Drought news

US Drought Monitor February 11, 2014
US Drought Monitor February 11, 2014

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

Summary

During the past 7-days, the first significant storm of the wet season (since October 1) inundated parts of central California and the northern Sierra Nevada with 6-12 inches of precipitation, with locally up to 15 inches. Although there were short-term local improvements from this week’s ample precipitation, the long stretch of subnormal precipitation dating back to 2011-12 wet season has accumulated large deficits, leaving rivers, lakes, reservoirs, and snow packs well below normal. Even though this storm was welcome, the central Sierra still needs 3-4 more copious storms to bring this wet season close to average. Farther north, lesser but welcome precipitation (2-4 inches) also fell on the southern Cascades, while unseasonably cold air dropped measurable snow from Portland, OR, to Seattle, WA. Unfortunately, little to no precipitation fell on southern California and the Southwest. Elsewhere, frigid conditions gripped much of the lower 48 States, with weekly temperatures averaging more than 10oF below normal from the Northwest into the Plains and Midwest. Decent precipitation from the Pacific storm also fell on parts of northern Nevada, southern Idaho, and the central Rockies. The central Plains into the Midwest saw light snow, while parts of the Southeast received 1-2 inches of rain. In the mid-Atlantic, sub-freezing air at the surface and mild air aloft generated a dangerous ice storm in parts of West Virginia, Maryland, Pennsylvania, and New Jersey. Alaska remained unseasonably mild, Hawaii saw additional showers in the northern and central islands, and eastern and western Puerto Rico reported light to moderate scattered showers…

Southwest

Little or no precipitation was reported in the Southwest as several locations in this region have yet to receive any measurable precipitation during 2014. The lack of appreciable winter precipitation has accumulated short-term deficits as most locations from southern California eastward into New Mexico have measured less than 25% of normal precipitation the past 60-days. Fortunately there was a surplus of rain at 6-months in most of these eastern and western areas; however, with drier conditions at 6-months in central Arizona and near the Salton Sea of southeastern California, D1 and D2 were slightly expanded there. According to the NRCS SNOTEL sites, Feb. 12 basin average snow water content remained low in central Arizona (13-33%, one site at 91%) and New Mexico (19-40% in the west and south, 41-60% in the north)…

The West

As mentioned in the opening Weekly Weather Summary, beneficial and overdue precipitation finally fell on much of the Far West, but especially on drought-stricken northern and central California. This was the first big storm of this year’s wet season (Oct-Apr) for California, bringing 8-15 inches of precipitation from just north of San Francisco (Marin, Sonoma, Napa counties) and to the western slopes of the Sierra Nevada. Although the amounts were large, the long-term drought in California since the 2011-12 wet season has accumulated huge deficits and brought severe hydrological, agricultural, and ecological impacts. Nevertheless, two small areas of improvement (D3 to D2) were made in locations where the greatest precipitation fell (8-15 inches). This caused localized stream and river flooding and did fill small water storages. On a larger scale, the Folsom Reservoir on the American River was the big winner in the recent event, doubling its storage; however, it would need to double again to get back to average. Oroville Reservoir was next best, going from 1.26 MAF (million acre-feet) to 1.33 MAF, with average for this time of year 2.37 MAF. Other large California reservoirs were not as fortunate. With respect to snowpack, the latest (2/12) NRCS Snotel average basin snow water content stood at 35-54% of normal for the Sierras (CA), 29-59% for the southern Cascades (OR), and 58-69% of normal for the northern Cascades (WA). Values were generally above-normal for the Rockies, and below normal to the west. So with this brief (1-week) glimmer of good news, the bad news is that California has a long, long way to go to get back to normal. To put this in historical perspective (which does NOT include the Feb. 4-10 storm), NCDC stated that except for January 2014 (3rd driest) and June 2013-January 2014 (2nd driest), all of the time periods from the last two months (Dec’13-Jan’14) through the last twelve months (Feb’13-Jan’14) ranked driest on record statewide for California since 1895. In addition, the last 24-months (Feb’12-Jan’14) was also the driest such 24-month period on record.

Elsewhere, from coastal Oregon southward to Sonoma County, 2-8 inches were measured. The northern Cascades generally saw 1.5 to 4 inches, while the southern Cascades 2 to 6 inches. Heavy precipitation (more than 2 inches) also spilled eastward into southern Idaho, northern Nevada, western Wyoming, northern Utah, and central Colorado. However, since the previous 3 months had been relatively dry in the West, only minor improvements were made where the greatest precipitation fell. This included: northeastern Nevada where 1.5 to 3 inches of precipitation diminished the D3 there; Idaho, a slight reduction of the northern D3 area and adjacent D2 area, and D2 to D1 improvement in the southeast; western Wyoming, D0 and D1 reduction; and northeastern Utah, D1 to D0 improvement. Elsewhere, the precipitation was enough to prevent any further deterioration, except in Washington.

In Washington, both short-term ACIS and AHPS precipitation amounts have been well below normal (<50%) at 30-, 60-, and 90-days, especially in the western and northeastern sections. In light of rapidly accumulating 90-day shortages of over 20 inches along the western coast and 4-8 inches in north-central sections, D2 was expanded northward from Oregon into the Seattle-Tacoma area, and introduced in north-central portions. D1 was also expanded eastward into northern Idaho while D0 slightly shifted into northwestern Montana…

Looking Ahead

During February 13-17, 2014, a departing Atlantic Coast storm (on Feb. 13) should drop moderate to heavy precipitation on the Northeast, while unsettled weather in the Northwest should bring heavy precipitation (4-12 inches) from the Cascades southward into northern California. Unfortunately, it appears as though the southern half of California will miss out on the precipitation. Decent precipitation should also fall on Idaho and the western parts of Montana and Wyoming. Light snows are expected for the northern Plains into the Great Lakes region and Ohio Valley. Dry weather is forecast for the southwestern quarter of the Nation. Much above-normal temperatures should envelop the western half of the U.S. while subnormal readings are expected in the northeastern quarter of the country.

For the ensuing 5-day period, February 18-22, 2014, the odds favor above-median precipitation across the northern half of the Nation, with the greatest probabilities in the Northwest and Great Lakes region. Below-median precipitation is favored across the southern third of the U.S., especially in the Southwest and Southeast. Above-median temperatures are likely east of the Rockies, while the odds for sub-median readings are probable in the Far West.

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