A slow moving, nearly stationary boundary was oriented across Iowa from southwest to northeast during the 13th. Storms initiated along and near the boundary during the overnight hours from the 12th to the 13th and onward through the day.
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.
A slow moving, nearly stationary boundary was oriented across Iowa from southwest to northeast during the 13th. Storms initiated along and near the boundary during the overnight hours from the 12th to the 13th and onward through the day. The environment on the warm side of the front was CAPE filled with SBCAPE values in excess of 3000-4000 J/kg. Additionally, much like the convective season to this point, other supporting severe weather parameters were lacking such as effective shear (under 30 kts), DCAPE (under 1000 J/kg), and hail CAPE (under 500 J/kg) to name a few. The result was typically short lived strong storms, but a few were able to at least briefly organized near the front or along outflow boundaries and produce sporadic strong and damaging winds.
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 Jul 13, 5:33 AM CST, 5 hours 52 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 633 AM CDT Fri Jul 13 2018 .DISCUSSION.../Today through Thursday/ Issued at 401 AM CDT Fri Jul 13 2018 Biggest concerns center around precip chances today into the weekend with heavy rain potential today into Saturday and temperatures throughout the forecast period. Some storms ongoing across the far north and expect activity to diminish somewhat through sunrise. Mainly westerly zonal flow across the western US into the central US with the an upper trough situated across the Hudson Bay region. This trough is associated with a surface low in the same area and a sfc trough extending back to the south/southwest through MN/NE into Colorado. Storms fired across southern MN/SE SD and northern NE later Thursday and have dropped slowly southward clipping NW into NC IA through the overnight hours. These storms formed along a boundary that is expected to slowly sag southward through Iowa today into Saturday. Additional activity expected to develop in the vicinity of this boundary across west central into central into northeast Iowa this afternoon and continue across the forecast area into tonight. A weak shortwave trough will continue to move through the central US today and tonight which will be the main support for additional thunderstorm development later today into tonight. Overall severe threat is somewhat marginal with the expected storms as deep layer shear is lower around 20-30 kts, with decent instability. Freezing levels quite high around 14-15kft so expect mainly a wind threat with any stronger storms. Of bigger concern is the threat for heavy rainfall with the warm cloud depths pushing 4000-4500 kft deep and high PWATs around 2+ inches. Storm motions likely to be slower with training of cells likely from west to east/southwest to northeast along the west to east situated boundary. Model solutions suggesting heaviest rainfall axis to is expected to the west of the forecast area where outputs of 4-6 inches are possible through Saturday across far western Iowa and into eastern NE, but still potential for a widespread 1-2 inches of rain across much of southwest to central to northeast Iowa, with locally higher amounts of 3+ inches possible. The area has dried out some from the heavy rainfall at the end of June/early July across central Iowa, but rainfall potential still enough that flash flooding could be possible especially if heavy rain falls over a more urban area. Therefore will go ahead and issue a flash flood watch for portions of the southwest/central and northeast for this late this afternoon into Saturday morning. As the front slowly sags southward into central and southern Iowa additional storms are forecast for Saturday into Saturday night, so the potential for heavy rainfall could go beyond the current watch headline period. The boundary will move south of the area Sunday, with another weak cold front dropping through the state Sunday into early Monday. This may allow for some additional thunderstorm chances into Sunday/Monday. Behind this front a much cooler airmass will move into the state with mainly dry and cooler conditions expected for Monday night into Tuesday. A fast-moving shortwave will impact the state into midweek with additional rain chances, but upper ridging will then build into the central US with an area of surface high pressure expected to bring dry conditions to the end of next week. Temperatures will be somewhat cooler across the north/central portions of the area today, with the far southeast still into the mid 90s today with humid conditions. Heat index values will approach 103 in the far southeast this afternoon, so even though it is just under our advisory criteria will go ahead and issue to match up with DVN which has lower criteria and also because it will be the 2nd to 3rd day straight of warmer temps/high humidity in that area. Temps will then trend a bit cooler for the weekend behind the initial boundary moving through the state, with much cooler conditions expected behind the second front to drop through Iowa. This should send temps below average with highs only in the upper 70s to low 80s through much of next week. && .AVIATION.../For the 12Z TAFS through 12Z Saturday morning/ Issued at 633 AM CDT Fri Jul 13 2018 Initially VFR conditions at all sites, with thunderstorm chances increasing from north to south through the late afternoon hours and continuing through tonight. Winds to become northerly toward early Saturday. && .HYDROLOGY... Issued at 401 AM CDT Fri Jul 13 2018 Have issued a Flash Flood Watch for the southwest, central and northeastern portions of central Iowa for later this afternoon into Saturday morning. Efficient rainfall production is expected with thunderstorm activity expected to move through central Iowa mainly tonight into early Saturday. Training of storms will be possible with widespread 1-2 inch rainfall amounts expected in the watch area and locally higher amounts possible. The potential for heavy rainfall could lead to flash flooding especially in and around urban areas. The heavy rainfall may lead to rises on local streams and could cause additional issues on area rivers where streamflows continue to be high. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 4 PM CDT this afternoon through Saturday morning for IAZ025>028-033>039-044>050-057>061-070>073-081-082- 092. Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for IAZ075-085-086-095>097. && DISCUSSION...Beerends AVIATION...Beerends HYDROLOGY...Beerends
