A large slow-moving area of low pressure wandered from Colorado to eastern South Dakota over a two-day period. Precipitation circulated back into northwest Iowa and southwest Minnesota, which started as a period of rainfall prior to evening on March 14.
Every event with a place to put it; 8 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 FSD wrote it up.
A large slow-moving area of low pressure wandered from Colorado to eastern South Dakota over a two-day period. Precipitation circulated back into northwest Iowa and southwest Minnesota, which started as a period of rainfall prior to evening on March 14. Rain mixed and changed to snow during the late evening and early overnight. Snow became heavy at times during overnight, with snowfall rates up to 2 inches per hour.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Mar 14, 6:04 PM CST, 3 hours 56 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Sioux Falls SD
704 PM CDT Sun Mar 14 2021
.UPDATE...
Issued at 652 PM CDT Sun Mar 14 2021
Cancelled the Wind Advisory slightly early due to sustained winds
and gusts weakening a bit by 6pm, added a portion of south
central SD to a Winter Storm Warning, and simplified the timing
of tonight's Winter Wx Advisories a bit.
Strong mid level warm air advection and pockets of unstable air
amidst southeasterly flow aloft continue to stream plentiful moisture
into the region early this evening. Surface observations at
Pierre, Chamberlain, and Winner show the sfc has dynamically
cooled to the freezing mark with a deep saturated DGZ. DOT webcams
show snow already accumulating on roads along and west of the MO
River. With temperatures trending cooler than previously expected
in this south central SD and support from CAM guidance for snow
totals of 6-8+ inches, this tipped the scales in favor of Warning
level snowfall amounts. Upgraded much of south central SD to a
Winter Storm Warning. Snowfall rates of 1-2 inches per hour of wet
heavy snow are expected this evening in this region.
Timing the ptype transition, as well as snowfall amounts for
other locations, looks to be on track otherwise. Will continue to
monitor trends and adjust as needed.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 404 PM CDT Sun Mar 14 2021
Light to moderate rain continues to lift northward across the CWA
this afternoon as expected. Soundings are indicating a shallow warm
layer below about 2000 feet, and with the dry low level air and
evaporative cooling we have begun to get reports of a mix of rain,
sleet, and even snow from just west of Sioux Falls into parts of
southwestern MN and northwestern IA with a heavier band of
precipitation lifting through that area. Surface temperatures are
presently in the upper 30s to lower 40s, so no accumulation is
expected for the next few hours until temperatures begin to fall.
Even so, precipitation type may not change back to all rain, so
could have a quick transition into all snow as temperatures cool -
which could bring even more snow than presently expected. This will
have to be monitored through the evening. Current radar is
indicating returns becoming more scattered through the MO River,
though a more significant band is seen from south central SD into
eastern NE - this associated with a band of vorticity swirling
around the upper level low presently located over eastern CO. It is
this band that will eventually evolve and lift across our area and
produce the more significant snow.
Most recent model runs do not differ significantly from previous
runs, and an intense band of snowfall is expected to develop and
lift across the area later tonight into Monday morning. Present HREF
ensembles indicate hourly snowfall rates of 1 to 2 inches as it
lifts to the north and east, and although the heaviest snowfall will
only occur for approximately 3 to 4 hours, at that rate quite a bit
of snow could accumulate in that time. Current models indicating
even a little light snow lingering into Monday afternoon over east
central SD/southwestern MN with some lingering warm air advection,
though any additional accumulation will be less than half an inch.
Soundings also suggest that saturation will be lost along the
southern edge of the area of precipitation as it ends on Monday, so
could see a brief period of freezing drizzle before it ends, though
no significant icing is anticipated.
As far as snow totals, still looking at 6 to 9 inches from east
central SD through southwestern MN and portions of northwestern IA,
then another maximum area of snowfall occurring from south
central SD into the western James River Valley. In between these
two areas, 4 to 6 inches looks appropriate. The lowest snowfall
will occur through the central and lower MO River Valley where 1
to 3 inches will be more common.
Current headlines are still appropriate with the forecasted snowfall
amounts, through one place that will have to be monitored is over
south central SD where an upgrade to a Winter Storm Warning will be
possible.
.LONG TERM...(Monday Night through Sunday)
Issued at 404 PM CDT Sun Mar 14 2021
Snow finally leaves the area by Monday evening, though with
remaining cloud cover and no real significant cold air with the
system, lows will only drop into the mid to upper 20s.
