This Week’s Drought Summary
Precipitation varied widely across the Lower 48 this week. Across the interior West, heavy monsoon rains set records in some locales, with tropical moisture streaming much farther north and west than normal (through southern Montana, the Great Basin, and parts of the Sonoran Desert). Death Valley, CA set an all-time record for 24-hour rainfall, being doused with 1.46 inches during August 5 and 6. The average annual rainfall in Death Valley is less than 2.5 inches, and the 24-hour total makes August 2022 the wettest month in Death Valley since February 2010, and more than half of all calendar years bring less rain than that 24-hour total.
Farther east, many areas from the Mississippi River eastward through the Piedmont and Middle Atlantic States recorded moderate to heavy precipitation. Most areas from southern Missouri and northeastern Arkansas through central Illinois recorded over 1.5 inches of rain, as did parts of the Tennessee and southern Ohio Valleys, the Upper Midwest and western Great Lakes Region, the Central Gulf Coast, and northern Maine. In other areas from the Mississippi Valley eastward, heavy rain was less widespread. Still, numerous patches of land across the Upper Midwest, the middle Mississippi Valley, the Ohio Valley, and the Gulf Coast east of Texas received over 3.5 inches of rain, with isolated totals of 6 to locally 11 inches reported in a swath from the middle Mississippi and lower Ohio Valleys northward through the Upper Midwest and western Great Lakes Region. In contrast, many areas across these regions recorded only a few tenths of an inch of rain or less, with tight gradients between heavy rain and lesser amounts common. This variable rainfall pattern had a similar effect on areas of dryness and drought, with deterioration noted very close to improvement in many cases, and only a few broad swaths with a consistent pattern. Looking at the western half of the Lower 48, outside the areas affected by the monsoon, much drier conditions prevailed, though there were a few small areas recording moderate to heavy rainfall. Little or no rain fell on the central and southern Great Plains, much of the central Rockies, and the Far West. Temperatures averaged over 3 deg. F above normal in a large area across the central Rockies, most of the Plains, and the northeastern quarter of the country, exacerbating dryness in areas that missed the heavier rains.
The eastern and western portions of this Region are trending in very different directions. Abundant rains have been falling on much of Tennessee, Arkansas, western Mississippi, most of Louisiana, and adjacent areas, where many areas of dryness and drought are improving. Over most of Oklahoma and Texas, however, rainfall has been scare of late, and with periods of excessive heat also affecting these areas, dryness is intensifying. In the last 2 weeks, over 3 inches of rain fell on most of Tennessee, northern Arkansas, and southern Louisiana. A few areas received over 4.5 inches of rain, with totals topping out at nearly a foot at one spot in northeastern Arkansas. Farther west, the have nots from central Oklahoma southward through most of Texas saw only several tenths of an inch, at best. From south of the Red River Valley through most of Texas to the Deep South regions, few areas saw any measurable rainfall. Conditions are not as dry in the Texas Panhandle, where enough rain fell (generally 2 to locally 5 inches) to provide some tangible relief from the recent dryness. Moisture shortages date back at least 6 months over most of Texas south of the Panhandle and north of Deep South Texas, extending across the entire breadth of the state. During the last 90 days, less than half of normal rainfall has been observed in most of these areas, with a few scattered patches getting less than 25 percent of normal. This equates to 3-month rainfall deficits of 5.5 inches or higher across most of central and eastern Texas, with parts of northeastern and southeastern Texas accumulating rainfall deficits of 7 to 10 inches. And for the last half-year, much of central and southeastern Texas racked up deficits of 11 to 16 inches. Not surprisingly, drought intensified or at best persisted across the south half of Oklahoma and most of Texas, most of the state is in extreme (D3) drought, with large swaths of D4 covering a good portion of the state from the Red River to Deep South Texas.