March 15-19, 2021 Weather & Climate News

[Mid-Atlantic Weather Station (MAWS) Mailing List]

(Source:  AMS, 3/15/21)

WEEKLY WEATHER AND CLIMATE NEWS 15-19 March 2021 Items of Interest:

• Becoming AWARE --During this coming week (14-21 March), Indiana, Maryland, Virginia and West Virginia are observing their Severe Weather Awareness Weeks. If you live in any of these states, you should take time to become familiar with the various public affairs announcements issued by your local National Weather Service Office. Other states will be observing their Severe Weather Awareness weeks in the next six weeks.
• Flood Safety Awareness -- Many locations around the nation annually experience spring floods that cause large monetary losses and occasionally the loss of life. Check the website http://www.floodsafety.noaa.gov/ for information concerning flooding caused by excessive rain events, rapid snowmelt, ice jams and debris flow, along with useful flood safety and mitigation measures. Arkansas, Indiana, New York State, the six New England States (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont), Virginia and Wisconsin are observing this Flood Awareness Week (14-20 Mar 2021) with special activities.
• Tsunami Preparedness -- Lantex 2021, an Eastern Atlantic Tsunami Warning Exercise will be held on 17 March 2021. This exercise is intended to improve Tsunami Warning System effectiveness along the U.S. and Canadian Atlantic coasts.
• Update on Iditarod Trail Sled Dog Race -- Over this past weekend, 40 mushers had reached the checkpoint at Iditarod, which is close to the midway point on this year's modified Gold Trail Loop. They were then heading back to the starting point of Deshka Landing near Willow, which also serves as the finish line because of the Covid-19 pandemic. As of midday on this Sunday, three mushers taking part in the 2021 Iditarod Trail Sled Dog Race had reached the final checkpoint at Skwentna, which is 67 miles from the finish line. The winner of the Iditarod race was expected to cross the finish line early Monday morning. Subzero temperatures were taking a toll on some of the mushers.
  A website is maintained for teachers and students interested in following the progress of the Iditarod and a 3rd-grade teacher from Ohio, who is the "2021 Iditarod Teacher on the Trail™." Current weather conditions and weather forecasts for this year's checkpoint stations are available.
• Nominations can be made for "Climate Adaptation Leadership Award for Natural Resources" -- An award called the "Climate Adaptation Leadership Award for Natural Resources" will be awarded to as many as eight recipients in recognition of their outstanding efforts to increase the resilience of America's valuable living natural resources in a changing world. This award has been made available through the efforts of the Association of Fish & Wildlife Agencies and an interagency group of federal, state, and tribal agencies that include NOAA and the US Departments of Interior and Agriculture. Individuals or groups can be nominated for this award until Friday, 15 May 2020. [Association of Fish & Wildlife Agencies]
• Notice the Equinox -- The vernal equinox, which marks the commencement of astronomical spring, occurs early Saturday morning at at 0349Z on 20 March 2021 or 5:37 AM EDT or 4:37 AM CDT, etc.
  If you have already checked the sunrise and sunset times in your local newspaper or from the climate page at your local National Weather Service Office, you would have found that by earlier this week, the sun should have been above the horizon for at least 12 hours at most locations. 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.
