24-28 February 2020

Items of Interest:

• Becoming AWARE -- During this coming week (23-29 February 2020), Tennessee has scheduled its Severe Weather and Flood Preparedness Week. If you live in the Volunteer State, you should take time to become familiar with the various public affairs announcements issued by your local National Weather Service Office. Other states farther to the north will be observing their Severe Weather Awareness weeks in the next ten weeks.
• Early upper-air weather data were obtained from kites and aircraft -- NOAA's National Centers for Environmental Information (NCEI) posted a "Planet Postcard" that featured information about the upper-air observations program operated by the U.S. Weather Bureau (the predecessor to the National Weather Service) from the late 19th century. The weather data collected from tethered kites, aircraft observations and balloons are now achieved at NCEI. [NOAA NCEI News]
• An author reflects on significance of a sunken slave ship in a national marine sanctuary -- Michael Cottman, who is the author of the book entitled The Wreck of the Henrietta Marie, recently reflected on the significance of the sinking of the slave ship Henrietta Marie in the waters of the present-day Florida Keys National Marine Sanctuary and the ship's place in African American history. In 1992, Cottman was a member of a dive team that placed a memorial plaque on the seabed where the ship sank. Based upon his experiences with this event, he did extensive research into the slave trade that flourished between Africa and the Americas in the 16th through 18th centuries, which resulted in several books. The Henrietta Marie sank in the Florida Strait due to a possible hurricane in June 1700. [NOAA National Marine Sanctuaries News]
• Mardi Gras climatology -- Since Ash Wednesday, the beginning of the 40-day Lenten season observed by Christians, will begin on Wednesday (26 February), the day before (Tuesday, 25 February) is a day of celebration in many locations that is variously called Mardi Gras (French for Fat Tuesday) or Shrove Tuesday. One of the more famous Mardi Gras celebrations occurs each year in New Orleans, LA. The National Weather Service Forecast Office at New Orleans/Baton Rouge has a 2020 Mardi Gras Climatology that provides the normal temperatures and precipitation along with extremes for New Orleans during the Mardi Gras week prior to Ash Wednesday. Some additional statistics involving a listing of the weather history for each Mardi Gras in New Orleans extending back to 1874 are provided.
• Leap years and calendars -- This year (2020) is considered a "leap" year with 366 days with one additional day inserted at the end of February (the last month of the old Roman year). Since the Earth completes one orbit around the Sun in 365.2422 days, calendars based upon integer days must be adjusted every few years so that recognizable events, such as the occurrence of the vernal equinox, do not progress through the year. In the first century BC the Julian calendar was developed by Julius Caesar who decreed a calendrical reform with a 365-day year that involved the inclusion of an extra day to the end of February. However, over several centuries, the timing of the vernal equinox (and the Christian celebration of Easter) crept earlier by roughly 10 days. To correct this inconsistency, an additional reform was instituted by Pope Gregory XIII in 1572 that included the requirement that only those centurial years divisible evenly by 400 (e.g., 1600, 2000) would be leap years, while the other centurial years (e.g., 1800 and 1900) would not.
  The National Centers for Environmental Information (formerly National Climatic Data Center) recommends that the climate normals for 28 February be used also for 29 February in a leap year.
• A change in meteorological seasons -- Saturday, 29 February 2020, marks the end of meteorological winter in the Northern Hemisphere, which by convention, is the three-month interval of December, January and February. The following day (1 March 2020) represents the beginning of boreal meteorological spring, the three-month interval of March, April and May. At the same time, summer in the Southern Hemisphere ends and autumn begins.
• High-quality maps of March temperature and precipitation normals across US available -- The PRISM Climate Group at Oregon State University's website has prepared high-resolution maps depicting the normal maximum, minimum and precipitation totals for March and other months across the 48 coterminous United States for the current 1981-2010 climate normals interval. These maps, with a 800-meter resolution, were produced using the PRISM (Parameter-elevation Regressions on Independent Slopes Model) climate mapping system.
• March weather calendar for a city near you -- The Midwestern Regional Climate Center maintains an interactive website that permits the public to produce a ready to print weather calendar for any given month of the year, such as March, at any of approximately 270 weather stations around the nation. (These stations are NOAA's ThreadEx stations.) The entries for each day of the month includes: Normal maximum temperature, normal minimum temperature, normal daily heating and cooling degree days, normal daily precipitation, record maximum temperature, record minimum temperature, and record daily precipitation; the current normals for 1981-2010.
