Monday, May 21, 2018

National Drought Mitigation Center

Drought and Climate for September 2017: Drought improves over northern Plains

Access the latest monthly drought outlook from NOAA's Climate Prediction Center.
The two maps above are from the High Plains Regional Climate Center.
Find these and other products related to the U.S. Drought Monitor on the USDM website.

By Curtis Riganti and Deborah Bathke, NDMC Climatologists


During September, drought degradation occurred over parts of the central and eastern United States, though improvement occurred in some regions, particularly in northwest Iowa. Drought improvement was common over much of the northern Plains during September, though some areas persisted in drought or degraded by one category. At the end of September, moderate drought coverage had increased from 11.82 to 14.36 percent, severe drought coverage had decreased from 5.74 to 4.73 percent, extreme drought coverage had decreased from 2.65 to 1.39 percent, and exceptional drought coverage dropped from 1.21 to 0.50 percent. The population affected by drought increased from 17.7 million to 30.6 million people during September.

Drought Outlook

In October, drought is forecast to persist in most of Montana and the western Dakotas, with some improvement likely in northeast Montana. Drought removal is forecast around Puget Sound, while ongoing drought is forecast to persist elsewhere in Oregon and Washington. Drought development is forecast across nearly all of Missouri, the northwestern two-thirds of Arkansas, southern Illinois, and southwest Indiana. Drought development is also forecast in eastern Ohio, most of West Virginia, most of Virginia, northern Delaware, most of Connecticut, southern New York, eastern Massachusetts, and all of Pennsylvania, New Jersey, and Rhode Island. Small areas of drought improvement or removal are forecast in central and south Texas, northwest Oklahoma, northeast Iowa, southeast South Dakota, north central Minnesota, and southwest Minnesota and neighboring areas of southwest Wisconsin. Elsewhere, persistence is forecast where drought was ongoing at the end of September.


The northeastern quarter of the United States experienced above-normal temperatures during September. The warmest weather occurred in Maine, the central Plains, and the upper Midwest, where temperatures were generally 4-6 degrees warmer than normal, with a few areas reaching 6-8 degrees above normal. The Intermountain West had temperatures near normal to 4 or more degrees below normal during September, while the Pacific Coast was generally 2-4 degrees warmer than normal. Southeast temperatures were generally near normal during September.


During September, precipitation was generally at or below 75 percent of normal from the Lower Michigan Peninsula southwestward through Chicago and St. Louis to the Texas Gulf Coast; under 1 inch of rainfall fell over most of this area. The central and southern High Plains had above-normal precipitation, where amounts ranged from 1 inch above normal to as high as 7 inches above normal in southwest Oklahoma and north central New Mexico. Above-normal precipitation also fell in southern Montana, southeast Idaho, and northwest Wyoming, where rain and snow amounts ranged from 1 to 4 inches of liquid. The rest of the western United States had variable precipitation, with below-normal precipitation in northern Washington and southern Arizona and above-normal precipitation in the Willamette region of Oregon. Above-normal rainfall, some of which fell as Hurricane Irma moved northward through Florida, ranged from 7 to 15 inches in the Florida Peninsula.


Regional Overviews


Precipitation in the Northeast was variable but generally below normal. Much of central and western Pennsylvania received less than 50 percent of normal precipitation in September, aside from a small region southeast of Lake Erie along the Pennsylvania-New York border that had precipitation up to 1.5 inches above normal. The drier than normal regions of Pennsylvania and New York had rainfall from 1.5 to 4.5 inches below normal. Rainfall was between 1.5 and 3 inches below normal in Maryland, much of New Jersey, northeast West Virginia, Delaware, and Connecticut, and 1.5 to 3 inches above normal in Cape Cod. Elsewhere, precipitation was within 1.5 inches of normal. Much of the Northeast was warmer than normal during September, with the warmest weather, 6 to 8 degrees above normal, taking place in southeast New York and central Maine. Elsewhere, in New York and coastal and interior New England, temperatures were 2 to 6 degrees warmer than normal. Temperatures in Delaware, southern Pennsylvania, northern West Virginia, and much of Maryland were normal to 2 degrees above normal, with a few areas of the Delmarva Peninsula reaching 2 to 4 degrees above normal. Southern West Virginia had near normal to slightly below normal temperatures. During September, few changes in drought occurred. Coastal Maine remained in moderate drought, though the regional coverage dropped from 4.61 to 3.93 percent.


