
decrease in speed overnight into the morning hours on Friday from
west to east. Heavy freezing spray will also develop later this
morning amd spread east across the entire lake throughout the day.
Expect the freezing spray to linger into the morning hours on Friday
before diminishing as the winds and waves gradually subside. High
pressure will move overhead throughout the afternoon hours on Friday
allowing wind speeds to decrease fairly rapidly from west to east
and gradually back around to the south-southwest. Friday into
Saturday southwest winds will increase in speed to around 20 to 30
knots ahead of a cold front pushing across the lake, before becoming
westerly as the front passes through early Saturday. Post frontal
westerly winds do not look impressive at this time and should remain
around 20 to 25 knots. Saturday night into Sunday a ridge of surface
high pressure will traverse the lake weakening wind speeds with flow
backing to the southwest again. Southwest winds will increase to
around 20 to 25 knots for Sunday.


Upper Michigan...
  Winter Weather Advisory from 1 PM this afternoon to 1 AM EST
     Friday for MIZ001-003.

Lake Superior...
  Heavy Freezing Spray Warning from 7 PM this evening to 11 AM EST
     Friday for LSZ251-267.

  Gale Warning from 4 PM this afternoon to 1 AM EST Friday for

  Heavy Freezing Spray Warning from 3 PM this afternoon to 11 AM
     EST Friday for LSZ248>250-265-266.

  Heavy Freezing Spray Warning from 11 AM EST /10 AM CST/ this
     morning to 11 PM EST /10 PM CST/ this evening for LSZ162.

  Gale Warning from noon EST /11 AM CST/ today to 10 PM EST /9 PM
     CST/ this evening for LSZ162-240>244-263-264.

  Heavy Freezing Spray Warning from 1 PM this afternoon to 9 AM
     EST Friday for LSZ243-244-264.

  Heavy Freezing Spray Warning from 11 AM this morning to 7 AM EST
     Friday for LSZ263.

  Heavy Freezing Spray Warning from 3 PM this afternoon to 7 AM
     EST Friday for LSZ245>247.

  Heavy Freezing Spray Warning from 11 AM EST /10 AM CST/ this
     morning to 5 AM EST /4 AM CST/ Friday for LSZ240>242.

Lake Michigan...


SHORT TERM...Ritzman
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