The late afternoon into the evening of Tuesday, February 28 brought a favorable setup for severe weather, including strong tornadoes across much of the Mid-Mississippi Valley and Lower Great Lakes regions. There were seven tornadoes confirmed in the NWS Chicago county warning area.
Every event with a place to put it. 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 LOT wrote it up.
The late afternoon into the evening of Tuesday, February 28 brought a favorable setup for severe weather, including strong tornadoes across much of the Mid-Mississippi Valley and Lower Great Lakes regions. There were seven tornadoes confirmed in the NWS Chicago county warning area. Large hail was reported in numerous areas.
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 Chicago, IL wrote its last area forecast discussion before the first event at Feb 28, 3:49 PM CST, 38 minutes earlier.
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
349 PM CST Tue Feb 28 2017
.MESOSCALE DISCUSSION...
349 PM CST
Convection has been developing and steadily intensifying over
eastern IA and northwest IL. Both ILX and DVN afternoon special
soundings indicated a formidable capping inversion. Continued low
level theta-e advection combined with increasing ascent has been
gradually eroding the cap and given intensity trends, its likely
storms are solidly surface based.
Over our western CWA, surface obs show slightly cooler temps and
slightly lower dewpoints, so current environment is possibly a bit
less favorable for surface based storms now. Short range guidance
continues to forecast environment to quickly improve and will
likely grow increasingly favorable for maintaining storms over
western IL as they move east. Given their fast movement, it is
possible they could eventually outrun the better air as they get
east into NE IL, but that is still a couple hours out and we'll
need to closely monitor.
Given the favorable instability and extremely strong deep layer
shear profiles would anticipate a continuation of the transition
of this activity to supercellular. Strongest low level shear
profile is over central and north central IL, with the current
best co-location of most favorable low level shear and instability
over north central IL, mainly south of I-88. This would suggest
that in the next couple hours the highest tornado threat would
exist with the storms developing from Bureau Co southwest to near
Burlington, with the highest short term threat likely to spread
into LaSalle and Livingston Counties.
Large hail, damaging wind, and perhaps a tornado risk cannot be
ruled out north of this area into Ogle and Lee Counties in the
next couple hours, but the greatest area of concern appears to be
LaSalle and into Livingston Counties. Extrapolation of storms
moving into Bureau County suggest the threat should move into
LaSalle County toward 430 PM.
Izzi
&&
.SHORT TERM...
218 PM CST
Through Wednesday...
Isolated thunderstorms are starting to fire, which is a little ahead
of schedule, but the latest RAP analysis features upwards of 1000-
1500 J/kg of CAPE along the MS River. CAPE values will continue to
climb through this evening to around 1500 J/kg. RAP analysis already
features of 60 kt of 0-6km shear and 25-35 kt of 0-1km shear.
Expecting scattered storms to continue to form this afternoon mostly
along the MS River and then shift eastward late this afternoon.
Steep upper level lapse rates will allow for hail. The strongest
storms will be capable of producing golfball size hail or larger
due to strong, possibly rotating updrafts.
The big question is where exactly will the low over Iowa track?
Current analysis is further north than most guidance members so I'm
leaning toward a more northerly path. That should translate in
increased shear and an even better chance of severe weather. Storms
should increase in coverage as the upper level vort streamer pushes
over the region late this afternoon into this evening. CAMs have
been pretty consistent as far as how the storms will evolve, but
still only have medium confidence in timing and mode of storms.
Storms through this evening will have mainly a hail risk as
mentioned above. Tornadoes will be possible but most likely tied to
discrete supercells. Supercells are possible given steep lapse
rates, shear, and CAPE values, but unsure about how many will be
able to form. Low level wind shear increases as the low nears
this evening and near the warm front which is just north of the
IL/WI state line.
Storm mode should change to more linear structures nearing midnight
as the cold front begins to approach the region. A strong low level
jet should keep the low levels well mixed allowing for damaging
winds at the surface.
If storms train, flooding will be possible. PWAT values are about
0.8-1 inch, but storms will be moving toward the northeast at 60-65
MPH, so individual storms will be moving very quickly.