September precipitation in the Southeast was variable. Virginia received generally near- or below-normal precipitation; rainfall in northern Virginia and southeastern Virginia was 3 to 6 inches below normal. September rainfall in the Carolinas was within 3 inches of normal. Southeast Georgia received 3 to 6 inches above normal rainfall, while other parts of the state were generally near normal, aside from a small area in central Georgia that received between 3 and 6 inches below normal rainfall. Most of Alabama received near-normal rainfall in September, except for the Gulf Coast region. The western Florida Panhandle, particularly coastal areas, also saw rainfall between 3 and 6 inches below normal. Meanwhile, most of the Florida Peninsula, except for a small area north of Gainesville, saw above-normal rainfall, with amounts as high as 9 to 15 inches above normal. Temperatures in the Southeast were variable in September; Alabama, Georgia, and western North Carolina were the coolest and the Florida Peninsula and coastal North Carolina were the warmest. Temperatures were between 1 and 4 degrees cooler than normal in northern Alabama, and between 1 and 3 degrees below normal in northern Georgia and western North Carolina. Temperatures in the Florida Peninsula were generally above normal, with most areas experiencing warmth from 1 to 4 degrees above normal. Coastal Georgia and southern South Carolina also had temperatures 1 to 3 degrees above normal. The Coastal Plain and southern Piedmont of North Carolina also were warmer than normal, with temperatures in parts of the Coastal Plain reaching 3 to 5 degrees above normal. Warm temperatures also occurred in southern Virginia, with some areas having temperatures 2 to 5 degrees warmer than normal. No areas in the Southeast were added into drought during September.

Movers & Shakers for September 2017

Percent area August 29, 2017

Percent area October 3, 2017 Status Percentage point change
Biggest increases in drought
Arkansas 0 29.13 Moderate 29.13
Colorado 0 3.70 Moderate 3.70
Illinois 6.26 13.27 Moderate 7.01
Indiana 0 8.46 Moderate 8.46
Iowa 27.62 34.72 Moderate 7.10
Michigan 0 5.40 Moderate 5.40
Missouri 4.65 22.17 Moderate 17.52
Ohio 0 14.22 Moderate 14.22
Oklahoma 0 14.10 Moderate 14.10
Oregon 0 28.57 Moderate 28.57
Washington 1.86 63.66 Moderate 61.80
Wisconsin 0 4.94 Moderate 4.94
Biggest improvements in drought
Kansas 19.90 10.08 Moderate 9.82
Maine 28.88 24.62 Moderate 4.26
Minnesota 17.50 2.45 Moderate 15.05
Montana 90.20 76.49 Moderate 13.71
39.42 23.40 Extreme 16.02
24.55 10.19 Exceptional 14.36
Nebraska 12.46 3.91 Moderate 8.55
North Dakota 65.84 59.79 Moderate 6.05
51.33 18.90 Severe 32.43
22.08 1.81 Extreme 20.27
South Dakota 68.85 57.96 Moderate 10.89
42.60 32.30 Severe 10.30


During September, drier than normal conditions prevailed along the Gulf Coast, in the Louisiana Bayou, in southwest Mississippi, and in a broad swath from northeast Texas through eastern Oklahoma and western Arkansas. Wetter than normal conditions occurred in western Tennessee, northern Mississippi, and adjacent east central Arkansas, with some areas receiving rainfall between 3 and 6 inches above normal. Elsewhere, most of the remainder of Texas and Oklahoma received near-normal precipitation, with rainfall in a few areas of western Oklahoma, western north Texas, and the Oklahoma Panhandle between 3 and 6 inches above normal. Rainfall from 3 to 9 inches above normal fell on parts of the South Texas Plains, though the Lower Rio Grande Valley was below normal for rainfall. Temperatures in the South were generally warmer than normal during September. Southwest Texas had the most above-normal temperatures, with a few locales having temperatures from 3 to 4 degrees above normal. Most other areas of Texas, Oklahoma, and Arkansas had temperatures between 1 and 3 degrees above normal. A small area in southwest Oklahoma had temperatures 1 to 3 degrees cooler than normal, and a few locales in central Texas and central Arkansas were 3 to 4 degrees warmer than normal. Temperatures in northern Louisiana were 1 to 4 degrees above normal, while temperatures were 1 to 3 degrees above normal in west central Mississippi and northeast Louisiana, and 1 to 2 degrees above normal in east central Mississippi. Overall drought coverage increased from 0.44 to 6.19 percent during September. Moderate drought expanded in the Lower Rio Grande Valley, and was added in northwest, southeast, and northeast Oklahoma; northwest Louisiana; northeast Texas; southwest Arkansas; east central Arkansas; and northern Arkansas. Moderate drought was removed in parts of south central Texas.