• Looking at the Sun and seasons from a kid's perspective -- NASA's Earth Observatory has produced a feature for its EO Kids series entitled "All About That Tilt; Sun and Season" that is intended to show youngsters (ages 9 to 12 years old) how the Earth's tilt and its position in orbit around the Sun, determines seasons all around the globe. [NASA Earth Observatory EO Kids]
• Following the advance of spring with phenological maps -- The USA-National Phenology Network (NPN)is producing a variety of maps of the 48 contiguous United States that show the advance of spring northward across the nation. Two "Status of Spring" maps, called the "Spring Leaf Index Anomaly" and the "Spring Bloom Index Anomaly" are generated on a weekly basis based upon the USA-NPN's model called the Spring Leaf and Bloom Indices. The timing of leaf-out, migration, flowering and other seasonal phenomena in many species are phenological events that are closely tied to local weather conditions and broad climatic patterns. These maps are anomaly charts showing how the calculated indices for each week compare with the corresponding 30-year averages (for 1981-2010) and provide a means of comparison of this spring with "normal" conditions. [USA-National Phenology Network Spring]
  USA-NPN is also generating some pilot Pheno Forecast maps that are based on their 6-day Accumulated Growing Degree Day (AGDD) forecasts. These Pest-detection, management, and treatment Maps are available for five pests: apple maggot, emerald ash borer, hemlock woolly adelgid, lilac borer and winter moth. The treatment window for these pests are displayed as it approaches, based on predicted life stage. [USA-NPN Pheno Forecasts]
• Cherry Blossom Watch in Washington, DC -- Many tourists usually descend upon Washington, DC during the spring to view the sights, including the blossoming cherry trees that line the Tidal Basin along the Potomac River. This year marks the 93rd anniversary of the first Cherry Blossom Festival. The 2021 National Cherry Blossom Festival had been scheduled to start on Saturday, 20 March, and run through Sunday, 11 April 2021. However, the National Cherry Blossom Festival is cancelling and postponing some Festival events occurring through 31 March because of concerns for the COVI-19 outbreak. With the Washington DC area assessed at a very high risk level due to the virus as of last week, the National Park Service (NPS) is discouraging in-person visits to the Tidal Basin due to COVID-19 mitigation efforts. A website reports the status of the cherry blossoms in anticipation of the timing of peak bloom and includes a listing of the observations for the dates of stages of bloom over the past seven years. The most current forecasts made by NPS of the dates of anticipated bloom range run from 2 to 5 April, while the Washington Post newspaper has a range of anticipated dates from 30 March to 3 April and the NBC4 television station has a range of dates from 4 to 9 April. For comparison, the average peak bloom date is 2 April. [Cherry Blossom Watch 2020]
  A four-minute video "Climate Change and Cherry Blossoms in Washington, DC" is available on the National Park Service website and describes how the earlier blossoming of cherry trees indicate a changing climate.
  A graph of the occurrence of the dates of peak cherry blossom occurrence in Washington, DC beginning in 1921 and running through last year is also available. Examination of this graph indicates that the anticipated peak bloom could be at least two weeks after the record earliest occurrence on 15 March 1990.
• Explaining how data from satellite sensors are transformed into views of Earth -- NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) has produced an educational feature that explains how "satellite images" of Earth that you can see your television, computer or mobile device are produced. Focusing upon the imagery obtained from GOES-East and GOES-West, the two NOAA Earth observing satellites in geosynchronous orbit around the planet, the sequence is traced, starting with the collection of electromagnetic radiation that is reflected or emitted from planet Earth by sensors on the satellite, which is then converted to digital signals that are sent to ground receiver stations on Earth. The digital signals, which are related to the amount of upwelling energy detected by the satellite sensors, are then assembled by computers on Earth to make a digital representation that represents satellite images of Earth and its clouds that are finally disseminated to your device for you to view. [NOAA NESDIS News & Articles]

Weather and Climate News Items:

• Eye on the tropics ---Two tropical cyclones were found to be traversing the South Indian Ocean during the last week:
  • Tropical Cyclone Habana was traveling toward the southeast across the open waters of the South Indian Ocean at the start of last week. At the time, Habana was nearly 900 miles southeast of Diego Garcia. Over the previous weekend, Habana had reached a peak intensity with 145-mph sustained winds, making it a major category 4 tropical cyclone on the Saffir-Simpson Scale. During the first two days of last week, Habana had weakened to a minimal category 1 tropical cyclone with sustained winds of 75 mph as dry air was entrained into the system. In addition, Habana curved to take a track toward the west and west-northwest. However, Habana quickly re-intensified on Wednesday as it curved to head toward the south-southwest. Habana became a high-end category 4 tropical cyclone by early Thursday as maximum sustained winds reached an estimated 150 mph. During the remainder of last week, Cyclone Habana weakened slowly as it traveled toward the southwest. On Sunday, Habana had weakened to a category 1 tropical cyclone with sustained winds of 75 mph. Weakening further as it made a turn toward the east, Habana was downgraded to a tropical storm early Monday as sustained winds had dropped to 65 mph. At that time, Habana was approximately 900 miles to the east of Port Louis, Mauritius. Habana was forecast to complete a clockwise loop over the ocean and head west late Monday and into Tuesday. By that time, Habana should weaken to a tropical depression as it heads toward the west by midweek.