Overall, the message is about the same as this morning. Scattered
storms will develop this afternoon and increase in coverage and
intensity this evening. All severe weather hazards are possible.
Severe storms come to an end late tonight as the cold front moves
through.
Gusty northwest winds are expected tomorrow with gusts of 30-35 MPH.
Temperatures will be falling through the day so daily highs will
likely happen early in the morning. Temperatures fall into the 30s
by late Wednesday afternoon. Precip on the backside of the low
spreads over the region and should start as rain. Expecting rain
to change over to snow as temperatures drop through the profile.
Only expecting accumulating snow along the IL/WI state line where
up to an inch is possible through Wednesday afternoon. Given
recent warmth and rain, only expecting snow to stick to grassy
surfaces.
JEE
&&
.LONG TERM...
156 PM CST
Wednesday night through Tuesday...
Deepening low pressure will be pulling away from the region
Wednesday evening, with the tail of the mid-level deformation zone
transiting the far east/northeastern parts of the forecast area
early. Lingering precipitation is expected to be primarily snow
based on thermal profiles, though there may be some rain/snow mix
early in the evening across the far east/southeast counties where
surface wet-bulb temps start out above freezing and 1000-850 mb
thickness values are just under 1300 meters. Forecast soundings
and time-height sections depict mid-level drying occurring from
the northwest during the late evening and overnight hours,
depicting an end to any significant precip generally by midnight.
QPF from various guidance is generally less than 0.05" (though the
NAM is a little more excited over northwest IN), which combined
with snow to liquid ratios approaching 12-15:1 would yield a
couple of tenths to perhaps a little under an inch of additional
snow accumulation with the highest additional amounts over
northwest Indiana. Otherwise, blustery northwest winds 25-35 mph
early in the evening will gradually diminish overnight as the low
moves away and the pressure gradient relaxes. Overnight lows fall
into the 20's, with partly to mostly cloudy skies.
Attention the turns quickly to a clipper system digging southeast
from the Dakotas Thursday morning. Guidance has been pretty
consistent with this feature, which tracks southeast across
northern IL and into northern/central IN Thursday afternoon and
evening. NAM appears a bit too far north with the track of the
surface low, based on the path of the vort max, and is thus
appears to be too warm in low levels and a little slow with the
arrival of precip. Prefer a blend of GFS/ECMWF with respect to
track, low level temperatures and with the QPF axis across the
northeast third of the cwa. This blend also maintains coldest
temps/thicknesses across that area, with areas farther south more
likely to see a mix of rain/snow or all rain while the far
north/northeast tier of counties remain primarily all snow, with
a quick accumulation of up to an inch near the IL/WI border by
early evening. This could have some impact on the afternoon rush
hour based on current expected timing. The short wave associated
with this system continues to dig southeast into the mid-upper
Ohio Valley Thursday night, aiding in amplification of the larger
scale upper trough across the eastern CONUS.
As the trough to our east deepens and moves away late Thursday
night and Friday, upper ridging develops across the Mississippi
Valley, with surface high pressure moving across the forecast
area. Dry weather is short lived however, with global guidance
bringing another quick-moving mid-level short wave across the
area Friday night into early Saturday and producing another
period of light snow which may initially mix with rain early
across our southern counties. Upper ridging then strengthens
across the area into the weekend as upper troughing moves ashore
out west. This portends a warm-up for the Midwest as southerly low
level flow becomes established, with temperatures in the 50's and
60's over the weekend and into early next week. Some differences
become evident in the global guidance by days 6-7, though it
appears rain chances (and potentially thunder chances too) will
ramp up by that time as the deepening upper trough moves out
across the region.
Ratzer
&&
.AVIATION...
For the 18Z TAFs...
IFR cigs spread over the region as a warm front lifted north
through the region this morning. South winds will continue to
gust arnd 20 kt into this evening. Scattered storms are expected
to form around 22Z this afternoon with periods of thunderstorms
through most of the night. Have high confidence in storms and
lightning impacting the terminals, and there may be multiple
periods of storms. However, have medium confidence in timing and
exact location of storms. Some of these storms will be strong and
possibly severe. The main threats would be large hail and damaging
winds, but there is a chance of tornadoes.
