California and National Drought Summary for March 12, 2019
March 14, 2019 - As spring nears, winter has kept its grip over much of the country. Temperatures were below average across the contiguous U.S, up to 25 degrees below normal for the week in the North. Following the wettest winter (December-February) on record for the contiguous U.S. as a whole, storms continued to bring heavy rain and snow, piling on snowpack and filling reservoirs in the West, but also causing avalanches in Colorado. Generally, heavy snow fell across high elevations in California, the Rockies into the Upper Great Lakes and Mid-Mississippi Valley, with heavy rain across parts of Southern California and the Tennessee Valley. The abundant precipitation in the West led to more widespread drought improvement. Little to no precipitation fell across the southern tier of the U.S., continuing a pattern of below-average rainfall seen over the last 2-3 months in parts of the Southeast, as dry conditions begin to emerge.
Temperatures for the most part were 5-15 degrees F below average across the region over the past week. While some areas continued to see heavier (and much heavier) than normal precipitation, several large areas, from northeastern Pennsylvania and much of New York to Connecticut, Massachusetts, New Hampshire, and Vermont received less than their typical amounts for this time of year. Even so, conditions overall remain good and the Northeast continues to remain drought-free.
Temperatures were about 5-10 degrees F below average across the region, and precipitation was below average in many areas, particularly notable in the far southern areas. Rainfall deficits are beginning to build in some areas. As such, abnormal dryness (D0) was expanded into southeastern Georgia and introduced to a couple of localized areas in southern and southeastern Alabama.
Drought-free conditions continued across most of the South. Western Oklahoma and northern and western Texas received rainfall late in the drought week that allowed some retreat of both moderate drought (D1) and abnormal dryness (D0). South central and southern Texas received little to no precipitation and D0 conditions expanded slightly eastward.
Every state in the Midwest received above-average to much-above-average precipitation during the meteorological winter season (December to February), leaving the area with deep snowpack and overall wet conditions. With temperatures around 10 to 20+ degrees F below average over the past week, the entire region remains free of drought and dryness.
Most areas of the High Plains were free of drought or saw little change in current status, the exception being Colorado, where heavy snow continued to build snowpack but also caused avalanches. With well-above average precipitation in February and adequate precipitation in March to date, improvements were made across the Yampa/White Basin. The Gunnison Basin, already well past its normal seasonal peak, received an additional 2-4 inches of precipitation over the last week. Severe drought (D2) improved to moderate (D1) over the San Juan Basin east through the San Luis Valley, where the San Juans have received well-above-average precipitation and basin-wide snowpack is already past the normal seasonal peak. North central Colorado into Carbon County, Wyoming saw as much as 2-category drought improvement to return to drought-free conditions. In this region reservoirs are expected to fill and there is deep snow, unfortunately with problematic avalanches.
Well-above-average precipitation continues in the West, improving long-term soil moisture deficits, building snow pack, and filling reservoirs, therefore leading to more widespread drought improvement. Areas of western Utah received up to double their typical precipitation in the last month, improving conditions across the region. From northern California into Oregon and Idaho, snowpack continues to build at mid and high elevations, compensating for long-term dry soil moistures. Reservoirs have also continued to fill. Improvements were made across this region, including a vast reduction in severe drought (D2) in Oregon and a return to normal conditions across most of Idaho and northern Nevada. Idaho’s central mountains received more snowfall in February than the previous three months combined. Snow there continued to accumulate, with continuing colder-than-normal temperatures. As such, no irrigation issues are anticipated and water supplies are expected to be adequate. Dry conditions also improved to normal to the north across parts of eastern Washington, northern Idaho, and northwestern Montana. Precipitation in recent months, including for the water year to-date, has been above average and enough to erase long-term impacts. In the Southwest, improvements were seen along the Mogollon Rim and White Mountains of eastern Arizona. Many of the lakes are full and spilling, and snow remains to melt in the higher elevations. Normal conditions also returned to most of southwestern Arizona to the Salton Sea in southeastern California. The rest of the region in Southern California is still abnormally dry due to very dry previous years. Reservoirs in San Diego County are only at 65% capacity. Big Bear Lake was down 18 feet in early March, although expected to continue to rise.
Alaska, Hawaii, and Puerto Rico
Hawaii has seen fairly consistent rainfall along the east facing slopes of the islands and drier conditions over leeward areas. Following wet conditions in February, areas that were experiencing abnormal dryness on the Big Island and Maui continue to recover well. Abnormally dry (D0) conditions improved to normal across both islands this week.
Puerto Rico also saw adequate precipitation over the past week to relieve some moderate drought (D1) and abnormally dry areas that had been building in the southern coastal region and southwest.
The central U.S. is anticipating a very strong storm from the12th to the 14th, with the threat of blizzard conditions from the Rockies to the Central and Northern Plains to the Upper Midwest, and severe storms with hurricane-force winds from the Southern Plains to the Mid-Mississippi River Valley. Heavy rains in the Midwest and Great Plains may melt snow that lead to significant flooding. The storm is expected to impact 70 million people. Looking further out into the next week, much of the nation may see dry, cool weather, with below-average temperatures and below-average precipitation forecast across most of the eastern half of contiguous U.S. Looking two weeks ahead, increased chances of above-normal precipitation are forecast for Alaska, the southern Florida Peninsula, and the western half of the contiguous U.S. The eastern half, on the other hand, is forecast to continue seeing drier-than-normal conditions.
Jessica Blunden, NOAA/NCEI
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 less than 6 months (e.g. agricultural, grasslands)
L Long-Term, typically greater than 6 months (e.g. hydrologic, ecologic)
Source: National Drought Mitigation Center