A large and slow moving low pressure area brought moderate to heavy sleet and snow to southern WI over a couple days. Light freezing rain occurred over south central WI at the beginning of the storm.
Every event with a place to put it; 17 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 MKX wrote it up.
A large and slow moving low pressure area brought moderate to heavy sleet and snow to southern WI over a couple days. Light freezing rain occurred over south central WI at the beginning of the storm. Numerous vehicle slide-offs and accidents occurred including one death. Some schools were cancelled or had early releases on April 16th. The heaviest snow amounts were toward central WI.
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 Milwaukee, WI wrote its last area forecast discussion before the first event at Apr 14, 4:54 AM CST, 3 hours 6 minutes earlier.
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
554 AM CDT Sat Apr 14 2018
.UPDATE...
Mixed precipitation mainly north and northwest of Madison.
After a brief period of freezing rain at Madison on mainly metal
surfaces, the precipitation changed back to rain. The rain should
transition back to a mix at Madison during the mid day to mid
afternoon hours.
&&
.AVIATION(12Z TAFS)...
IFR to LIFR will persist for the next 24 hours, with low ceilings
and reductions in visibility. Very windy conditions will
continue through the day, with winds peaking from mid to late
morning through the afternoon hours. Peak gusts between 40 and 45
knots are expected. In addition, the wintry mix of sleet and
freezing rain that was occuring well north and northwest of
madison will continue a slow progression to the south. After a
brief period of freezing rain at MSN on mainly metal surfaces, the
rain should transition back to a mix at MSN during the mid day to
mid afternoon hours, then UES during the late afternoon and at
MKE during the evening hours. For KENW, it is a little more
questionable whether precipitation will switch over or not, but
temperatures will be very close.
Rain/freezing rain/sleet will continue through Saturday evening,
gradually transitioning to mainly snow Sunday.
&&
.PREV DISCUSSION... (Issued 257 AM CDT Sat Apr 14 2018)
SHORT TERM...
TODAY THROUGH SUNDAY NIGHT...Forecast Confidence - Medium.
Have went with the wind advisory as of 3 am. otherwise no change
in the headlines.
Quite the mixed bag of weather types are expected as strong low
pressure moves across northern Illinois and into southern lower
Michigan. Models are having a hard tome with the low level thermal
structure depending on how strong convective cooling is. Despite
this, as temperatures cool off from the northwest, the mixed
precipitation will continue to sag southward during the day
Saturday. Mainly rain will hold on through late afternoon toward
the Illinois border and the far southeast. Mainly freezing rain,
sleet, and snow is then expected Sunday into Sunday night, with
some rain mixing in southeast during the day Sunday.
Will keep Winter Weather Advisory for all but southeast portions
of the forecast area. Milder temps will lead to more rain and less
snow/ice in the southeast. The main factors for keeping an
advisory vs a warning are: mild ground temps which will make icing
difficult on pavement, long duration of the event (melting will
occur), and a lot of precip falling during the day Saturday and
Sunday (more melting likely). Model soundings were right on the
edge of sleet and freezing rain...so could end up seeing more
sleet than currently in the forecast. In general went with line
Ice accumulations, for the total ice accumulation grids.
Strong winds will help bring down some tree branches given enough
icing. Went with a Wind Advisory for the whole area to 7 pm
Saturday. Peak gusts of 40 to 50 mph are likely.
Prolonged period of onshore winds with a favorable fetch from the
East-northeast to northeast expected tonight into Sat night. Onshore
winds are expected to gust from as high as 45 knots at the
lakeshore and coastlines later tonight into Saturday night. With
Lake Michigan water levels running about a foot above the period
of record average, thinking there is an increased threat for
lakeshore flooding and erosion along the coastlines from Sheboygan
south to Kenosha. Posted Lakeshore Flood Advisory to heighten the
awareness for this period.
SUNDAY NIGHT AND MONDAY...Forecast Confidence - Medium.
Lingering mid-level circulation and deformation will likely bring
some light snow to the area Sunday night. Colder air will be
funneling back into southern WI behind surface and 850H low
pressure moving through the central Great Lakes. Minor
accumulations of snow will be possible.
LONG TERM...
MONDAY NIGHT THROUGH FRIDAY - Forecast Confidence...Medium.
Some recovery in temperature is expected early in the period as
short wave ridging results in a brief period of quiet weather around
Tuesday. 850H temps warm above freezing on Tuesday but cloud cover
and east to southeast winds will prevent much of a warm up. Medium
range guidance in good agreement on another low pressure system
deepening over Iowa, and pushing into southern Wisconsin.
Interests across the area should check back for updates on the
weather later Tuesday night into Wednesday. This system will move
moving along a tightening baroclinic zone and will likely bring
another round of mixed precip to southern Wisconsin during this
period. ECMWF is a little slower than the GFS, and is preferred.
clouds and possible flurries may linger into Thursday. Some
recovery in temperature on Friday, but another low pressure system
will be poised to affect the area over the weekend. The ECMWF has
a warmer and more western track than the GFS.
AVIATION(06Z TAFS)...
IFR to LIFR will persist for the next 24 hours, with low ceilings
and reductions in visibility. For the rest of tonight, rain
showers are expected, along with some fog and very gusty winds.
Winds will gust from the northeast between 30 and 40 knots
through sunrise. LLWS will also be a concern overnight into
Saturday morning.