Decided to keep cigs in the IFR to MVFR range throughout the
forecast since almost all sites in the region are MVFR or lower.
Some guidance members suggest cigs could go VFR late this evening
before the cold front arrives, but do not have enough confidence
to go VFR at this time. The cold front moves through after
midnight with winds becoming northwest and cigs lowering to IFR.
There should be a brief break in precip behind the cold front but
then more precipitation is expected Wednesday morning. The precip
should start as rain, and then transition to snow as temperatures
fall. Have low confidence in when rain will become snow so only
have -RASN in the TAFs.
JEE
&&
.MARINE...
317 PM CST
Headlines...Upgraded the gale watch to a warning for early Wednesday
morning through late Wednesday night. Made no changes to the current
small craft advisory, but added another small craft advisory beginning
mid Wednesday morning and going into Thursday morning.
The low over Iowa will pass over the southern end of the lake
tonight. Winds are below small craft advisory criteria, but gusts
up to small craft criteria are possible so will keep the small
craft going. The low continues northeast tonight through Wednesday
and winds become north to northwest behind the low. Gale force
winds are expected early Wednesday morning through Wednesday
evening. Thinking gales will not be observed in the nearshore
waters. Northwest winds decrease through Thursday and another
weak low passes south of the lake Thursday evening. High pressure
moves over the lake Friday and continues east over the weekend.
Winds become south behind the high Saturday. A surface low travels
east over southern Canada early next week and then another
surface low is progged to form over the plains Sunday night or
Monday.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...LMZ777-LMZ779...9 AM Wednesday TO MIDNIGHT
Thursday.
Small Craft Advisory...NEARSHORE WATERS
UNTIL 4 AM Wednesday.
Small Craft Advisory...LMZ744-LMZ745...10 AM Wednesday TO 10 AM
Thursday.
Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743...10 AM
Wednesday TO 4 AM Thursday.
&&
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WWW.YOUTUBE.COM/NWSCHICAGOHazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
339 PM CST Tue Feb 28 2017
ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
012145-
Winnebago-Boone-McHenry-Lake Illinois-Ogle-Lee-De Kalb-Kane-
DuPage-Cook-La Salle-Kendall-Grundy-Will-Kankakee-Livingston-
Iroquois-Ford-Lake Indiana-Porter-Newton-Jasper-Benton-
339 PM CST Tue Feb 28 2017 /439 PM EST Tue Feb 28 2017/
THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE...Tonight.
WEATHER HAZARDS EXPECTED:
Significant Thunderstorm Risk...with an associated:
Elevated Tornado Risk.
Extreme Hail Risk...larger than golf ball size.
Significant Thunderstorm Wind Damage Risk.
DISCUSSION:
Low pressure over eastern Iowa this afternoon will move east
across northern Illinois tonight. Unseasonably mild and moist
air will continue to spread across the area this evening as a
warm front lifts north across the region ahead of the low,
which combined with strong mid and upper level winds will set
the stage for strong to severe thunderstorms across the area.
Any thunderstorm which develops in this environment will have
the potential to produce large hail, and some storms especially
this evening will likely have the potential for producing
damaging winds and isolated tornadoes. While areas south of
Interstate 88 across northern Illinois and Interstate 80 across
northwest Indiana may have a slightly higher potential to
produce damaging wind and isolated tornadoes, some threat
exists all the way north to the Wisconsin border. Storms will
initially be scattered during the late afternoon and early
evening hours, but should develop into a line which will move
slowly east across the outlook area by mid or late evening.
Storms may linger well into the overnight hours especially
south and southeast of Chicago, with the potential for
locally heavy rainfall in some of these locations.
.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
Wednesday...
Limited Thunderstorm Risk.
Elevated Snow Risk.
Thursday...
Elevated Snow Risk.
Sunday and Monday...
Limited Thunderstorm Risk.
.SPOTTER INFORMATION STATEMENT...
