WEEKLY CLIMATE NEWS

18-22 May 2015

DataStreme Earth Climate System will return for Fall 2015 with new Investigations files starting during Preview Week, Monday, 24 August 2015. All the current online website products will continue to be available throughout the summer break period.

ITEMS OF INTEREST

Zenithal Sun -- This week marks one of the two times during the year when the noontime sun is directly overhead to residents on the Big Island at the start of this week (on 19 May) at Hilo; those on Oahu (Honolulu metropolitan area) will experience the noon sun at the zenith in approximately one more week (25-27 May). The sun will again be over the Big Island during the last week of July. [US Naval Observatory, Data Services]
National Heat Awareness Day -- The National Weather Service along with other national partners has declared this coming Friday, 22 May 2015, as Heat Awareness Day across the nation. Local NWS Weather Forecast Offices will also hold Heat Awareness Days, but not necessarily at the same time as the week recognized by national partners. For more information consult the Weather Preparedness Events Page and the National Weather Service's webpage entitled "Heat: A major killer." Attention is directed to the cases where deaths of small children have been left unattended in closed vehicles.
Climatology of Indy 500 Race Day-- Next Sunday, 24 May 2015, is the scheduled running of the 99th Indianapolis 500-Mile Race. The Indianapolis Forecast Office of the National Weather Service has a list of the pertinent weather and climate statistics for race day, including the average high and low temperatures, rainfall and wind for the 1911-2014 period and a listing of the top 20 temperature, precipitation and wind extremes for the previous races.
North American Safe Boating Week -- This week of 16-22 May has been declared 2015 National Safe Boating Week, to help kick off the 2015 North American Safe Boating Campaign. Check the Safe Boating Week site maintained by the Safe Boating Council.

CURRENT CLIMATE STATUS

National weather and climate reviewed for April 2015 -- Scientists at the NOAA National Climatic Data Center (NCDC) reported that their analysis of preliminary April 2015 data indicates the monthly average temperature for the 48 coterminous states was 2.1 Fahrenheit degrees above the 20th-century (1901-2000) average, which made this past month the 17th warmest April since 1895 when comprehensive climate records became available nationwide. In addition, the nationwide maximum or daytime temperature was 2.3 Fahrenheit degrees above the long-term average (or 22nd highest on record), while the nationwide minimum or nighttime temperature was 1.9 Fahrenheit degrees above average, (or 15th highest since 1895.) More than half of the 48 contiguous states (34) reported above to much above average April statewide average temperatures. Florida experienced its highest statewide average temperature in the 121-year period of record, while the April 2015 statewide temperatures for South Carolina and Georgia were within the highest ten April temperatures on record. Alaska experienced its eleventh warmest April since sufficiently dense weather records began in 1925.
Monthly precipitation across the lower 48 states for April 2015 was approximately 0.26 inches above the 20th-century monthly average, which made this month the 37th wettest April on record. States across the Ohio Valley, the Southeast and the Gulf Coast reported above to much above average statewide precipitation for the month. In the Ohio Valley, Kentucky had its second wettest April in 121 years, while West Virginia experienced its fourth wettest April. In the lower Mississippi Valley and Gulf Coast, April 2015 was the ninth wettest on record. Conversely, states along the West Coast and across the northern Rockies, the northern Plains and the Upper Midwest had below to much below average statewide precipitation totals for April. South Dakota experienced its 11th driest April since 1895. States in the Northeast also reported below average precipitation totals. Alaska had its eleventh wettest April on record.
According to the Rutgers Global Snow Lab, the snow cover extent across the contiguous US for the month of April 2015 was the tenth smallest April snow cover extent in the 49-year period of record. However, above-average April snow cover was reported across sections of the northern Rockies and the Northeast. Alaska had its seventh smallest April snow cover on record.
[NOAA NCDC State of the Climate] NOTE: A description is provided of the climatological rankings employed by NCDC for their monthly and seasonal maps. [NOAA/NCDC]
April national drought report -- The National Climate Data Center has posted its April 2015 drought report online. Using the Palmer Drought Severity Index, approximately 13 percent of the contiguous United States experienced severe to extreme drought conditions at the end of April, while four percent of the area had severely to extremely wet conditions.

