531 
FXUS63 KMQT 061736
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1236 PM EST Sat Feb 6 2021

.SHORT TERM...(Today and tonight)
Issued at 427 AM EST SAT FEB 6 2021

...Very Cold Wind-Chills in the Interior West Half Tonight...

As an mid-upper level low within broad longwave troughing continues 
to hover over the Upper Great Lakes, the cold airmass over the 
region will persist, as will the lake effect snow. With the wind 
continuing to be breezy over the region, cold wind chills will 
continue this morning. Tonight, as the next wave of cold air moves 
in, widespread wind chill concerns are expected.

At the moment, water vapor imagery highlights a subtle shortwave 
currently moving into the eastern UP and another upstream moving 
into the Arrowhead region. From what I can see via the limited radar 
coverage of the ongoing lake effect snow, showers have persisted 
through the night in the northwest wind snow belts of the east. 
Webcams and the nighttime Microphysics RGB show the same in the 
west. Cloud cover has been mainly confined to the Lake Superior 
shoreline, which has allowed a good part of the interior west to 
sink zero to -5 and the interior east into low single digits. By the 
lakeshores, overnight temps have generally hovered between 5 and 10F.

Through the day today, winds are expected to back to more westerly, 
shifting the snow bands some and limiting their coverage to the 
west wind snow belts. Along the shoreline in the east, there might 
be enhanced convergence from a land breeze component of the wind. 
850mb temps will continue around -22F today, which puts the DGZ at 
or below the ground. This will limit snowflake growth and cut into 
snowfall accumulations. Opted to extend the on going winter advisory 
in the east and the Keweenaw, not necessarily for the additional 2 
to 4 inches expected today, but more because the winds will continue 
to be gusty, which with the smaller flake size, will result in 
blowing snow concerns. During snow showers, its possible 
visibilities could drop to white out conditions. Daytime highs will 
struggle to hit the zero mark in parts of the interior west today. 
Much of the interior west is actually expected to be near zero for 
most of the day. Elsewhere, generally 5 to 10F above is expected.

This evening the lake effect showers will continue, mainly in the 
west wind snow belts. Another surge of cold air is expected; 850mb 
temps are progged to drop to around -27C which will send surface 
temps into negative territory for most of Upper Michigan. 
Approximately from Marquette-Delta county line westward and south of 
L'Anse, area's away from the lakeshores should fall into the 
negative teens. Per our model certainty tool, there's even a a 30-
40% probability that temps in the parts of Iron and Gogebic could 
fall below -20. With the modest wind speeds, widespread -25F to -35F 
windchills are expected in the west half interior regions of Upper 
Michigan. The coldest locations look to be in the interior western 
areas of Gogebic, Ontonagon, and southern Houghton where wind chill 
warning criteria could be met. These wind chills are dangerous and 
exposed skin will result in frostbite and frostburn after only a 
short amount of time. Even with proper clothing, prolonged exposure 
in these conditions could have dangerous consequences.

.LONG TERM...(Sunday through Friday)
Issued at 440 AM EST SAT FEB 6 2021

Continued trends of much below average temperatures for daily highs 
and bitter cold overnight lows are expected for approximately the 
next week. Persistent jet stream energy from both the Polar jet and 
Subtropical jet will remain south of the CWA through the end of next 
week. There will be a strong upper level ridge at the H5 heights 
over the next several days with the ridge axis remaining over Alaska 
and the Bering Sea. This will gradually shift south and east by 
Friday of next week per the GFS. This feature will keep the the 
bitter cold temperatures centered near and around the Great Lakes 
through the end of next week. One of the notable differences for the 
0Z GFS run earlier today versus 24 hours ago is that it has a mid-
latitude weather system affecting the lower Great Lakes by the end 
of the week. This path is slightly further east and south compared 
to the most recent surface low that came through the region, but it 
has the potential to bring additional synoptic-based snowfall and 
another push of cold air behind it. 

