Map released March 19, 2021 | Data valid March 16, 2021
This week’s drought summary: A vigorous and slow-moving area of mid-level low pressure tracked from the Four Corners region to the Central Great Plains from March 13 to 15. Widespread precipitation (rain and snow totaling 2 to 6 inches, liquid equivalent) fell across the Central Rockies, Central Great Plains, and Lower Missouri River Basin. Snowfall amounts ranged from 2 to 4 feet from Colorado north to Wyoming. However, across North Dakota, dry weather continued. As a low pressure system tracked eastward, rainfall (locally more than two inches) overspread the Ohio and Tennessee Valleys along with parts of the Southeast on March 14 and 15. Mostly dry weather prevailed along the East Coast from March 9 to 15. During this seven-day period, below normal precipitation was observed throughout much of the Pacific Northwest while precipitation amounts exceeded two inches (liquid equivalent) for the Sierra Nevada Mountains and coastal ranges of California. A low pressure system and trailing front resulted in heavy rainfall and flooding across parts of the Hawaiian Islands during early March.
South: As an intense mid-level low pressure system crossed the Four Corners Region, an early season severe weather outbreak occurred across the Texas Panhandle on March 13. According to the Storm Prediction Center, more than a dozen tornado reports were tallied. Along with the severe weather, locally more than 1 inch of rainfall was observed across the Texas Panhandle, resulting in drought improvement. This 1-category improvement extended east to parts of southwest Oklahoma where Oklahoma Mesonet gauges recorded 1 to 2.5 inches of rainfall this past week. Elsewhere across the southern Plains, western Gulf Coast, and lower Mississippi Valley, mostly dry weather prevailed along with above normal temperatures and periods of increased winds. Based on short-term indicators, abnormal dryness (D0) and drought (D1-D3) were expanded in coverage across south-central Oklahoma and Texas. Wheat is entering the critical hollow stem stage across south-central Oklahoma. The northeast quarter of Louisiana has received less than 4 inches of precipitation during the past 60 days which prompted a slight increase in the coverage of short-term moderate drought (D1). An increase in the coverage of D0 was made across parts of Louisiana and Mississippi, due to increasing short-term precipitation deficits along with soil moisture and 28-day streamflows below the 30th percentile.
Looking ahead: During the next five days (March 18 to 22), a low pressure system is forecast to bring widespread precipitation (0.5 to two inches, locally more) to the Ohio and Tennessee Valleys and Mid-Atlantic. Farther to the south across the Florida Peninsula, dry weather is likely to persist. Little to no precipitation is also forecast for the Southwest and northern Great Plains. As a mid-level area of low pressure progresses inland from the East Pacific, rain and high-elevation snow are expected to overspread the Pacific Northwest, northern California, and the northern and central Rockies.
The CPC 6-10 day extended range outlook (valid from March 23 to 27) favors above normal precipitation throughout most of the central and eastern U.S. except for the Florida Peninsula, where probabilities for below normal precipitation are slightly elevated. Increased chances of above (below) normal precipitation are forecast for the Southwest (West Coast). Above normal precipitation is favored for Alaska. Above normal temperatures are likely from the Mississippi River to the East Coast, while below normal temperatures are favored for much of the western U.S. and Alaska.