  • Tropical Storm Iman was traveling toward the east-southeast last Monday at a distance of approximately 320 miles to the south-southeast of St. Denis, La Reunion. Maximum sustained winds were estimated to have reached 50 mph. Iman accelerated toward the south-southeast on Monday with little noticeable change in intensity. By late Monday, the structure of Iman deteriorated as it became a remnant low.
• Review of national weather and climate for February 2021 and the 2020-21 winter -- Scientists at NOAA's National Centers for Environmental Information (NCEI) recently reported their preliminary analyses of the monthly and seasonal statistics:
  • For February 2001:
    The national average temperature for the contiguous United States during February 2021 was 30.6 degrees Fahrenheit, or approximately 3.2 Fahrenheit degrees below the 20th-century (1901-2000) average. This temperature makes February the 19th coldest February since a comprehensive national climate network began in 1895. Half of the 48 contiguous states reported statewide temperatures that were below to much-below average. Eight states, running from Nebraska, Iowa and Illinois southward to Texas, Louisiana and Mississippi had statewide February average temperatures that were in the top 10 lowest on record. Conversely, two states in the Southwest and three states along the East Coasts had above-average February temperatures. The remaining 19 states stretching across the Eastern Seaboard and scattered across the West had statewide temperatures in February that were close to average.
    In addition, the average maximum (or daytime) February 2021 temperature across the contiguous U.S. was the 16th lowest in the 127 years of record for the month. Eleven states across the nation's midsection had statewide maximum temperatures that ranked with the lowest 13 in their respective records. Correspondingly, the average minimum (or nighttime) nationwide temperature for the month was the 25th lowest since 1895, with seven states from Nebraska and Iowa south to Texas reporting statewide minimum February temperatures ranking within the lowest 13 of each state's record.
    The statewide February 2021 average temperature for Alaska was 3.6 Fahrenheit degrees below the 1925-2000 average, as this month was the 25th coldest since statewide records began in 1925.
    The February 2021 precipitation averaged across the contiguous U.S. was 1.99 inches, or 0.14 inches below the long-term (1901-2000) average, making last month the 50th driest February in 127 years.
    Twelve states primarily located across the Plains and extending across the Southwest reported below- to much-below average statewide precipitation totals in February. Kansas had its eleventh driest February on record, while Minnesota and North Dakota experienced their twelfth driest February. On the other hand, eleven states in the Middle Atlantic and Southeast, along with five in the Northwest had above- to much-above average February precipitation. Delaware had its fifth highest monthly precipitation totals on record, while North Carolina had its eight wettest and South Carolina its 10th wettest February in 127 years. The remaining 20 states had close to average precipitation totals.
    Alaska had a statewide precipitation average for February 2021 that was 3.22 inches, equaling the 1925-2000 average statewide February precipitation.
    Data analyzed by the Rutgers Global Snow Lab indicate the February 2021 snow cover extent across the contiguous U.S. was the fifth largest February snow cover extent in the 55-year period of record using satellite observations. According to the National Operational Hydrologic Remote Sensing Center (NOHRSC), the daily snow cover across the "Lower 48" states reached 73.2 percent on 16 February 2021. which is the highest daily value in the NOHRSC's historical record that commenced in October 2003.
  • For meteorological winter season (December 2020 through February 2021):
    The average temperature across the contiguous United States for the meteorological winter season was 36.0 degrees F, or 3.8 Fahrenheit degrees above the 20th century average, making the recently-concluded winter the 30th warmest winter since 1895. The northern tier of states in the "Lower 48" and across the West had winter average temperatures that were above- to much-above the long-term average. Of these 23 states, California had a winter average temperature that was the seventh highest since 1895 and Maine its 12th highest. On the other end of the spectrum, three states (Arkansas, Oklahoma and Texas) had winter average temperatures that were below-average. The remaining 22 states, stretched out across the Southeast, Midwest, the central Plains and the Rocky Mountains had near-average winter temperatures
    Alaska's statewide average temperature for the 2020-21 meteorological winter was 4.0 Fahrenheit degrees above the monthly average for 1925-2000, which ranks it as 24th highest in the state's 97-year record.