CURRENT CLIMATE MONITORING

Antarctica's Larsen B Ice Shelf seen to be disintegrating -- Scientists from NASA's Jet Propulsion Laboratory, the University of California, Irvine and Norway's University Centre in Svalbard have been monitoring Antarctica's weakening Larsen B Ice Shelf using data collected by instrumented aircraft participating in NASA's Operation IceBridge. They predict that the last remaining section of this Ice Shelf is likely to disintegrate completely before the end of the decade. [NASA Jet Propulsion Laboratory News]
The elusive "tropospheric hot spot" is found -- Scientists at Australia's University of New South Wales (UNSW Australia) have confirmed that strong warming is occurring in a region of the upper levels of the Earth's troposphere dubbed the "tropospheric hot spot." This phenomenon was long predicted in global warming theory and in global climate models. The researchers based their findings upon analysis of the temperature and wind data set of the upper troposphere obtained from radiosonde observations extending from 1958-2012. In addition, the researchers found a ten percent increase in winds over the Southern Ocean, which may be related to ozone depletion in the stratosphere. [UNSW Australia Newsroom]

CLIMATE FORCING

Antarctic ice shelf found to be thinning from above and below -- Using data collected by satellites and eight radar surveys over a 15-year interval from 1998 to 2012, scientists from the British Antarctic Survey and their colleagues from the United States have found that Antarctica's Larsen C Ice Shelf is thinning from both its surface and beneath. This new study helps in assessing Antarctica's likely contribution to future sea-level rise. [British Antarctic Survey Press Release]
Varying strength of a volcanic eruption attributed to gaseous state within volcanic conduits -- Researchers from the United Kingdom's University of Plymouth and their colleagues from other institutions claim that the varying scale and intensity of several volcanic eruptions are directly influenced by the distribution of gases within magma inside the volcano's conduit. The researchers used high-tech equipment including UV cameras and electron microscopes to analyze the eruptive plumes and ash generated by Mexico's Volcán de Colima, considered to be one of the most active volcanoes in the Americas. [University of Plymouth News]
Reduced ozone levels in Houston metro area helped by changing climate -- Researchers at the University of Houston claim that the observed drop in high-ozone days in the Houston (TX) metropolitan area could be attributed to a changing climate that created higher soil temperatures along the Gulf Coast that then resulted in a stronger sea breeze that reduced low-level ozone levels. Their research was based upon 23 years of ground-level zone data collected by the Texas Commission on Environmental Quality and meteorological data from NOAA. The researchers suggest that these changes in low level ozone associated with climate change also should be true for coastal regions globally. [University of Houston News]

CLIMATE FORECASTS

An El Niño event has developed across the Pacific -- Above average sea surface temperatures across the equatorial Pacific as of early May 2015 together with corroborating atmospheric response indicates that a weak to moderate El Niño event is underway. Forecasters with NOAA's Climate Prediction Center have issued an El Niño advisory that indicates atmospheric and oceanic conditions across the tropical Pacific appear favorable for an El Niño event in the next six months. These forecasters foresee that an approximately 90 percent chance that this El Niño event would continue through the Northern Hemisphere summer of 2015, together with an 80 percent chance that it will last through the remainder of 2015. [NOAA Climate.gov News] A detailed El Niño/Southern Oscillation Diagnostic Discussion with supporting maps and charts is available from CPC.
Improving water supply forecasts are being made for the Rio Grande watershed -- Scientists at the National Center for Atmospheric Research (NCAR) and their colleagues at partner agencies at local, state and federal levels are attempting to improve the measurement of the amount of water available from snowpack in the sections of the southern Rockies lying in the Rio Grande watershed in an effort to improve their water supply forecasts for that river basin. [NCAR/UCAR AtmosNews]

