The United States is in the thralls of summer, and with that can come heat, flash droughts, and occasional, if not frequent, thunderstorm activity. Several areas of the U.S. experienced extreme heat this past week, particularly notable across much of the South and in the East. Parts of western Texas and eastern New Mexico were 6-10 degrees F above their typical averages, with little rainfall to speak of in much of the region. On the other hand much of the northern tier of the U.S. into the Upper Midwest was cool for this time of year, although precipitation amounts there were a mixed bag. In the Southwest, the North American monsoon continues to fail, worsening conditions in areas that had received more than ample precipitation over the winter and spring. To the north, south central Alaska continues to see record or near-record heat and dryness, and conditions are deteriorating quickly there, with severe impacts.
Over the week beginning Tuesday, August 20, according to NOAA’s Climate Prediction Center, dry conditions are expected to continue across much of the western half of the continental U.S. Some heavy rain may fall over parts of the Midwest and Southeast, with as much as five inches in areas of southern Iowa, northern Mississippi, eastern Nebraska, and parts of the Carolinas. Southern Louisiana may see up to seven inches. Looking further ahead to August 25-29, below-normal temperatures are favored across parts of eastern Montana, the Dakotas, Nebraska, Kansas, Minnesota, Iowa, and Missouri, while above-normal temperatures are forecast for parts of the Southern Plains and the Southwest. There are enhanced probabilities of above-normal temperatures for most southern coastal locations of Alaska due to above-normal sea surface temperatures. Near to below-normal precipitation is possible for the west, although parts of Southern California may see above-average rainfall. Rainfall may be above normal across the central and eastern U.S., except for parts of the Northeast. Above-normal precipitation is favored across northern and eastern Alaska, but may be below-normal across southwestern mainland Alaska and the Aleutians, where drought conditions prevail. Please note the forecast confidence for this period is average, according to CPC.
Heat and a lack of substantial rain in many areas contributed to expansion of abnormally dry (D0) conditions across parts of the Midwest, including northern Michigan into the Upper Peninsula, west central Ohio, eastern Indiana, and Kentucky. An area of moderate drought (D1) was also introduced in central Kentucky, with reports that late planted corn, soybeans, and pastures are affected and that some farm ponds are beginning to get low, especially in Hardin, LaRue, and Breckinridge Counties. Ohio reports indicate that crop stress and brown lawns are now evident. In Iowa, the rainfall had a relatively strong gradient, as conditions improved across parts of southern Iowa, although D1 did expand a bit in the southeastern corner.