Area Forecast Discussion

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FXUS63 KMQT 162124
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
424 PM EST Sun Feb 16 2025

.KEY MESSAGES...

- Northwest flow lake effect snow continues for the next few 
  days, heaviest tonight through Monday night. Over western 
  Upper MI, Ontonagon County will be favored for most persistent
  heavier snow, up to around 1 foot tonight through Monday 
  night. Over the east, Alger, northern Schoolcraft and Luce 
  counties will be favored for heavier snow. Snow accumulations 
  of 10 to 20 inches tonight through Monday night, greatest 
  between Grand Marais and Seney. 

- Gusty northwest winds will create areas of blowing and 
  drifting snow. Brief whiteouts expected in Alger County, 
  particularly along M-28 where the road is exposed to winds off
  of Lake Superior. 

- Cold conditions for the next few days. Low temperatures 
  mostly zero to around 10 below tonight through Tuesday night. 
  Wind chills 15 below to 25 below interior western Upper 
  Michigan Monday morning and Tuesday morning.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 243 PM EST Sun Feb 16 2025

Upper air pattern consists of a 500 mb closed low near Lake Winnipeg 
and a trough over the upper Great Lakes. The closed low heads slowly 
southeast into western Ontario by 12z Mon just north of 
International Falls. Lake effect snow will continue for this 
forecast period with winds becoming northwest. Northwest wind 
affected lake effect snowbelts will come into play this forecast 
period where the heaviest snow will be. Couple of things to be 
concerned about for this forecast. First is the lake effect snow 
will continue overnight. With northwest winds occurring, strong 
directional convergence sets up which will cause some strong lake 
effect snow bands to move across Ontonagon, Alger and Northern 
Schoolcraft counties and the winter storm warning looks good still. 
Advisory areas look good as well where they are. Second issue is 
possible apparent air temperature values. With northwest winds, this 
will tend to cause lake effect clouds to continue to move inland. 
The wind does not look to decouple tonight, so ideal radiational 
cooling does not set up. Think cloud cover will be persistent enough 
over the west combined with the wind which will keep apparent 
temperatures above -25F, so no cold advisory will be needed. A few 
places will get close though.

&&

.LONG TERM /MONDAY THROUGH SUNDAY/...
Issued at 423 PM EST Sun Feb 16 2025

Significant positive height anomalies have recently dominated the 
Arctic, dislodging Arctic air southward as negative height anomalies 
tend to dominate to the s toward the mid-latitudes in this type of 
situation. That includes Canada where an expansive Arctic air mass 
still currently resides. Widespread -20s and -30s F were observed 
early this morning across the Prairie Provinces into northern 
Ontario. A -51F was even noted in northern Saskatchewan. This Arctic 
air is spilling across the International Border into the Northern 
Plains and Upper Mississippi Valley. The Arctic positive height 
anomalies are currently breaking down and are on the move. One piece 
will drop s to Hudson Bay, forcing negative height 
anomalies/troffing s into the Great Lakes thru Tue. This will 
support the moderating core of Arctic air pushing thru the Upper 
Mississippi Valley into the Great Lakes region. So, for Upper MI, 
blo normal temps will prevail thru Wed with the coldest day likely 
on Mon. Thereafter, a trend toward positive height anomalies 
expanding all along the vcnty of the International Border will lead 
to a warming trend during the last half of the week, bringing temps 
back to around normal or a little above normal by the weekend. As 
for pcpn, the evolving pattern will not be favorable for any system 
snows this week. The lack of system snows for Upper MI has been a 
theme of this winter, just like it was last winter. The Arctic air, 
however, will support LES through about Thu morning.

