From Climate Central (Andrea Thompson):
For a swath of states from New Mexico over to Florida and up to Ohio, 2017 has been the hottest year on record through April. For the Lower 48 as a whole, the year is the second warmest in records going back to 1895.
Several states in the mid-Atlantic had their hottest April on record and a few Southeastern states were near-record warm, according to National Oceanic and Atmospheric Administration data released Monday.
The average temperature for the contiguous U.S. through April was 43.7°F (6.5°C), 4.5°F (2.5°C) above the 20th century average, NOAA said. This put the four-month period behind only 2012, which saw major heat waves and drought across much of the central part of the nation.
The exceptional heat of February is what’s keeping 2017 so high in the rankings, Jake Crouch, a NOAA climatologist, said in an email. With eight months left, though, it is unclear whether 2017 will stay warm enough to ultimately beat 2012 as the hottest calendar year for the Lower 48…
Fourteen states along the southern tier of the country and up the Ohio Valley are record hot for the year so far, with another 17 states having a top 5 warmest year through April. Numerous cities in those states, including Atlanta, Washington, D.C., Miami and Charleston, S.C., are also running record hot so far in 2017, according to the Southeast Regional Climate Center. Only the Pacific Northwest had temperatures at or below average for the year.
During April, the eastern half of the country was the center of warmth, with the West Coast running closer to average. North Carolina, Virginia, West Virginia, Maryland, New Jersey, Pennsylvania and Ohio all had their hottest April. Several other states surrounding that area had a top 5 warmest April.
Two natural climate patterns, called the North Atlantic Oscillation and the Arctic Oscillation, were in phases that tend to bring warm conditions to the eastern U.S., Crouch said. The phases of those patterns have just switched, bringing the much cooler conditions of the last couple weeks.
But rising global temperatures have also titled the balance in favor of more record heat. April was the 29th month in a row where heat records outpaced cold records in the U.S., the longest such stretch in the books and 10 months longer than the previous record stretch. Of the five longest such streaks, four have occurred since 1998 (in a stable climate, record heat and record cold would be roughly even over time).
Global temperatures are rising because of the continued release of heat-trapping greenhouse gases into the atmosphere. The most important of those gases, carbon dioxide, recently passed the threshold of 410 parts per million at the Mauna Loa observatory in Hawaii for the first time in recorded history.
Global temperatures for April will be released next week by both NOAA and NASA, but through March, 2017 was the second hottest year on record. It trailed behind only the record heat of 2016, which was the third record-hot year in a row.
From NOAA (click through to follow their links):
Climate Highlights — April
The average temperature for the contiguous U.S. was 53.8°F, 2.7°F above the 20th century average during the month of April. This was the 11th warmest April on record for the Lower 48 and warmest April since 2012.
Locations from the Mississippi River to East Coast were much warmer than a
verage. Delaware, Maryland, New Jersey, North Carolina, Ohio, Pennsylvania, West Virginia, and Virginia each had their warmest April on record. The average April temperature for Washington, D.C. was also record high at 63.8°F, 1.8°F warmer than the previous record set in 1994. Reliable temperature data for D.C. date back to 1872. Near- to below-average temperatures were observed across the Northwest, Great Basin, Northern Rockies and Northern Plains. For the third time this year, the Washington state monthly averaged temperature was below average. The Alaska statewide average temperature was 29.9°F, 6.6°F above average. This was the sixth warmest April in the 93-year record for the state. Above-average temperatures spanned Alaska during April, with much-above-average temperatures across the southern third of the state. The contiguous U.S. average maximum (daytime) temperature during April was 65.9°F, 2.4°F above the 20th century average, the 20th warmest on record. Above-average maximum temperatures were observed across the Southwest and Southern Plains and locations from the Mississippi River to East Coast. Twenty-two states had much-above-average maximum temperatures with maximum temperatures for Delaware and Maryland record warm. Below-average maximum temperatures were observed in the Northwest. The contiguous U.S. average minimum (nighttime) temperature during April was 41.7°F, 3.0°F above the 20th century average, the sixth warmest on record. Above-average minimum temperatures were observed for most locations across the country, with the exception of the Northwest, Great Basin, and Northern Plains. Much-above-average minimum temperatures were observed across the East, where 15 states from South Carolina to New Hampshire were record warm. During April there were 3,126 record warm daily high (989) and low (2,137) temperature records, which is more than three times the 962 record cold daily high (749) and low (213) temperature records. Based on NOAA’s Residential Energy Demand Temperature Index (REDTI), April 2017 was zero and ranked as the lowest in the 123-year record for April, due to much-warmer-than-normal temperatures across the densely populated Midwest and Northeast.
