Key Points
- Cold temperatures may pose issues for perennials or crops ahead of schedule in terms of phenology.
- Quickly transitioning out of El Niño to La Niña conditions, which may increase risks for heat.
Past Weather
During the past week, CoCoRaHS reports showed around 1 inch of rain fell across the state. Most of Iowa has seen 2-4” of rain in the last 30 days, which is 90-300% of normal precipitation. Long-term deficits of precipitation are keeping us from breaking through drought, even though we have seen average precipitation this spring. Still, there are improvements to the drought monitor in eastern Iowa. Despite a chilly start, April has been mostly warmer than average, with daily temperatures around 10°F greater than average. The last 30 days have been around 2°F warmer than average.
Cool Temperatures Before Warming Again
After severe thunderstorms moved across much of Iowa on April 16th, the following cold front and northerly winds are bringing in chilly low temperatures. A freeze warning was issued for western and northern Iowa. Central Iowa is under a frost advisory. Concerns may exist for perennials and crops ahead of schedule in terms of phenology. The spring leaf index shows that much of Iowa is 20 days earlier than average.
This cold spell isn’t expected to last long, temperatures should warm up again by next week. Soil temperatures will remain in the mid to high 40s despite cold air temperatures. Existing soil moisture helps to maintain soil temperatures.
The Weather Prediction Center quantitative precipitation forecast shows Iowa receiving 0.25-1.00 inches of rain in the next 7 days. However, an active pattern can be expected in the next 6-10 days as there are elevated chances for warm temperatures and precipitation is likely.
El Niño is weakening and transitioning into ENSO-neutral during April-June. This rapid transition out of El Niño increases the risk for heat. Be prepared for warmer and drier conditions as we transition into La Niña by the middle to end of summer.
Soil Moisture
NASS reports show that topsoil and subsoil moisture is still short to very short across the state. Soil moisture percentile is around 5-30% in the driest areas across Iowa. Rainfall continues to help shorter term drought issues and soil moisture is seeing improvement, but long-term drought issues have significant deficits to overcome yet.
