WEEKLY CLIMATE NEWS

17-21 September 2018

ITEMS OF INTEREST

September is National Preparedness Month -- The month of September has been declared National Preparedness Month (NPM), which is aims to educate and empower Americans to prepare for and respond to all types of emergencies, including natural disasters. NPM is managed and sponsored by the Federal Emergency Management Administration's (FEMA) Ready Campaign in conjunction with the Ad Council. A toolkit of marketing materials is provided to help promote the month and represents the lead on this campaign that was originally launched in 2004. The overarching theme for 2018 NPM is "Disasters Happen. Prepare Now. Learn How" with an emphasis on planning. Week 3 of the 2018 NPM ends this Saturday (22 September) with the theme of "Check Your Insurance Coverage."
Week 4 of the 2018 NPM (23-29 September) has the theme "Save For an Emergency." [FEMA's Ready.gov]
Free admission into the National Parks -- Next Saturday, 22 September 2018, has been designated by the National Park Service as fee-free day in honor of National Public Lands Day, which is celebrated annually at public lands across the nation on a Saturday in late September. This fee waiver will cover entrance and commercial tour fees in many of the national parks and monuments administered by the Park Service. [National Park Service Fee Free Days] Coincidently, this year represents the 25th anniversary of National Public Lands Day as well as the 50th anniversary of the National Trails System and National Wild & Scenic Rivers System. [National Environmental Education Foundation] [National Trails System] [National Wild & Scenic Rivers System]
The Autumnal Equinox --The Autumnal Equinox will occur early this coming Saturday evening (officially at 0154Z on 23 September 2018 or 9:54 PM EDT or 8:54 PM CDT, etc. tonight, on the 22nd). At that time the noontime sun will appear directly above the equator, representing one of the two times during the year for such an occurrence, with the other being at the vernal equinox in March. The term "equinox" arises from the fact that this time of year represents "equal night" and equal day essentially everywhere. Within the subsequent several days, the length of daylight will become noticeably shorter. This decrease in daylight will continue for another three months to the winter solstice during the late afternoon of Friday, 21 December 2018.
Editor's note: John White, a meteorologist from North Carolina involved with the AMS Education program, reported that the geosynchronous (or geostationary) satellites make an "satellite eclipse" of the sun near the spring and autumnal equinoxes because of their equatorial orbit, such that these satellites pass through the earth's shadow and the satellite is powered down when the solar array does not receive sufficient sunlight. EJH.
If you check the sunrise and sunset times in your local newspaper or from the climate page at your local National Weather Service Office, you would probably find that early next week the length of time when the Sun is above the local horizon would be precisely 12 hours at most locations. By the end of next week, the length of night will exceed that of the length of daylight. The effects of atmospheric refraction (bending of light rays by the varying density of the atmosphere) along with a relatively large diameter of the sun contribute to several additional minutes that the Sun appears above the horizon at sunrise and sunset.
September is National Preparedness Month -- The month of September has been declared National Preparedness Month (NPM), which aims to educate and empower Americans to prepare for and respond to all types of emergencies, including natural disasters. NPM is managed and sponsored by the Federal Emergency Management Administration's (FEMA) Ready Campaign in conjunction with the Ad Council, A toolkit of marketing materials is provided to help promote the month and represents the lead on this campaign that was originally launched in 2004. The overarching theme for 2017 NPM is "Disasters Don’t Plan Ahead. You Can.," with an emphasis on preparedness for youth, older adults, and people with disabilities and others with access and functional needs.
Week 3 of the 2017 NPM (17-23 September) the theme is "Practice and Build Out Your Plans."
[FEMA's Ready.gov]
Fall coloration -- By mid-September, deciduous trees begin to turn color across the nation, starting first across the higher elevations of New England and the Rocky Mountains, followed quickly across sections of the upper Midwest. During autumn, the peak in fall color progresses southward and toward lower elevations. Some locales hold events in an effort to welcome tourists who come as "leaf peepers." The Department of Agriculture's U.S. Forest Service maintains a Fall Colors Web page containing fall foliage status updates for National Forests across the continental United States. Additional information is also available through the tourism bureaus of the various states; links to some of these state sites are available from this Forest Service web page.
[Editor's Note: An interesting explanation of fall coloration can be found in The Chemistry of Autumn Colors from "Science is Fun in the Lab of Shakhashiri" from a popular chemistry professor at the University of Wisconsin-Madison. EJH]
Monitoring the seasonal motions of the sun -- If you would like more background information concerning how the sun appears to across your local sky, along with the times of local sunrise and local sunset, for your hometown on any day throughout year, please read this week's Supplemental Information...In Greater Depth.