For Sunday, expect w to wnw winds over the lake continue the trend 
of lake effect snow showers. 850mb temperatures will be very cold, 
approximately -25C, so the DGZ will be too low and not maximized for 
better snowfall rates. The very small snowflakes will cause sharply 
reduced visibility at times over the w to wnw wind snowbelts over 
the Keweenaw Peninsula and areas furthest east in the CWA adjacent 
to the lake shoreline in Luce and Alger County. This will be for 
areas primarily north of M-28 in the eastern counties. The small 
snowflakes will easily be blown around by wind gusts throughout the 
day, totaling generally 1-3 inches over the w to wnw wind snow belts 
mentioned previously by evening. Snowfall accumulation over the same 
LES wind snow belt regions may reach an additional by 1-3 inches by 
Monday morning, or every 12 hours. The Arctic air mass will cause 
surface temperatures to be bitter cold on Sunday. Wind chills will 
be most likely reaching headline criteria for a majority of the 
western half of the CWA Sunday morning, and most of the CWA 
overnight Sunday into Monday morning. Wind chills of -25F to -35F 
are likely early Sunday and overnight Sunday into Monday morning, 
which will be dangerous for individuals that are outside for only a 
short timeframe. 

Winds will shift to the w and wsw by Monday afternoon. The westerly 
direction will persist most likely through Tuesday afternoon, so 
this will limit LES snowfall to the Keweenaw Peninsula as additional 
accumulation in that region will occur with sharp visibility 
reductions at times. From Tuesday night to Wednesday afternoon, 
winds will slowly veer to the w and wnw, gradually shifting 
snowbands further inland over the wind snowbelts. Wednesday night 
into early Friday will have winds further veer from the wnw to 
nw/nnw, continuing the trend of light LES over the CWA. As mentioned 
earlier, a surface lo progged by the GFS has the potential to swing 
through the Great Lakes on Friday, but will need to have more model 
consistency for it to increase confidence in a CWA wide snowfall 
event. Lastly, continued bitter cold temperatures will occur over 
the Upper Peninsula for the extended period as well. Temperatures 
will range from the negative single digits to 10 above for daytime 
maximums in the coming week. Overnight lows will potentially reach 
the -20F and colder threshold over the interior western zones in the 
coming week, with negative single digits to near 0 degrees further 
in the east for minimums. This will most certainly keep the area 
much below normal for the first half of February regarding average 
daily temperatures.
&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1235 PM EST SAT FEB 6 2021

Conditions at KIWD have improved to MVFR as the lake-effect snow 
moves north. KIWD should become VFR by late this afternoon as the 
blowing snow subsides due to wind speeds slowing down; the lake-
effect snow should remain north of KIWD for the rest of the TAF 
period. KCMX looks to remain at or below airport minimums for the 
rest of the TAF period, as lake-effect snow and blowing snow 
continues. KSAW looks to remain VFR for the TAF period, as the 
terminal should only get, at most, occasional cloud cover at VFR 
cigs.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 427 AM EST SAT FEB 6 2021

With anomalously cold air set to remain locked in place for the next 
several days, gusty northwesterly winds and heavy freezing spray 
will persist through at least next Wednesday. Northwesterly gales 
will subside this morning and the gales should expire this morning. 
20-30 kt west to northwesterly winds will persist after that through 
at least Wednesday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 7 PM EST this evening for MIZ006-
     007-085.

  Winter Weather Advisory until 7 AM EST Sunday for MIZ001>003.

  Wind Chill Advisory until noon CST today for MIZ009-010.

Lake Superior...
  Heavy Freezing Spray Warning until 7 PM EST /6 PM CST/ Sunday 
     for LSZ162-240>251-263>267.

  Gale Warning until 11 PM EST /10 PM CST/ this evening for 
     LSZ240>251-263>267.

Lake Michigan...
None.
&&

$$

SHORT TERM...JP
LONG TERM...BW
AVIATION...TAP
MARINE...JP