Tuesday, April 24, 2018

National Drought Mitigation Center

Drought and Climate for April 2017: Contiguous U.S. sees smallest area of drought since 2000

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 Deborah Bathke, NDMC Climatologist


Thanks to a very wet April, the May 2 U.S. Drought Monitor showed just 4.98 percent of the contiguous United States in drought.  This was the smallest drought area depicted on the map since it began in 2000.  According to the National Centers for Environmental Information, April 2017 ranked as the second wettest April in the 123-year period of record, largely because of much above average precipitation across the Mid-Atlantic, Mid-Mississippi Valley, Great Lakes, Central Plains, and Northwest.  Most drought areas saw improvements, with the exception of the extreme southeastern United States and patches of north-central Texas, southeast Utah, the southern Arizona-New Mexico border, North Dakota, and Nebraska.  During the month, the percentage of the contiguous United States experiencing drought (D1-D4) improved from 9.83 to 4.98 percent, moderate drought (D2) improved from 1.5 to 1.3 percent, and severe drought (D3) increased slightly, from 0.10 to 0.13 percent.  Exceptional drought was not present.  Drought continued in Hawaii while Alaska and Puerto Rico remained drought free.

Drought Outlook

The Climate Prediction Center’s May drought outlook calls for existing drought conditions to persist in the southern sections of California and Arizona as these regions enter the climatologically warm, dry summer season.  Below-normal rainfall forecast for much of the Southeast is expected to result in the persistence of existing drought conditions and a deterioration of abnormally dry regions in southeastern Alabama, southern Georgia, South Carolina, and Florida. Seasonal precipitation favors the removal of remaining drought areas in the rest of the contiguous United States.


Temperatures were above normal in the eastern half of the country, with the National Centers for Environmental Information declaring that Delaware, Maryland, New Jersey, North Carolina, Ohio, Pennsylvania, West Virginia, and Virginia experienced their warmest April on record.  Mean temperatures across these areas ranged from 6 to 8 degrees above average. In the western half of the country, near- to below-average temperatures were observed across the northern Plains, northern Rockies, Great Basin, and Northwest.  Here, temperatures generally ranged from 0 to 4 degrees below average.


Above-average precipitation was observed across much of the United States.  Heavy rains brought excess rainfall and flooding to the southern Plains, Mid-Mississippi River Valley, and Carolinas. The wettest areas received 200-400 percent of their average rainfall for the month of April.


Regional Overviews


Warmer than normal temperatures dominated the entire Northeast during April.  Temperatures ranged from 1 degree above normal in Maine to over 7 degrees above normal in Pennsylvania. Much of the Northeast also experienced above-normal precipitation, helping to ease many of the remaining drought conditions in the region.  Overall, precipitation ranged from less than 50 percent of normal in Delaware to more than 200 percent of normal in western New York.  At month’s end, only 3 percent of the region was experiencing drought, compared to 10.5 percent at the beginning of the month.  Severe drought (D2) was eliminated and the region remained free of extreme (D3) and exceptional (D4) drought.


Temperatures were much above average across the southeastern United States.  Temperatures generally ranged from 5 to 9 degrees above normal northward of central Alabama and Georgia.  Precipitation ranged from 2 inches below normal in Florida to a record wettest April in North Carolina, where departures of more than 7 inches above average were noted.  Accordingly, the southern part of the region saw an expansion of drought conditions while the northern part saw improvements in drought.  As a whole, drought decreased slightly, from 35.61 to 34.35 percent.  Severe drought (D2) expanded over southern Georgia and Florida, increasing the percent area in this category from 9.05 percent to 12.97 percent.  An introduction of extreme drought over Florida resulted in a slight increase in the region’s percent area in this category, from 1.08 to 1.32 percent.