CURRENT CLIMATE STATUS

US national weather and climate reviewed for August and Summer 2018 -- Based upon preliminary data, scientists at NOAA's National Centers for Environmental Information (NCEI) report that August 2018 was the 17th warmest August across the contiguous United States since sufficiently reliable climate records began in 1895. The nationwide August 2018 average temperature was 73.6 degrees Fahrenheit, which was 1.5 Fahrenheit degrees above the 20th-century (1901-2000) average. The average maximum (or daytime) temperature for the "Lower 48 States" was the 33rd highest of record. Likewise, the average minimum (or nighttime) temperature for these states was the ninth highest value for August in 124 years. The majority (32) of the contiguous states reported statewide average August temperatures that ranged from above to much above average temperatures. Four New England States (Connecticut, Massachusetts New Hampshire and Rhode Island) and Delaware experienced their highest August temperatures in the 124-year period of record. Neighboring states, stretching from the Middle Atlantic to Michigan had temperatures that were in the top ten for each state's record. In the Southwest, Arizona, California, Nevada and Utah also top ten August temperature records. On the other hand, Kansas and Nebraska were the only two states to report below average August temperatures.
Alaska had its 41st warmest August since 1925.
The recently concluded meteorological summer of 2018 (June, July and August) tied the summer of 1934 as the fourth warmest summer since 1895, with a three-month average temperature of 73.5 degrees, which was 2.1 Fahrenheit degrees above the 20th century average. Forty-seven of the "Lower 48 States" had statewide average summer temperatures that were above- or much-above the long-term average; only Nebraska had a statewide summer temperature close to average. Utah and Rhode Island had their warmest summers in 124 years. The average maximum (daytime) temperature across the "Lower 48 States" for summer 2018 was eleventh highest on record, while the average minimum (nighttime) temperature was the highest on record, breaking the record previously set in 2016. According to NCEI, summer overnight low temperatures across the contiguous U.S. have been increasing since 1895 at a rate nearly twice that as afternoon high temperatures.
Alaska had its 17th warmest summer in 94 years.
The nationwide August 2018 average precipitation was 2.99 inches, which meant that this month tied August of 1979 and 2005 for the twentieth wettest August in 124 years. Many of the states across the eastern half of the nation had above-to much above-average statewide monthly precipitation totals. Arkansas, Indiana, Iowa, Massachusetts, New Hampshire, New York State, Pennsylvania and West Virginia had statewide precipitations that ranked within the top twelve on record for their respective states. Conversely, five states across the West had below-average precipitation totals. California reported its tenth lowest precipitation total on record.
Alaska had its fourth wettest August since 1925.
The nationwide summer (JJA) 2918 precipitation was 0.63 inches above the 1901-2000 average, which was makes this past summer the twenty-fifth wettest across the "Lower 48 States" since 1895. Nearly two dozen states had statewide summer precipitation totals that were above to much above average. Most of these states where in the northeastern quarter of the nation. Pennsylvania experienced its wettest summer on record. On the other hand, ten states had below to much below average summer rainfall. Many of these states were across the West. The state of Washington reported its eleventh driest summer since 1895.
Alaska reported its eleventh wettest summer since 1925. [NOAA/NCEI State of the Climate] NOTE: A description is provided of the climatological rankings employed by NCEI for their monthly and seasonal maps. [NOAA/NCEI]
August national drought report -- The National Centers for Environmental Information posted its August 2018 drought report online. Using the Palmer Drought Severity Index, approximately 23 percent of the coterminous United States experienced severe to extreme drought conditions at the end of August, while 10 percent of the area had severely to extremely wet conditions.
Describing changes in nation's September climate since 1895 -- A contractor with NOAA's Climate Program Office wrote a feature blog for the ClimateWatch Magazine in which she describes how the September climate across the contiguous U.S. has changed since 1895. She provided a plot of the time-series of the nationwide September monthly temperatures for the last 123 years showing this temperature has increased with an average trend of +0.86 Fahrenheit degrees per century. Interestingly, when considering the nation's meteorological autumn temperature (September through November), the average trend is larger at +1.16 Fahrenheit degrees per century, while that for the entire year is even greater at +1.51 Fahrenheit degrees per century. She also showed a map of the changes in September temperatures across the contiguous U.S. since 1895, which featured warming across most Western States by as much as 2 Fahrenheit degrees, while sections of the Mid-South had cooling, with a lowering of the temperature by as much as 1 Fahrenheit degree. [NOAA Climate.gov News]
El Niño/Southern Oscillation (ENSO) Diagnostic Discussion -- NOAA's Climate Prediction Center (CPC) and the International Research Institute for Climate and Society (IRI) recently released their El Niño/Southern Oscillation (ENSO) Diagnostic Discussion that showed ENSO-neutral conditions in both the oceans and atmosphere were observed during the month of August 2018, meaning that neither an El Niño or La Niña event was underway. A blend of slightly below- to slightly above-average sea surface temperatures (SST) was found across the central and eastern equatorial Pacific during this past month. Near-surface winds were from the west over the western and east-central equatorial Pacific. Convection returned to near average levels near the Dateline and over Indonesia. Most of the available forecast models indicate a transition from ENSO-neutral to weak El Niño conditions during this Northern Hemisphere meteorological autumn (September-November), with a continuation through the Northern Hemisphere's 2018-19 winter (December-February). Consequently, forecasters at CPC are continuing their El Niño Watch, which indicates a 50 to 60 percent chance of El Niño developing during the Northern Hemisphere fall, along with the chance of El Niño increasing to between 65 and 70 percent during winter 2018-19. An ENSO blog written by a CPC contractor describes in relatively plain terms the ENSO-neutral conditions that continued into early September and why her colleagues at CPC decided to post a El Niño watch for the upcoming autumn and winter months. [NOAA Climate.gov News]
A detailed and more technical El Niño/Southern Oscillation Diagnostic Discussion with supporting maps and charts is available from CPC.
Forecasters with the Australian Bureau of Meteorology recently issued an updated ENSO forecast from a Southern Hemisphere perspective. They reported continuation of ENSO-neutral conditions. However, based upon the outlook model outputs and current conditions, they foresee the possible onset of El Niño conditions by the end of the calendar year of 2018, which corresponds to Southern Hemisphere summer. Therefore, they have set their Bureau's ENSO Outlook to El Niño WATCH, meaning an approximately 50 percent chance of El Niño formation. [Australian Government Bureau of Meteorology]

