Source: droughtmonitor.unl.edu | Map released 2/27/20 | Data valid 2/25/20
This week’s drought summary: High pressure continued to persist over the eastern Pacific Ocean, forcing a split in the normal west to east upper-air flow for Pacific storm systems. As a result, storms bypassed the central West (e.g. California and the Great Basin), instead tracking northward into the Pacific Northwest and British Columbia, and southward across Baja California and the Southwest. This pattern has produced a very dry January and February in California, normally the two wettest months of the year, resulting in an expansion of short-term D0 and D1 that are impacting non-irrigated land and non-managed rivers. Fortunately, the statewide reservoir storage stood at 104% of average for this time of year. Farther to the east, once these systems reached the Plains, Gulf moisture was entrained into them, generating widespread precipitation across the South and Southeast and mixed or frozen precipitation in more northern locations. The week’s greatest precipitation (1-4 inches) fell on the northern Cascades, parts of the Southwest (mostly Arizona), the central Plains (mainly Kansas), and from central Texas eastward across the lower Mississippi, Tennessee, and Ohio Valleys, the Southeast, and southern Appalachians. Little or no precipitation, however, fell on most of California, the Great Basin, and Intermountain West, northern Plains and upper Midwest, parts of the southern Plains, most of Florida, and the mid-Atlantic. Weekly temperatures averaged below normal in southwestern Alaska, the Northwest, Rockies, Plains, upper Midwest, Southeast, and New England. In contrast, above-normal readings were observed in eastern and southern Alaska, the Southwest, eastern Great Lakes region, mid-Atlantic, and along the eastern Gulf and southern Atlantic Coasts.
South: Similar to last week, another storm system dropped moderate to heavy rain (1-4 inches, locally to 7) from Central Texas eastward across North Louisiana, Central Mississippi, and into Central Alabama and Georgia. Decent totals (0.5-2 inches) also fell on Southwestern and Northern Oklahoma, Central and East Texas, and much of Arkansas, Louisiana, Tennessee, and Mississippi. Little or no precipitation was reported in far West and South Texas, the eastern half of Oklahoma, and extreme Northwestern Arkansas. And like last week, one- and a few two-category improvements were made in Central and Southeast Texas, while most of the D0 in South Louisiana was alleviated. USGS stream flows have responded, with seven-day averaged values in the 75th to 90th percentiles in East Texas eastward.
In contrast, where weekly totals were lower (less than 1.5 inches) and decent 60- to 90-day deficits remained, D0 was left. This included Southeast Louisiana and extreme South Mississippi. A small portion of the D0 was removed in Southwest Oklahoma where 1-1.5 inches fell. Status-quo was decided for South Texas even though it was mostly dry since major degradations were made last week there. The only change was the removal (downgrade) of a small D1area (to D2) in southwestern Starr County. USGS stream flows have also responded here, but the opposite way as seven-day averages were in the 10th to 25th percentiles. If it remains dry this week with low humidity and gusty winds (red flag warnings), potential deterioration is possible next week as reported impacts were on the rise.
Looking ahead: During the next five days (Feb. 27-March 2) in the West, light to moderate precipitation is expected in the Cascades, Sierra Nevada, Great Basin, and Northern and Central Rockies later in the 5-day period. Dry weather should prevail across the Plains, while a departing storm system early in the period brings light to moderate totals to the Northeast, Ohio Valley, and Central Florida.
In the extended range forecast for the ensuing five days (March 3-7), odds are tilted toward above-normal precipitation east of the Rockies, especially from the lower Missouri and Tennessee Valleys northeastward into western New England, and across most of Alaska. Subnormal precipitation is favored in the Far West, especially California, Nevada, and Utah, and in extreme South Texas. Above-normal temperatures are likely east of the Mississippi River, the Far West (mainly California), and northern High Plains. Enhanced probabilities for subnormal temperatures were found across Alaska, and in the Central and Southern Rockies.