WEEKLY CLIMATE NEWS

20-24 August 2018

ITEMS OF INTEREST

• Investigating the history of weather data -- NOAA's National Centers for Environmental Information (NCEI) maintains a Historical Observing Metadata Repository (HOMR) that is designed to help researchers as well as the public get a better understanding of the weather records archived by NCEI from around the world. In this case, metadata are data providing information about other data, such as weather and climate data obtained from observations. HOMR contains accessible records of historical names, identifiers, locations, observation times, and equipment for stations not only in the United States, but for many other participating nations. [NOAA NCEI News]
• Online tool is available to assess daily weather records -- NOAA's National Centers for Environmental Information (NCEI) has a readily accessible Daily Weather Records Data Tool that provides summaries of recent global and U.S. daily weather records with options to view monthly, annual, all-time, or selected records. This tool, which provides insight into recent weather and climate behavior, analyzes maximum and minimum temperature, precipitation and snowfall records from a selected set of weather observing stations in NCEI's Global Historical Climatological Network. [NOAA NCEI News]
• Understanding the meaning of sea level and its changes -- NOAA has a five-part Explainer feature that defines several terms used to describe sea level (global sea level, local sea level and mean sea level). Knowledge of these terms is important for answering several questions that involve measurement of sea level, the changes in sea level, relating sea level changes with a changing climate and in how changes in sea level would affect the public. [NOAA News]

CURRENT CLIMATE STATUS

• July 2018 weather and climate for the nation reviewed -- Scientists at the NOAA National Centers for Environmental Information (NCEI) recently reported on their analysis of preliminary weather data collected during the month of July 2018. The average temperature for the contiguous US during July was 75.5 degrees F, or 1.9 Fahrenheit degrees above the 20th century (1901-2000) average. Therefore, July 2018 was the eleventh warmest July since comprehensive nationwide temperature records began in 1895. Ten of the 48 contiguous states along the West Coast and over the Southwest reported average monthly temperatures that were above to much above-average for July. California experienced its hottest July on record. The six New England States and New York State had statewide average temperatures for this past month that ranked in the top ten on record for their respective states. Above average temperatures were also reported across the Middle Atlantic States, sections of the Midwest and the Gulf Coast. Only Nebraska reported a statewide July temperature that was below average. Sixteen states stretching from Montana southeastward to the Carolinas had near-average temperatures.
  The average maximum (or daytime) temperature for July 2018 across the "Lower 48 States" was the 19th highest on record, while the average minimum (or nighttime) temperature for the month was the eighth highest since 1895.
  Alaska was unseasonably warm in July, with a statewide average temperature that tied 2016 for the fifth highest since statewide records began in 1925.
  The nationally-averaged July precipitation total across the contiguous United States was 2.80 inches (or 0.02 inches above the 20th century average), which made July 2018 the 60th driest (or 65th wettest) July in the 124-year record. Four states across the Northwest reported below to much below monthly statewide totals, with Idaho having its sixth driest July. Below average July precipitation totals were also reported for states in the nation's midsection, stretching from Wisconsin and Michigan southward to Alabama and Arkansas. On the other hand, six states west of the Mississippi River and nearly all the states along the Atlantic Seaboard reported above to much above-average July rainfall. Pennsylvania experienced its wettest July on record, while Maryland had its second wettest July in the 124-year period of record.
  Alaska had a statewide precipitation total for July 2018 that was the 22nd smallest since reliable statewide records began in 94 years ago.
  [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]
• July national drought report -- The National Centers for Environmental Information has posted its July 2018 drought report online. Using the Palmer Drought Severity Index, approximately 25 percent of the contiguous United States experienced severe to extreme drought conditions at the end of July, while eight percent of the area had severely to extremely wet conditions.

CLIMATE FORECASTS

• New Seasonal Climate Outlooks for fall issued -- Near the end of last week, forecasters at the NOAA Climate Prediction Center (CPC) released their new national Three-Month (Seasonal) Climate Outlooks new three-month seasonal national climate outlooks for September through November 2018, corresponding to the meteorological autumn season (in the Northern Hemisphere). Specific details of their outlooks include:
  • Temperature and precipitation outlooks -- According to their temperature outlook, nearly all of the 48 contiguous United States along with Alaska should have a better than even chance of experiencing above average temperatures for the upcoming three months of autumn. The regions with the best chances for warmer than normal conditions would be across the Four Corners region of the Southwest, the Northeast (New England and New York State) and northwestern Alaska. Only the Southeast, which includes Florida, Alabama and Georgia, could have equal chances of either above or below average autumn temperatures.
    Their precipitation outlook calls for better than even chances of wetter than average conditions for the autumn of 2018 across the Southwest, extending from Arizona northward across Utah, along with sections of the Southeast, centered upon the Florida Peninsula. Alaska could also have a better than average change of having above average precipitation. Conversely, the Pacific Northwest, primarily along the coast of Washington and Oregon, could have good chance of having below average precipitation through November. The rest of the 48 contiguous states should have equal chances of below and above average autumnal precipitation.
    A summary of the prognostic discussion of the 3-month outlook for non-technical users is available from CPC. These forecasts were based in part in the assessment that the current ENSO-neutral conditions (meaning no significant El Niño or La Niña event were occurring) should continue through the next several months. However, the chances for formation of an El Niño have increased from previous forecasts. On the other hand, a weak La Niña was also possible. A description is also provided as how to read these 3-class, 3-month Outlook maps.
  • Seasonal Drought Outlook -- The forecasters at NOAA's Climate Prediction Center also released their US Seasonal Drought Outlook last week that would run from late-August through November 2018. Their outlook would call for persistence of drought conditions across the Northwest, sections of California, the Great Basin, the northern Rockies of western Montana, the southern Plains (especially across Texas) and the northern Plains (eastern Montana eastward to northwestern Minnesota). The interior Northwest could see development of drought or expansion of current drought conditions. A large area of the Southwest, centered upon the Four Corners, and sections of the lower Missouri and mid-Mississippi Valley in the nation's midsection could experience some improvement in drought conditions, with some areas possibly seeing elimination of drought conditions. Upstate New York also could have the removal of drought during this autumn.
    Note: a Seasonal Drought Outlook Discussion is included describing the forecasters' confidence in their Drought Outlook.

