Pictured: 7-day precipitation anomalies as a percent of normal for the U.S. (left) and the day 11-15 total precipitation change forecast by the 0600 GMT GFS OP.
The excessive rains in the Mid-South/Missouri Valley late April/early May has been historic and triggered by climate factors including an emerging strong negative arctic oscillation and an injection of moisture from the warmer than normal East Pacific tropics caused by the Madden Julian oscillation. As the -AO strengthens and MJO influence in the tropics shifts east the climate pattern in the Central U.S., particularly the Midwest States turns much drier and cooler. Nevertheless super wet soils are established in the central/south Great Plains, Missouri Valley and parts of the Corn Belt. There is a tendency for regional wet soil moisture to attract more rainfall. The dry medium-range forecasts see a wetter change Nebraska/Kansas to the Ohio Valley in the 11-15 day period looking at the most recent GFS OP (model). So…sneaky wet conditions returning are definitely worth monitoring for later May into early June.
Meanwhile the cool regime eases very slowly over the next 2-3 weeks. The wet soils in the Mid-South will attract returning cool weather once summer arrives. When the air mas sis warmer than normal the residual moisture leads to increased shower/thundershower risk defeating extreme heat.
Pictured: Widespread chill in the 6-10 day forecast (left) eases east of the Divide days 11-15 (middle) with marginal warmth by days 16-20 (right).