Beginning Mon, fcst soundings show inversion heights around 7-8kft 
as mid-level low currently over southern Manitoba shifts over Lake 
Superior while opening up. Combined with 850mb temps ranging from 
around -23C over eastern Lake Superior to around -28C over western 
Lake Superior, expect vigorous LES under northwesterly low-level 
flow. Models over the last 24hrs have been very consistent in 
showing strong low-level convergence off of western Lake Superior 
into Ontonagon County tonight lingering thru Mon morning before 
weakening, but still remaining thru the aftn. To the e, another area 
of strong low-level convergence persists thru the day and holds 
nearly steady across eastern Alger County, ne Schoolcraft County and 
western Luce County. In both of these areas, expect hvy LES, but it 
will be most persistent thru the entire day in the latter area. In 
Ontonagon County, another 2-5 to locally 6 inches of snow is likely 
on Mon. In eastern Alger, ne Schoolcraft and western Luce, 8-12 
inches of new snow is easily achievable during the day Mon. If the 
convergence becomes highly focused and stationary, accumulations on 
Mon could reach 12-16 inches in a small localized area. Across the 
rest of the eastern fcst area affected by nw flow LES, expect 2-5 
inches of snow in general. Over western Upper MI, expect 1-3 inches 
of snow outside of Ontonagon County. With the opening up mid-level 
low arriving, expect some diurnal component -shsn, resulting in  
-shsn/flurries extending well inland in the aftn. With temps of -5 
to -10F in the morning across the interior w and winds 5-10mph, wind 
chills will be -18 to -25 range, not quite to cold weather advy 
criteria of widespread -25 or lower. Afternoon high temps will range 
from the lower single digits above 0F interior w to around 10F above 
s central and e. 

Inversions gradually begin to fall during Mon night as troffing 
weakens/heights rise over the area. So, snowfall rates will also 
begin to ease. The low-level convergence zone into Ontonagon County 
remains nearly stationary during Mon night. To the e, the low-level 
convergence zone into eastern Alger/northern Schoolcraft/Luce 
counties also remains near stationary. As a result, those areas will 
continue to see the heavier, most persistent shsn, about 2-4 inches 
of new snow w and 4-7 e. Outside of those favored convergence zones, 
the ongoing nw flow LES will leave another 1-3 inches of new snow 
during Mon night. Temps by early Tue morning will be down near -10F 
in the interior w with wind chills again down in the -18 to -25 
range. 

Inversions settle in the 4-6kft range for Tue/Wed, lowest w, leading 
to lighter nw flow LES. Expect 1-3 to locally 4 inch accumulations 
per 12hrs with the higher accumulations over the e. Winds 
temporarily veer a little more northerly Tue night and then again 
Wed night into Thu morning, so the LES may shift to cover more of 
northern Upper MI during those times. WAA from the n will then raise 
850mb temps toward -10C on Thu, so LES will wind down and likely 
end. Dry weather expected for at least Fri with broad sfc high pres 
ridging moving across the Mississippi River Valley. WAA regime and 
uncertain timing of shortwaves in wnw flow will probably lead to a 
little -sn at some point over the weekend. Temps Fri thru the 
weekend will be around normal to a little above normal for mid to 
late Feb.  

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1132 AM EST Sun Feb 16 2025

Northwesterly lake effect snow will continue for this forecast 
period. Conditions will stay MVFR for the most part at IWD with 
periods of IFR in the lake effect snow showers. CMX will remain IFR 
through the period with lake effect and at times will be LIFR. SAW 
will be IFR this afternoon and improve to VFR tonight as winds back 
more northwesterly and push the lake effect northeast out of the 
area.

&&

.MARINE...
Issued at 423 PM EST Sun Feb 16 2025

NW winds of 20-30kt will generally be the rule across much of Lake 
Superior thru Tue, strongest across the e half. Some gale force 
gusts will occur into Mon in the area generally between Grand 
Marais, Stannard Rock and Munising. The gale gust potential expands 
over more the east half of the lake during Mon night as probability 
of peak gusts to 35kt increases to 50-70pct. With the brisk winds 
and the cold airmass in place, expect periods of heavy freezing 
spray thru Tue. NW to N winds drop back to mostly below 20kt for Wed 
and Thu.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 7 AM EST /6 AM CST/ Monday for 
     MIZ001-003-009-084.

  Winter Storm Warning until 7 PM EST Monday for MIZ002.

  Winter Storm Warning until 1 AM EST Tuesday for MIZ006-007-085.

Lake Superior...
  Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Tuesday 
     for LSZ240>251-263>267.

  Gale Warning until 10 PM EST this evening for LSZ249.

Lake Michigan...
None.

&&

$$

SHORT TERM...07
LONG TERM...Rolfson
AVIATION...07
MARINE...Rolfson