Movers & Shakers for April 2017

Percent area April 4, 2017

Percent area May 2, 2017 Status Percentage point change
Biggest increases in drought
Alabama 26.17 32.03 Severe 5.86
Florida 42.41 66.00 Moderate 23.59
13.01 39.42 Severe 26.41
0 5.53 Extreme 5.53
Georgia 29.94 56.83 Moderate 26.89
15.05 24.06 Severe 9.01
Biggest improvements in drought
Alabama 4.87 1.50 Severe 3.37
Arkansas 18.90 1.11 Moderate 17.79
Colorado 21.88 3.57 Moderate 18.31
3.03 0 Severe 3.03
Connecticut 74.81 24.06 Moderate 50.75
33.95 0 Severe 33.95
Georgia 4.16 1.11 Extreme 3.05
Hawaii 17.55 9.55 Severe 8.00
Illinois 6.05 0 Moderate 6.05
Kansas 10.41 0 Moderate 10.41
Louisiana 15.96 6.33 Moderate 9.63
Massachusetts 16.65 0.01 Moderate 16.64
Mississippi 9.58 5.08 Moderate 4.50
Missouri 12.73 0 Moderate 12.73
Nebraska 3.77 0 Moderate 3.77
New York 6.01 0 Moderate  6.01
North Carolina 36.05 0.25 Moderate 35.80
5.09 0 Severe 5.09
Oklahoma 14.50 0 Severe 14.50
Pennsylvania 11.56 7.64 Moderate 3.92
South Carolina  42.49 15.80 Moderate 26.69
15.41 0.15 Severe 15.26
South Dakota 16.62 0 Moderate 16.62
Tennessee 5.90 0 Moderate 5.90
Vermont 10.34 0 Moderate 10.34
Virginia 40.63 15.88 Moderate 24.75
Wyoming 9.33 0.12 Moderate 9.21


Above-average temperatures dominated most of the southern region, with departures ranging from more than 6 degrees above normal in Alabama and Tennessee to near normal in parts of Texas. Parts of eastern Oklahoma, Arkansas, and Louisiana observed more than 6 inches of rainfall above average April values. The wet weather alleviated drought and dry conditions across the area, leaving just 2.43 percent of the region in drought compared to 13.44 percent at the beginning of the month.  Severe drought (D2) was eliminated and the region remained free of extreme (D3) and exceptional (D4) drought.


Most of the Midwest was warmer than average in April.  Departures ranged from 1 degree below normal in northwest Iowa to as much as 8 degrees above average in northern Ohio.   Precipitation ranged from near normal in pockets of Minnesota, Iowa, Indiana, Ohio, and Kentucky to more than 12 inches above normal in southern Missouri.  With the excess precipitation, drought was eliminated from the region.


Temperatures in the West ranged from 3 degrees below average in parts of the Pacific Northwest to 6 degrees above normal in southern California.  Much of the Pacific Northwest was also wetter than normal, with coastal areas recording more than 6 inches above average April totals.  Southern California and Arizona remained dry, with precipitation shortages near 1 inch.  Overall, drought in the West decreased from 5.49 to 2.72 percent of the region.  Moderate drought (D2) is now at 0.16 percent, down from 0.43 percent at the beginning of the month.

Alaska, Hawaii, and Puerto Rico

Alaska continued to remain drought free, though 33.01 percent of the state was experiencing abnormally dry conditions, up from 31.15 at the beginning of the month.  In Hawaii, severe drought (D2) decreased from 17.55 to 9.55 percent, but the total area in drought remained constant, with 25.69 percent of the islands experiencing drought.  Puerto Rico remained free from drought and abnormally dry conditions.








April 2017 impact summary: Florida sees wildfires and water shortages

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

By Denise Gutzmer, NDMC Drought Impact Specialist

Drought concerns ramped up in Florida, southern Alabama, and southern Georgia during April as the month was relatively dry, while drought eased in other parts of the county, thanks to abundant spring rains.  Wildfire activity and water shortages were the main issues of concern for Floridians, who endured an unusually parched dry season.  The state had 48 impacts in the Drought Impact Reporter, far more than any other state.  At a distant second, California and North Carolina both had nine impacts, documenting California’s emergence from drought and North Carolina’s lingering drought, which was largely alleviated in April.

State of emergency declared in Florida

Governor Rick Scott declared a state of emergency for Florida on April 11 because of the multitude of wildfires burning in the parched state. Flames had scorched 250 percent more land in the first three months of 2017 than during the same time in 2016. On the morning of April 28, the Florida Forest Service reported 99 active wildfires in Florida scorching 28,621 acres, apart from the fires affecting 107,346 acres of federal land. 