CLIMATE AND THE BIOSPHERE

• Sections of south Florida experienced harmful algal blooms this summer -- A meteorologist with NOAA's Climate Prediction Center posted an "Event Tracker" blog on the ClimateWatch Magazine describing the numerous blooms of toxin-producing algae that exploded in both fresh and salt water ecosystems across many sections of southern Florida during July and August 2018. Blue-green algae exploded across freshwater water bodies, such as Lake Okeechobee, while large bloom of Karenia brevis algae created a "red tide" at various locations along the Gulf Coast of southwestern Florida. He noted that these harmful algal blooms resulted in dead wildlife and negative impacts on the people and communities that rely on those ecosystems. The blue-green algae was the result of hot summer weather and abundant rainfall causing large concentrations of phosphorus and nitrogen derived from fertilizer to runoff into the lakes. The incidence of "red tide" is due in part to warmer Gulf waters and to other factors including coastal upwelling. He mentions that harmful algal blooms may be increasing with a changing climate, citing a recent study reporting that the number of days of a cyanobacteria bloom across the U.S. would likely increase from a current average of seven days per year to 16-23 days by 2050 and 18-39 days by 2090. [NOAA Climate.gov News]

CLIMATE AND SOCIETY

• Earthweek -- Diary of the Planet [earthweek.com].

• 22 August 1816...The growing season for corn was cut short as damaging frosts were reported from North Carolina to interior New England in the "Year-without-a-Summer". (David Ludlum)
• 22 August 1976...The temperature soared to record high for Newfoundland: with a 98.1-degree reading at Botwood. (The Weather Doctor)
• 24 August 1906...The maximum 40-minute rainfall record for the U.S. was set with 9.25 inches at Guinea, VA. (National Weather Service files)
  
• 24 August 1992...Hurricane Andrew slammed into south Florida, devastating the community of Homestead with 181-mph winds. With a central pressure at landfall of 922 millibars (27.22 inches of mercury), which at the time was the third lowest ever recorded in a hurricane at landfall in the United States. Camille (1969) and the Labor Day Hurricane (1935) were more intense. In 2005, Hurricane Katrina became the third most intense land-falling hurricane with a 920-millibar pressure reading (or 27.17 in Hg) when it reached the Louisiana Gulf Coast. (The Weather Doctor)
• 25 August 1910...The temperature at Bowen, MT dropped to 5 degrees, the lowest ever for the 48 states in August. (Intellicast)
• 25 August 1940...New Jersey experienced its coldest August morning of record, with lows of 32 degrees at Layton and Charlotteburg. (The Weather Channel)
• 25 August 1987...A new record for monthly rainfall was set at Chicago when a storm brought the total to 15.73 inches erasing the previous record for any month, which had been 14.17 inches in September, 1961. (Storm Data) (Intellicast)
• 26 August 1883...Krakatoa Volcano exploded in the East Indies. The explosion was heard more than 2500 miles away, and every barograph around the world recorded the passage of the air wave, up to seven times. Giant waves, 125 feet high and traveling 300 mph, devastated everything in their path, hurling ashore coral blocks weighing up to 900 tons, and killing more than 36,000 persons. Volcanic ash sent into the stratosphere was carried around the globe in thirteen days producing blue and green suns in the tropics, and then vivid red sunsets in higher latitudes. The temperature of the Earth was lowered one degree for the next two years, finally recovering to normal by 1888. (David Ludlum)
• 26 August 1935...San Francisco, CA had their heaviest 24-hour rainfall for August when 0.25 inches fell. (Intellicast)
• 26 August 1989...Anchorage, AK was soaked with a steady rain, and the 24-hour total of 4.12 inches smashed their previous 24-hour precipitation total of 2.10 inches. It also pushed their rainfall total for the month past their previous record for August. (The National Weather Summary)

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Prepared by Edward J. Hopkins, Ph.D., email hopkins@aos.wisc.edu
© Copyright, 2018, The American Meteorological Society.