This U.S. Drought Monitor week saw a number of notable storms. One dumped copious amounts of precipitation in Louisiana leading to a governor-declared state of emergency. Parts of the state saw 15 inches of rain that led to areas of flooding. Another notable storm was a slow-moving system affecting the Hawaiian Islands for nearly a week. This storm dumped over 40 inches of rain on areas of Kauai and almost that much on parts of Oahu. The week of wet weather was topped-off by thunderstorms, hail, and a tornado that formed as a water spout and moved onshore on Oahu on March 9. This was Hawaii’s first tornado in four years and one of only 41 recorded for the state since 1950.
The Southeast: Rains in the Southeast this week generally fell outside of existing drought areas with the exception of South Florida, where rain staved off mounting deficits south and southwest of Lake Okeechobee. Mounting deficits through North Carolina led to the expansion of Moderate Drought (D1) and Abnormal Dryness (D0) there. Likewise, conditions deteriorated slightly in southern Alabama.
The Northeast and Mid-Atlantic: Mounting deficits led to expansion of Abnormal Dryness (D0) from upstate New York east and south to coastal Connecticut and Rhode Island, where rain has been sparse.
The South and Southern Plains: Another week of above normal precipitation from Oklahoma through central and eastern Texas and into Louisiana alleviated drought there. In Louisiana, up to 15 inches of rain fell on March 12-13, mainly in areas unaffected by drought. Flooding plagued large areas and a state of emergency was declared by the governor. Severe (D2) and Moderate (D1) Drought and Abnormal Dryness (D0) were alleviated in the western and southern part of the state. In Texas, areas of Severe (D2) and Moderate (D1) Drought and Abnormal Dryness (D0) were alleviated in the central and eastern part of the state while Extreme Drought (D3) expanded slightly in the south. In Oklahoma, widespread rains led to considerable improvements in most areas, with the exception of the western Panhandle. Across Oklahoma Exceptional (D4), Extreme (D3), Severe (D2), and Moderate (D1) Drought all decreased. In certain areas, this left behind lingering Abnormal Dryness (D0). In Kansas, areas of Moderate Drought (D1) and Abnormal Dryness (D0) expanded in the north and west.
The Central and Northern Plains and Midwest: Conditions improved slightly in northern North Dakota as a result of a multi-day rain event. In Nebraska, Abnormal Dryness (D0) expanded over a large portion of the western part of the state based upon mounting long-term deficits beginning to be felt as agriculture ramps up for the year.
The West: A storm moved onshore dumping rain and snow from northern California, up the coast and into Canada. To the south of the storm and into the Southwest, conditions generally degraded. Severe (D2) and Moderate (D1) Drought expanded in eastern California through the Las Vegas area and across most of southern Arizona, where Extreme Drought (D3) was also introduced.
Hawaii, Alaska and Puerto Rico: Drought conditions remained unchanged in Alaska and Puerto Rico this week. In Hawaii, Torrential rains slammed the state, according to the National Weather Service. Forty-plus inches of rain fell on parts of Kauai while parts of Oahu received nearly the same amount. Overall, the rain led to improvements in Exceptional (D4), Extreme (D3), Severe (D2), and Moderate (D1) Drought and Abnormal Dryness (D0) on Molokai, Maui, and Oahu.
Looking Ahead: During the March 15-19, 2012 time period, there is an enhanced probability of precipitation in the Pacific Northwest throughout the period and in the central part of the country late in the period. Temperatures are expected to be above normal east of the Rockies.
For the ensuing 5 days (March 20-24, 2012), the odds favor normal to warmer than normal conditions over the entire US, east of the Rockies. West of that, normal to below-normal temperatures are expected. Precipitation is expected to be below-normal along the East Coast and in the Southwest. Above-normal precipitation is expected in the Northwest and from the Southern Plains through the Midwest. In Alaska, both temperatures and precipitation are expected to be normal to below-normal.
Author: Michael Brewer, National Climatic Data Center, NOAA
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)