• Weekly Drought Monitor map is important to many interests -- The weekly U.S. Drought Monitor map that is posted each Thursday morning by the National Drought Mitigation Center at Lincoln, NE draws the attention from a wide variety of groups across the nation including water resource managers and those in agriculture such as farmers, ranchers and agribusiness. In addition, Federal bureaucrats also need to inspect the weekly maps as many programs operated by the government depend upon the drought level classifications to calculate aid for the various agricultural assistance programs. The drought intensity categories appearing on these maps are based upon objective analysis based upon five key indicators that are obtained from precipitation, air temperature and streamflow observations. A team of over one hundred drought specialists, state climatologists and other experts provide recommendations to refine the weekly analysis. [National Public Radio]

Weather and Climate News Items:

• Eye on the tropics ---During the last week several organized tropical cyclones were found over the waters of the Southern Hemisphere:
  • In South Indian Ocean
  • Tropical Cyclone Gabekile was traveling toward the south across the central South Indian Ocean over 900 miles to the south of Diego Garcia at the start of last week. At the time, Gabekile had reached peak intensity as a category 1 tropical cyclone on the Saffir-Simpson Scale with maximum sustained surface winds of 85 mph. Gabekile began weakening to a tropical storm as it curved toward the south-southwest last Monday and Tuesday. By Wednesday, Gabekile had become a tropical depression before becoming a remmant low. The NASA Hurricane Blog has additional information and satellite images for Tropical Cyclone Gabekile.
  • In the South Pacific Ocean
  • Tropical Storm Uesi was traveling to the southwest approximately 350 miles to the west of Port Vila, Vanuatu at the start of last week. By early Tuesday, Tropical Storm Uesi had strengthened to become a category 1 tropical cyclone (on the Saffir-Simpson Scale). Traveling to the south and then to the south-southwest, Uesi passed to the west of New Caledonia late on Tuesday. However, Uesi began to curve to the south and then south-southeast by the end of the week, heading for New Zealand's South Island. Eventually, Uesi lost its tropical characteristics and became an extratropical (midlatitude) system. Satellite imagery and additional information on Tropical Cyclone Uesi are available on the NASA Hurricane Blog.
  • A tropical disturbance developed last Wednesday near Samoa and intensified into a tropical depression. By late Thursday this system had strengthened to become Tropical Storm Vicky. At peak intensity on Friday, maximum sustained surface winds reached 50 mph. However, this tropical storm did not intensify further and became a remnant tropical cyclone by Saturday, little more than 24 hours after forming. Additional information on Vicky can be found on the NASA Hurricane Blog.
  • A tropical disturbance formed late last week to the north of the Territory of the Wallis and Futuna Islands. By early Saturday, this disturbance had organized into Tropical Cyclone 18P as it was approximately 325 miles to west-northwest of Pago Pago, American Samoa. This system strengthened and became known as Tropical Cyclone Wasi late Saturday. Over this past weekend, Wasi curved to take a path toward the southeast and then south-southeast as it passed to the west of Pago Pago and headed toward Niue. Torrential rains associated with Wasi and with Tropical Storm Vicky spread across the Samoan islands of Upolu and Savai'i. At peak intensity, Wasi was a strong tropical storm with maximum sustained surface winds reaching 65 mph late Saturday. As of early Monday, Wasi had weakened rapidly to a tropical depression as it was approximately 150 miles to the north-northwest of Niue. This system was expected to become a post-tropical cyclone on Monday, before approaching Niue on Tuesday. Consult the NASA Hurricane Blog for additional information on Tropical Cyclone 18P or Wasi.
  • In the Australian region:
  • A tropical low pressure system formed over the waters of the Gulf of Carpentaria at the end of last week. By late Sunday, this low had strengthened to become Tropical Cyclone 19P. At that time, this southward-traveling tropical storm was located approximately 610 miles to the east-southrast of Darwin, Australia. By Monday (local time), Tropical Cyclone 19P had strengthened to become Tropical Storm Esther that was traveling to the southwest, approximately 570 miles to the east-southeast of Darwin. Esther was forecast to make landfall along the coast on Monday and then continue to travel westward across interior sections of Australia, weakening to a tropical depression by early Tuesday.