The April precipitation total was 3.43 inches, 0.91 inch above the 20th century average, making it the second wettest April in the 123-year period of record. Above-average precipitation was observed across a large portion of the nation, including much-above-average precipitation in the Northwest, Northern Rockies, Central Plains, Mid-Mississippi Valley, Mid-Atlantic and Great Lakes. Record precipitation was observed in parts of the Northwest, Southern Plains and Mid-Atlantic. North Carolina had its wettest April on record with 6.75 inches of rain, 3.22 inches above average. Below-average precipitation was observed in parts of the Southwest and Northern Plains. Several storm systems impacted the Southern Plains and Mid-Mississippi River Valley in late April with the precipitation continuing into May, resulting in widespread flooding across the region. At the time of this report’s release, at least five fatalities were attributable to the flooding with significant impacts on agriculture. During April there were over 200 preliminary tornado reports, continuing an active tornado year. Large tornado outbreaks impacted the central and southern U.S. in early and late April resulting in eight tornado-related fatalities in Louisiana, South Carolina and Texas.
Alaska had its second driest April on record with 0.92 inch of precipitation, 0.97 inch below average. Only April 1932 was drier with 0.84 inch of precipitation. Record and near-record dry conditions were observed across the central and eastern parts of the state. April is climatologically the driest month of the year for Alaska.
According to the May 2 U.S. Drought Monitor report, 5.0 percent of the contiguous U.S. was in drought, down 9.2 percent compared to the March 28 values. This is the smallest drought footprint reported by the U.S. Drought Monitor since its inception in 2000. Drought improved across the Great Plains, Mississippi River Valley, interior areas of the Southeast, and Northeast. Drought worsened in the Southwest and across parts of the Southeast where several large wildfires burned in Florida and southern Georgia.
Climate Highlights — year-to-date (January-April)
The year-to-date average temperature for the contiguous U.S. was 43.7°F, 4.5°F above average. This was the second warmest January-April, behind the record of 44.7°F set in 2012. Above-average temperatures spanned the nation with only the Northwest being colder than average. Forty states were much warmer than average during January-April with 14 states record warm. Record warmth stretched from the Southern Rockies to Southeast and Midwest. The contiguous U.S. average maximum (daytime) temperature during January-April was 54.6°F, 4.2°F above the 20th century average, the third warmest on record. Above-average maximum temperatures were observed across the Southwest and from the Great Plains to East Coast. Thirty-six states had much-above-average maximum temperatures with maximum temperatures record warm for nine states across the South and Midwest. Below-average maximum temperatures were observed in the Northwest. The contiguous U.S. average minimum (nighttime) temperature during April was 32.7°F, 4.9°F above the 20th century average, the second warmest on record. Above-average minimum temperatures were observed for most locations across the country, with the exception of the Northwest. Forty-one states has much-above-average minimum temperatures with 18 states record warm.
The year-to-date contiguous U.S. precipitation total was 11.46 inches, 1.99 inches above average. This was the fifth wettest January-April on record and wettest since 1998. Above-average precipitation spanned most of the West into the Great Plains and Great Lakes. Seven states in the West, three in the Great Plains and two in the Great Lakes had year-to-date precipitation totals that were much above average. Idaho had its wettest January-April on record with 15.17 inches of precipitation, 5.42 inches above average, and 0.12 inch above the previous record set in 1904. Below-average precipitation was observed in the Northern Plains, Northeast and Southeast.
