Drought news

Click here to go to the Climate Prediction Center Website. Click here to go to the US Drought Monitor website. Here’s an excerpt:

Summary

During the past week, 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. Additionally, the precipitation was accompanied by mild air, producing mainly rain instead of snow in southern sections of the Cascades in Oregon and limiting any snow pack increase for those mountains. Farther north, however, the precipitation fell as snow in the northern Cascades (Washington) and northern Rockies, increasing the average basin SNOTEL snow water content by 10-20 percentage points in six days (from Feb. 12 to 18). Farther east, a series of winter storms brought wintry precipitation to the Midwest (light to moderate snow), Southeast (severe icing in Georgia and South Carolina), and the Northeast (heavy snow) as cold air remained entrenched in those regions. In contrast, dry and mild weather continued in the southwestern quarter of the Nation, further degrading conditions there. In Hawaii, scattered showers continued, with Kauai and Oahu receiving the greatest totals, while Puerto Rico and most of Alaska saw light precipitation, except for moderate amounts (more than 2 inches) in the southeastern Alaskan Panhandle…

Southern and Central Plains

Mostly dry weather and a west to east warming trend occurred in the central and southern Plains, 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…

Southwest

The Water Year to Date (WYTD; since October 1) continued to be dismal as little to no precipitation and unseasonable warmth (temperatures averaging 8 to 12oF above normal, highs in the 70’s and 80’s) were observed this week. With the exception of copious and flooding rains back in early to mid-September, especially in New Mexico and Colorado, most southwestern locations have measured well below normal precipitation since then. The few exceptions to this were small WYTD surpluses in southwestern and northeastern Arizona, northern New Mexico, and most of western and central Colorado, the latter state faring the best this season. Elsewhere, WYTD SNOTEL basin average precipitation ranged from 50-63% of normal in central Arizona, 30-46% in southern New Mexico, 52-73% in northern New Mexico, 51-90% in southern Utah, and 81-102% in southern Colorado. Values generally rose to above normal in more northward basins. The Feb. 18 basin average snow water content ranged from 0-83% in central Arizona, 10-19% in southern New Mexico, 8-60% in northern New Mexico, and close to normal in southern sections of Utah and Colorado. With such poor values, a 1-category degradation was made in southwestern Arizona (D0 expanded); southern Nevada (D1 expanded, only 0.05” of precipitation at Las Vegas McCarron Airport since Dec. 1 and non-irrigated, drought-tolerant landscaping plants starting to dry out); D2 expansion across central and southern Arizona and into western New Mexico; D3 development in southeastern Arizona (where 6-month totals less than 50%); and slight D2 and D3 increases in central New Mexico – after their driest January on record. As of Feb. 1, average state reservoir capacities were 23% (normal=44%) for New Mexico and 13% (normal=47%) for Nevada. Colorado and Utah were close to normal, and Arizona data was unavailable (on Jan. 1, 44% vs normal=51%)…

The West

Unfortunately, last week’s overdue and welcome moisture was short-lived for most of California as the weather pattern shifted and brought moderate to heavy precipitation (4 to 8 inches, locally 12-18 inches) northward to the Pacific Northwest. Extreme northern California did benefit from this week’s moisture, including Del Norte County in extreme northwestern California, where 10-15 inches of precipitation fell as the Smith River rose 20 feet and passed monitoring stage, and has since receded to a flow 6 feet higher than before the rain started. In addition, along coastal Oregon and Washington and in the Cascades, widespread heavy precipitation was enough to make a general 1-category improvement in the drought, especially since the dryness was more short-term than compared to California’s multi-year drought. Unfortunately, the moisture was accompanied by mild air, and most of the precipitation that fell on the southern Cascades was rain and not snow. As a result, southern Oregon’s basin average snow water content remained low, between 30-39% of normal on Feb. 18, and no changes were made here. Farther north, however, temperatures were lower, and much of the precipitation fell as snow in the higher elevations. In northern Oregon, the average basin snow water contents for the central Cascades increased to 51-63% of normal, while the northern Cascades in Washington rose to between 71-87% of normal. Short and medium-term deficits, however, still remain, and additional moisture will be needed to bring the WYTD precipitation to normal. Weekly totals (about an inch) were lower in northeastern Washington, and the D2 area remained. Additional moderate to heavy snows fell on the northern and central Rockies, boosting WYTD average basin precipitation and Feb. 18 snow water contents to near or above normal, justifying a 1-category improvement where the heaviest precipitation fell and deficits were greatly reduced.

In contrast, southern California missed out on both week’s precipitation while unseasonable warmth persisted, further degrading conditions similar to the Southwest. With WYTD precipitation running at a meager 10-30% of normal across coastal southern California and deficits of 4-12 inches the past 6-months, D3 was extended southward into the San Diego area, and D4 was expanded southward into Santa Barbara and Ventura Counties. In Santa Barbara County, Lake Cachuma, currently at 39% capacity and 90% of the water supply for the cities of Santa Barbara and Goleta, the water level is nearing the lowest intake on the outlet works. To remedy this, the water district is working on installing a floating barge and pipes to get lake water to the outlet portal. The city is also contemplating the re-establishment of a desalination plant built in the late 1980s that was shut down in the early 1990s. And the Twitchell Reservoir, along the Santa Barbara/San Luis Obispo County line, is at less than 1% capacity. Ranchers are reducing their herds due to the lack of water and food sources. As of Feb. 18, the Sierra Nevada basin average snow water content ranged from 32 to 53% of normal. Widespread heavy precipitation is badly needed in this state as the normal wet season nears its end by early to mid-spring (e.g. in April)…

Looking Ahead

During February 20-24, 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 the ensuing 5-day period, February 25-March 1, 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.

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