High pressure dominated across much of the central U.S. this week, bringing much below-normal temperatures (more than 10 degrees F below-normal) to the Eastern Rockies, Great Plains, and parts of the Mississippi Valley. Much of the north-central U.S. remained below freezing last week.
However, where daytime high temperatures did average above the freezing mark, below-normal precipitation and high winds resulted in some drought degradation across parts of the Great Plains.
A series of low pressure systems moving across the southern and eastern U.S throughout this week brought heavy rainfall to parts of the Gulf Coast states and Eastern Seaboard, leading to drought improvements. Northern Florida received the greatest rainfall amounts, with several areas picking up anywhere from 5 to 10 inches of rain through Saturday.
South
A series of low pressure systems, tracking across the Gulf Coast states throughout this week, resulted in heavy rainfall across parts of eastern Texas and the Lower Mississippi Valley, leading to broad 1-category improvements where the heaviest rains fell. Some parts of central Louisiana and west-central Mississippi received more than 5 inches of rainfall.
Farther west across central Texas and parts of Oklahoma, drought continued to intensify. Conversely, high winds and below-normal precipitation prevailed across central Texas and western Oklahoma this week, leading to continued drought degradation. Fire risk remains a concern across many of these areas.
Midwest
Areas experiencing daytime high temperatures above freezing saw targeted changes to their drought status. In western Iowa, moderate drought (D1) was expanded a bit where standardized precipitation indices (SPIs) depict severe drought (D2) or worse conditions going back 90 days and seasonal snowpack is lacking. Some small D1 removal was observed near the Twin Cities, where snow cover has been enough to seep into the top soils in recent weeks, as the ground begins to thaw, corroborated by NASA SPoRT soil moisture data. D1 removal was also warranted for parts of northern Wisconsin in areas that have seen 1 to 2 inch surpluses of precipitation for the water year (since Oct. 1, 2021). Although soil moisture is lagging a bit, decent snow water equivalent values are present across much of the region. Unfortunately, the lack of seasonal snow cover is a real concern for several areas farther southward as spring approaches and the ground begins to thaw, as the soils will then become more susceptible to fluctuating temperatures and increased moisture demand as vegetation comes out of dormancy.
High Plains
Although the High Plains region experienced widespread much below-normal temperatures this week (10 degrees F to 15 degrees F below-normal; even exceeding 15 degrees F below-normal in the High Plains and Eastern Rockies), several areas saw continued deterioration of drought conditions. This was particularly true across parts eastern Nebraska and central Kansas, where high winds and below-normal 7-day precipitation only exacerbated ongoing short-term dryness brought about by a very dry winter season.
Several of these areas have received only 5 to 20 percent of normal precipitation over the past 120 days and the fire risk has rapidly increased as a result. Shallow soil moisture is ranking below the 5th percentile of the climatological distribution, according to NASA SPoRT, and average stream flows are continuing to decline.
Parts of southeastern Colorado, which is experiencing short to long-term drought, also experienced degradation this week from severe (D2) to extreme (D3) drought, supported by Keetch-Byram Drought Indices and short-term precipitation deficits (25 to 50 percent of normal precipitation over the past 90 days). Parts of northwestern Wyoming also experienced deteriorating drought conditions, due to depleted groundwater and year-to-date precipitation deficits that are now on the order of 5 to 10 inches. Conversely, there were targeted improvements across central Wyoming and northern Colorado, based on where positive weekly precipitation anomalies were observed, precipitation amounts are above-normal for the water year (since October 1, 2021), and NASA SPoRT soil moisture and USGS 7-day average stream flows are near and above-normal locally.
West
Following a very wet December 2021 (in some cases a record wet December) for many areas in the West, a very dry pattern has persisted since the start of 2022, mainly from southern Oregon southward. Average snow water equivalent (SWE) values have continued to decline across many basins in the West and are now below-normal since the start of the water year (October 1, 2021). Despite, the drying trend leading up to this week across many areas, a stormy pattern brought above-normal precipitation to parts of the Pacific Northwest and Northern Rockies this week, leading to targeted improvements in the central Cascades, northeastern Oregon, and central Montana, where short-term SPEIs and average stream flows are improving, basin SWE values are near 100% of normal, and precipitation is above-normal for the water year.
