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Who conducts the National Climate Assessment?
The U.S. National Climate Assessment is mandated by the Global Change Research Act of 1990. The assessment has been conducted about every four years since 2000 and is an authoritative scientific analysis of climate change risks, impacts, and responses in the U.S. The resulting report, mandated by Congress, explains how climate change affects every region of the U.S.
The nation completed its fifth National Climate Assessment (NCA5) in November 2023. The assessment results from an extensive process that includes internal and external review from federal agencies, the public, and external peer review by a panel of experts. The National Oceanic and Atmospheric Administration (NOAA) is the administrative agency for NCA5 and certifies that the report meets the standards required by the Information Quality Act and Evidence Act. Continue reading
What is a landspout?
According to the American Meteorology Society’s glossary, a landspout is a colloquial name for a small tornado whose vorticity (a vector that measures local rotation in a fluid flow) originates in the boundary layer and has a parent cloud in its growth stage. Landspouts occur when colliding winds at the surface begin to make a vortex and then a developing thunderstorm passes overhead. The updrafts from that thunderstorm draw the rotating vortex upward and give it a tornado-like appearance. While relatively weak compared to traditional tornadoes, landspouts can be strong enough to cause damage and warrant caution.
The term “landspout” was coined by atmospheric scientists in the 1980s to describe a type of vortex associated with thunderstorms that do not possess a strong mid-level mesocyclone. A mesocyclone is a cyclonically rotating vortex, around 2–10 km in diameter, in a convective storm. Strong tornadoes form in mesocyclones.
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Has the EPA rolled back regulations on greenhouse gas emissions?
On June 11, Environmental Protection Agency Administrator Lee Zeldin proposed repealing all “greenhouse gas” (their quotes, not ours) emission standards for the power sector under Section 111 of the Clean Air Act.
This proposal is based upon the false assertion that “emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution.” This assertion flies in the face of centuries of evolving understanding of the influence that carbon dioxide, the primary by-product of such combustion, has on the radiation balance of Earth’s atmosphere. Continue reading
Category: Climate, Meteorology
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Does North America have a hurricane season?
Recently FEMA Director David Richardson claimed he was unaware that there is a hurricane season in the United States. There most certainly is such a season. The Atlantic hurricane season climatologically runs from June 1 through November 30, with the most active part of the season being mid-August through mid-October. Hurricanes are tropical storms over the Atlantic Basin (Atlantic Ocean, Caribbean Sea, and Gulf of Mexico). Based on a 30-year climate period from 1991 to 2020, the average Atlantic hurricane season has 14 named storms, 7 hurricanes, and 3 major hurricanes. A developing tropical cyclone is given a name when it reaches sustained winds of 39 mph and it becomes a hurricane at 74 mph.
Hurricanes can occur outside this season but these are the months with favorable conditions for formation of the storms. One such condition is the ocean temperature exceeding 79.7F, which is common in the Atlantic Basin between June and November. Hurricanes have difficulty forming off the U.S. west coast due to cold water, cold currents, and unfavorable winds. Continue reading
Did weather forecasting play a role in D-Day?
Last Friday was the 81st anniversary of the Allied invasion of Europe that began with the landings on the beaches at Normandy. The combined land, air, and sea assault of June 6, 1944 remains the largest such event in history. The success of the invasion was extraordinarily dependent of weather conditions. More than three months before the invasion, a combined British and American forecasting team began rigorous forecast exercises designed to iron out the physical and logistical kinks of such a coordinated effort. As June drew near, the nature of this collaboration was still problematic as the two groups employed vastly different methods in fashioning the requisite 3-5 days forecasts – at the time, absolutely primitive in the underlying science as compared to what is possible at such ranges today. The British were attempting to make such forecasts based upon the understanding of atmospheric dynamics that had grown substantially during the war. The Americans were employing a method based on a statistically- based search through old weather data for historical analogues that could be used to guide the forecast. Continue reading
Category: History, Meteorology, Severe Weather
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