Rainfall over an inch in upper portions of the Little Sioux River Basin on June 8-9 resulted in sharp and brief rises in river levels, which produced minor flooding at Spencer.
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The episode as NWS FSD wrote it up.
Rainfall over an inch in upper portions of the Little Sioux River Basin on June 8-9 resulted in sharp and brief rises in river levels, which produced minor flooding at Spencer.
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 Jun 10, 9:59 PM CST, 1 hour 1 minute earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1059 PM CDT Wed Jun 10 2020 .SHORT TERM...(This Evening through Thursday) Issued at 354 PM CDT Wed Jun 10 2020 Much quieter across the region today, with only immediate concern being some gusty (largely sub-advisory) winds, and diurnal cumulus, both of which should dissipate quickly as we approach sunset. Seeing a few light echoes on radar with the thicker cumulus approaching from the northwest but these, too, should diminish with loss of heating. After sunset, looking at another comfortable night, with relatively dry surface air allowing overnight temperatures to fall into the 50s. Could see a little afternoon cumulus development again on Thursday, but model soundings overall are drier, so do not expect coverage to be as extensive, nor would we expect any sprinkles that we are seeing today. Still in predominantly west-northwest flow, but with a slackening pressure gradient, so while still a bit breezy, should be much less windy than several of our recent days. Slightly warmer low level temperatures begin to push into the region Thursday, so should see temperatures pretty close to normal in the upper 70s-lower 80s. .LONG TERM...(Thursday Night through Wednesday) Issued at 354 PM CDT Wed Jun 10 2020 Northwest flow dominates through Friday, with upper ridge then building eastward into the Plains through the weekend. A few models produce light QPF in parts of northeast South Dakota/Minnesota, mainly northeast of our forecast area, late Friday/Friday night as the warmer air begins to build back into the region. Moisture looks somewhat limited at this point, and with stronger warm advection to our northeast, will carry little if any pops for our counties at this time. Broader spread in model temperatures for the weekend, which appears to be largely in response to a wave dropping through the western periphery of the eastern Canadian upper trough. 10/00Z ECMWF was stronger/farther westward with this wave, driving a backdoor cool front through much of Minnesota. The 12Z EC seems to have trended back toward the weaker/farther east solutions, which lends a little more confidence in sticking with the blended temperatures, which were slightly warmer than the median of the available models. This should allow for highs in the 80s for most areas over the weekend, with the building ridge keeping the region dry, but with breezy southerly winds. By Sunday night, the upper ridge axis shifts east, placing us in warm southwest flow aloft for the first half of next week. Subtle waves sliding through this flow may bring us occasional chances for showers/storms. Monday night appears to be a favored time in some of the models for this to occur, but with timing differences among the broad range of model solutions at this range, confidence is not high enough to focus pops in any single period just yet. Confidence is higher in the potential for a couple hotter days in the Monday-Wednesday time frame, with 850mb mean temperatures pushing the 90th percentile of climatology in both the GEFS and ECMWF ensemble. So could be looking at more 90 degree days in parts of the forecast area by Tuesday and/or Wednesday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1057 PM CDT Wed Jun 10 2020 VFR conditions through the period. Cumulus around 7000-8000ft agl may develop across southwest Minnesota after 15Z Thursday. Gusty winds are also expected after 15Z from the northwest. Gust should subside Thursday evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...JH LONG TERM...JH AVIATION...BT
Hazardous Weather Outlook National Weather Service Sioux Falls SD 700 AM CDT Wed Jun 10 2020 SDZ038-039-050-052>054-057>060-063-064-111200- Beadle-Kingsbury-Gregory-Jerauld-Sanborn-Miner-Brule-Aurora-Davison- Hanson-Charles Mix-Douglas- 700 AM CDT Wed Jun 10 2020 This Hazardous Weather Outlook is for central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MNZ071-072-080-097-098-SDZ040-055-056-061-062-065>070-111200- Lincoln-Lyon-Murray-Pipestone-Rock-Brookings-Lake-Moody-McCook- Minnehaha-Hutchinson-Turner-Bon Homme-Yankton-Clay- 700 AM CDT Wed Jun 10 2020 This Hazardous Weather Outlook is for southwest Minnesota, east central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. IAZ001>003-012>014-020>022-031-032-MNZ081-089-090-NEZ013-014-SDZ071- 111200- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Cottonwood-Nobles-Jackson-Dixon-Dakota- Union- 700 AM CDT Wed Jun 10 2020 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska and southeast South Dakota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
938 PM CDT WED JUN 10 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1012 PM HAIL 4 SSW DELMONT 43.21N 98.19W
06/08/2020 M1.25 INCH CHARLES MIX SD PUBLIC
&&The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Rainfall of 1.34 inches at Spencer and 1.30 inches 4 miles northwest of Milford on June 8-9 brought the Little Sioux River at Spencer (gage site SPWI4) briefly into minor flood, with a crest of 0.25 feet above flood stage on June 11. Minor flooding occurred in the Spencer City Park.
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