During September, dry conditions prevailed in much of Michigan, Wisconsin, Illinois, Indiana, Ohio, and Missouri. Much of the Lower Michigan Peninsula, the eastern Michigan Upper Peninsula, Wisconsin, Illinois, and Missouri received rainfall between 1.5 and 4.5 inches below normal, with Missouri experiencing the most widespread dry conditions. Rainfall in northeast Iowa and southeast Minnesota was generally 1.5 to 3 inches below normal. Rainfall in northern Minnesota and south central Kentucky was 1.5 to 4.5 inches above normal and 1.5 to 7.5 inches above normal, respectively. In southeastern Kentucky, rainfall was 1.5 to 3 inches below normal. With the exception of Kentucky, warmer than normal temperatures covered the Midwest. The warmest areas, with temperatures 4 to 5 degrees above normal or higher, were south central Iowa, the central Michigan Lower Peninsula, the eastern Michigan Upper Peninsula, southwest Minnesota, west central Wisconsin, and parts of northern Minnesota. Elsewhere, temperatures 2 to 4 degrees warmer than normal were common. In Kentucky, a few areas along the Ohio River and in south central Kentucky were 1 to 2 degrees above normal. Otherwise, temperatures from 1 to 3 degrees below normal were common in Kentucky. During September, moderate drought coverage expanded from 7.43 to 11.91 percent and extreme drought coverage slightly expanded from 0.26 to 0.36 percent, while severe drought coverage slightly decreased from 1.08 to 1.02 percent. The moderate drought in parts of the St. Louis metropolitan area expanded northward along the Mississippi River and southwestward into the Ozarks. Moderate drought was added in northern and far south central Missouri, northern Illinois, northeast Iowa, southwest Wisconsin, southwest Minnesota, the central Lower Michigan Peninsula, northeast Ohio, and east central Indiana. Moderate drought in northwest Minnesota decreased in coverage such that it only covered a small area of north central Minnesota. Small areas of extreme drought were added in central Iowa, northeast Iowa, and the southwest tip of Minnesota, while the extreme drought area in south central Iowa shrank in areal coverage. The area in extreme drought in south central Iowa shrank slightly into two separate areas, though some areas surrounding the extreme drought at the beginning of the month degraded to extreme drought.

High Plains

Precipitation in the High Plains was generally near normal or slightly above normal, though rainfall in southeast Nebraska and eastern Kansas was between 1.5 and 3 inches below normal. In southeast Colorado, western Kansas, western Nebraska (not including the Panhandle), northwest Wyoming, east central South Dakota, and northeast North Dakota, precipitation was 1.5 to 3 inches above normal. Precipitation in isolated areas of western Nebraska, south central Kansas, and northwest Wyoming was between 3 and 4.5 inches above normal. Temperatures in Nebraska and Kansas were generally above normal; temperatures between 3 and 5 degrees warmer than normal were common in central and eastern Nebraska and in northern Kansas. Temperatures in the Dakotas were generally 1 to 4 degrees above normal, though a small region of west central North Dakota was 1 to 2 degrees cooler than normal. Most of Colorado was between 1 and 3 degrees warmer than normal, while parts of northeast, west central, and south central Colorado and southeast Wyoming were 3 to 4 degrees warmer than normal. Meanwhile, central and northwest Wyoming were generally 1 to 3 degrees cooler than normal. Overall, drought coverage shrank during September in the High Plains. The small area of exceptional drought in northwest North Dakota was removed. Extreme drought coverage in North Dakota was greatly reduced, such that it only covered far northwestern North Dakota at the end of the month. Severe drought coverage in the Dakotas also was reduced during September. A small area of moderate drought was removed from southwest Nebraska. The moderate drought in Kansas also shrank, though two severe drought areas were introduced, one in southwest Kansas and the other in northeast Kansas. Moderate drought was also added in western Colorado. Moderate drought coverage dropped from 25.09 to 20.46 percent, severe drought from 13.64 to 7.73 percent, extreme drought from 4.01 to 1.10 percent, and exceptional drought from 0.05 percent to none.


