Rapid snowmelt from a few day period of well above normal temperatures focused on the 11-13th of April resulted in minor to locally moderate flooding through much of the Big Sioux River Basin. Some areas north of I-90 lost between 2 to 5 inches of snow water equivalent (SWE) from the first to second week of April, but antecedent drought conditions resulted in only a percentage of this water…
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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.
Rapid snowmelt from a few day period of well above normal temperatures focused on the 11-13th of April resulted in minor to locally moderate flooding through much of the Big Sioux River Basin. Some areas north of I-90 lost between 2 to 5 inches of snow water equivalent (SWE) from the first to second week of April, but antecedent drought conditions resulted in only a percentage of this water actually making it into the river system.
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 Apr 8, 9:51 PM CST, 5 hours 9 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1051 PM CDT Sat Apr 8 2023 .SHORT TERM...(This Evening through Sunday Night) Issued at 255 PM CDT Sat Apr 8 2023 Key Messages: 1. A Red Flag Warning is in effect until 8:00 pm this evening for parts of southeastern South Dakota, far northeastern Nebraska and all of northwest Iowa, and portions of southwest Minnesota. 2. Light showers arrive for Easter Sunday, mainly along and east of I-29. Light accumulations are expected. 3. Sunny and warm for most of the week! However, due to gusty winds and low relative humidity, fire weather is a concern. 4. Friday brings our next chance for widespread precipitation, though model agreement is low. --------------------------------------------------------------------- Red Flag conditions dominate the area this afternoon as temperatures have warmed to the 50s in snow covered areas and 60s and 70s in snow free areas, relative humidity (RH) has fallen to teens and 20s, and southwesterly winds are gusting to 30-35 mph. Red Flag conditions have spread a bit further north early this afternoon due to the previously mentioned warm front drifting further north, up towards the highway-14 corridor. As such, have expanded the Red Flag Warning a row of counties further north, now including parts of the I-90 corridor in South Dakota and southwest Minnesota. This is mainly from Alexandria, South Dakota to Jackson, Minnesota. These conditions will continue for the rest of the afternoon hours before nocturnal stabilization shuts off mixing and ends the fire danger today. Despite a building inversion tonight, the low level jet (LLJ) will strengthen overhead which will be able to mix some gusts up to around 20-25 mph down to the surface. Locations along the Buffalo Ridge in southwest Minnesota will see slightly stronger gusts up to about 35 mph. This strengthening LLJ is in response to an approaching mid-upper level wave. The wave will supply weak quasi- geostrophic (QG) ascent while also cooling mid and upper level thermal profiles to saturation. Remaining dry air at the surface from the daylight hours will make it a bit harder for rain to reach the surface. With little to no instability in place, expect mainly plain rain with a possible rumble of thunder. Low temperatures overnight will be on the warm side thanks to the LLJ, falling to the 30s to upper 40s. A mostly cloudy and slightly cooler Easter Sunday is in store as the previously mentioned wave moves through. The chance for light showers continues through the day, mainly along and east of I-29 where better forcing for ascent resides. Will again be fighting dry air in the low levels so this by no means will be a washout or brief heavy rain. Expect light rain showers to move through predominately during the afternoon hours. However, those with outdoor plans may want to keep a rain coat and umbrella handy. Highs will warm to the 50s where lingering snow cover resides and 60s elsewhere. Thanks to the rain chances and associated cloud cover, relative humidity will be higher, above critical thresholds. Winds will also fall below critical thresholds as mid level winds weaken as the wave continues its track eastward. Any shower activity will come to an end as the wave finally pushes east of the forecast area. Rainfall totals will be light with amounts up to around a few hundredths to a tenth of an inch expected. Skies will clear for the overnight hours, allowing low temperatures to fall to the 30s and 40s. .LONG TERM...