According to the January 23, 2024 U.S. Drought Monitor (USDM), moderate to exceptional drought covers 23.0% of the United States including Puerto Rico, a decrease from last week’s 24.1%. The worst drought categories (extreme to exceptional drought) decreased from 4.1% last week to 3.7%.
The atmospheric circulation over the contiguous U.S. for most of this U.S. Drought Monitor week (January 17–23) was dominated by an upper-level trough of low pressure east of the Rockies and a ridge of high pressure over the West. The trough sent reinforcing waves of cold arctic air across the central and eastern U.S., resulting in well-below-normal weekly temperatures for all of the country east of the Rockies.
Only the western U.S.—except for the northern tier states—averaged warmer than normal beneath the western ridge. A series of Pacific weather systems slammed into the West, spreading above-normal precipitation across most western states. Once they crossed the Rockies, the weather systems tapped Gulf of Mexico moisture to generate above-normal precipitation across southern Texas to Illinois. But the arctic air was dry as well as cold, so outside of that area, most of the CONUS east of the Rockies had a drier-than-normal week. The upper-level circulation pattern shifted as the USDM week ended, with a ridge developing over the East Coast and a trough moving into the Southwest.
The building ridge brought a welcome warming trend to the central and eastern contiguous U.S. A ridge of high pressure kept Puerto Rico and the U.S. Virgin Islands warmer and drier than normal. Hawaii also had a warmer- and drier-than-normal week, while Alaska precipitation and temperatures were both below normal. The El Niño inhibited precipitation in the western Pacific, so abnormal dryness and drought continued across much of Micronesia.
Drought or abnormal dryness contracted or was reduced in intensity over parts of the Pacific Northwest, central to southern Rockies, central to southern Plains, Mid-Mississippi and Tennessee Valleys, and in Hawaii on Maui. Drought or abnormal dryness expanded or intensified in areas that have seen persistently dry conditions, especially in parts of the northern Rockies, Puerto Rico, and the Big Island of Hawaii. Nationally, contraction was greater than expansion, so the nationwide moderate to exceptional drought area decreased this week.
Abnormal dryness and drought are currently affecting over 89 million people across the United States including Puerto Rico—about 28.6% of the population. This has been a significant decrease compared to four weeks ago.
The full U.S. Drought Monitor weekly update is available from Drought.gov.
In addition to Drought.gov, you can find further information on the current drought as well as on this week’s Drought Monitor update at the National Drought Mitigation Center
The most recent U.S. Drought Outlook is available from NOAA’s Climate Prediction Center and the U.S. Department of Agriculture provides information about the drought’s influence on crops and livestock
For additional drought information, follow #DroughtMonitor on Facebook and Twitter.
