Current U.S. Drought Monitor

National Drought Summary for March 17, 2015

Summary

The week was characterized by drier than normal conditions across much of the Lower-48. However, there was a system that brought significant precipitation to the south and eastern part of the country. A wide swath of 2-5 inch precipitation fell in the lower Mississippi and Ohio Valleys. Across the country, temperatures for the most part were above average, as record high temperatures stretched from California eastward to the north-central U.S. In the northern Plains, departures were 20 degrees above normal. These warm temperatures began the melt season from the Great Lakes eastward into New England. Only the Deep South and extreme Northeast saw cooler than normal temperatures. Light precipitation fell in and around the Northwest, but snowpack levels remain low. Snowpack deficiencies are an even larger concern in the Sierra Nevada and Southwest mountains where the snow water content values are record or near record low levels.

Hawaii, Alaska, and Puerto Rico

No changes were made in Alaska or Puerto Rico this week. Above normal rainfall during the start of March across Hawaii led to a reduction in drought and dryness. The rains have reduced the drought footprint along the northeast-facing slopes and lower elevations of the east on the Big Island. Below normal temperatures affected Alaska during the past week.

Mid Atlantic and Northeast

Precipitation was below normal while temperatures were above normal for much of the area during the past week. Only the eastern sections of the Carolinas saw precipitation totals that exceeded their normal for the period. Precipitation in Florida and south Alabama measured less than 50 percent of the normal for the period. This exacerbated the long term dryness, resulting in an expansion of D0 in some areas.

Plains and Upper Midwest

Recent and long term dryness coupled with much above normal temperatures expanded D0 conditions in much of the Upper Plains. D1 conditions also expanded, occupying most of Minnesota. In Minnesota, record temperatures sped up the drying process and precipitation is 2.5 to 3.5 inches short since October 1. In the Dakotas and Minnesota, temperatures were 18-24 degrees above normal this past week. Similar anomalous conditions also led to the expansion of D0 in Nebraska. Precipitation deficits there are below the 75th percentile in most of the area. Soil moisture values in Nebraska are 2-3 inches behind normal. It was also noted that wheat broke dormancy in the McCook, Nebraska area during late February to early March. About 100 miles further east, wheat was just beginning to green up.

South and Southwest

Drought conditions in Texas were reduced in some areas, while other areas saw intensification this week. D0 and D1 conditions were trimmed back in the Coastal Bend and east Texas. Meanwhile, D2 and D3 conditions were expanded towards the south in central Texas due to the below normal reservoir levels which are less than 70 percent full in those areas.

In southwest New Mexico, the snowpack is sitting at zero percent snow water equivalent (SWE) in the Mimbres Basin, and 23 percent SWE in the Gila River Basin and 26 percent SWE in the San Francisco Basin. Based on this data, D1 was extended to the north. Across the border, D2 was extended in the Eastern Mogollon Rim and White Mountains. Further to the north in central Arizona, the snowpack melt is about 1-2 weeks ahead of schedule but Lake Mary, near Flagstaff, is at or above normal for this time of year – its highest level since 2011.

Southeast

Precipitation was below normal while temperatures were above normal for much of the area during the past week. Only the eastern sections of the Carolinas saw precipitation totals that exceeded their normal for the period. Precipitation in Florida and south Alabama measured less than 50 percent of the normal for the period. This exacerbated the long term dryness, resulting in an expansion of D0 in some areas.

West, Northwest and Southwest

Precipitation did fall along the northern tier of the region during the week; however, aside from the highest elevations, temperatures were too warm to support much-needed snowfall. Degradation was made in Oregon and Utah due to low snowpack amounts that have plagued the west coast this past winter. Mountain snowpack across the Olympic, Cascade, Coastal Range, and Sierra Nevada is at least 25 percent below the 30-year normal. In the Sierra Nevada, precipitation amounts for the water year are 10 inches or more below normal. To exacerbate matters, average temperatures were well above normal. Temperatures in Los Angeles reached 90 degrees F for a March record four consecutive days. This just after California besting their winter (Dec-Feb) average temperature, set just last year (2013/14), by 1.5 degrees F. Washington State also had one of their warmest winters on record with an anomaly 6.0F above the 20th century average. The average temperature in Nevada, Utah, and Arizona was also record warm this past winter.

Looking Ahead

Through March 24, two low-pressure systems will track their way across the Deep South. The first system may bring upwards of 2 inches in the Southeast. The second system may bring 2 or more inches to eastern Texas and, depending on the track of the low, the Carolina Coast. To the north, more snow is expected in the Northeast as a clipper system interacts with a costal low. The heaviest snows may fall in Upstate New York and along the New England coastline. Elsewhere, two small Pacific storms will affect the Northwest during this period. For temperatures, the highest probabilities of below and above normal values are in the Northeast and Southwest, respectively.

Looking further out through the end of the month, warmer than normal temperatures continue their dominance in the West, while a series of short-wave impulses support cooler than normal temperatures in the Northeast. The Climate Prediction Center precipitation probabilities are below average for the West, Southwest and Deep South. Above average probabilities are forecasted for the Northwest, Upper Plains and East Coast.

Author(s):
Chris Fenimore, NOAA/NESDIS/NCDC


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)