Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 090851
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
351 AM EST Fri Dec 9 2016

.SHORT TERM...(This evening through Friday)
Issued at 309 PM EST THU DEC 8 2016

WV loop shows deep troughing across eastern Canada and the Great
Lakes. Cold airmass continues to pour across Upper Great Lakes with
h85 temps of -13c to -16c lowering to -16c to -19c by Fri aftn. IR
satellite loop showed colder cloud tops this morning with shortwave
working through then that faded this aftn but more hints of larger
scale forcing is showing up this aftn north of Lk Superior so lake
effect late this aftn into tonight should get a boost from this
forcing. Lake effect thus far today has been cellular instead of
banded, likely due to some shear present in the lake convective
layer and lingering sfc based instability over the land areas.
Earlier enhanced snow over the Keweenaw has shifted more over scntrl
Lk Superior and ncntrl Upper Michigan since 19z/2 pm ET while what
looks like convergence band off Lk Nipigon is quickly developing
ncntrl Lk Superior. Seems the combination of the subsidence to west
of the enhanced snow showers moving over ncntrl Upper Michigan and
lack of larger scale forcing for a time has put crimp on lake effect
over western Upper Michigan with vis sateliite showing less vertical
extent to the clouds there. Overall this event thus far at least
during the day is behaving much more like a fall or spring hybrid
type instead of a more typical setup with multiband and embedded
dominant bands.

RAP and HRRR do show winds becoming unidirectional late this aftn
into early evening and the ambient cape diminishing. Overall expect
the organization of the lake effect to increase through the evening.
Instability into later tonight and Fri remains very favorable with
inversions to at least 8kft/lake induced capes over 500j/kg and much
of the dgz within the lake convective layer. Decent agreement that
enhanced snow will continue to swing across ncntrl Upper Michigan
mainly Alger county late aftn then additional snow showers will
orient toward eastern Marquette into western half of Alger county
this evening. Elsewhere inversions to 5kft and some shear within
convective layer will limit lake effect to moderate instensity.
Stronger convergence will be over far west near IWD.

Later this evening stronger convergence band with origin off Lk
Nipigon and tip of Keweenaw peninsula should setup vcnty of far
eastern Marquette county into western half of Alger county. This
band of snow will be helped along by increasing sfc convergence with
W winds over cntrl Upper Michigan and NNW winds over scntrl Lk
Superior. Expect very fluffy lake effect snow to result with several
inches of accumulation with snowfall rates at least to 2 inches per
hour if not more. This heavy band of snow should persist over
western Alger county on Fri morning before shifting to the east
through the day. Elsewhere on Friday, expect similar setup to the
lake effect with inversions to 5kft and most of that convective
layer within the dgz. Thus, expect additonal fluffy accumulations to
continue. Winds diminish near Lk Superior so blowing snow so become
less of an issue as the day goes on. Since the dominant band is
expected to persist over western Alger county later tonight into Fri
morning, put a lake effect snow warning out earlier today for Alger
county into Friday and Friday night. Otherwise, will let all other
headlines continue as planned at this time.

.LONG TERM...(Saturday through Thursday)
Issued at 350 AM EST FRI DEC 9 2016

Sat through Sun: Continued lake effect setup through the weekend,
with a weak northwest flow along the lee-side of a surface ridge
stretching from the Upper Midwest southeast through Chicago. This
will keep likely POPs going for the Keweenaw and the favored areas
east of Marquette thru Sat ngt. Mid-lvl flow will begin to
transition to more of a zonal orientation briefly Sun with weak
surface ridging sliding over the Upper Peninsula. This should bring
a lull to lake effect snow; however, this may only be temporary as
guidance continues to prog a developing mid-lvl wave across the
Northern Rockies Sun ngt.

By Sun ngt the mid-lvl vort max will be strengthening as it lifts
northeast through the Missouri Valley towards Southeast Wisconsin.
Guidance continues to develop a robust surface low over Chicago
lifting northeast across Lower Michigan early Mon morning. The
challenge for POPs for Sun ngt into early Mon will be heavily driven
by the path the shortwave takes. A further north path and POPs will
need to be adjusted higher for Sun ngt/early Mon, due to the more
favored iscentropic ascent region entering the Eastern U.P. Temps
for the weekend will continue to be seasonal in the 20s with
overnight lows in the single digits above zero Sat ngt due to less
cloud cover, then back into the lower teens Sun ngt with increasing
clouds.

Mon through Thur: With the surface low lifting northeast of Lower
Michigan, the main focus will be on the arctic airmass poised to
drop south from Central Canada early next week. Flow will quickly
turn northwesterly with optimal conditions for LES to kick-in Mon
ngt through much of the extended periods. Guidance continues to prog
a potent surface ridge over the Missouri Valley, which places a
modest northwest flow over the Upper Peninsula. Thermal trough of -
14 to -18 deg c at 850mb slides overhead and will lock the region
into sub-seaonal temps as highs may struggle to warm beyond the
single digits above zero.
&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1255 AM EST FRI DEC 9 2016

Lake effect snow continues for mainly IWD and CMX. Some blowing snow
as well but with winds less than 20 kts, main vsby reduction is from
the snow. Overall at IWD and CMX expect the snow showers to produce
IFR vsby with MVFR cigs. Vsby may trend toward VFR later tonight
into Fri at IWD as winds back more nw or wnw. Winds backing nw at
SAW overnight should ensure mainly VFR conditions into Friday
although a stray les band could briefly lower vsby down to MVFR late
tonight.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 309 PM EST THU DEC 8 2016

NW winds will reach 30 kts through Fri with gale gusts to 35 kts
still possible over central and eastern sections, especially in the
vcnty of stronger lake effect snow showers over cntrl sections.
Winds diminish to less than 20 kts Sat through Mon. W to NW winds
increase to 30 kts by later Tue with gales possible Tue night into
Wed as bitter cold air arrives. There is a good chance of heavy
freezing spray by the middle of next week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Lake Effect Snow Warning until 7 AM EST /6 AM CST/ Saturday for
     MIZ002-003-006-009.

  Lake Effect Snow Advisory until 7 AM EST Saturday for MIZ007-084-
     085.

  Lake Effect Snow Advisory until 7 PM EST this evening for MIZ004-
     013.

  Lake Effect Snow Warning until 7 PM EST this evening for MIZ005.

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

$$

SHORT TERM...JLA
LONG TERM...Beachler
AVIATION...Titus
MARINE...JLA



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