) were experienced with this event. The overall pattern was not conducive for traditional severe weather, but with a short wave moving through the upper level flow, precipitable water values around 2 inches, decent 850 mb moisture transport, and MUCAPE values around 1000-1500 J/kg, heavy rainfall prevailed.
Every event with a place to put it. 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.
Heavy rainfall continued to affect the Midwest and portions of Iowa, though fortunately no severe weather (hail, winds, etc...) were experienced with this event. The overall pattern was not conducive for traditional severe weather, but with a short wave moving through the upper level flow, precipitable water values around 2 inches, decent 850 mb moisture transport, and MUCAPE values around 1000-1500 J/kg, heavy rainfall prevailed.
The majority of values were held in check below some of the large values seen earlier in the year, but a wide area from southwest to northeast Iowa did record 2 to around 3 inches of rainfall.
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 1, 5:54 PM CST, 5 hours 6 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 654 PM CDT Sat Sep 1 2018 ...Updated 00z Aviation... .DISCUSSION.../Tonight through Saturday/ Issued at 323 PM CDT Sat Sep 1 2018 Very active weather pattern to persist through much of the forecast period. Large sub-tropical high over the east central CONUS will move slightly east and north over the next 24 hrs and will allow the surface boundary to lift slightly north and focus over central Iowa. This boundary will be the area of focus for thunderstorms tonight through Monday. Very heavy rainfall remains the primary concern during this period as repeated rounds of thunderstorms capable of producing heavy rainfall. Currently there is a lull in the thunderstorm activity. Weak surface boundary was located from near Omaha to Des Moines then northeast towards Waterloo. This boundary may settle a bit south tonight before the aforementioned push back to the north. Another wave of theta-e advection will lift into central Iowa late this afternoon and into the early evening. This will moving into an area of nearly uncapped instability near the surface boundary. This forcing may be enough to trigger a few thunderstorms during this time period and could have the potential for some large hail and possibly a damaging wind gusts. Additional storms are expected to develop over Kansas late this afternoon then the system may become linear and lift northeast along the boundary and into central Iowa overnight. PWAT values will remain near to above 2 inches along the boundary as deep layer moisture advection continues with Gulf flow in the low levels thanks to the high to the east and monsoonal flow in the mid-levels. Based on heavy rain potential overnight and recent heavy rains along with expected focus overnight, will be reorienting the Flash Flood watch farther north tonight. Likely will need additional headlines the next few days over central Iowa for heavy rainfall. The rainfall potential by Tuesday will shift further northwest on Tuesday with heavy rain remaining possible. The upper flow will flatted on Wednesday with westerly flow prevailing through the rest of the period. This will allow the boundary to drop south but should hangup over southern Iowa/northern Missouri as it becomes parallel to the upper flow. This should bring lower threat for thunderstorms north while the south remains active. Temperature by the end of the week will drop into the 70s. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 640 PM CDT Sat Sep 1 2018 Rain showers and thunderstorms will continue to be the main concern overnight and into the morning. Thunderstorms will be isolated in nature, and showers will become more widespread throughout the period. For the most part, conditions will prevail in the lower range of MVFR. There may be brief periods of IFR if a downpour occurs directly over a terminal. Confidence in thunderstorm is occurrence is high across central Iowa is high, direct impacts to specific terminals is medium. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Sunday morning for IAZ025>028-034>039- 045>050-057>062-070>075. && DISCUSSION...Donavon AVIATION...Krull
Hazardous Weather Outlook National Weather Service Des Moines IA 354 PM CDT Sat Sep 1 2018 IAZ004>007-015>017-023-024-033-044-081>086-092>097-022100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Sac-Crawford-Adams-Union-Clarke-Lucas-Monroe- Wapello-Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis- 354 PM CDT Sat Sep 1 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Periods of strong to severe storms will be possible this evening and overnight, especially over the southern half to two thirds of the state. Main threats will be for damaging winds and heavy rainfall, though severe hail is not out of the question. Heavy rainfall may cause localized water issues. .DAYS TWO THROUGH SEVEN...Sunday through Friday There will be periods of thunderstorms, especially during the overnight hours throughout this period. Widespread severe weather is not likely but a few storms from time to time may be strong to severe. Damaging winds will likely be the main threats with any stronger storms. Heavy rainfall will be possible with any thunderstorm. River flooding and flash flood threats could increase Sunday into next week due to the continued heavy rain threat. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected though severe weather and rainfall reports are appreciated. IAZ025>028-034>039-045>050-057>062-070>075-022100- Wright-Franklin-Butler-Bremer-Calhoun-Webster-Hamilton-Hardin- Grundy-Black Hawk-Carroll-Greene-Boone-Story-Marshall-Tama- Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-Cass-Adair-Madison- Warren-Marion-Mahaska- 354 PM CDT Sat Sep 1 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Strong to possibly severe thunderstorms and heavy rainfall are possible this evening and overnight. The main threats will be for heavy rainfall and damaging winds, though large hail is not out of the question. Areas that see heavy rainfall may experience exacerbated water issues since many have received recent moderate to heavy rainfall. A flash flood watch is in effect for the area, please visit www.weather.gov/desmoines for more details. .DAYS TWO THROUGH SEVEN...Sunday through Friday There will be periods of thunderstorms, especially during the overnight hours throughout this period. Widespread severe weather is not likely but a few storms from time to time may be strong to severe. Damaging winds will likely be the main threats with any stronger storms. Heavy rainfall will be possible with any thunderstorm. River flooding and flash flood threats could increase Sunday into next week due to the continued heavy rain threat. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected though severe weather and rainfall reports are appreciated. CURTIS
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1045 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1043 PM FLASH FLOOD 1 NNE GRANGER 41.78N 93.81W
09/01/2018 POLK IA PUBLIC
SOCIAL MEDIA REPORT STATES THAT HIGHWAY 17
NORTHBOUND IS UNDERWATER AND CLOSED
APPROXIMATELY 1 MILE NORTH OF GRANGER.
