6/19/25 - Two words: "Blast Furnace"

• Iowa Weather History:

  • On June 19, 1996, severe thunderstorms produced very large hail in northwest Iowa, with a 3.5-inch stone near Hinton (Plymouth County) and a 4.5-inch stone at Cushing (Woodbury County), causing $200,000 in damage to vehicles and buildings.

• 7-Day Weather Forecast:

  • Iowa is entering a "blast furnace" pattern: temperatures will soar 15–20°F above average, with highs in the 90s to upper 90s and overnight lows in the mid to upper 70s.

  • Persistent high overnight lows will make it difficult for people and plants to recover.

  • Strong southwesterly winds will continue, bringing high dew points and Gulf moisture.

  • By days 4–6 (early next week), the northwestern two-thirds of Iowa could see 2–5 inches of rain, especially in western Iowa, which needs relief from drought.

• Climate Outlook:

  • The 6–10 day forecast shows the heat shifting east, with a tighter temperature gradient and continued potential for heavy rainfall, especially in northern Iowa.

  • The 8–14 day outlook keeps a warm and wet signal, which is positive for the wettest month of the year after recent dryness.

  • The 3–4 week outlook still leans warm, with no clear signal on rainfall.

  • The initial July outlook (issued June 19) leans slightly warm statewide, with a slight lean dry in the western third of Iowa.

• Recent Weather and Notables:

  • The past week was slightly warmer than average with an unsettled pattern of pulse and “popcorn” thunderstorms across the state.

  • Severe weather ingredients did not come together for widespread severe storms, but there was a landspout tornado in eastern Iowa.

  • Landspouts are weaker, photogenic tornadoes (a step above dust devils), typically anticyclonic, and distinct from stronger tornadoes.

• Specialty Crop Impacts:

  • Hot weather is negatively affecting broccoli development, leading to issues like “brown bead” (brown florets) and heat-delayed buds.

    • Brown bead can be caused by hot, humid nights; broccolini is less susceptible and can regrow after harvest.

    • Hollow stem in broccoli may result from fast growth due to excess nitrogen and water, not just boron deficiency. Tighter in-row spacing and careful nitrogen management can reduce hollow stem.

    • Boron deficiency causes brown, dead cells lining the hollow stem, while fast growth causes uniformly green or white hollows.

    • Boron should be mixed with other powders for uniform soil application to avoid toxicity.

    • Some broccoli varieties (e.g., Green Magic) are more prone to hollow stem than newer ones (e.g., Eastern Crown).

    • Heat can also cause uneven, lighter green patches in broccoli heads (heat-delayed buds).

    • Brown bead does not grow out, but heat-delayed buds sometimes do

  • Cabbage White butterflies and their caterpillars are active.

    • BT (Bacillus thuringiensis) sprays are effective when caterpillars are first seen, especially on new growth and broccoli heads.

    • Rotate BT with other organic insecticides if resistance is suspected.

    • Cabbage moth caterpillars can hide inside broccoli heads, making washing difficult.

Summary created using Perplexity.ai