Precipitation in the West was generally within an inch of normal; the driest areas were southeast Arizona, northwest Montana, and northern Washington, and the wettest areas were northwest Oregon, Idaho, central Nevada, and central and northern Utah. Rainfall was between 1 and 2 inches below normal in southeast and central Arizona, southwest Wyoming, and northwest Montana, and 2 to 3 inches below normal in northwest Washington.  Rainfall was 1 to 3 inches above normal in northwest Oregon and central and southeast Idaho, while small areas of west central Oregon and the Yellowstone region of Idaho received 3 to 4 inches above normal precipitation. Rainfall was 1 to 2 inches above normal in central Nevada and central Utah. Temperatures in the Intermountain West were generally within 2 degrees of normal, while the Pacific Coast was generally 2 to 6 degrees warmer than normal. The warmest areas were in coastal central California, with widespread warmth also taking place in western Washington, east central Oregon, the Idaho Panhandle, and parts of northern Montana. West central Nevada, south central California, and southwest Arizona were below normal in September, with temperatures ranging from slightly below normal to 6 degrees cooler than normal. Temperatures were 6 to 8 degrees below normal in west central Nevada. During September, moderate drought coverage increased, as parts of Washington and Oregon degraded to moderate drought. Elsewhere, minor expansions of moderate drought took place in western Idaho and eastern Utah. Severe drought coverage in Montana and Idaho was mostly unchanged; severe drought in far southeast Montana improved, though severe drought expanded in northwest Montana. Extreme drought coverage decreased overall; much of east central Montana improved out of extreme drought, though parts of north central Montana degraded to extreme drought. The exceptional drought in northeast Montana also shrank in coverage. Moderate drought coverage increased from 15.27 to 19.71 percent, while severe drought coverage slightly decreased from 8.27 to 8.24 percent. Extreme drought coverage decreased from 4.89 to 2.90 percent, and exceptional drought coverage decreased from 3.04 to 1.26 percent.

September 2017 impact summary: Fall foliage affected by drought

The two charts above summarize information from the Drought Impact Reporter.

By Denise Gutzmer, NDMC Drought Impact Specialist

In many parts of the United States, trees were dropping leaves early, with some leaves not fully changing colors or turning brown, due to hot, dry conditions in September. Reports on variations in fall foliage boosted the number of impacts in the Drought Impact Reporter considerably, at a time of year when impacts typically begin to wind down as the growing season nears an end. The NDMC logged another 319 impacts in the Drought Impact Reporter in September, with more than two-thirds of those coming from CoCoRaHS observers. 

More hay needed in northern Plains

As intense drought persisted in the northern Plains, ranchers looked for hay to purchase because little grew over the hot, dry summer. In the Dakotas and Montana, nearly 1,400 drought-stricken ranchers applied for a chance to win hay through the hay lottery organized by North Dakota's Agriculture Department, North Dakota State University and the Michigan-based nonprofit Ag Community Relief. 

In Montana, donations continued to pour in for ranchers who have faced drought and wildfires during the summer, prompting the Montana Department of Agriculture to set up their own hay lottery to benefit Montanans. 

Donated hay being divided among Northern Plains ranchers, by Blake Nicholson, Associated Press, Minneapolis-St. Paul Star-Tribune, Sept. 1, 2017

MT expands hay lottery as drought, fire situation worsen, by Jenny Schlecht, The Dickinson (North Dakota) Press, Sept. 10, 2017

Montana experiences smoky summer of wildfires

Wildfire activity in Montana was unusually high as the state experienced fierce drought, which led to a merciless wildfire season. The latter part of July and August brought nonstop firefighting, until at the end of August, a lightning storm that offered little rain sparked 45 fires in Montana. Much of the state was in moderate to exceptional drought and was primed to burn.

On September 1, Governor Steve Bullock issued an executive order declaring a state of disaster due to the multitude of wildfires. The order allowed the governor to utilize more state resources and permitted the Montana National Guard to fight fires. The governor also issued a directive to the Montana Department of Transportation, temporarily suspending certain regulatory requirements to assist with the transport of heavy firefighting equipment.

By the end of September, more than 1.2 million acres had burned in Montana since the start of the year, with fire suppression costs nearing $400 million.  Montana’s share of the bill was about $62 million.

Governor declares disaster exists in Montana, by Phil Drake, Great Falls Tribune (Montana), Sept. 1, 2017

Fire Torches Historic National Park Chalet in Montana, by Matt Volz, Associated Press, U.S. News & World Report, Sept. 1, 2017

$400 million spent on Montana wildfires this year, by Tom Kuglin, Helena (Montana) Independent Record, Sept. 30, 2017

Eastern United States sees early fall color

Many areas across the eastern United States had early leaf color or other episodes of unusual fall color that numerous news articles and individuals blamed on dry weather during the growing season. In south Illinois, brown leaves littered the ground, after dry conditions led trees to skip the color change, turn brown and drop leaves early. Nearby in eastern Ohio, the absence of moisture over the past couple of months hastened leaf drop before the leaves displayed their full range of color. CoCoRaHS observers from Maine to South Carolina to Texas have similarly noted a departure from typical fall foliage. 

Fall foliage impacted by dry weather, by Nick Hausen, WSIL-TV (Harrisburg, Illinois), Sept. 27, 2017

Dry weather and hot temps cause leaves to fall early, by Emily Morgan, New Philadelphia (Ohio) Times-Reporter, Sept. 27, 2017


For more drought information, please visit the Drought Impact Reporter.



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