&&
FOWLEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1048 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 PM HAIL 2 N URBANDALE 41.66N 93.74W
09/01/2018 E1.25 INCH POLK IA PUBLIC
&&
AKPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1111 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1101 PM HAIL 2 S AMES 41.99N 93.62W
09/01/2018 E0.88 INCH STORY IA PUBLIC
VIA SOCIAL MEDIA.
&&
BSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1116 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1055 PM HEAVY RAIN 1 SE LAMBS GROVE 41.69N 93.07W
09/01/2018 M4.25 INCH JASPER IA TRAINED SPOTTER
SINCE 7PM.
&&
BSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1153 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1147 PM FLASH FLOOD 2 SE GRANGER 41.75N 93.80W
09/01/2018 POLK IA DEPT OF HIGHWAYS
THE IOWA DOT REPORTS THAT HIGHWAY 141
BETWEEN GRIMES AND GRANGER WAS ESSENTIALLY A
SHEET OF WATER WITH SPEEDS OF ONLY 10 MPH
POSSIBLE.
&&
BSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1159 PM CDT SAT SEP 1 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1158 PM HEAVY RAIN 1 N MONTEZUMA 41.60N 92.53W
09/01/2018 M6.48 INCH POWESHIEK IA TRAINED SPOTTER
RAINFALL REPORTED WAS FOR A 24 HOUR PERIOD.
&&
FABThe Des Moines radar (KDMX), 54 km away, was scanning. The volume nearest the first event began at 05:00 UTC.
17 heavy rain, 3 flash flood, 2 flood, 1 lightning. Local standard time, as filed.
A local photographer came across a smoldering wind turbine that had been struck by lightning overnight. It also had previous damage from a tornado earlier in the year.
Trained spotter reported heavy rainfall of 2.00 inches over the last 24 hours.
Coop observer reported heavy rainfall of 2.74 inches over the last 24 hours.
Coop observer reported heavy rainfall of 2.05 inches over the last 24 hours.
Coop observer reported heavy rainfall of 2.10 inches over the last 24 hours.
Coop observer reported heavy rainfall of 2.27 inches over the last 24 hours.
Coop observer reported heavy rainfall of 2.99 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.06 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.11 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.85 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.05 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.26 inches over the last 24 hours.
Trained spotter reported heavy rainfall of 2.10 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.47 inches over the last 24 hours.
CoCoRaHS observer reported heavy rainfall of 2.38 inches over the last 24 hours.
A trained spotter reported that multiple gravel roads west of Plainfield have water flowing over them, as much as 2-3 feet deep.
Emergency management reported multiple road closures due to standing or running water over the roadways. Creeks across much of the county were overwhelmed with flooded fields as well.
Emergency management reported multiple road closures due to standing or running water over the roadways. Creeks across much of the county were overwhelmed with flooded fields as well. The Bremer County dispatch also noted closures at 200th and Hawthorne, 130th and Midway, 310th and Morgan, 1900 block of Marquis Rd, 200 block of 200th St. and 150th and Dakota.
Trained spotter reported heavy rainfall of 4.89 inches since midnight. They estimated that 2.5 inches of that was in the last 1 to 2 hours.
Des Moines International Airport ASOS recorded heavy rainfall of 2.31 inches over the last 12 hours.
KWWL relayed images of street flooding in Cedar Falls. The water appeared to be fairly rapidly moving in the image.
KWWL relayed images of stalled cars in around 1 to 2 feet of water. The water did not look to be moving.
Public reported heavy rainfall of 2.20 inches over approximately the last 30 minutes.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2018Every state in 2018This day in weather historyWarnings in Iowa, September 2018
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: 786735, 779818, 779819, 779820, 779821, 779822, 779823, 779824, 779825, 779826, 779827, 779828, 779829, 779830, 779831, 785805, 786297, 786298, 779836, 779832, 779833, 779835, 779837.