Florida brush fires, wildfires lead to emergency declaration, by Brian Ballou, Fort Lauderdale Sun-Sentinel & SouthFlorida.com, April 11, 2017

Hot, Dry Weather Elevates Tampa Bay’s Weekend Fire Concerns, by Sherri Lonon, Pinellas Beaches Patch (Fla.), April 28, 2017

Water shortage warning issued for South Florida

A water shortage warning was issued by the South Florida Water Management District as the precipitation deficit continued to climb. Since November 1, precipitation in the district’s 16 counties has been 6.75 inches below normal, and the level of Lake Okeechobee has dipped to 12.04 feet. The district also prohibited fires on its lands and was preparing to close navigation locks on the north shore of Lake Okeechobee.

Water shortage warning for 8M from Orlando to the Keys, Palm Beach Post (Fla.), April 16, 2017

Lackluster dry season, dry shallow wells noted in southwest Florida

Florida’s dry season, which begins on November 1 and extends through May 31, brought 45 percent of normal rainfall for the southwest coast area of the South Florida Water Management District.  This region was also seeing a rash of dry or inoperable shallow wells as the water table dropped for lack of rain to replenish it.  In Lee County, 181 wells—149 domestic wells and 32 irrigation wells—have gone dry or are not working, according to Kurt Harclerode, operations manager for Lee County Natural Resources. 

Southwest Florida so dry that canals, wells, pumps, lawn watering are concerns, by Patrick Riley, Naples News (Fla.), April 28, 2017

Fire near Georgia-Florida state line could burn for 6 months

A wildfire burning in the Okefenokee National Wildlife Refuge near the Georgia-Florida state line has charred more than 200 square miles and could continue to burn for the next six months, said fire officials.  The fire, which was sparked by a lightning strike on April 6, grew rapidly in the parched swampland in the last days of April.  The conflagration is expected to continue for several months and may not be extinguished or completely contained until November, unless a large storm event puts the fire out sooner.

Forestry official: National refuge fire could burn 6 months, by Russ Bynum, The Washington Post, April 24, 2017

Okefenokee wildfire spreads, forces evacuations in Georgia, by Nicole Chavez, CNN, May 8, 2017

Florida's wildlife feeling pinch of drought

Wildlife was also having a tough time with the dry conditions.  Florida’s drying lakes and swamps were driving venomous snakes out of their normal habitat to seek more water somewhere else, sometimes bringing the serpents into people’s yards. In St. Petersburg, warm water in a fish pond resulted in the deaths of thousands of fish because warm water holds less dissolved oxygen than cool water does, causing fish to suffocate.  The Florida Fish and Wildlife Conservation Commission received 50 calls on their fish kill hotline. 

Experts: Drought conditions mean venomous snakes could be on the move, WFTV9 (Orlando, Fla.), April 25, 2017

FWC: Drought killing thousands of fish, by Sara Hollenbeck, WFTS (Tampa bay, Fla.), April 26, 2017

Deep snowpack in California means plentiful water allocations

The final snowpack measurement of the 2016-17 season on May 1 showed a snow-water equivalent (SWE) of 27.8 inches, or 190 percent of the historic average.  Electronic measurements revealed the water content of the statewide snowpack was 42.5 inches, 196 percent of the May 1 average. The SWE of the northern Sierra snowpack was 39.9 inches (199 percent of average); the central and southern Sierra readings were 47.1 inches (202 percent of average) and 37.6 inches (180 percent of average), respectively.  The annual precipitation tally begins with the start of the water year on Oct. 1.

Lake Oroville, the primary reservoir for the State Water Project (SWP), was at 91 percent of average, or 74 percent of its 3.5 million acre-foot capacity.  In April, the Department of Water Resources increased its estimate of this year’s SWP supply to 100 percent of requests for contractors north of the Sacramento-San Joaquin Delta and 85 percent of requests for other contractors, the highest since the last full allocation in 2006.

Final Survey of 2017 Finds Water-Rich Snowpack, by Doug Carlson and Ted Thomas, California Department of Water Resources, May 1, 2017

Millions of trees dying in Southern California

Southern California is undergoing a massive tree die-off as the stress of drought, water restrictions, higher salinity levels in recycled water, wind, and new pests continues to take a terrible toll on the region’s trees, particularly those poorly suited to California’s climate.

One of the most affected native urban trees is the sycamore. An insect known as the polyphagous shot hole borer beetle is expected to kill all sycamore trees if the bug cannot be stopped. It is then expected to move on to destroy other tree species.

The trees that make Southern California shady and green are dying. Fast, by Louis Sahagun, Los Angeles Times, April 19, 2017


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



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