CLIMATE MODELING

Research designed to help forecast bad ozone days across the West --Researchers at NOAA's Geophysical Fluid Dynamics Laboratory recently reported that a strong connection appears between high ozone days in the western United States during late spring and LaNiña, the cold phase ocean-atmosphere phenomena that affects global weather patterns. This link would provide an opportunity to forecast low-level ozone intrusions several months in advance, which could improve public education to reduce health effects as well as help air quality managers across the West prepare to track these events, which can have implications for attaining the national ozone standard. [NOAA Oceanic and Atmospheric Research News]
"Landfall drought" in major land falling hurricanes on US coasts reaches a record -- A hurricane researcher with NASA's Goddard Institute for Space Studies and his colleagues report that the nine-year span that encompasses the time since the last major hurricane (category 3 or larger on the Saffir-Simpson Scale) to make landfall along the mainland of the United States in 2005 represents the longest interval since reliable hurricane records began in 1850. Statistical analyses from hurricane track data indicate that for any particular Atlantic Hurricane season, a 40 percent chance exists that a major hurricane will make landfall in the continental United States. The researchers found that a nine-year period without a major landfall would likely occur once every 177 years on average. [NASA Goddard Space Flight Center]

CLIMATE AND SOCIETY

Tactics and strategies identified to improve drought science, forecasts and data products -- Early last week NOAA released its "NOAA California Drought Service Assessment" that identifies tactics and strategies the agency can take to better provide California decision makers with the scientific data and tools they need to lessen the impacts of extreme drought. This service assessment was followed the solicitation of feedback from more than 100 stakeholders and employees. [US Drought Portal News]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Historical Events:

18 May 1960...Salt Lake City, UT received an inch of snow, marking their latest measurable snowfall of record. (The Weather Channel)
18 May 1980...Mount St. Helens in Washington State erupted, ejecting smoke and ash to a height of 63,000 feet. The smoke plume rose to a height of 80,000 feet. The ground was covered with heavy ash to the immediate northeast and visibility was reduced to less than one mile for a downwind distance of 400 miles. Five deaths were caused and over 2000 people were evacuated due to mudslides and flooding when the snowpack melted. Small particles in the cloud reached the East Coast in 3 days and circled the world in 19 days. (David Ludlum) (Intellicast)
19 May 1780...The infamous "dark day" in New England tradition occurred as noon was nearly as dark as night. Chickens went to roost, and many persons were fearful of divine wrath. Forest fires to the west of New England caused the phenomena. (David Ludlum)
19 May 1955...Lake Maloya, NM received 11.28 inches of rain in 24 hours to establish a state record. (The Weather Channel)
19 May 1962...An all-time May record was set when the temperature climbed to 99 degrees at Central Park in New York City. (Intellicast)
20 May 1996...Bridgeport, CT soared to 97 degrees for its highest temperature on record in May. (Intellicast)
21 May 1895...The temperature at Norwalk, OH dipped to 19 degrees to set a state record for the month of May. (The Weather Channel)
21 May 1896...The mercury soared to 124 degrees at Salton, CA to establish an U.S. record for May. (Sandra and TI Richard Sanders - 1987)
21 May 1980...The temperature at Williston, ND reached 102 degrees to set a record for May, and the next day the mercury hit 106 degrees. (The Weather Channel)
22 May 1876...Denver, CO was drenched with 6.53 inches of rain in 24 hours, an all-time record for that location. (The Weather Channel)
22 May 1911...The temperature at Lewiston, ME soared to 101 degrees, the highest temperature ever recorded in New England during the month of May. (David Ludlum)
22 May 1922...The United Kingdom recorded its hottest May day on record when the thermometer hit 91 degrees at Camden Square, London, England. (The Weather Doctor)
22 May 1980...The temperature at Winnipeg, Manitoba rose to 98.6 degrees, setting a record high for May. (The Weather Doctor)
23 May 1953...The temperature at Hollis, OK soared from a morning low of 70 degrees to an afternoon high of 110 degrees, to establish a state record for the month of May. (The Weather Channel)

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