Drought expanded due to very warm temperatures and much below normal rainfall.
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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.
Drought expanded due to very warm temperatures and much below normal 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 Jul 20, 10:25 PM CST, 1 hour 35 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1125 PM CDT Mon Jul 20 2020 .DISCUSSION.../Tonight through Monday/ Issued at 310 PM CDT Mon Jul 20 2020 Key Points: 1.) Precipitation... Best rainfall potential for this week may be tonight, with spotty chances through the remainder of the week ahead. 2.) Temperatures... Near to above normal temperatures generally continue, with a signal for increased heat towards the end of next week. ------------------------------------------------------------------- 1.) Precipitation: Tonight... All eyes on potential for a LLJ to transport a decent amount of moisture into Iowa- as reflected by 1.5 to nearly 2 inch PWATs making it to the state. Trend and timing has been to delay the arrival and lessen the magnitude. As of the 12-18z runs, LLJ down to around 30 kts versus the 40 kts mentioned this morning. Subsequently, PWATs slightly lowered. Decent saturation from 0-6km supports increased rainfall efficiency. The biggest challenge is the timing delay. Area of best moisture may not arrive until 12z-ish... which climatologically is a less favored time for more significant precip generation. Another key player in this event is the MCS that hi-res models have been pinging to form across northern Nebraska and propagate southeastward overnight. Given the delayed timing of the overall setup, MCS may be more decayed than previously thought by the time it reaches Iowa. Tuesday afternoon... Two areas of instability to key on... the first area looks to generally focus near/along the IA/MO border. Potential for daytime convection to occur in this area. Lapse rates are not the most impressive ever. Another area of instability may be oriented more N-S over west-central Iowa. The focusing mechanism here would be a weak boundary that is attendant to low pressure that is slated to propagate across northern Minnesota through the day Tuesday. Lapse rates may actually be more impressive over this part of the state. Will see how this setup plays out overnight, but may need SPC to extend marginal risk to this portion of the state. Rest of the week... Upper ridge still driver of precip as overall pattern looks to feature numerous impulses that propagate across its northern edge. Will likely be tough to pin down exact timing and precise location/magnitude of these possible rounds of showers with much more than 24ish hours of lead time. 2.) Temperatures: Highly dependent upon precip/cloud cover, but primed to be slightly above normal. Fairly simplistic in that where there is clouds/precip during the afternoon, temperatures will be comparably cooler than where there is sunshine. Tuesday is a day where this will likely play out as lingering precip from the aforementioned setup lingers. Through the first half of the week, 850mb temps look to stay in the +15C to +19C range... near 0 to +0.5 std dev which would generally support highs near normal for this time of year as a starting point. With clouds hanging around as the instability axis may linger near southern Iowa, temperatures may be a few degrees below normal. Trend towards the end of the week for the upper level high to migrate southwestward, which would help WAA processes boost temps towards Friday-ish. && .AVIATION.../For the 06Z TAFS through 06Z Tuesday night/ Issued at 1125 PM CDT Mon Jul 20 2020 Main changes for the 06Z forecast was to delay the onset of precip and lessen the areal extent of the precip initially. Based on current radar trends, storms that move in from the west initially may produce some small hail but heavy rain will be the main threat. MVFR with local IFR cigs possible in storms otherwise VFR conditions are forecast. Stronger storms may also yield MVFR vsbys as well however this will likely not be near TAF locations until after 12Z. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Kotenberg AVIATION...FAB
Hazardous Weather Outlook National Weather Service Des Moines IA 321 PM CDT Mon Jul 20 2020 IAZ007-017-026>028-039-212030- Worth-Cerro Gordo-Franklin-Butler-Bremer-Black Hawk- 321 PM CDT Mon Jul 20 2020 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...Tuesday through Sunday Periods of thunderstorms are possible Tuesday then again Wednesday night and into the weekend. Severe weather is not expected on Tuesday. Beyond Tuesday, the predictability of severe weather is low. Hot and humid conditions are expected to return Friday through Sunday. Heat Index values in excess of 100 degrees are possible. .SPOTTER INFORMATION STATEMENT... Spotter activation is not needed at this time. IAZ004>006-015-016-023>025-033>038-044>050-057>062-070>075- 081>086-092>097-212030- Emmet-Kossuth-Winnebago-Palo Alto-Hancock-Pocahontas-Humboldt- Wright-Sac-Calhoun-Webster-Hamilton-Hardin-Grundy-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- 321 PM CDT Mon Jul 20 2020 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Thunderstorms are possible tonight. Brief heavy rainfall is possible. Severe weather is not expected. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Periods of thunderstorms are possible Tuesday then again Wednesday night and into the weekend. Severe weather is not expected on Tuesday. Beyond Tuesday, the predictability of severe weather is low. Hot and humid conditions are expected to return Friday through Sunday. Heat Index values in excess of 100 degrees are possible. .SPOTTER INFORMATION STATEMENT... Spotter activation is not needed at this time. Zogg
The national radar mosaic for the moment the first event began.
3 drought. Local standard time, as filed.
Acute short term dryness led to the development of severe drought conditions in much of Sac county during the last weeks of July.
Acute short term dryness led to the development of severe drought conditions in much of Calhoun county during the last weeks of July.
Acute short term dryness led to the development of severe drought conditions in portions of Webster county during the last weeks of July.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2020Every state in 2020This day in weather historyWarnings in Iowa, July 2020
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: 915452, 915453, 915454.