Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 222019

Area Forecast Discussion
National Weather Service Marquette MI
319 PM EST Tue Jan 22 2019

Issued at 309 PM EST TUE JAN 22 2019

Due to numerous reports of freezing drizzle making roads icy in
spots, have expanded the ongoing winter weather advisory westward
through Baraga, S. Houghton, and Iron counties into this evening.
Radar returns continue to show additional light freezing drizzle,
at times mixed with snow, moving into the Upper Peninsula. In
fact, a pocket of perhaps heavier freezing drizzle has remain
persistent on radar over the last few hours across Baraga and
western Marquette counties. Any roads that are cleared of snow or
are untreated may quickly become icy due into this evening. Elevated
surfaces, such as bridges, overpass and trees will have the
potential to see a glaze of ice.


.SHORT TERM...(This evening through Wednesday)
Issued at 232 PM EST TUE JAN 22 2019

Water vapor imagery shows elongated troughing spanning from the
Upper Great Lakes down into the southern Rockies. The lead shortwave
that traversed the Upper Great Lakes and it`s associated warm air
advection/isentropic lift brought about fairly widespread snow at
times today. With lake-air temperatures differences over Lake
Michigan around 8 to 10 degrees, lake enhanced snow developed rather
nicely during the late morning/early afternoon hours around and east
of Rapid River. Further upstream of the area, additional snow
remained loosely organized across central and southern Wisconsin.

Through the rest of this afternoon into tonight, the main forecast
concerns are snow across portions of western and central Upper
Michigan switching over to freezing drizzle, ongoing lake enhanced
snow out east, and multiple waves of snow expected to track across
the south central. Webcams north of Lake Michigan this afternoon
have showed the onset of snow nicely, with roads quickly becoming
snow covered in spots. As the main trough axis continues to move
overhead an area of frontogenesis is progged to tighten up, leading
to the potential for a narrow band of locally heavier snow. This
band is rather unorganized at this time, but has begun to move into
Menominee County this afternoon. Expect this Fgen band to bring
multiple rounds of snow across the south central and locations near
Lake Michigan into the evening hours, before gradually dropping
south into Wisconsin and over Lake Michigan. As this frontal zone
drops south, the ongoing lake enhanced snow north of Lake Michigan
may remain loosely organized, but given the introduction of
increasing directional shear any additional snowfall amounts
overnight are expected to remain light around or after midnight.
Over the Keweenaw Peninsula, snow is expected to taper off over the
next 2-3 hours. Across portions of central and eastern Upper
Michigan, we have had reports of snow transitioning over to freezing
drizzle as we lose cloud ice this afternoon. Due to this, have
issued an SPS to highlight potential travel impacts this afternoon
into the evening hours. See updated discussion for details on
headlines for freezing drizzle this evening.

Early morning and through the day on Wednesday, the main shortwave
currently working on rounding the based of the elongated trough
draped across the central CONUS is progged to lift northeast towards
the western Great Lakes. As a result, the main surface low down
across the Plains will race northeast, tracking over lower
Michigan. With the surface low expected to remain to our south,
colder air rotating about the Upper Great Lakes and the development
of north-northwest flow will allow lake effect snow to developing
across the respective snow belts, and there is the potential for
synoptic/lake enhanced snow out east. As for the lake effect snow
off of Lake Superior, low-level flow through the convective layer
doesn`t appear to be unidirectional throughout the entire time
period, that coupled with low inversion heights should keep snowfall
amounts below advisory criteria. The big question is how things will
play out over eastern Upper Michigan mid-day on Wednesday. The
overall trends throughout this period have been a bit slower and
further south with the area of low pressure and resulting
precipitation. Right now the Canadian is by far the most aggressive
across eastern Upper Michigan, but is also close in regards to
advisory level snow. Given the extreme ends of the spectrum, being
close to advisory level system snow or little to no system snow at
all across the east did opt for more of a middle of the road
approach, with around 1-3`` across north-northwest wind belts, south
central and eastern Upper Michigan.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 309 PM EST TUE JAN 22 2019