Spotters will likely be needed this afternoon into tonight. Due
to very fast storm motion and the likelihood of the most intense
storms in the region occurring after dark, spotters should use
extreme caution.
GENERAL STORM MOTION OF THE DAY:
Moving to the northeast or east at 40 MPH and increasing to 65 MPH
later this evening.
&&
LMZ740>745-012145-
Winthrop Harbor to Wilmette Harbor-
Wilmette Harbor to Northerly Island-
Northerly Island to Calumet Harbor-Calumet Harbor to Gary-
Gary to Burns Harbor-Burns Harbor to Michigan City-
339 PM CST Tue Feb 28 2017
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE illinois NEARSHORE
WATERS OF LAKE MICHIGAN AND THE indiana NEARSHORE WATERS OF LAKE
MICHIGAN.
.DAY ONE...Tonight.
Hazardous Conditions for Small Craft are likely, including the
potential for severe thunderstorms this evening.
.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
Wednesday through Friday...
Hazardous Conditions for Small Craft are likely.
Monday...
Hazardous Conditions for Small Craft are likely.
&&
LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-012145-
Lake Michigan from Michigan City IN to St. Joseph MI 5 NM
offshore to Mid Lake-
Lake Michigan from Seul Choix Point to Rock Island Passage 5 NM
offshore to Mid Lake-
Lake Michigan South of a line from Seul Choix Point to the
Mackinac Bridge and north of a line from Charlevoix MI to South
Fox Island 5 NM offshore-
Lake Michigan from Charlevoix to Point Betsie MI 5 NM offshore to
Mid Lake-
Lake Michigan from Point Betsie to Manistee MI 5 NM offshore to
Mid Lake-
Lake Michigan from Rock Island Passage to Sturgeon Bay WI-
Lake Michigan from Sturgeon Bay to Two Rivers WI 5 NM offshore to
Mid Lake-
Lake Michigan from Two Rivers to Sheboygan WI 5 NM offshore to
Mid Lake-
Lake Michigan from Sheboygan to Port Washington WI 5 NM offshore
to Mid Lake-
Lake Michigan from Port Washington to North Point Light WI 5 NM
offshore to Mid Lake-
Lake Michigan from North Point Light to Wind Point WI 5 NM
offshore to Mid Lake-
Lake Michigan from Wind Point WI to Winthrop Harbor IL 5 NM
offshore to Mid Lake-
Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5 NM
offshore to Mid Lake-
Lake Michigan from Wilmette Harbor IL to Michigan City IN 5 NM
offshore to Mid Lake-
Lake Michigan from Pentwater to Manistee MI 5 NM offshore to Mid
Lake-
Lake Michigan from Whitehall to Pentwater MI 5 NM offshore to Mid
Lake-
Lake Michigan from Grand Haven to Whitehall MI 5 NM offshore to
Mid Lake-
Lake Michigan from Holland to Grand Haven MI 5 NM offshore to Mid
Lake-
Lake Michigan from South Haven to Holland MI 5 NM offshore to Mid
Lake-
Lake Michigan from St. Joseph to South Haven MI 5 NM offshore to
Mid Lake-
339 PM CST Tue Feb 28 2017
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE
MICHIGAN.
.DAY ONE...Tonight.
Thunderstorms are likely across southern Lake Michigan tonight.
Some storms may be severe this evening and early overnight. Fog
is possible across southern parts of the Lake overnight. Gales
are likely across northern Lake Michigan late tonight.
.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
Gale force winds are likely Wednesday and Wednesday evening.
&&
Ratzer
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www.youtube.com/nwschicagoThe national radar mosaic for the moment the first event began.
22 hail, 8 tornado, 6 thunderstorm wind, 2 flood. Local standard time, as filed.
The location and time of this tornado were estimated from spotter photos and videos from the area. No damage was identified, so the intensity is estimated. (Tornado #1 of 7).
Penny to nickel size hail was reported in DeKalb, including at the Northern Illinois University.
