Discussion: Rainfall required to neutralize dry Palmer Drought Severity Index (PDSI) has increased dramatically during early June in the East U.S. (Fig. 1). Already steep departures across the West U.S. have also worsened. The California and Washington/Oregon (along the Cascades) rainfall deficits are off-the-chart >15 in. The North Dakota drought is ongoing. The most impressive dry change is in the East the past 1-2 weeks including deficits of 6-9 in. for parts of 11 eastern states. Rainfall deficits are also increasing in Iowa and across the northern Ohio Valley and Michigan. Once we’re into the 6-9 in. deficit range hazardous effects on agriculture, water supply and increased fire risk is generated. Large areas of soil moisture deficit (i.e. drought) also have a tendency to inspire upper level high-pressure ridging which in-turn generates more dryness and heat causing soils accelerate dryness. Monitoring precipitation for June before the peak of summer arrives in July becomes EXTREMELY important for all risk mitigation analysts, engineers and traders from many industries.
U.S. soil moisture anomalies are typical of the climate change era. Extremes are dominant! Record dry soil moisture is indicated for parts of the West and Midwest U.S. as of June 6th (Fig. 2). Meanwhile the wettest soil moisture pattern on record is evident in the northwest Gulf States. The relationship to June temperature anomalies so far (Fig. 3) certainly identifies the dry soil/anomalous heat and wet soil/suppressed heat consequence often promoted by Climate Impact Company.
Fig. 1: Weekly NOAA/CPC analysis of rainfall needed to eliminate dry Palmer Drought Severity Index.
Fig. 2: Daily U.S. soil moisture anomalies analysis by NOAA/CPC.
Fig. 3: June 2021 U.S. temperature anomalies so far.