As the upper level low continues to wobble across the region,
another trough comes ashore on the west coast. As relative humidity
values remain fairly high throughout the sounding profiles, cloud
coverage will remain mostly cloudy throughout the day. Multiple
lobes of vorticity branch out of the mid-level low, resulting in
upward vertical motion that will likely be enough to create some
light precipitation throughout the day. During the morning hours,
this will likely be in the form of snow before turning to mostly
rain by the afternoon. A few sounding profiles are suggesting that
we lose saturation in the DGZ during the morning, but with the NBM
weather type probabilities not reflecting this am considering those
soundings to be outliers. With the fresh coating of snow on the
ground from Monday, look for afternoon temperatures in the mid to
upper 30s, with a couple locations getting into the lower 40s.
As the upper level flow splits, the southern portion is looking to
form another surface low down by the Texas panhandle on Tuesday. For
Wednesday, inconsistencies amongst the models on how they handle
this system is leading to low confidence on which solution to
choose, with the ensembles suggesting vast majority of the
precipitation should stay off to our south. Overall, expect
temperatures to remain in the upper 30s, with best chances for
precipitation occurring south of the I-90 corridor. Upper level
ridging takes place on Thursday, which keeps us dry with
temperatures warming as we head into the weekend. Good southerly
surface flow will further keep temperatures warm, with highs in the
50s possible Friday and Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 652 PM CDT Sun Mar 14 2021
VFR stratus and rain early this evening will degrade to MVFR ceilings
and MVFR to IFR visibility as rain transitions over to snow from
west to east late this evening. Snow will mix in with rain after
03z, becoming primarily snow around or after 06z. Then expect
IFR/LIFR visibility and ceilings at most sites along and east of
HON to FSD to SUX from 06-09z, due to heavy snowfall rates and
gusty east winds. This is most likely to begin west of HON to MHE
early this evening as an area of heavy snow progresses eastward.
Conditions should begin to improve as snow tapers off after 15z
Monday morning, but MVFR to IFR ceilings may linger well into
Monday. Additionally, east or northeast winds will gradually
weaken late tonight and through Monday.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from 10 PM this evening to 1 PM CDT
Monday for SDZ066-070-071.
Winter Storm Warning until 1 PM CDT Monday for SDZ050-052-057-
058-063-064.
Winter Storm Warning from 1 AM to 4 PM CDT Monday for SDZ040-056.
Winter Weather Advisory until 1 PM CDT Monday for SDZ038-053-054-
059>061-065-068-069.
Winter Storm Warning from 10 PM this evening to 1 PM CDT Monday
for SDZ039-055-062-067.
MN...Winter Storm Warning from 1 AM to 4 PM CDT Monday for MNZ071-072-
080-081-089-090-097.
Winter Storm Warning from 10 PM this evening to 1 PM CDT Monday
for MNZ098.
IA...Winter Weather Advisory from 10 PM this evening to 1 PM CDT
Monday for IAZ020-031-032.
Winter Storm Warning from 1 AM to 4 PM CDT Monday for IAZ002-003-
014-022.
Winter Storm Warning from 10 PM this evening to 1 PM CDT Monday
for IAZ001-012-013-021.
NE...Winter Weather Advisory from 10 PM this evening to 1 PM CDT
Monday for NEZ013-014.