    The precipitation averaged across the 48 coterminous states between December 2020 and February 2021 was 6.10 inches, or 0.69 inches below the 20th-century average, making this past winter the 26th driest winter on record. Twenty states stretching across a large area of the "Lower 48" states had below- to much-below-average winter precipitation this past winter. North Dakota experienced its third driest winter. Seven states registered above- to much-above-average winter precipitation, primarily along the Middle Atlantic Coast. Virgina had its 10th wettest winter, Delaware its 12th and North Carolina its 14th wettest winter on record. The remainding 21 states scattered across the Plains, the Southeast and Northeast had statewide winter precipitation totals close to the long-term average.
    Alaska experienced above average precipitation during this just-concluded winter, with a precipitation total that ranked in 20th place in the 97-year state record. [State of the Climate NOAA/NCEI]
    NOTE: A description is provided of the climatological rankings employed by NCEI for their monthly and seasonal maps. [NOAA/NCEI]
  • A map entitled "U.S. Selected Significant Climate Anomalies and Events for February and Winter 2021" graphically summarizes several significant weather and climate events that occurred across all 50 states and Puerto Rico during the past three months, but with the focus upon February. NOTE: A description is provided of the climatological rankings employed by NCEI for their monthly and seasonal maps. [NOAA/NCEI]
• February national drought report -- The Nation///al Climate Data Center has posted its February 2021 drought report online. Using the Palmer Drought Severity Index, approximately 27 percent of the contiguous United States experienced severe to extreme drought conditions at the end of February, while approximately five percent of the area had severely to extremely wet conditions.
• New soil moisture data tool designed to help increase crop yields -- A computer application program or app called Crop Condition and Soil Moisture Analytics (Crop-CASMA) has been developed using high resolution soil moisture data from NASA satellites to power a new U.S. Department of Agriculture (USDA) Soil Moisture Portal. The tool provides free access to data collected from NASA’s Soil Moisture Active Passive (SMAP) mission and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The SMAP soil moisture data are for the top-soil and root zone levels, extending from the Earth's surface to a depth of three feet, with a horizontal resolution of one kilometer. This app, which was developed by the USDA’s National Agricultural Statistics Service (NASS), NASA's Jet Propulsion Laboratory and George Mason University, should help researchers, meteorologists and farmers track droughts or floods, as well as to better forecast agricultural yields. [NASA Jet Propulsion Laboratory News]
• Taking a sneak preview at how new winter normals will change -- The managing editor of NOAA's Climate.gov News recently posted a feature containing images that provide a sneak peak at the new 1991-2020 normals for winter (December, January and February) temperature and precipitation across the contiguous United States and how they differ from the currently used 1981-2010 normals. One of the maps shows that the new normals will show an increase in temperature from the 1981-2010 interval by as much as 1.5 Fahrenheit degrees in some sections of the nation, although a few areas across the northern Plains have slightly lower winter mean temperatures with the new normals. The other map displays the percentage changes in winter precipitation between the 1991-2020 and 1981-2010. The Upper Midwest and the northern Plains experienced the largest percentage increases in winter precipitation, while areas across the Southwest and southern Plains were having the largest percentage decreases. At the present time, NOAA NCEI climate scientists are preparing the latest update to the U.S. Climate Normals that should be released in May 2021. [NOAA Climate.gov News]
• El Niño/Southern Oscillation (ENSO) Diagnostic Discussion for March -- Forecasters at NOAA's Climate Prediction Center (CPC) and the International Research Institute for Climate and Society (IRI) released their monthly El Niño/Southern Oscillation (ENSO) Diagnostic Discussion late last week. They reported that La Niña conditions continued to persist through February, although the atmospheric and oceanic indicators suggested that this La Niña was showing signs of weakening.