CURRENT CLIMATE MONITORING

Claim that "global warming stopped in 1998" is refuted -- A contractor with NOAA's Climate Program Office recently posted a discussion on the Climate Q&A blog for the ClimateWatch Magazine showing that the global temperature dataset shows that the rise in global temperature between 1998 and 2012 was slower than the temperature rise during the two previous 15-year periods, refuting the claim by some that "global warming stopped in 1998," which was also termed a "hiatus" in the warming. In fact, the temperature increase of 0.14 Fahrenheit degrees per decade during this recent 1998-2012 interval was nearly identical to the global average surface temperature rate of increase by 0.13 Fahrenheit degrees per decade since 1880. The slight slowdown in the recent warming from the three preceding decades could be attributed to natural variability in the Pacific Ocean associated with El Niño and La Niña events; recent solar cycles that were atypical; and recent volcanic eruptions that emitted sun-reflecting airborne particles. [NOAA NCEI News]
Monetary awards made to advance community resilience to weather and climate hazards -- Nine new projects in eight states and the U.S. Virgin Islands will receive a total $3 million from NOAA's Environmental Literacy Program to use in build the foundation for resilience to weather and climate hazards through education. This year marks the fourth year that NOAA's Office of Education is funding community resilience projects through its Environmental Literacy Program. [NOAA News]

CLIMATE AND SOCIETY

Monetary awards made to advance community resilience to weather and climate hazards -- Nine new projects in eight states and the U.S. Virgin Islands will receive a total $3 million from NOAA's Environmental Literacy Program to use in build the foundation for resilience to weather and climate hazards through education. This year marks the fourth year that NOAA's Office of Education is funding community resilience projects through its Environmental Literacy Program. [NOAA News]
Major UN climate change initiative supported by the World Meteorological Organization -- The World Meteorological Organization (WMO) Secretary-General was in recently at the United Nations (UN) in New York to provide scientific support for a major policy statement made by the UN Secretary General and to stress WMO's commitment to the UN Secretary General's vision of raising ambition for climate action in support of the Paris agreement and the 2030 development Agenda. A climate summit will be convened in September 2019 to address climate change. [WMO News]
Earthweek -- Diary of the Planet [earthweek.com]

