A low pressure system passing south of Upper Michigan produced moderate to heavy snow across much of Upper Michigan from the evening of the 22nd into the morning of the 23rd.
Every event with a place to put it; 13 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MQT wrote it up.
A low pressure system passing south of Upper Michigan produced moderate to heavy snow across much of Upper Michigan from the evening of the 22nd into the morning of the 23rd.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Marquette, MI wrote its last area forecast discussion before the first event at Feb 22, 11:42 PM EST, 18 minutes earlier.
Area Forecast Discussion
National Weather Service Marquette MI
1142 PM EST Thu Feb 22 2018
.SHORT TERM...(This evening through Friday)
Issued at 341 PM EST THU FEB 22 2018
Initial forecast problem for tonight will deal with anticipated
widespread snowfall that is expected to develop as the evening
progresses. Isentropic ascent combined with increasing moisture
(precipitable water values above 0.50 inch) on the nose of an
increasing low level jet (and subsequent moisture convergence) and
some increasing divergence aloft ahead of a subtle short wave
trough. Weak mid level static stability won't hurt the cause either
(700-500mb lapse rates around 7C/km overnight into Friday morning)
Focus for heaviest QPF tonight into Friday morning looks to be
across the western half of Upper Michigan...with some enhancement
across the higher terrain along the spine of the Keweenaw Peninsula.
22/12z HREF snowfall probabilities show a decent shot of more than
8"/12h ending 12z Friday morning over parts of the Keweenaw...at
least fairly confident in a 4-6 inch swath of snow across Ontonagon/
Houghton/Keweenaw Counties through 12z Friday..with 3-5 inch amounts
west of an IMT-MQT line where best low level frontogenetic forcing
will be focused...and 1-3 inches east of that line where snow will
start latest (as low level dry air will take some time to overcome).
Push of warmer air into the upper Great Lakes will have an impact
on snow ratios...with forecast soundings implying a deep layer (on
the order of 300-400mb) of temperatures warmer than -10C...which
support more riming/aggregation of snowflakes and tend toward a
wetter/high density type of snowfall (SLR in the 9-14:1 range???).
This type of snowfall...though perhaps not of "cement mixer"
consistency...will still be more difficult to drive through
especially with system timing (during morning drive time to
work/school).
Snow will still be ongoing at daybreak Friday morning...but is
expected to taper off from west to east as the morning wears on as
drying/subsidence take hold (though low level moisture/cloudiness
may persist). Can't rule out snow tapering off to drizzle/freezing
drizzle during the afternoon...some weak QPF signals especially in
the high-res guidance though usually prefer to see more of a low
level warm advection/convergence signal (though low level lapse
rates to steepen as cold advection kicks in). Additional snowfall
for Friday expected to be in the 1 to 2 inch range (higher east)...
for event totals of 5 to 8 inches for Ontonagon County northeast
through the Keweenaw...3 to 6 inches west of IMT-MQT line and 2 to 4
inches east. As for headlines...seems to make sense to expand
current advisory to encompass remaining central U.P. counties
(Alger/Schoolcraft/Luce) given similar snowfall amounts and concerns
about snow density (will simply shift the start/end times about 3h
forward). This has been coordinated with our "friends" at APX
(since I'm staring at them from above my workstation). Other
headlines look fine...including the Keweenaw warning.
.LONG TERM...(Friday night through Thursday)
Issued at 341 PM EST THU FEB 22 2018
Next forecast problem arrives for the latter half of the weekend as
a more substantial short wave trough lifts northeast out of the
southern Plains Saturday night...and pushes a deep but compact
surface low probably across the Upper Peninsula Sunday morning. The
threat for precipitation will increase ahead of the low late
Saturday into early Sunday...possibly starting as snow but could
become mixy as warm air surges north. Potential snow amounts will
depend on the evolution of this warm push...but at this point
another round of wintry headlines may be in the offing. A glancing
blow of cold air on the backside of this system to start next
week...but lake effect pattern overall not looking impressive at
this distance. Gusty west winds Sunday afternoon especially across
the Keweenaw.
No other impactful weather systems on the horizon next week as low
amplitude ridging aloft takes hold of the eastern CONUS. There is
some mischief possible in the southern branch of a split flow
pattern that will need to be monitored.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1138 PM EST THU FEB 22 2018
Overnight periods continue to be greatest concern for reduced CIGs
and VSBYs, possibly trending towards IFR conds for several hours
between 7-12z at TAF sites. Snow will potentially be moderate at
heavy at times especially at KCMX and KIWD. Exact timing of
snowfall is the greatest uncertainty, but confidence in the
forecast is otherwise good.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 341 PM EST THU FEB 22 2018
Relatively light winds tonight with high pressure ridge giving way
to a wave of low pressure expected to lift northeast across the
upper Lakes Friday. Winds will increase from the northwest Friday
afternoon in the wake of the front...gusts may kick up to 30 knots
over the eastern half of Lake Superior. More substantial winds are
likely Sunday as a sub 985mb low is forecast to lift northeast
across Lake Superior. Some easterly gales may occur Saturday night
to the north of the approaching surface low...with winds veering to
west Sunday with more gale force gusts likely especially over the
eastern half of Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 1 PM EST Friday for MIZ006-007-014-
085.
Winter Weather Advisory until 10 AM EST /9 AM CST/ Friday for
MIZ002-004-005-009>013-084.
Winter Storm Warning until 10 AM EST Friday for MIZ001-003.