  • A tropical low formed early last Sunday over the far-eastern Indian Ocean, nearly 200 miles to the south-southwest of Indonesia's Sumba Island. This low headed to the southwest, approaching the northern coast of Western Australia and strengthened to become a tropical storm. As of Monday, Tropical Storm Ferdinand was traveling toward the southwest, approximately 380 miles to the northwest of Broome, Western Australia. Ferdinand was forecast to travel toward the west-southwest during this upcoming week. Strengthening was forecast, with this tropical storm expected to strengthen to a category 1 tropical cyclone (on the Saffir-Simpson Scale) by late Tuesday.
• Review of global weather and climate for January 2020 -- Using preliminary data collected from the global network of surface weather stations, scientists at NOAA's National Centers for Environmental Information have determined that the combined global land and ocean surface temperature for January 2020 was 2.05 Fahrenheit degrees (or 1.14 Celsius degrees) above the 20th-century (1901-2000) average, which is the highest global temperature for any January since global climate records began in 1880. When considering land and ocean separately, the global land surface temperature for January 2020 was highest in the 141-year record, while the January 2020 ocean surface temperature was the second highest, trailing the record January temperature for over the ocean surface set in January 2016. The land-only surface temperature last month was the third highest global land surface temperature for any month in the 1681 months of record. Interestingly, the January 2020 combined global land and ocean surface temperature departure from average was the highest for any month during ENSO neutral conditions, meaning neither an El Niño nor a La Niña event was present in the tropical Pacific Ocean to influence the global temperature. [NOAA/NCEI State of the Climate]
  According to the National Snow and Ice Data Center, the extent of Arctic sea ice for January 2020 tied January 2014 for the eighth smallest monthly extent for any January since satellite surveillance began in 1979. Antarctic sea ice extent in January tied January 2011 for the tenth smallest on record in the Southern Hemisphere.
  The extent of the Northern Hemisphere snow cover during January 2020 was 18th smallest for the 54-year period of record that started in 1967. [NOAA/NCEI Global Snow & Ice]
  NCEI also provides a map showing the "Global Significant Weather and Climate Events map for January 2020."
• Preparation of NOAA's Monthly Global Climate Report is highlighted -- A member of the Climate Monitoring Branch of NOAA's National Centers for Environmental Information posted a blog on the ClimateWatch Magazine in November 2018 that describes how colleagues have been preparing NOAA's Monthly Global Climate Reports from the NOAA Merged Land Ocean Global Surface Temperature Analysis Dataset (NOAA GlobalTemp) that are released by around the 18th day of the following month. These climatologists compile and analyze observed temperature and precipitation data that have been collected by land-based stations, ships and buoys from around the globe during the previous month, producing their report in timely fashion. In addition to producing tabulated data sets, they create a variety of global anomalies and percentiles maps showing the departure of the observed monthly temperatures from a long-term average or the temperatures ranked in terms of percentiles. Attention was also given to the early portion of the global records that extend back to 1880, while the continental record only goes back to 1910. NOTE: Since this original blog was written, NOAAGlobalTemp has been updated to the new versions comprised of the Global Historical Climatology Network-Monthly version 4 (GHCNM v4) and Extended Reconstructed Sea Surface Temperature version 5 (ERSST v5) in 2019. [NOAA NCEI News]
• Spring snow cover in Northern Hemisphere responds to a changing climate -- A feature written for the "Understanding Climate" blog in the ClimateWatch Magazine reports that snow records from the last five decades show that spring snow is disappearing earlier in the year on average than it had in the past. The snow cover records have been obtained from satellite surveillance since the 1960s. The most rapid decreases in snow-covered area have been occurring in June, a month when Siberia, Alaska and northern Canada have historically remained partially snow-covered. An earlier decrease in snow cover would result in increasing the solar radiation absorbed by Earth, which in turn, elevates surface temperatures. [NOAA Climate.gov News]
• Nation's operational weather and climate supercomputing capacity to be tripled -- Late last week, NOAA officials announced that a significant upgrade was being made to computing capacity, storage space, and interconnect speed of its Weather and Climate Operational Supercomputing System. By 2020, two new Cray computers will have become operational and ready to implement model upgrades. Each new computer will have a 12-petaflop capacity, with one serving as the operational primary and the other a backup. These computers will be located in Manassas, VA and in Phoenix, AZ. The computers, which will replace existing replace existing Cray and Dell systems, will have a supercomputing capacity designed to support NOAA's new operational prediction and research. [NOAA News]