The U.S. Climate Extremes Index (USCEI) for the year-to-date was more than twice the average and the second highest value on record. The January-April USCEI in 2012 was slightly higher. On the national scale, extremes in warm maximum and minimum temperatures, one-day precipitation totals, and days with precipitation were much above average. The USCEI is an index that tracks extremes (falling in the upper or lower 10 percent of the record) in temperature, precipitation and drought across the contiguous United States. Regionally, the was record high for the Southeast, second highest for the Northeast, Upper Midwest, Ohio Valley, and South. In each of the regions above, extremes in both warm maximum and warm minimum temperatures were record or near record high. In the Southeast, the spatial extent of drought and one-day precipitation totals was much above average. In the Northeast, one-day precipitation totals were much above average. In the Upper Midwest, the spatial extent of wetness and days with precipitation was much above average. In the South, one-day precipitation totals were much above average. The West had its third highest CEI due to extremes in warm minimum temperatures, the spatial extent of wetness, one-day precipitation totals, and days with precipitation
High Plains Region: (Information provided by the High Plains Regional Climate Center )
The wet pattern that has been a primary feature since March continued in places like Wyoming, Kansas, and eastern Colorado during April. As a result of the wetness, mountain snowpack continued to increase throughout the month and is expected to peak later than normal in the Missouri River Basin. Continued wet conditions also nearly eliminated drought in Kansas and eastern Colorado and vastly improved topsoil moisture as well. However, storm systems that passed through the High Plains toward the end of the month caused devastating impacts, particularly to agriculture and livestock. Heavy rain and snow, sub-freezing temperatures, and high winds accompanied a couple of storm systems that came through in late April. These conditions killed cattle in Colorado and especially put calves at risk. The long-term presence of drought conditions and early emergence put a stressed winter wheat crop at additional risk for damage in western Kansas. Losses are projected to be greatest in southwestern Kansas where the crop was at a critical growth stage and the greatest impacts occurred. Even in areas that did not sustain sub-freezing temperatures, prolonged cold and wet conditions caused diseases to emerge, such as wheat stripe rust and leaf rust. Besides winter wheat, corn that had already been planted was put at risk in north-central and western Kansas where soil temperatures took a dive. While it appears that southwestern Nebraska may have escaped damage to winter wheat from these storms, the heavy snow may have damaged the alfalfa crop. Damage will be assessed in May after temperatures rise and the snow melts. An excessive northern Plains snowpack caused flooding in North Dakota during April. Major flooding occurred in Devils Lake, the Pembina River, and the Souris River. Although April was not a particularly wet month in the northern Plains, excess soil moisture from last fall was preventing producers from getting into the fields. Cool and wet conditions in late April slowed planting of sugar beets in North Dakota and corn in North Dakota and South Dakota. After a very warm March, April’s temperatures were closer to normal throughout the region. Temperatures ranged from about 2.0 degrees F (1.1 degrees C) below normal to 3.0 degrees F (1.7 degrees C) above normal. Areas experiencing the greatest warmth included southwestern Nebraska through western Kansas, as well as eastern Kansas. However, the region did not experience the record-breaking warmth that occurred in February and March. The biggest story of the month in regard to temperatures was several potentially damaging freezes throughout the region. While freezes are common in the area during April, the early emergence of plants due to late winter/early spring warmth put them at risk for freeze damage. With the exception of southeastern Kansas, most of the region had a freeze during April. Prolonged freezing temperatures occurred in conjunction with the late-April storm system that impacted much of the region. In particular, the swath of snow that fell throughout central Nebraska and western Kansas held maximum temperatures down into the 30s. The following locations experienced their lowest maximum temperatures on record for April 30th: Grand Island, NE (tie); Dodge City, KS; Garden City, KS; and Ulysses 3NE, KS (COOP). In Dodge City, the high temperature was only 37.0 degrees F (2.8 degrees C), which crushed the previous record by 6.0 degrees F (3.3 degrees C), set in 2004 and 1893. Minimum temperatures were also quite low in some places, and areas of western Kansas sustained sub-freezing temperatures for 12-24 consecutive hours, likely causing freeze injury to winter wheat.
Precipitation varied across the High Plains during April. Wet conditions were present throughout much of Wyoming, Kansas, and southeastern Colorado, as these areas received greater than 200 percent of normal precipitation. Heavy rain and snow that fell during the month led to several top 10 records for wettest April in these locations. Meanwhile, dry conditions prevailed across much of the Dakotas, but the dryness was not record-breaking.