Primary focus in long term is the shortwave and associated cold
front moving through late Wed night into Thu. Models have shown
fairly good continuity and agreement with this system, so confidence
is high. Shortwave energy will signal the arrival of a deep upper
trough and frigid airmass. Forcing with the shortwave is somewhat
limited so there may not be much in the way of synoptic snow with
clipper although any forcing will enhance lake effect especially
along the frontal boundary. The lake effect will kick in quickly
along the frontal boundary as 850mb temps decrease from around
-14C at 09Z Thu to -20C or colder by late Thu morning/afternoon and
around -30C by late Thu night. Temps around -30C stick around into
Fri night, with NW winds the whole time. The NW wind snow belts will
be favored for widespread LES. With how cold the airmass will be,
dendrite production will poor, resulting in very small snow flakes
that are very effective at reducing visibilities. Strong NW winds
will gust to 30-45mph along the Superior shorelines Thu and Thu
evening, resulting in widespread blowing snow in open areas. Expect
blizzard conditions at times with near zero visibilities in snow and
blowing snow. The bitter cold will also be a significant impact.
Temps Thu will fall into the single digits over the western third of
the CWA before noon and across the rest of the area by the evening
(wind chills even lower). Lows Thu night are forecast to be zero to
-18F (coldest W) with minimum wind chills of -25F to -35F. Fri highs
are forecast to in the single digits above and below zero and wind
chills most areas won`t rise above the teens below zero (lowest NW).
Lows Fri night bottom out in the teens to low 20s below zero with
minimum wind chill values again in the -25F to -35F range. Primary
messaging will continue to be very poor visibilities and extreme
cold dangers. Snowfall amounts will not be as big of a deal (2-4"
every 12 hours in the NW wind snow belts), but will still present a
hazard. Will issue a SPS to highlight all these hazards for Thu into
the weekend.

Temps moderate to around -22C on Sat with winds turning W-SW ahead
of the next cold air surge. This will favor the Keweenaw for
moderate to heavy LES and gusty winds. Models since yesterday have
trended colder with the next clipper and associated surge of Arctic
air Sat night and Sun. Currently, models show 850mb temps -25c to -
30C. Lake effect will be hampered somewhat by very dry air and
anticyclonic flow Sun as a ridge of high pressure moves in. Sat
night lows will be 0 to -15F with minimum wind chill values of
-25F to -30F.

With a surface low moving well S of the CWA Sun night into Mon
(track through northern IA and along the WI/IL border) and 850mb
temps steady around -23C, LES will be favored in ENE turning N wind
snow belts Sun night through Mon. Only a dusting of snow expected
over southern tier counties at best. Models show cold persisting
into Tue in a north-northwest flow which will allow LES to persist.
GFS advertises another clipper moving in dropping 850 mb temps to
-27c to -30C which could enhance lake effect snow and blowing snow
for the Lake Superior NW wind snowbelts especially over the eastern
half counties. Nevertheless, bitter cold temps/wind chills and lower
vsbys in lake effect snow will continue to highlight messaging in
headline statements and social media posts into early next week.

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1248 PM EST TUE JAN 22 2019

Low confidence aviation forecast today with many moving parts and
models not handling them well. Main features are trough approaching
from west and low pressure sliding by to south. Ahead of the trough,
a band of light snow stretches from the Keweenaw to the SW into MN.
Most upstream obs have IFR vis and MVFR cig, so will carry that
through the afternoon at CMX. At IWD, expect some fluctuations next
few hours as that band of snow continues to lift away to the north.

Behind the trough, should see some clearing in the evening and then
winds shifting from W to N at all three sites overnight. Lake-effect
snow showers begin late tonight at CMX and IWD and tomorrow morning
at SAW, but are expected to be weak/widely-scattered so have kept
conditions mostly MVFR in the extended, except for a period of IFR
vis at IWD late tonight.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 232 PM EST TUE JAN 22 2019

Winds will remain between 15 to 25 knots through Wednesday. Then,
in the wake of a passing Arctic cold front, northwest to north gales
35 to 40 knots will overspread the lake Thursday into Thursday night.
While the winds relax, elevated speeds of 20 to 30 knots Friday into
the weekend will work in concert with the bitterly cold air mass to
allow for a prolonged period of freezing spray.

Upper Michigan...
  Winter Weather Advisory until 1 AM EST /midnight CST/ Wednesday
     for MIZ006-007-012>014-085.

  Winter Weather Advisory until 8 PM EST /7 PM CST/ this evening
     for MIZ004-005-010-011-084.

  Winter Weather Advisory until 4 PM EST this afternoon for MIZ001-

Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
MARINE...Ritzman is the U.S. government's official web portal to all federal, state and local government web resources and services.