7/11/25 - More rain to come, cooling a bit next week

Recent Iowa Weather Highlights

• Heavy Rainfall:

  • Rain gauges in the Des Moines area report 1–2.2 inches; some areas in western/central Iowa received up to 6 inches in the past week.

  • Southeast Iowa remains much drier, with some locations getting less than 0.1 inch.

   

• Historical Context:

  • July 11, 1993: Major flooding in Des Moines, with 250,000 residents losing water after levee breaches.

  • 1993 marked 20 out of 37 consecutive days of measurable rain somewhere in Iowa.

• Current Wet Stretch:

  • Statewide rainfall is 137% of normal for July so far.

  • Several stations have received half a month’s rainfall in just the last 10 days.

  • Dew points remain high (60s–70s), signaling ongoing Gulf moisture.

Weather Outlook

• Short-Term Forecast:

  • Active weather continues for the next two days, with a chance of severe storms (supercells transitioning to linear systems).

  • Flood warnings and flash flood watches remain in effect.

  • After the weekend, temperatures return to the 90s, then cool down.

• Medium & Long-Term Outlook:

  • July 16–20: Likely below-normal temperatures, leaning wet.

  • July 18–24: Continued cool and wet trend.

  • End of July: Warmer temperatures expected, with equal chances for precipitation.

  • Southeast Iowa may remain drier than other regions.

• Regional Details:

  • The "blue bullseye" for cooler weather covers eastern Nebraska, most of Iowa, Minnesota, and Wisconsin.

Weather Patterns & Impacts

• Storm Dynamics:

  • Stationary fronts and ample Gulf moisture are causing repeated thunderstorms.

  • Linear wind profiles have led to more squall lines and fewer tornadoes.

  • "Training" thunderstorms have produced localized heavy rain.

• Precipitation Trends:

  • 40% of Iowa’s annual precipitation typically falls on just 10 days.

  • High-intensity, short-duration rain events are becoming more common, often leading to localized flooding and drought in different parts of the state.

National Weather Note: Texas Flooding

• Recent Event:

  • Two Texas locations received 11 inches of rain in just over 24 hours.

  • Catastrophic flooding on the Guadalupe River, with water rising 20–30 feet in under an hour.

  • Factors: Gulf and monsoonal moisture, remnants of Tropical Storm Barry, and stalled weather systems.

  • Similar patterns have caused flash flooding in Iowa (e.g., Clive in 2018, Des Moines metro in 2019).

Specialty Crop & Pest Updates

• Disease Risks:

  • Continued wetness raises concerns about foliar diseases (e.g., black rot in brassicas and cabbage).

  • Wet conditions and heavy dews may increase disease pressure as the season progresses.

• Pest Observations & Management:

  • Japanese Beetles:

    • Active on crops like zinnias, basil, and sweet corn (can affect pollination if silk is heavily clipped).

    • Control options: Conventional sprays (e.g., Mustang Maxx), manual removal, and using trap crops.

  • Colorado Potato Beetle:

    • Reports of spinosad resistance.

    • Alternative controls: Physical removal (bucket method), azadirachtin, or biological products (though some, like certain BT strains, are hard to find).

    • Potatoes can tolerate 33% defoliation before yield loss.

  • Onion Thrips:

    • High populations observed in some fields, causing silvery-white damage.

    • Economic thresholds vary (1–3 thrips/leaf per Cornell/UMass; up to 30 per UC).

    • Control: Multiple modes of action, increased spray volume, horticultural oils, azadirachtin, and soil treatments with fungi or nematodes.

Other Notes & Events

• Field Days & Workshops:

  • August 2: Field day at Grow Johnson County’s Poor Farm, covering no-till vegetable research and a short food safety workshop (counts as an annual update for PSA-trained growers).

  • Agrivoltaic field days in Ames: Ongoing research on crops grown under solar panels, with field days every other week through September.

Podcast summary generated using perplexity.ai