• Seasonal (3-month) Seasonal weather outlook released -- Late last week, forecasters at the NOAA Climate Prediction Center released their new national Seasonal Outlook for the next three months that consists of meteorological spring 2020 in the Northern Hemisphere (March-May). Specific details of their outlooks include:
  • Temperature and precipitation outlooks -- According to their temperature outlook, over half of the contiguous states should experience a high chance of above average temperatures for Spring 2020. The greatest probability of unseasonably warm weather should be found across the southern tier of states, stretching from Florida and southern Georgia in the Southeast westward along the Gulf Coast to west Texas and northward across the Four Corners States of Arizona, Utah, Colorado and New Mexico. On the other hand, sections of the northern Plains centered in eastern Montana and the western Dakotas could see a good chance for below average spring temperatures. The outlook indicates that the remainder of the "Lower 48 States" that lie across the interior Northwest, the northern Rockies, the central Plains and upper Mississippi Valley would have nearly equal chances of below, near or above average temperatures (identified by the "EC" label). The entire state of Alaska appears to have a high chance of a warm spring, the northwestern section of the 49th State have the highest probability of above average temperatures.
    Their precipitation outlook calls for most of the states in the eastern half of the nation to have a better than even chance of above average precipitation for Spring 2020. The region with the highest chances of a wet spring would be centered across the Ohio Valley. Conversely, sections of the Southwest and the Pacific Coast should expect a drier than average spring. Southern sections of Arizona and New Mexico, along with coastal sections of northern California and southern Oregon would have the highest chance of a dry spring. The remainder of the "Lower 48 States" are considered to have essentially equal chances of below, near or above average precipitation for meteorological spring. A large section of Alaska could also have a wet spring, especially across the Yukon Valley and the southern slopes of the Brooks Range.
    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 on the existence of a continuation of ENSO-neutral conditions in both the atmospheric and oceanic components across the equatorial Pacific Ocean basin through meteorological spring and into summer. Other factors considered include recent temperature and soil moisture trends and the output from numerical weather prediction models influencing both the temperature and precipitation outlooks. The forecasters' confidence on their outlook discussion for individual regions of the nation is given. 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 mid-February through May 2020. Their CPC outlook shows that the current drought conditions across the West should either persist or expand into surrounding regions. The largest area where drought conditions should continue would be across the Four Corners area, followed by areas in south Texas and the interior Northwest. Drought was expected to expand southward across a large section of California. Improvement of current drought conditions could occur across sections of east Texas and over the Florida Panhandle.
    Note: a Seasonal Drought Outlook Discussion is included describing the forecasters' confidence.
• Precipitation frequency atlases across the nation are explained -- A meteorologist with the National Weather Service's Hydrometeorological Design Studies Center (HDSC) explains the current version of the "NOAA Atlas 14 Precipitation Frequency Atlas of the United States," a project undertaken by HDSC to provide updated precipitation frequency information for the U.S. states and territories. He describes what information appears in this atlas and how this information can be used as de-facto standards for designing, building and operating infrastructure that would withstand the forces of heavy precipitation and floods. Currently, ten volumes have been prepared beginning in 2002 to cover 45 states, along with the U.S. territories in the Caribbean and Pacific basins. Some future improvements to the atlas are also described. [NOAA Climate Program Office News]
• Annual river ice cover is globally decreasing with a changing climate -- Scientists at the University of North Carolina at Chapel Hill and at Texas A&M University have discovered that the persistence of river ice on major rivers in the mid- and polar latitudes has diminished due to climate change. Using 400,000 LandSat satellite images from 1984 to 2018, the researchers found that on average, annual river ice cover declined by almost one week for every one Celsius degree increase in global temperature over those decades. The greatest declines were found in the Tibetan Plateau, eastern Europe and Alaska. These findings have important implications for the regional economics and for the health of these river ecosystems. [University of North Carolina at Chapel Hill News]
• An All-Hazards Monitor -- This Web portal provides the user information from NOAA's National Weather Service, FAA and FEMA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [NOAA/NWS Daily Briefing]
• Earthweek -- Diary of the Planet [earthweek.com]