Hazardous Weather Outlook National Weather Service Des Moines IA 422 AM CDT Fri Jul 13 2018 IAZ025>028-033>039-044>050-057>061-070>073-081-082-092-140930- Wright-Franklin-Butler-Bremer-Sac-Calhoun-Webster-Hamilton-Hardin- Grundy-Black Hawk-Crawford-Carroll-Greene-Boone-Story-Marshall- Tama-Audubon-Guthrie-Dallas-Polk-Jasper-Cass-Adair-Madison-Warren- Adams-Union-Taylor- 422 AM CDT Fri Jul 13 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight A Flash Flood Watch is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Thunderstorm chances will spread across most of Iowa today into tonight. Locally heavy rainfall is the primary threat, especially later this afternoon into tonight. Any heavy rainfall could lead to flash flooding or additional river flooding. In addition, a few strong to perhaps severe storms posing a risk of damaging wind gusts will be possible this afternoon into early this evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Locally heavy rainfall will be a concern into Saturday with scattered thunderstorms. Non-severe thunderstorms are expected Sunday into the first part of Monday. Thunderstorms will return Wednesday into Thursday with the risk of severe weather better determined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon into tonight. In addition, reports of rainfall greater than an inch would be appreciated today into Saturday. IAZ005>007-016-017-062-074-083-084-093-094-140930- Kossuth-Winnebago-Worth-Hancock-Cerro Gordo-Poweshiek-Marion- Clarke-Lucas-Ringgold-Decatur- 422 AM CDT Fri Jul 13 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Thunderstorm chances will spread across most of Iowa today into tonight. Locally heavy rainfall is the primary threat, especially later this afternoon into tonight over central Iowa. Any heavy rainfall could lead to flash flooding or additional river flooding. In addition, a few strong to perhaps severe storms posing a risk of damaging wind gusts will be possible this afternoon into early this evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Locally heavy rainfall will be a concern into Saturday with scattered thunderstorms. Non-severe thunderstorms are expected Sunday into the first part of Monday. Thunderstorms will return Wednesday into Thursday with the risk of severe weather better determined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon into tonight. In addition, reports of rainfall greater than an inch would be appreciated today into Saturday. IAZ075-085-086-095>097-140930- Mahaska-Monroe-Wapello-Wayne-Appanoose-Davis- 422 AM CDT Fri Jul 13 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight A Heat Advisory is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Thunderstorm chances will spread across most of Iowa today into tonight. Locally heavy rainfall is the primary threat, especially later this afternoon into tonight over central Iowa. Any heavy rainfall could lead to flash flooding or additional river flooding. In addition, a few strong to perhaps severe storms posing a risk of damaging wind gusts will be possible this afternoon into early this evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Locally heavy rainfall will be a concern into Saturday with scattered thunderstorms. Non-severe thunderstorms are expected Sunday into Monday. Thunderstorms will return Wednesday into Thursday with the risk of severe weather better determined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon into tonight. In addition, reports of rainfall greater than an inch would be appreciated today into Saturday. IAZ004-015-023-024-140930- Emmet-Palo Alto-Pocahontas-Humboldt- 422 AM CDT Fri Jul 13 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight River Flood Warnings are in effect for parts of the Des Moines River basin. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Thunderstorm chances will spread across most of Iowa today into tonight. Locally heavy rainfall is the primary threat, especially later this afternoon into tonight over central Iowa. Any heavy rainfall could lead to flash flooding or additional river flooding. In addition, a few strong to perhaps severe storms posing a risk of damaging wind gusts will be possible this afternoon into early this evening. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Locally heavy rainfall will be a concern into Saturday with scattered thunderstorms. Non-severe thunderstorms will also be Sunday into the first part of Monday. Thunderstorms will return Wednesday into Thursday with the risk of severe weather better determined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon into tonight. In addition, reports of rainfall greater than an inch would be appreciated today into Saturday. Ansorge
Special Weather Statement
National Weather Service Des Moines IA
1148 AM CDT FRI JUL 13 2018
IAZ033-044-045-131745-
Sac IA-Carroll IA-Crawford IA-
1148 AM CDT FRI JUL 13 2018
...Line of Strong Thunderstorms Moving into Crawford, Sac, Carroll
Counties...
At 1146 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 8 miles east of Galva to near Denison to 7
miles north of Persia. Movement was east at 25 mph.
Dime size hail and wind gusts up to 50 mph will be possible with
these storms.
Locations impacted include...
Denison, Sac City, Manning, Lake View, Odebolt, Black Hawk Lake,
Schleswig, Wall Lake, Manilla, Schaller, Early, Dow City, Arcadia,
Breda, Vail, Templeton, Westside, Kiron, Deloit and Halbur.
LAT...LON 4202 9548 4221 9545 4221 9532 4247 9532
4248 9539 4256 9539 4256 9492 4187 9493
4187 9554
TIME...MOT...LOC 1646Z 252DEG 23KT 4246 9526 4205 9537 4169 9560
KrullThe Des Moines radar (KDMX), 126 km away, was scanning. The volume nearest the first event began at 17:25 UTC.
7 thunderstorm wind, 2 funnel cloud, 1 lightning. Local standard time, as filed.
Emergency manager reported wind gusts of up to 60 mph east of Sac City.
Hardin County Sheriff relayed public reports of a funnel cloud near Ackley.
Two men were taken to the hospital after being struck by lightning at a golf course. Both men were injured and then released the following day from the hospital. One suffered nerve damage and the loss of hearing on one of his ears.
Report via social media.
Public relayed pictures of several large tree limbs down. This is a delayed report.
Pella Municipal Airport recorded a 58 mph wind gust.
Law enforcement reported a large tree down covering about 3/4 of the road near Highway 63 in Eddyville. Time estimated by radar.
Law enforcement reported a large tree down blocking the road near the high school in New Sharon.
Trained spotter reported tree limbs broken.
Law enforcement reported tree limbs down, of unknown size, on power lines in Oskaloosa.
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, July 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: 773484, 773485, 775107, 775112, 773486, 773487, 773488, 773489, 773490, 773491.