U.S. Drought Monitor Update for July 9, 2019

According to the July 9, 2019, U.S. Drought Monitor, moderate to extreme drought covers 3.6% of the United States including Puerto Rico, an increase from last week’s 3.3%. For the eighth week in a row, the worst drought categories (extreme to exceptional drought) remain at 0.1%.   

High pressure dominated the South with an upper-level ridge extending north along the Mississippi River into Canada. Another upper-level ridge of high pressure was anchored over Alaska. Low-pressure troughs became trapped over the West between these two ridges. The ridge kept temperatures warmer than normal across the eastern half of the continental United States, while temperatures were cooler than normal over the western half beneath the trough. 

Pacific lows and fronts that managed to reach the continental United States stalled out over the central to northern Plains and Midwest. Gulf of Mexico moisture spread into the central United States, increasing humidity and fueling the fronts. The result was above-normal precipitation across the central to northern Plains and parts of the southern Plains. Some fronts reached the East Coast, where they generated above-normal precipitation over the Mid-Atlantic region and parts of the Southeast. Otherwise, much of the West and parts of the South, Midwest, and Northeast were drier than normal.

In Alaska, where numerous large wildfires were burning across the state, the upper-level ridge blocked precipitation and kept temperatures much warmer than normal. Parts of Hawaii and Puerto Rico were wetter than normal, and other parts drier than normal for the week. As a result, drought and abnormal dryness expanded in Alaska, Puerto Rico, and the Pacific Northwest, with some expansion and some contraction over the South, Southeast, and Hawaii. 

Abnormal dryness and drought are currently affecting over 31 million people across the United States including Puerto Rico—about 10.1% of the population.