Severe to Extreme Drought conditions persisted into early October in portions of southern Iowa. However, generous rainfall in mid to late October improved conditions dramatically across the drought area.
Every event with a place to put it; 13 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 DMX wrote it up.
Severe to Extreme Drought conditions persisted into early October in portions of southern Iowa. However, generous rainfall in mid to late October improved conditions dramatically across the drought area.
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 Des Moines, IA wrote its last area forecast discussion before the first event at Sep 30, 10:44 PM CST, 1 hour 16 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1144 PM CDT Sat Sep 30 2017 ...Updated for 06z Aviation Discussion... .SHORT TERM.../Tonight/ Issued at 336 PM CDT Sat Sep 30 2017 For Tonight...The upper ridge is now well east of Iowa with southwest flow aloft. Water vapor imagery was showing a significant piece of shortwave energy across the central and southern rockies and a weak energy across eastern Nebraska. Scattered light showers where downstream across northeast Nebraska into northwest Iowa. As the showers move into northwest, they are fighting dry air resulting in virga. Equiv potential temperature advection tonight across northwest Iowa tonight supports additional shower development. Like today, showers will be fighting dry air in lower levels as the move east. As a result will progress precipitation changes slowly across the northwest late night. Lows tonight will be 5-10 degrees warmer than last night. .LONG TERM.../Sunday through Saturday/ Issued at 336 PM CDT Sat Sep 30 2017 We will remain in an unsettled pattern this week with the blocking pattern remaining. A stout upper ridge over the Eastern U.S. and a deep trough over the Rockies will cause very slow movement of features. As a result, the main changes to the forecast are with respect to precip timing based on what the models are currently depicting. For Sunday, soundings are showing a lot of dry air in place and not really eroding much so I don't see much of a precip threat. Pops for tomorrow were slowed and lowered some. The upper trough over the Rockies does appear to pivot some so pops were not completely removed but the amount of dry air in place does raise questions. In time as the ridge to the east tilts some causing the flow over the region to become more southwesterly and allowing the trough to the west to influence things over our area more. Precip chances will increase more over the west and northwest through Monday night. Shear will be sufficient mainly west of the state in the vicinity of a cold front for storms to become more organized but for us we will still be in the warm sector ahead of the boundary. Still it's possible that some stronger elevated storms could make it into our far northwest producing a hail threat Monday afternoon and evening. On Tuesday, the cold front finally pushes through the state with dry high pressure building in for Wednesday. I put the best pop chances in for Tuesday through Tuesday evening but see little pop potential for Wednesday. Collaboration with neighbors yielded a lower of pops on Wednesday but with the exception of the far southeast, I see little chance at all for precip Wednesday with that dry high pressure building in. The break in precip chances ends by Thursday as a trough swings into the Upper Midwest and a surface low over the Plains draws a frontal boundary in/near southern Iowa. Instability while meager...will increase across southern Iowa with better shear mainly over northern Iowa so while uncertainty exists as to where the best chance for storms will exist and the strength of them, slight chance to chance pops were added south...near where I believe the boundary will reside. Friday into Saturday, the upper wave sweeps by ending that precip chance. However we stay in this pattern of stronger shortwaves dropping down the flow over the Northern Rockies and evolving into a low somewhere over the Plains/Upper Midwest then moving east. This will keep periodic chances for showers/storms going beyond the current long term period, with low confidence on timing and location. && .AVIATION.../For the 06Z TAFS through 06Z Sunday night/ Issued at 1144 PM CDT Sat Sep 30 2017 Maintained low level wind shear later tonight and early Sunday morning over the northern terminals where it is most likely to occur as winds around FL020 will be around 40 knots with surface winds near 10 knots. Winds from the southeast will become gusty by mid-morning with plenty of mid and high level clouds. Showers will ever so slowly try to arrive in the morning hours, but dry air in low levels should delay the arrival until around midday at KFOD and later in the afternoon at KMCW. Have incorporated VCSH to put a most likely time that showers may impact those terminals. Future TAFs will evaluate the impact showers may have on ceiling and visibility restrictions. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Johnson LONG TERM...FAB AVIATION...Ansorge
Hazardous Weather Outlook National Weather Service Des Moines IA 350 PM CDT Sat Sep 30 2017 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-012100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene- Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper- Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union- Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne- Appanoose-Davis- 350 PM CDT Sat Sep 30 2017 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday Periodic chances for showers and thunderstorms are forecast Sunday through late Wednesday. While the overall threat for severe weather is low, there is a marginal risk for large hail across the northwest Monday afternoon and evening. There will also be the potential for periodic heavy rainfall, especially over the northwest half of Iowa. .SPOTTER INFORMATION STATEMENT... Spotter activation is not likely at this time. FAB
The national radar mosaic for the moment the first event began.
13 drought. Local standard time, as filed.
Severe drought conditions persisted across far southeast Adair county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across far southern and central Madison county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of Warren county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of Marion county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of Mahaska county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of central and eastern Union county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across Clarke county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of Lucas county in early October but generous rainfall ended the dry conditions by mid-month.
Severe drought conditions persisted across far northern Lucas county in early October but generous rainfall ended the dry conditions by mid-month.
Severe drought conditions persisted across northern Wapello county in early October but generous rainfall ended the dry conditions by mid-month.
Severe drought conditions persisted across far northeast Ringgold county in early October but generous rainfall ended the dry conditions by mid-month.
Severe drought conditions persisted across northern Decatur county in early October but generous rainfall ended the dry conditions by mid-month.
Severe to extreme drought conditions persisted across much of central and northern Wayne county in early October but generous rainfall ended the dry conditions by mid-month.
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, October 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: 766031, 766032, 766033, 766034, 766035, 766036, 766037, 766038, 766039, 766040, 766041, 766042, 766043.