Very windy conditions will continue through the day Saturday, with
winds peaking from mid to late morning through the afternoon
hours. Peak gusts between 40 and 45 knots are expected. In
addition, precipitation will begin to transition to a wintry mix
of sleet and freezing rain at the TAF sites. This is likely to
first impact MSN during the mid day to mid afternoon hours, then
UES and MKE during the late afternoon into the evening hours. For
KENW, it is a little more questionable whether precipitation will
switch over or not, but temperatures will be very close.
Rain/freezing rain/sleet will continue through Saturday evening.
MARINE...
Winds have already reached gale force, and gusts will increase
further this morning. Gusts to 45 knots expected today.
Very high waves reaching 12 to 16 feet. These very high waves
will continue through Saturday evening. Waves should slowly
diminish on Sunday and Monday.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 5 PM this afternoon to midnight CDT
Sunday night for WIZ062>065-067>069.
Wind Advisory until 7 PM CDT this evening for WIZ046-047-051-052-
056>060-062>072.
Lakeshore Flood Advisory until 7 AM CDT Sunday for WIZ052-060-
066-071-072.
Winter Weather Advisory until midnight CDT Sunday night for
WIZ051-052-058>060.
Winter Weather Advisory until midnight CDT Sunday night for
WIZ046-047-056-057.
LM...Gale Warning until 7 AM CDT Sunday for LMZ643>646.
&&
Update...Hentz
Today/Tonight and Aviation/Marine...Hentz
Sunday THROUGH Friday...HentzHazardous Weather Outlook National Weather Service Milwaukee/Sullivan WI 342 AM CDT Sat Apr 14 2018 WIZ046-047-051-052-056>060-062>072-150845- Marquette-Green Lake-Fond Du Lac-Sheboygan-Sauk-Columbia-Dodge- Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee- Lafayette-Green-Rock-Walworth-Racine-Kenosha- 342 AM CDT Sat Apr 14 2018 This Hazardous Weather Outlook is for portions of east central Wisconsin, south central Wisconsin and southeast Wisconsin. .DAY ONE...Today and Tonight A Winter Weather Advisory is in effect for Sauk, Columbia, Marquette and Green Lake Counties. The Winter Weather Advisory will expand to include all but extreme southeastern Wisconsin today. A wintry mix of snow, sleet and freezing rain is expected in the advisory area. Total snowfall by Sunday night will range from around an inch in the south to around 5 inches in the far north toward central Wisconsin. There is also the potential for freezing rain accumulating up to a quarter of an inch. Strong, gusty northeast to east winds with wind gusts of 45 to 50 mph are also expected. A Wind Advisory is in effect across the entire area. Also, the strong winds will help build high waves. These high waves may cause localized lakeshore flooding or erosion from Sheboygan south to Kenosha. A Lakeshore Flood Advisory is in effect until 7 am Sunday morning. Periods of heavy rain are expected to continue. This will cause some rivers to rise. Isolated thunderstorms are expected today. .DAYS TWO THROUGH SEVEN...Sunday through Friday Due to the heavy rain, some rivers may approach flood stage by Sunday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed, however your snow and rain reports, glazing, and wind reports will be appreciated. LMZ643>646-150845- Sheboygan to Port Washington WI- Port Washington to North Point Light WI- North Point Light to Wind Point WI- Wind Point WI to Winthrop Harbor IL- 342 AM CDT Sat Apr 14 2018 This Hazardous Weather Outlook is for portions of Lake Michigan. .DAY ONE...Today and Tonight A Gale Warning is in effect with northeast gusts to 45 knots. .DAYS TWO THROUGH SEVEN...Sunday through Friday The Gale Warning will remain in effect through 7 am Sunday morning for strong northeast winds and high waves. Winds and waves will remain at Small Craft Advisory levels Sunday into Monday. www.weather.gov/mkx
The national radar mosaic for the moment the first event began.
13 winter weather, 4 winter storm. Local standard time, as filed.
A light glaze of ice from freezing rain followed by 2 to 5 inches of sleet and snow accumulation.
Four to six inches of sleet and snow accumulation.
Four to six inches of sleet and snow accumulation.
A light glaze of ice from freezing rain followed by 3 to 6 inches of sleet and snow accumulation.
A light glaze of ice from freezing rain followed by 2 to 5 inches of sleet and snow accumulation.
Six to twelve inches of sleet and snow accumulation.
Four to seven inches of sleet and snow accumulation.
Four to seven inches of sleet and snow accumulation.
A glaze of ice from light freezing rain followed by 6 to 8 inches of sleet and snow accumulation.
A glaze of ice from light freezing rain followed by 6 to 8 inches of sleet and snow accumulation.
Six to ten inches of sleet and snow accumulation. A glaze of ice and brisk winds before the snow and sleet caused tree branches to fall on power lines.
Four to seven inches of sleet and snow accumulation.
One to four inches of sleet and snow accumulation.
Two to five inches of sleet and snow accumulation.
Four to six inches of sleet and snow accumulation.
One to three inches of sleet and snow accumulation.
One to three inches of sleet and snow accumulation.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Winter Weather, Columbia | 2018-04-14 | 30 | Female | Vehicle/Towed Trailer | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2018Every state in 2018This day in weather historyWarnings in Wisconsin, April 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: 743644, 743651, 743654, 743643, 743645, 743658, 743652, 743655, 743656, 743657, 743659, 743646, 743647, 743648, 743653, 743649, 743650.