According to the National Drought Monitor, 53.21% of the contiguous U.S. was in some form of drought as of Feb. 18. That is down slightly from 55.46% the previous week and down from 66.84% a year ago. During the past week, the monitor says, a persistent pattern of ridging (high pressure) over the Southwest and troughing (low pressure) over the East prevailed. Unfortunately, the ample moisture that finally visited drought-ravaged California (especially north-central sections) last week was shunted northward by the southwestern ridge into the Pacific Northwest this period, dumping widespread precipitation totals of 4-8 inches, locally 12-18 inches, from extreme northwestern California into western Washington.
Across the High Plains, the monitor notes mostly dry weather and a west to east warming trend occurred, with precipitation (0.2-0.8 inches) limited to eastern Texas. With significant precipitation (0.5-1 inch liquid equivalent) falling the past 30 days across the central Plains, plus relatively low normal precipitation amounts for this time of year, no changes were made in the central Plains. Farther south, however, growing short-term dryness interlaced with long-term drought (out to 2 years) led to a slight degradation of conditions in Texas, particularly in south-central and southeastern, sections and in the northern Panhandle. Similarly, D0 was slightly expanded eastward in southeastern and central Oklahoma where the 30-day precipitation missed.
For the Corn Belt and Mississippi Valley, the monitor says precipitation fell on both the northern (0.3-0.8 inches liquid equivalent) and extreme southern sections (1-2.5 inches) of the Mississippi Valley this week, providing enough moisture to diminish drought in parts of Louisiana, Iowa, and Wisconsin. In the north, cold and snowy weather has dropped near to surplus precipitation during the past 60-days, building a snow cover of 1-2.5 feet deep with a liquid water equivalent of 2-4 inches in northeastern Iowa, northern Illinois, and most of Wisconsin and Minnesota.
Before the ground froze, late November USDA subsoil moisture readings were much better than a year ago statewide in Iowa, so with ample snow cover, a slight reduction of D2 was made in central Iowa and southwestern Wisconsin; D1 removed in southwestern Iowa and southwestern Wisconsin, and D0 erased in northeastern Iowa. In contrast, drier weather and less snow cover in northwestern Iowa called for the merging of the two separate D1 areas. In Louisiana, two weeks of wet and cool weather have eased or eliminated short-term deficiencies (at 30-, 60-, and 90-days), allowing for a general 1-category improvement in southern and eastern parts of the state, and extending into extreme southeastern Texas. Less precipitation (about 0.5 inches) fell on northwestern Louisiana and adjacent sections of Texas, thus maintaining conditions. Although little or no precipitation fell on Arkansas and southern Missouri, past conditions were wet enough (at least this week) to keep D0 development at bay; however, this region will need to be watched, the monitor states.
In its outlook for February 20-24, the monitor states, a drier weather pattern is expected for the Northwest, while significant precipitation is expected across the eastern half of the Nation, particularly in the Midwest, Southeast, and New England. Unfortunately, dry weather should persist across the southwestern quarter of the U.S., including California, Nevada, Arizona, and New Mexico, and most of Texas. Temperatures will also average above normal for much of the lower 48 States, except for another blast of Arctic air entering the northern Rockies and Plains and upper Midwest later in the period.
For February 25-March 1, the monitor notes the odds favor subnormal readings east of the Rockies and above-normal temperatures in the Southwest. Chances are favorable for above-median precipitation in the West, especially along the California-Oregon border and northern Sierra Nevada. To the east, precipitation is likely along the Gulf Coast States. In contrast, the odds for below median precipitation are forecast for the southern Rockies northeastward into the northern Plains, upper Midwest, and Great Lakes region, with slight chances of below-median precipitation in the Northeast, the monitor concludes.