  Specifically, sea surface temperatures (SST) remained below the long-term average across sections of the equatorial Pacific extending from west of the International Dateline eastward to the eastern Pacific. Farther to the east, SST values in the eastern equatorial Pacific off the coast of South America were tending to have above-average SST levels. Likewise, the far western Pacific SST values were above-average in the waters surrounding Micronesia and New Guinea. As of last week, the SST anomaly (differences between observed and 1991-2020 average temperatures) in the regions of the equatorial Pacific identified as the Niño3.4 and the Niño4 sectors ranged between -0.7 and -0.8 Celsius degrees, which were at levels beyond the threshold of -0.5 Celsius degrees considered to represent La Niña conditions. Farther to the east, the SST anomaly in the Niño3 sector was at -0.5 Celsius degrees and at zero Celsius degrees in the Niño1+2 sectors. (Editor's note: CPC has a map of the four El Niño regions across the equatorial Pacific Ocean basin used to determine if El Niño or La Niña conditions are occurring. EJH)
  Atmospheric conditions especially involving near-surface and upper-level wind regimes across the western and central regions of the basin remained consistent with La Niña conditions. Prevailing low-level easterly trade winds across the east-central equatorial Pacific Ocean remained above average during February, while upper-level winds were westerly. Tropical convection over the central to the western Pacific was not as suppressed in February as it had been earlier. In addition, rainfall associated with tropical convection had weakened around the Philippines and parts of Indonesia. The Southern Oscillation Index (SOI), a measure of the strength of the tropical atmospheric circulation regime known as the Walker Circulation, remained positive, indicating stronger than average circulation that would be conducive for La Niña.
  The majority of the various numerical prediction models that the CPC and IRI forecasters have their disposal suggest SST anomalies in the Niño3.4 sector (the main region used to assess the likelihood of an El Niño or La Niña) the (Niño-3.4 index to drop to less than -0.5°C) during Northern Hemisphere meteorological spring (March-May) 2021, meaning a shift to ENSO-neutral conditions, which would then remain through boreal summer (June-August). Based upon this model guidance along with current conditions, the forecasters gave a 60-percent chance that La Niña conditions would transition to ENSO-neutral conditions during the next three months of April through June, which covers the remainder of the Northern Hemisphere's meteorological spring and the first month of summer. While the probability of ENSO-neutral conditions increases to more than 60 percent, the probability of the continuation of La Niña conditions only falls to approximately 34 percent chance and the probability of El Niño remains below 10 percent. Therefore, the CPC's ENSO Alert System Status remains as a "La Niña Advisory." Note: The criteria used for CPC's ENSO Alert System is available.
  An ENSO blog written by a scientist at the University of Miami's Cooperative Institute for Marine & Atmospheric Sciences provides a non-technical description and clear graphics. In one of these graphics, she shows that monthly SST anomalies for 2020-21 in the Niño 3.4 region of the tropical Pacific would suggest the SST could come closer to average by summer. Finally, she discusses the issue of "spring predictability barrier," where ENSO computer model predictions made in spring are often seen to be less reliable than predictions made in other times of the year. [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 their "Climate Driver Update" that includes an updated ENSO forecast from a Southern Hemisphere perspective. They noted that the current 2020-21 La Niña had peaked during during January 2021 and were approaching ENSO-neutral conditions in terms of atmospheric and oceanic conditions across the tropical Pacific. They saw SST anomalies close to the La Niña threshold, while clouds and easterly trade winds across the central tropical Pacific remained at La Niña levels. Most of the international climate models used by the Australian forecasters, indicate the La Niña conditions should transition to an ENSO-neutral phase during this upcoming austral autumn. Therefore, the forecasters currently maintain their Bureau's ENSO Outlook at "La Niña". [Australian Government Bureau of Meteorology]
• Maps of global ground-level ozone air pollution are created -- Researchers from the Cooperative Institute for Research in Environmental Sciences (CIRES), University of North Carolina and their colleagues recently produced a set of maps showing global ground-level ozone concentrations by year running from 1990 to 2017 for the Global Burden of Disease study. As many as 365,000 people died globally in 2019 from exposure to ozone pollution. The researchers used a novel data fusion method that combined different sources of information, making use of the advantages of each. Ozone observations were obtained from more than 8800 sites around the globe along with output from nine different global atmospheric models. Annual maps of ozone concentrations for every year were produced with a spatial resolution of approximately 10 kilometers. [CIRES 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]

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