Statistics
California and National Drought Summary for August 21, 2018
Summary
August 23, 2018 - Areas of low pressure brought heavy to excessive rainfall to many parts of the U.S. during this past drought week (August 14-21). Some storms brought more rainfall to already inundated areas such as the Northeast, but some activity occurred over drought regions badly in need of moisture, including the Central and Southern Plains, the Midwest, and the South. Other areas, especially along the northern tier of the country, continued to dry out amid a combined lack of rainfall and anomalously high temperatures. Some areas of northern Michigan and Wisconsin averaged daily maximum temperatures 6-8 degrees F above their typical average for this time of year.
Northeast
Rainfall was above normal across most of the region, allowing for some small improvements in western New York, where the moderate drought (D1) footprint was reduced. This week’s rainfall led to the return of normal conditions in the same general region, along with southern Vermont, southern New Hampshire, and central Maine. The remainder of the region is drought free, and in some instances extremely wet. Pennsylvania has received its record highest year-to-date (January-July) precipitation in its 124 year record, according to NOAA NCEI.
Southeast
Most of the Southeast has received adequate to above-normal rainfall this summer. At this time, no areas of the Southeast are experiencing any drought conditions, although there are a few pockets of short-term abnormal dryness (D0) in Alabama, most notably leading to some low stream flows. These conditions expanded a bit in the western part of the state this week, but improved to normal in the east compared with the previous week.
South
Drought has plagued this region, but heavy, and in some instances, extremely heavy rainfalls, (ranging from 1 to 6 inches or more) brought much needed relief as most areas saw vast improvements or, at the very least, no degradation. In extreme northeastern Arkansas, several counties experiencing D2 conditions received 6 or more inches of rain over the past week. In facet, enough rain fell over the state that widespread 1-category improvements were made. Many stations received record rainfall for the month of August, including Long Pool (12.35 inches), Clinton (12.41 inches), and Murfreesboro (12.11 inches), leading to much improved conditions across the state, with no primarily drought and only lingering long-term dry conditions. Similarly, Oklahoma saw drought conditions fade as heavy rains fell, bringing normal conditions back to a large swath of the state stretching from the northwest to the southeast. Conditions also improved in Louisiana, northern, and western Texas, while dryness spread in southeastern Texas.
Midwest
Some regions of the Midwest received excess rainfall this week from heavy downpours, while other areas mostly missed out on the events, leading to some improved drought areas and some degraded drought areas. Along the U.S./Canadian border of Minnesota, several areas reported precipitation accumulations among their lowest 20 percent (since April 1), leading to expanded abnormal dryness (D0) and moderate drought (D1). Likewise, Michigan’s northern lower peninsula has continued to experience below-average rainfall, leading to reported dying foliage (ferns). Here, an area of moderate drought (D1) expanded and severe drought (D2) was introduced. Rainfall was deficient in central to southern Iowa, where D0, D1, D2, and a bit of D3 (extreme drought) expanded. Parts of northern Illinois also remained dry over the past month or so, leading an expanded area of abnormal dryness (D0), while northern Indiana and northern Ohio saw some improvement. Missouri saw more than 5 inches of rain fall in places. Conditions in this state improved considerably in many areas, although rainfall, even more than an inch or two, wasn’t enough to overcome the lingering longer-term dryness in other areas.
High Plains
Similar to the Midwest, the northern tier of the High Plains saw conditions continue to dry out over this past week, exacerbated by high temperatures in some areas. Mercer County, North Dakota, for example, saw temperatures reach 104 degrees F on two days and 10 consecutive days of upper 90s. Crops have been impacted as soil moisture is depleted, with very dry topsoil and subsoil. There are reports of corn burning and severely stressed soybeans, among other impacts. As such, areas of abnormal dryness (D0), moderate drought (D1), and severe drought (D2) were expanded in various parts of the state. Eastern Montana saw an expansion of D0, including along the North Dakota border. Nebraska and Kansas, on the other hand, were the recipients of heavy rainfall events, which led to improvements across their drought regions. Although rainfall was 2-6 inches in several inches in places, long-term dryness persists across parts of the regions and thus was not adequate to erase all drought. However, two category improvements (D3 to D1) were made in southeastern Kansas, for example, as the rain did vastly improve conditions there. In Colorado, D1 was reduced in El Paso and Douglas Counties, which received 1 to 4 inches of rain over the past few weeks, improving conditions there.
West
Most of the West continues to experience dry conditions and drought, with dozens of wildfires burning record acreage; however, while conditions remain poor, no areas required further degradation this week. The only change made this week occurred in far eastern New Mexico, where rainfall was 1 inch or more above average for the week. This allowed for 1-category drought improvements of extreme drought (D3), severe drought (D2), and moderate drought (D1).
Alaska, Hawaii, and Puerto Rico
No changes were made to the depiction in Puerto Rico this week. The upper panhandle of Alaska recently received rainfalls in excess of 13 inches over an 8-day period (August 6-13) and thus the area of abnormal dryness (D0) from Yakutat through most of Glacier Bay National Park to around the coastal region of Silka improved to normal on the drought scale. Conditions were dry in Hawaii, where severe drought (D2) replaced the existing moderate drought (D1) area over southwest Maui and Molokai, and D1 expanded eastward over south Maui, where dry conditions were reported over leeward areas of Maui County. There are federal reports that pasture conditions are poor over the lower leeward slopes of Maui and Molokai. A small area of D0 was also introduced on the lower slopes of south
Looking Ahead
Over the next week, beginning Tuesday August 28, up to 2 inches of rain is forecast for western Colorado and western New Mexico, where extreme (D3) and exceptional (D4) drought conditions prevail. No rain to less than half an inch are forecast for most of the remainder of the West. Between 0.1 and 2 inches are forecast for most of the rest of the U.S. at this time. Looking further ahead at NOAA’s Climate Prediction Center (CPC) 6-10 day Outlook (August 26-30), the probability of dry conditions are highest in the Plains, with a bullseye over western Oklahoma, while wet conditions may occur along the northern tier of the U.S., the Pacific Northwest, and Alaska. During this period, below-average temperatures are expected in the West while above-average temperatures are forecast for the eastern two-thirds of the country, particularly stretching from the Midwest to the Northeast. Looking two weeks out (August 28 - September 3), above-average temperatures are expected across the eastern two-thirds of the U.S. and stretching across the southwestern U.S./Mexico border. Below-average temperatures are expected over most of the West. The probability of above-average precipitation is highest over the North and Northwest with the highest probability of dryness expected over western Oklahoma.
Author(s):
Jessica Blunden, NOAA/NCEI
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 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