The first area of significant damage in the EF2 range was in the area around the La Salle County Nursing Home and La Salle County Highway Department, with lighter damage upstream from this location. The tornado continued into Naplate and produced widespread EF2 damage to numerous homes. EF3 damage also was identified in two locations. The first was where a minivan was thrown about 30 yards and a home was lifted off its foundation and left with only its interior walls intact. The second was at the Pilkington Glass plant where one section of the factory was completely destroyed. The tornado then crossed the Illinois River and moved through the south side of Ottawa, producing an 800 yard wide path of EF1 damage to trees and homes. The fatalities in Ottawa occurred from a tree falling onto two men who were working outside. The tornado then crossed the Illinois River again and continued to produce EF1 and EF0 damage as it exited Ottawa, finally dissipating in the area northwest of Marseilles. (Tornado #2 of 7).
Hail was estimated to be the size of baseballs in Ottawa.
The tornado moved along N 30th Road south of Interstate 80 and produced damage at two farmsteads, both on the north side of the road, and to a tower on the south side of the road. Videos of this tornado suggested the condensation funnel possibly was wider than documented by the survey, but the path width was estimated based on the areas of damage. (Tornado #3 of 7).
The path of this tornado was estimated based on video evidence as well as debris found along Interstate 80 near mile marker 104. (Tornado #4 of 7).
The tornado toppled farm equipment, collapsed outbuildings, damaged roofs of homes, and broke large branches out of trees. Straight line winds estimated to be up to 80 MPH produced additional damage 1 to 1.5 miles beyond the tornado path. (Tornado #5 of 7).
Nickel size hail was reported near Harrison Avenue and Mulford Road.
Quarter size hail was reported near Larkin Avenue and Black Road.
Half dollar size hail was reported near Lily Cache Road.
The tornado weakened in southeast Marshall County as it crossed I-39 west of Rutland. As the tornado entered LaSalle County and moved into Rutland, it damaged trees and did minor damage to house roofs, before dissipating 0.4 miles east of Rutland at 5:50 pm. (Tornado #6 of 7).
Penny size hail was observed at the National Weather Service office in Romeoville.
A tornado began east of Rutland, producing isolated tree damage.The tornado increased in intensity as it crossed into Livingston County, where it tore the roof off of a house as it was likely at its peak intensity of EF2.
A tornado began east of Rutland in La Salle County and increased in intensity as it crossed into Livingston County, where it tore the roof off of a house as it was likely at its peak intensity of EF2.The tornado then weakened and snapped a couple of trees before dissipating one mile west of Long Point.
Nickel size hail was reported in Homer Glen.
Quarter size hail was reported near Seil Road and Sarver Drive.
Standing water 3 to 4 inches deep was reported near Interstate 55 and Houlbolt Road.
One foot of standing water was reported on Route 30 near Briggs Road.
A window was blown out of a house near 175th Street and Dixie Highway.
Nickel size hail was reported near Route 30 and Pfeiffer Road.
Nickel size hail was reported at the Lansing Municipal Airport.
Quarter to golf ball size hail was reported with half dollar size hail reported between Route 30 and Saint Francis Road.
Wind gusts were estimated to 60 mph.
A semi truck was blown over near Interstate 80 and Interstate 39.
Wind gusts were estimated to 70 mph.
Large trees were blown down blocking Roods Road. Power lines were also damaged.
A metal roof was blown off a large barn but the rafters were still intact.
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 |
|---|---|---|---|---|---|
| Tornado, La Salle | 2017-02-28 | 31 | Male | Outside/Open Areas | Direct |
| Tornado, La Salle | 2017-02-28 | 76 | Male | Outside/Open Areas | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2017Every state in 2017This day in weather historyThe tornado archive for Illinois, 2017Warnings in Illinois, February 2017
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: 674612, 722432, 722431, 674614, 722434, 722433, 674617, 674620, 674622, 722436, 722437, 722439, 722438, 722445, 677693, 722440, 1244230, 1244231, 722441, 722444, 722443, 722548, 722527, 722528, 722519, 722450, 722520, 722446, 722447, 722448, 722518, 722521, 722523, 722524, 722525, 722540, 722546, 722547.