Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 110851

Area Forecast Discussion
National Weather Service Marquette MI
351 AM EST Sun Dec 11 2016

Issued at 1018 PM EST SAT DEC 10 2016

...Warnings for Alger and Luce Counties cancelled...

The MQT radar indicates the les bands that have been impacting ern
Alger and nrn Luce Counties are shifting offshore as the llvl winds
at even Grand Marais have turned to the sw, shifting the axis of
stronger llvl cnvgc out over the open lake. So the warnings that
were in effect until 05Z for Alger and Luce Counties have been canx.

.SHORT TERM...(This evening through Sunday)
Issued at 409 PM EST SAT DEC 10 2016

...Lake effect snow ends tonight then widespread system snow moves
in on Sunday...

Lake effect snow continues but the areas affected have become less
over the last 24 hours. Persistent sfc trough over southern Lk
Superior is main focus with one or two dominant bands of snow over
parts of Keweenaw and multiple dominant bands with some connection
to Lk Nipigon converging over eastern Alger and northern Luce. Over
water instability remains favorable for lake effect with inversions
over western Lk Superior around 5kft/h85 with inversion top temps to
-20c and up to 8kft/h75/-25c over eastern Lk Superior. Winds back
steadily to the WSW-SW this evening over Keweenaw so expect heavier
snow to remain on the move and will not extend the warning or advy
there. However, convergence remains strong into far eastern Alger
and northern Luce so extended warning there until midnight when HRRR
indicates blyr winds turn SW enough to push heavier lake effect
offshore. Away from the lake effect this evening skies should be
mostly clear allowing temps to fall off toward zero this evening for
the interior west. Mid-high clouds increase overnight as low
pressure system over eastern WY and CO this aftn pushes across the
central Plains. Min temps will depend how quickly the clouds move in
but a few zero to 5 below readings for favored cold spots seems

Low pressure system crosses IA and WI/northern IL on Sun morning.
WNW flow aloft and lack of very tight baroclinic zone at h85 should
keep stronger isentropic ascent snow mainly south of cwa into Sun
morning. However by aftn shortwave trough that is currently over
Pacific NW moves across Dakotas and northern MN. Deep layer q-vector
convergence increases markedly through the aftn and that forcing
along with increasing moisture advection ahead of low pressure
trough over WI (mixing ratios at h7 up to 2g/kg) running into cold
airmass should start to produce light to moderate snow. H85 low
tracking across northern WI as the shortwave moves through also
increases larger scale lift and there is some mid-level fgen on
northern edge of this low. That forcing along with SE winds off Lk
Michian and E winds off Lk Superior should result in lake
enhancement with h85 temps -8c to -10c and water temps around 5c.
Overall snow amounts with this system should fall into advy range of
3 to 5 inches in 12 hours (12z-24z/7 am ET to 7 pm ET) along WI
border, but lake enhancement could add to the totals for scntrl
Upper Michigan and across the Keweenaw Peninsula. Highlighted this
potential in the WSW statement and it is possible eventually could
need warnings but will start with advy for now. Does look like after
this event all areas of Upper Michigan will have at least light
snow cover.

.LONG TERM...(Monday through Saturday)
Issued at 350 AM EST SUN DEC 11 2016

The leading 500mb vort will be lifting northeast across Lake
Superior early Mon, helping to further eject the weakly organized
surface low to Quebec. In the wake will be a lull in activity with
some diffluence and should result in a dry day Mon for most
locations. The only exception could be areas adjacent to Lake
Superior where a light west/northwest wind could be able to produce
some light snow.

Mon ngt into Tue the focus will be the developing arctic push, as
the stronger 500mb vort will begin to dive south from Central
Canada. This will help to sharpen the baroclinic zone as an arctic
frontal boundary arrives early Tue. With the potent thermal trough
arriving, the favored snow growth zone will quickly crash towards
the surface by later Tue. This could challenge the longevity to
stronger LES bands, nonetheless portions of the Keweenaw will likely
continue to see a potent band setup and produce efficient snowfall.
As the arctic airmass settles into the region, temps will fall into
the single digits Tue aftn and then overnight fall into the single
digits below zero. Temps will be slightly warmer closer to Lake
Superior though.

Wed thru Sat: Ensembles continue to show good agreement in the
longwave pattern with the 500mb shortwave retrograding Thur/Fri,
with weak ridging from the Northern Plains pushing east towards the
Great Lakes Fri ngt. But with a quasi-zonal orientation to the
longwave pattern, this lull in activity will be short-lived.
Guidance then has a trough pushing east into the Southwest CONUS
Fri, and quickly arriving across the Central Plains late Fri ngt.
Some of the operational solutions differ on placement/track of the
system beyond early Sat; however, they are consistent in a system
further developing as another robust 500mb shortwave slides south
from Central Canada next weekend. If all of these items can come
together, widespread snow looks favorable for next weekend.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1224 AM EST SUN DEC 11 2016

With llvl dry air in place, expect VFR conditions at the TAF sites
thru at least sunrise under some thickening mid/hi clds ahead of the
next lo pres advancing toward the Upr Midwest. Sn in advance of this
lo pres wl overspread Upr MI later this mrng/early aftn, resulting
in IFR conditions by the aftn at all 3 sites. The best chc for some
LIFR conditions wl be at CMX and SAW, where the expected e wind wl

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 435 PM EST SAT DEC 10 2016

Expect NW winds up to 25 kts to diminish under 20 kts tonight but
may increase to around 25 knots as a trough lifts into Upper
Michigan Sunday. A steady WNW wind to 30 kts with potential for
brief periods of gales Mon night into Thu following a strong cold
frontal passage that will introduce arctic air into the Upper Lakes.
Expect some heavy freezing spray over at least portions of the Lake
on Tue night/Wed as this arctic air moves into the area and waves at
the end of fetch build to at least 10 feet.

Upper Michigan...
  Winter Weather Advisory from 10 AM EST /9 AM CST/ this morning
     to 1 AM EST /midnight CST/ Monday for MIZ002-004>007-

  Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
     Monday for MIZ001-003.

Lake Superior...
Lake Michigan...


LONG TERM...Beachler
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