&&
UPDATE...BP
SHORT TERM...JM
LONG TERM...APT
AVIATION...BPHazardous Weather Outlook...UPDATED National Weather Service Sioux Falls SD 805 PM CDT Sun Mar 14 2021 SDZ038-053-054-059>061-065-068-069-151300- Beadle-Sanborn-Miner-Davison-Hanson-McCook-Hutchinson-Bon Homme- Yankton- 805 PM CDT Sun Mar 14 2021 This Hazardous Weather Outlook is for east central South Dakota and southeast South Dakota. .DAY ONE...Tonight. Rain will rapidly change to snow later this evening with snow continuing into early Monday. Total snow accumulations between 3 and 6 inches will be possible by Monday morning. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Up to one inch of additional snow expected early Monday before precipitation ends. Rain and snow chances may redevelop Tuesday into Wednesday. Accumulations are expected to be light if they occur. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. IAZ020-031-032-NEZ013-014-SDZ066-070-071-151300- Plymouth-Woodbury-Ida-Dixon-Dakota-Turner-Clay-Union- 805 PM CDT Sun Mar 14 2021 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, northeast Nebraska and southeast South Dakota. .DAY ONE...Tonight. Rain will rapidly change to snow later this evening with snow continuing into early Monday. Total snow accumulations between 2 and 6 inches will be possible by Monday morning. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Up to one inch of additional snow is possible early Monday before precipitation ends. Rain and snow chances may redevelop Tuesday into Wednesday. Accumulations are expected to be light if they occur. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. SDZ050-052-057-058-063-064-151300- Gregory-Jerauld-Brule-Aurora-Charles Mix-Douglas- 805 PM CDT Sun Mar 14 2021 This Hazardous Weather Outlook is for central South Dakota and south central South Dakota. .DAY ONE...Tonight. Heavy snowfall and patchy blowing snow will reduce visibility to as low as one quarter mile this evening. The heaviest snow will fall by midnight with total snow accumulations expected to range from 4 to 8 inches, perhaps with isolated higher amounts. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Up to one additional inch of snow is possible early Monday before precipitation ends. Rain and snow chances may redevelop Tuesday into Wednesday. Accumulations are expected to be light if they occur. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. IAZ001-012-013-021-MNZ098-SDZ039-055-062-067-151300- Lyon-Sioux-O'Brien-Cherokee-Rock-Kingsbury-Lake-Minnehaha-Lincoln- 805 PM CDT Sun Mar 14 2021 This Hazardous Weather Outlook is for northwest Iowa, southwest Minnesota, east central South Dakota and southeast South Dakota. .DAY ONE...Tonight. Rain is expected to rapidly change to snow later this evening, with a period of several hours of heavy snow occurring late tonight. Patchy blowing snow and heavy snowfall rates may reduce visibility to one quarter mile at times. Snow will continue into Monday morning with total accumulations of 4 to 8 inches expected many areas. Isolated amounts greater than 8 inches are possible for parts of Southwest Minnesota. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Snow will continue through Monday morning, with additional light accumulation likely less than one inch. Additional rain and snow chances may redevelop Tuesday into Wednesday. However amounts should be on the lighter side if they occur. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. IAZ002-003-014-022-MNZ071-072-080-081-089-090-097-SDZ040-056-151300- Osceola-Dickinson-Clay-Buena Vista-Lincoln-Lyon-Murray-Cottonwood- Nobles-Jackson-Pipestone-Brookings-Moody- 805 PM CDT Sun Mar 14 2021 This Hazardous Weather Outlook is for northwest Iowa, southwest Minnesota and east central South Dakota. .DAY ONE...Tonight. Rain is expected to rapidly change to snow later this evening, with a period of several hours of heavy snow occurring late tonight. Patchy blowing snow and heavy snowfall rates may reduce visibility to one quarter mile at times. Snow will continue into Monday morning with total accumulations of 4 to 8 inches expected many areas. Isolated amounts greater than 8 inches are possible for parts of Southwest Minnesota. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Snow will continue through Monday morning, bringing an additional one to three inches of snow. Additional rain and snow chances may redevelop Tuesday into Wednesday. However at this time amounts may be on the lighter side if they occur. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
5 winter storm, 3 winter weather. Local standard time, as filed.
Snowfall was heavy at times between 0000CST and 0400CST on March 15, resulting in very hazardous travel conditions. A total of 6.0 inches at Rock Rapids was recorded.
Snowfall was heavy at times between 0000CST and 0400CST on March 15, resulting in very hazardous travel conditions. A total of 7.0 inches at Sibley was recorded.
Snowfall was heavy at times between 0000CST and 0400CST on March 15, resulting in very hazardous travel conditions. Totals of 7.2 inches at Sanborn, and 5.5 inches at Primghar and Sheldon were recorded.
Snowfall was heavy at times between 0000CST and 0400CST on March 15, resulting in very hazardous travel conditions. A total of 6.0 inches 4 miles north of Cleghorn was recorded.
Snowfall was heavy at times between 0000CST and 0400CST on March 15, resulting in very hazardous travel conditions. A total of 6.3 inches at Spirit Lake was recorded.
Snowfall totaled 5.5 inches 3 miles south of Storm Lake and 5.2 inches at Sioux Rapids. Travel become hazardous as snow rates increased at night.
Snowfall totaled 5.8 inches at Spencer and 5.0 inches 3 miles west northwest of Everly. Travel become hazardous as snow rates increased at night.
Snowfall totaled 5.0 inches at Orange City and Hull, and 4.0 inches at Sioux Center and Rock Valley. Travel become hazardous as snow rates increased at night.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2021Every state in 2021This day in weather historyWarnings in Iowa, March 2021
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: 947146, 947148, 947149, 947150, 947151, 947152, 947154, 947155.