Two storm systems that brought rain and snow to the region toward the end of the month contributed to much of the wetness experienced by a large part of the region. One system came through on the 25th-26th, bringing snowfall to the Rockies of Wyoming and Colorado, as well as South Dakota. According to the National Weather Service office in Aberdeen, South Dakota, Aberdeen received 1.8 inches (5 cm) of snowfall on the 26th, which was the most snow to fall there that late in the season since April 1994. In fact, a tornado drill was held on the 26th while snow was on the ground in Aberdeen! A second, more impactful storm system moved through the region from April 28th-May 1st. This potent system produced heavy precipitation across parts of Colorado, Wyoming, Kansas, Nebraska, and southeastern South Dakota. This same system spawned tornadoes across the South and Midwest and caused deadly flash flooding in Missouri and Arkansas. A band of heavy snow fell across central Nebraska and western Kansas, with some areas receiving as much as one to two feet (30-61 cm), resulting in several locations setting records for top 10 snowiest April. Because this storm system also impacted the region on May 1st, more details on records will be provided in the May climate summary. While this system helped eradicate drought conditions across the central and southern Plains, it caused many negative impacts, particularly for agriculture and ranching. According to agronomy specialists at Kansas State University, snow covered approximately 40 percent of the wheat acreage in Kansas. Heavy snow in the western part of the state knocked winter wheat to the ground, causing stems to break. Damage will be assessed in May after the snow melts and the wheat stands back up. Meanwhile, in Baca County, Colorado, hundreds of cattle were lost or killed due to deep snow and blizzard conditions. Another wet month allowed snowpack to continue to build in the Rockies of Wyoming and Colorado. Once again, the Wind River Range in Wyoming received precipitation that exceeded 300 percent of normal for the month. Temperatures were near normal in both states during April, which helped keep the snowpack in place. According to the U.S. Army Corps of Engineers, Snow Water Equivalent (SWE) above Fort Peck Dam was 107 percent of average at the end of April, which was a 13 percent increase from the previous month. Snowpack greatly increased between Fort Peck and Garrison Dams, as SWE went from 129 percent of average to 155 percent of average during the month. The Missouri River Basin mountain snowpack normally peaks near April 15, but given the increase in SWE in both reaches, snowpack will peak late this year. Major improvements in drought conditions occurred during April, as beneficial precipitation fell across drought-stricken areas in the High Plains. Regionwide, all severe drought (D2) and extreme drought (D3) were removed by the end of the month on the U.S. Drought Monitor map. The area in drought (D1-D4) in the region decreased from 17 percent to 4 percent, and the area experiencing drought or abnormal dryness (D0-D4) decreased to 20 percent. The biggest improvements occurred throughout Kansas. Most of the state received at least 150 percent of normal precipitation, while precipitation exceeded 300 percent of normal in western portions of the state. As of the end of March, nearly half the state was in drought, but it was drought-free by the end of April and only 12 percent of the state was experiencing abnormally dry (D0) conditions. Portions of eastern Colorado and western South Dakota experienced relief in drought conditions as well. Reports state that regionwide, April precipitation has helped grasslands recover in drought-stricken areas. Despite recent precipitation and improving conditions, the impacts of drought are still being felt across the parts of the region. Drought conditions during the past six months have caused the winter wheat crop to suffer in Colorado and Kansas. Additionally, ranchers in Kansas are still dealing with the impacts from devastating wildfires in March, which included the loss of cattle and miles of fence, and many are culling herds and buying costlier feed.
