January 13, 2015 - California

Light to moderate precipitation fell on southern parts of the state away from the deserts, with amounts exceeding an inch common along the southwest coastline and the adjacent windward slopes. Little or none fell elsewhere.

Benefits from last month’s storms continue to be felt in west-central California, prompting improvements to D2 in Marin, adjacent Sonoma, San Francisco, and northernmost San Mateo Counties.

Farther east, improvement has not been as resilient in much of the Sacramento Valley, and following a month of subnormal precipitation, D4 has been brought back into part of the Sacramento Valley from Sacramento, Yolo, and western El Dorado Counties northward through Butte County. Reservoirs near and north of this region are still above their levels at the start of the current wet season, but water-year-to-date totals have dropped back to near average and 24-month precipitation totals are among the lowest 2 to 10 percent of historical occurrences.

Along and east of the central and southern Sierra Nevada, D4 was expanded eastward past the ridge line to include the eastern slopes of the range from Inyo County, California northward through Douglas County, Nevada. Subnormal winter precipitation has combined with abnormal warmth to leave Sierra Nevada snowpack well short of the historic mid-January average in central and southern parts of the range. Since October 1, 2014, precipitation totals are 3 inches to locally over a foot below normal from the slopes of eastern Fresno and adjacent Inyo Counties northward through eastern Nevada County.

Looking Ahead

The upcoming 5-day period (January 14 – 18, 2015) looks generally mild and dry across the contiguous 48 states. According to the Weather Prediction Center, heavy precipitation (2 to 7 inches) should be limited to northwest California and the Pacific Northwest along and west of the Cascades, with the largest amounts expected along parts of the immediate coastline and windward mountain slopes. Moderate to locally heavy precipitation (1.5 to 3.0 inches) is expected in parts of central and northern Idaho. Elsewhere, amounts of 0.5 to 1.5 inches are forecast across the remainders of northern California, the Pacific Northwest, and Idaho, plus adjacent portions of western Montana and northwestern Wyoming. Farther south and east, totals above 0.5 inch should be limited to New England, the Outer Banks, and the immediate central Gulf Coast. The rest of the East Coast, southern sections of the central Gulf Coast states, and the upper Great Lakes regions are expected to receive light precipitation, with little or none anticipated elsewhere. Temperatures should average at least somewhat above normal from the Mississippi Valley westward, with daily highs averaging 9oF to 18oF above normal from south-central sections of the Plains and Front Range northward to the Canadian border.

For the ensuing 5 days (January 19 – 23, 2015), warmer than normal weather is favored across almost all of the 49 continental states, except northwestern Alaska and parts of the central and northern High Plains and adjacent Rockies. Subnormal precipitation is anticipated throughout the West Coast states, western Arizona, and most of Nevada while surplus precipitation is expected from the eastern edge of the Rockies eastward through the Great Lakes region, the middle Ohio Valley, and the central Gulf Coast region. Wet weather is also favored throughout Alaska.

Author(s):
Richard Tinker, NOAA/NWS/NCEP/CPC

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Dryness Categories

D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.

Drought Intensity Categories

D1 ... Moderate Drought

D2 ... Severe Drought

D3 ... Extreme Drought

D4 ... Exceptional Drought

Drought or Dryness Types

S ... Short-Term, typically <6 months (e.g. agricultural, grasslands)

L ... Long-Term, typically >6 months (e.g. hydrology, ecology)