(Monday through Saturday) Issued at 255 PM CDT Sat Apr 8 2023 Sun enthusiasts rejoice!! An upper ridge builds in for Monday and persists through Thursday. Mostly sunny skies with a few passing clouds and warm temperatures for these few days. The warmer temperatures are supported by geopotential heights at their maximum for climatology as indicated by the NAEFS table through Wednesday. Geopotential heights remain at the 99th percentile for climatology through Thursday. In addition, temperatures at 850mb will range between 10 and 14 C which translates to surface temperatures in the 60s and 70s F for Monday. Tuesday will be even warmer with 850 mb temps 16 t0 22 C. Look for highs on Tuesday to be upper 70s and 80s F along the Missouri River Valley from Chamberlain through Sioux City. Slightly cooler for Wednesday with highs mainly in the 70s. Highs for Thursday rebound back into the upper 70s and 80s again focused along the Missouri River and expanding east toward the James River. Winds will be out of the south with gusts 15-20 mph for Monday. Gusts increase for Tuesday. If mixing potential is met, BUFKIT soundings as well as GFS, NAM, and the Canadian indicate gusts up to 30-40 mph are possible. Wednesday and Thursday winds remain breezy but relax into the 20-25 mph range for gusts. The persistently subsiding air dries out the entire column aloft. At the surface, very dry conditions develop as a result with relative humidity dipping into the 25-35% range. During this period, fire weather will be a concern. Meanwhile, off along the pacific coast a strong trough has been digging and forming a closed off upper low. By Friday this system brings our next chance for precipitation. There is very low model agreement on how this system comes together, but all indicate widespread precipitation is possible into Saturday. As agreement is low, did not make adjustments to the NBM. && .AVIATION...(For the 06Z TAFS through 06Z Sunday Night) Issued at 1050 PM CDT Sat Apr 8 2023 A boundary will be laying across the region into Sunday, with KHON having light and variable winds overnight. These winds will pick up slightly on Sunday morning, becoming westerly through the day. With a low level jet to the south, KFSD and KSUX will have LLWS through 13Z on Sunday. Winds will be gusty at KFSD and KSUX during the night, though decreasing by late tonight into Sunday morning. With the boundary pushing through KFSD, there will be southerly winds to start the day, then transitioning to the northwest by evening. Winds at KSUX will remain southerly through the day. Latest model guidance has indicated a lesser chance of showers on Sunday, most likely being mainly sprinkles with dry air in the lower levels. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...Meyers LONG TERM...AJP AVIATION...JM
Hazardous Weather Outlook National Weather Service Sioux Falls SD 909 PM CDT Sat Apr 8 2023 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-100215- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory- Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- Union- 909 PM CDT Sat Apr 8 2023 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Periods of gusty south winds, combined with seasonably warm afternoon temperatures and low humidity levels, will bring a risk of elevated fire danger to snow-free areas again toward the middle of next week. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
7 flood. Local standard time, as filed.
Flandreau Creek near Flandeau, SD rose above flood stage on the early morning of April 9th before cresting around 0.28 feet above flood stage (9.28 feet) on April 9th. The creek then quickly fell below flood stage midday on April 9th.
Flandreau Creek near Flandeau, SD rose above flood stage on the early morning of April 9th before cresting around 0.28 feet above flood stage (9.28 feet) on April 9th. The creek then quickly fell below flood stage midday on April 9th.
Areal flooding from rapid snowmelt resulted in damage to several gravel roads and culverts across Lyon County, Minnesota during mid April. The most concentrated area of issues occurred in Westerheim Township in northern Lyon County. This flooding resulted in a Presidential Disaster Declaration for several townships across the county.
The Redwood River near Russell, MN rose above flood stage during the early morning of April 12th before cresting around 0.63 feet above flood stage (14.63 feet) on April 13th. The river then fell below flood stage on the evening of April 13th.
The Redwood River near Russell, MN rose above flood stage during the early morning of April 12th before cresting around 0.63 feet above flood stage (14.63 feet) on April 13th. The river then fell below flood stage on the evening of April 13th.
The West Fork of the Des Moines River near Avoca, MN rose above flood stage on the afternoon of April 12th before cresting around 0.67 feet above flood stage (1425.67 feet) on April 15th. The river then fell below flood stage on the morning of April 17th.
The West Fork of the Des Moines River near Avoca, MN rose above flood stage on the afternoon of April 12th before cresting around 0.67 feet above flood stage (1425.67 feet) on April 15th. The river then fell below flood stage on the morning of April 17th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2023Every state in 2023This day in weather historyWarnings in Minnesota, April 2023
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: 1091993, 1091994, 1092019, 1092012, 1092013, 1092015, 1092017.