Lake Superior...
None.
Lake Michigan...
None.
&&
SHORT TERM...JPB
LONG TERM...JPB
AVIATION...Beachler
MARINE...JPBHazardous Weather Outlook National Weather Service Marquette MI Issued by National Weather Service GAYLORD MI 402 PM EST Thu Feb 22 2018 MIZ001>007-009>014-084-085-230500- Keweenaw-Ontonagon-Northern Houghton-Baraga-Marquette-Alger-Luce- Gogebic-Iron-Dickinson-Menominee-Delta-Southern Schoolcraft- Southern Houghton-Northern Schoolcraft- 402 PM EST Thu Feb 22 2018 /302 PM CST Thu Feb 22 2018/ This Hazardous Weather Outlook is for portions of western Upper Michigan and central Upper Michigan. .DAY ONE...Tonight Moderate to heavy snow is expected late tonight over especially the west half of Upper Michigan. See the latest winter weather message for complete details. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Snow may mix with or change to freezing drizzle Friday morning before ending. Moderate snow remains possible, especially through mid morning Friday. Snow is expected to be of a wetter consistency and thus will cause travel issues. See the latest winter weather message for complete details. A storm system moving northeast into the Great Lakes over the weekend will bring a wintry mix of precipitation to west and central Upper Michigan Saturday night into Sunday morning. The greatest chance for heavy snow will occur over western Upper Michigan. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to submit reports of snow and ice. Any road condition reports are also appreciated. The public may provide reports through our Facebook or Twitter pages. LSZ162-240>251-263>267-230500- Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM-Saxon Harbor WI to Black River MI- Black River to Ontonagon MI- Ontonagon to Upper Entrance of Portage Canal MI- Upper Entrance of Portage Canal to Eagle River MI- Eagle River to Manitou Island MI- Manitou Island to Point Isabelle MI- Point Isabelle to Lower Entrance of Portage Canal MI- Lower Entrance of Portage Canal To Huron Islands MI Including Keweenaw and Huron Bays-Huron Islands to Marquette MI- Marquette to Munising MI-Munising to Grand Marais MI- Grand Marais to Whitefish Point MI- Lake Superior from Saxon Harbor WI to Upper Entrance to Portage Canal MI 5NM off shore to the US/Canadian border including Isle Royale National Park- Lake Superior from Upper Entrance to Portage Canal to Manitou Island MI 5NM off shore to the US/Canadian Border- Lake Superior West of Line from Manitou Island to Marquette MI Beyond 5NM from shore- Lake Superior East of a line from Manitou Island to Marquette MI and West of a line from Grand Marais MI to the US/Canadian Border Beyond 5NM from shore- Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off shore to the US/Canadian border- 402 PM EST Thu Feb 22 2018 /302 PM CST Thu Feb 22 2018/ This Hazardous Weather Outlook is for portions of Eastern Lake Superior...Central Lake Superior and Western Lake Superior. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Gale force gusts to 35 knots are possible Saturday night through Sunday night, especially over the east half of Lake Superior. .SPOTTER INFORMATION STATEMENT... The need for weather spotter reports is not anticipated at this time. LMZ221-248-250-230500- Green Bay North of line from Cedar River MI to Rock Island Passage-Seul Choix Point to Point Detour MI- 5NM East of a line from Fairport MI to Rock Island Passage- 402 PM EST Thu Feb 22 2018 This Hazardous Weather Outlook is for portions of Northern Lake Michigan. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Friday through Wednesday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... The need for weather spotter reports is not anticipated at this time. JPB
The national radar mosaic for the moment the first event began.
11 winter weather, 2 winter storm. Local standard time, as filed.
Observers from Chassel and Painesdale through Houghton to Laurium measured between seven and nine inches of snow in nine hours.
Reports from area observers supported an estimated six to eight inches of snow in nine hours near Allouez.
There was a report of seven inches of snow in ten hours at Iron River. Amasa and Stambaugh received four to five inches over the same time period.
There was a public report of six to eight inches of snow in Bessemer in eight hours. Around six inches of snow was reported in Ironwood. Watersmeet Schools were closed on the 23rd due to the snow.
There was a report of three inches of snow in eight hours at McMillan. A glaze of ice was also reported.
There were several reports of four to five inches over a nine-hour period mainly over the higher terrain from Big Bay through Negaunee to Harvey.
The observers from Greenland to Paulding reported from five to six inches of snow over eight hours.
Observers across much of Baraga County measured from four to five inches of snow over nine hours. Many schools were delayed two hours on the morning of the 23rd.
There was a report of six inches of snow in nine hours at Au Train. Roads were reported to be slushy and slippery.
There were reports from Daggett and Perronville of a mix of light freezing rain and snow.|Hannahville Schools were closed on the 23rd due to the mixed precipitation.
There was a report of light freezing rain over the Garden Peninsula. Big Bay de Noc Schools were on a two-hour delay on the 23rd due to the slippery roadways.
There was a report of light freezing rain in Manistique with a light glaze of ice on vehicles.
There was a report of three inches of snow in approximately eight hours at Iron Mountain. A light glaze of ice was also reported. Many schools throughout the county were on a two-hour delay on the 23rd due to the slippery roadways.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2018Every state in 2018This day in weather historyWarnings in Michigan, February 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 739413, 739414, 739415, 739416, 739418, 739419, 739420, 739421, 739422, 739423, 739424, 739425, 739417.