Concept of the Week: Developing a Quality Long-term Instrumental Climate Record

Systematic temperature and precipitation observations have been made at various locations across the nation for nearly two centuries. While only a handful of stations were available in the early 19th century, weather and climate observations currently are made from several hundred automatic weather sites operated by the National Weather Service and the Federal Aviation Administration as well as approximately 8000 stations in the Cooperative Observers Network administered by the National Weather Service. The weather data from these networks are also used to quantitatively assess changes of climate during the instrumental period of the past as well into the future. However, a variety of factors can affect the homogeneity of the record. For example, the locations of many of the stations have moved, from original downtown building roofs to current locations at airports. And the physical surroundings of the stations have changed, many becoming more urbanized.

In the late 1980s, the National Climatic Data Center (NCDC), the predecessor to the National Centers for Environmental Information (NCEI), in conjunction with the US Department of Energy's Oak Ridge National Laboratory created the United States Historical Climatology Network (USHCN) of 1218 stations across the 48 coterminous states having long-term records of both daily temperature and precipitation. This network was designed to provide an essential baseline data set for monitoring the nation's climate commencing in the late 19th century. These stations were created from a subset of the Cooperative Observers Network, chosen based upon long-term data quality that included length of record, percent of missing data, spatial distribution and number of station changes. Many of the selected USHCN stations were rural in an attempt to reduce the influence of urbanization. Using statistical analyses, data for these stations have been adjusted to account for movement of stations, or when a different thermometer type was installed. An urban warming correction was applied based upon population of the surrounding area.

More recently, NOAA began the US Climate Reference Network (USCRN), a project designed to collect and analyze climate data of the highest possible quality for the next 50 to 100 years. Each USCRN station would have electronic sensors that would make routine measurements of air temperature, precipitation, IR ground surface temperature, solar radiation and wind speed with a frequency of every five minutes and transmit these data to both NCDC and to National Weather Service offices via orbiting satellites on nearly a real-time basis. In addition to these measurements, additional sensors could be added to the USCRN stations that would measure soil temperature and soil moisture. Conscientious and detailed site selection was made for all stations so that they would not only be spatially representative, but that they would be in locations where the surrounding physical conditions would have a high likelihood of remaining the same over the next 50 to 100 years. Many of the sites were placed on federal or state-owned lands, helping minimize the contamination of the climate record by urbanization or other changes in local ground cover.

These long-term, comparative, spatially representative values are vital to detect and verify the subtle changes in climatic conditions before they become overwhelmingly obvious.

Historical Events:

17 September 1932...Westerly, RI received 12.13 inches of rain, which set a 24-hour precipitation record for the state. (NCDC)
17 September 1963...Nearly 2.5 inches of rain fell in 24 hours, the most intense rain for Yuma, AZ during the period between 1909 and 1977. (The Weather Doctor)
18 September 1991...2.4 inches of snow fell at Duluth, MN to set a new record for September. (Intellicast)
19 September 2004...The single-day rainfall record at Vancouver (British Columbia) International Airport was set 3.59 inches. The accumulation came in a month when rainfall is exceptional across the region. By mid-month, dozens of stations in British Columbia broke all-time September rainfall totals. (The Weather Doctor)
20-23 September 1942...A rainstorm deluged the Maritime Provinces. Four-day totals included 13.99 inches at Stellarton, Nova Scotia and 10.83 inches at Charlottetown, Prince Edward Island. Halifax, Nova Scotia recorded 9.40 inches of rain on the 21 September climatological day. (The Weather Doctor)
20 September 1967...Hurricane Beulah moved into South Texas, spawning a record 115 tornadoes for a hurricane. (David Ludlum) (Intellicast)
20 September 1973...Britain's greatest September daily rainfall floods Kent with 7.51 inches of rain. (The Weather Doctor)
22 September 1913...Des Moines, IA experienced their earliest freeze of record. (The Weather Channel)
22 September 1934...Edmonton, Alberta reported its greatest September snowstorm to date with 8.7 inches of snow. (The Weather Doctor).
23 September 1904...The temperature at Charlotteburg, NJ dipped to 23 degrees, the lowest reading of record for so early in the autumn for the Garden State. (The Weather Channel)

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