Western Region: (Information provided by the Western Region Climate Center)
Temperatures were near normal across most of the West this month, with some areas of above normal temperatures along the far southern boundary of the region. Precipitation was variable across the West, though with generally wetter than normal conditions across the northern half of the region and drier than normal conditions across southern portions of California, Nevada, and Arizona. The first half of April saw a continuation of the very active storm track that has persisted throughout the cool season. Portions of northern California, notably along the I-80 corridor and in the Sierra Nevada, experienced over 200% of normal precipitation. Sacramento received 3.36 in (85 mm) precipitation, 258% of normal. In the Feather River basin, Portola observed 5.76 in (146 mm), 420% of normal and the second wettest April since records began in 1915. At some higher elevation Sierra Nevada stations, April snowfall was sufficient to eclipse previous snowpack records. At 8801 ft (2683 m), the Mt. Rose Ski area SNOTEL recorded its largest highest snow water equivalent value on record at 94 in (238.8 cm), surpassing the previous record of 87.1 in (221.2 cm) set in May 1995. SNOTEL observations began at Mt Rose in 1979. Areas in and around the Washington Cascades logged over 200% of normal precipitation this month. Wenatchee recorded 2.15 in (55 mm), 467% of normal and the second wettest April since records began in 1959. Above normal precipitation also occurred in areas of western and central Montana, where Great Falls observed 3.58 in (91 mm), 252% of normal, the 3rd wettest April since records began in 1937. Further south, in northeastern New Mexico, Clayton reported 3.33 in (85 mm), 354% of normal and the 10th wettest April in a 122-year record. Above normal rainfall prompted improvements in drought conditions for eastern New Mexico this month. The Sierra Nevada, Cascades, Great Basin ranges, and northern and central Rockies continued to report above normal snowpack values at the end of April, ranging from roughly 125% to over 250% of normal. The southern Rockies reported near normal snowpack with SWE values, roughly 85-110% of normal. Drier than normal conditions dominated far southern California, southern Nevada, and much of Arizona this month, not uncommon for the spring season. San Diego, California, recorded only 0.01 in (0.3 m), 1% of normal and tie for 5th driest April since records began in 1939. Both Tucson and Phoenix, Arizona, recorded no measurable precipitation this month, as in many other years in their records. Only 3.8% of the West is currently denoted as having moderate drought conditions or worse; most of this area is in southern California and southwestern Arizona. Temperatures were slightly (0-4 F/0-2 C) cooler than normal from the Rocky Mountains westward, with the exception of southern portions of California, Arizona, and New Mexico. These areas reported temperatures +2-4 F (1-2 C) above normal. In Los Angeles, California, temperatures averaged to 67.8 F (19.9 C), 4.7 F (2.6 C) above normal, the 4th warmest April since records began in 1877. Phoenix reported an average temperature of 75.3 F (24.1 C), 2.6 F (1.4 C) above normal and the 8th warmest April in an 85-year record. Areas east of the Rockies were generally within 2 F (1 C) of normal with scattered locations reaching 2-4 F (1-2 C) above normal. April was warmer and drier than normal across Alaska. Stations north of the Arctic Circle experienced the greatest temperature departures from normal; Kotzebue reported an average temperature of 24.3 F (-4.3 C), 11 F (6.1 C) above normal. This was the 3rd warmest April since records began in 1897. In the southern part of the state, Anchorage observed an average temperature of 40.4 F (4.7 C), 3.6 F (2 C) above normal and the 4th warmest April in a 66-year record. April is typically a dry month in Alaska, and this year was no exception. Anchorage received 0.4 in (10 mm), which was 85% of normal. Kodiak was the only long-record station with above normal precipitation at 7.35 in (187 mm), 127% of normal. The breakup of ice on various Alaska rivers typically occurs in April, and this year’s breakups were within a few days of normal. Further south, above normal temperatures were observed at most reporting stations across the state of Hawaii; departures from normal were typically 1-2 F (0.5-1 C). Hilo recorded an average April temperature of 74.2 F (23.4 C), 2 F (1 C) above normal and the 6th warmest since records began in 1949. Precipitation was variable across the state, though most stations on Oahu and several on Maui reported above normal rainfall. Kahului recorded 7.77 in (197 mm), 501% of normal and the 4th wettest April in a 113-year record. Much of Big Island observed drier than normal conditions; 5.08 in (129 mm) of rain fell at Hilo, 44% of normal. The leeward side of the Big Island saw a small area of drought improvement, while abnormally dry conditions were introduced across the rest of the islands. Central Maui and western Molokai were classified as moderate drought this month. April 6-8: Strong late season storm impacted West Coast: High winds (60+ mph/97 kph) downed trees and power lines in northern California and western Oregon, causing temporary power outages for thousands of households. One death was reported in Oregon due to a falling tree. Heavy rainfall associated with this storm initiated a landslide near Oakland, California, destroying three homes. Snowfall of 12+ in (30 cm) was observed in the Sierra Nevada. April (all month) landslides cause/threaten damage in West: Saturated soils due to the above average wet winter have primed western soils for landslides. A series of large landslides caused closure of Highway 101 in Mendocino County, California. In Washington, geologists are tracking a slow-moving landslide near Oso. This event prompted temporary closure of a state highway and officials have recommended evacuation for several homes.