Persistent below normal precipitation since July 2017 allowed severe drought conditions to develop across portions of northeast Iowa, including Allamakee County. These conditions continued into October 2017.
Every event with a place to put it; 1 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 ARX wrote it up.
Persistent below normal precipitation since July 2017 allowed severe drought conditions to develop across portions of northeast Iowa, including Allamakee County. These conditions continued into October 2017.
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 La Crosse, WI wrote its last area forecast discussion before the first event at Sep 12, 5:36 AM CST, 24 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 636 AM CDT Tue Sep 12 2017 .UPDATE... Issued at 330 AM CDT Tue Sep 12 2017 Issued a Dense Fog Advisory for Taylor County in collaboration with surrounding offices. Calls to counties from Clark County south and westward indicated little in the way of fog development as of now. Will continue to monitor for any southward expansion of the widespread fog over the next several hours. Otherwise, farther south, expect more typical valley fog in prone areas. && .SHORT TERM...(Today and tonight) Issued at 230 AM CDT Tue Sep 12 2017 Latest 08z surface analysis shows surface ridge extending from Michigan into southern Minnesota/Iowa. Mostly clear skies were seen across the forecast area per latest infrared satellite imagery. Latest 07z metars over north central Wisconsin and in the Wisconsin River valley indicate visibilities reduced to less than a mile due to fog. Surface ridge will remain in control of the area today into tonight and provide mostly sunny/mostly clear skies across the forecast area. High temperatures today are expected to be above normal with highs in the upper 70s to lower 80s. Tonight...the combination of light winds and clear skies...will allow fog to form...especially in river valleys and the favored areas of central Wisconsin. Have introduce patchy to areas of fog in these areas...however with the lack of rainfall the past week...fog may not be as widespread/dense in certain river valleys. .LONG TERM...(Wednesday through Monday) Issued at 230 AM CDT Tue Sep 12 2017 Upper level/surface ridge remains the dominant weather feature Wednesday into Wednesday night and provide dry weather across the forecast area. Then the focus turns to the upper level/surface ridge building into the eastern Great Lakes Region and southerly moisture flow returns into the Upper Midwest while a surface warm front lifts north into central Minnesota and northern Wisconsin Thursday into Thursday night. The 12.00z GFS/NAM/ECMWF suggest first impulse to eject out of a upper level trough over the Rocky Mountains and track along the surface warm front Thursday night. Main moisture axis per 925-850mb moisture transport will be west of the forecast area. Small chance of shower/thunderstorm at this time look to be warranted for western most portion of the forecast area Thursday night. Main forecast concerns Friday into Monday are periodic shower/thunderstorms Friday into Sunday. The 12.00z GFS/ECMWF are in good agreement in ejecting pieces of energy embedded in the southwesterly flow aloft into the Upper Midwest and Great Lakes region through the period. With the 12.00z GFS/ECMWF indicating increasing moisture convergence/lift over much of the forecast area...confidence is increasing the forecast area will see periodic scattered shower/thunderstorms Friday night into Sunday. Timing of the shower/thunderstorm activity at this time appears to be an issue...as models differ on strength and placement of the pieces of energy moving into the Upper Midwest/Great Lakes region. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) Issued at 636 AM CDT Tue Sep 12 2017 Mainly VFR conditions will persist into Wednesday morning with surface high pressure resulting in light winds and mostly clear skies. With light winds through the lowest 5kft and clear skies, fog formation is expected late tonight, especially in valleys, possibly impacting KLSE. Have begun to trend towards this scenario, but will not introduce any IFR/LIFR cigs/visibilities near the end of the TAF period with some uncertainty in fog coverage. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ017. MN...None. IA...None. && UPDATE...JM SHORT TERM...DTJ LONG TERM...DTJ AVIATION...JM
Hazardous Weather Outlook National Weather Service La Crosse WI 322 AM CDT Tue Sep 12 2017 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ029-032>034- 041>044-053>055-061-130830- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Clark- Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon- Crawford-Richland-Grant- 322 AM CDT Tue Sep 12 2017 This Hazardous Weather Outlook is for portions of southeast Minnesota...northeast Iowa and southwest into central Wisconsin. .DAY ONE...Today and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible Thursday night through Sunday night. It is too early to discern any severe weather potential at this time. .SPOTTER INFORMATION STATEMENT... No action needed. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. WIZ017-130830- Taylor- 322 AM CDT Tue Sep 12 2017 This Hazardous Weather Outlook is for portions of north central Wisconsin. .DAY ONE...Today and Tonight A Dense Fog Advisory is in effect through 9 am this morning. Dense fog will reduce visibilities to less than a half mile at times. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Thunderstorms are possible Saturday night through Sunday night. It is too early to discern any severe weather potential at this time. .SPOTTER INFORMATION STATEMENT... No action is needed. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. DTJ/JAM
The national radar mosaic for the moment the first event began.
1 drought. Local standard time, as filed.
Persistent below normal precipitation since July 2017 allowed severe drought conditions to develop across the northwest corner of Allamakee County. These conditions continued into October 2017.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2017Every state in 2017This day in weather historyWarnings in Iowa, September 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: 717695.