After landfall, Florence’s forward motion slowed as it dropped large amounts of rain throughout the region before moving farther inland on 17 September 2018. This paper reviews the forecasted attribution with the benefit of hindsight.įorecast attribution framework applied to Hurricane Florenceįlorence, a North Atlantic hurricane, made landfall as a category 1 storm on the coast of North Carolina at 11:15Z on 14 September 2018. These statements were made on the basis of simulations using the hindcast attribution method but as a forecast in advance of the storm’s landfall. Two days before the landfall of Hurricane Florence ( 28), we publicly forecasted the following attribution statements:ġ) Hurricane Florence would be slightly more intense (lower surface pressure) for a longer portion of the forecast period due to climate change.Ģ) Hurricane Florence rainfall amounts over the Carolinas would be increased by over 50% due to climate change and are linked to warmer sea surface temperatures and available moisture in the atmosphere.ģ) Hurricane Florence would be about 80 km larger due to the effect of climate change on the large-scale environment around the storm. It appears that the human influence on tropical cyclone precipitation is emerging faster than on maximum wind speeds ( 16). Three of the aforementioned Hurricane Harvey studies directly found large attributable increases (10 to 38%) on that storm’s precipitation, each using different methodologies. However, trends in extreme precipitation over all storm types have been detected in global analyses and attributed to human-induced changes to the composition of the atmosphere ( 26, 27). While both theoretical models of intense tropical cyclones ( 20, 21) and multidecadal integrations of tropical cyclone permitting climate models suggest that the most intense tropical cyclones become more frequent and more intense in a warmer climate ( 22, 23), the detection of these changes in the observational record is questionable ( 24, 25). Because of these stringent conditions, especially the last one, storyline attribution statements must be considered as incomplete assessments of the effect of anthropogenic climate change on extreme weather events and conditional on the event’s underlying existence. In the hindcast attribution approach, the following conditions are imposed: (i) observed human-caused changes in the composition of the atmosphere, including greenhouse gases and aerosols (ii) credible estimates of human-induced changes in the ocean surface temperatures and mean atmospheric state aloft and (iii) that cyclogenesis has occurred under a plausible synoptic environment. Event attribution statements then are statements about the changes in the magnitude or probability of an event. The role of anthropogenic climate change on a tropical cyclone’s existence, if any, is manifested through changes in the magnitude or frequency of these causal conditions. As with any complex phenomena, the genesis of a tropical cyclone occurs when the state of the atmosphere-ocean system is favorable for it ( 18, 19). This attribution methodology has been used to identify the current and future human influence, if any, on the wind speed and precipitation of 15 historical tropical cyclones, including Hurricanes Katrina, Maria, and Irma ( 16), and has been referred to as a “storyline” approach to attribution ( 17).Įxtreme event attribution is an exercise in causality. Recently, the “hindcast attribution method” ( 13), described in Methods, was introduced to make attribution statements about present-day tropical cyclones and other severe storms, similar to the “pseudo–global warming” approach for the projection of future climate extremes ( 14, 15). The lag time between extreme weather events and subsequent attribution statements has been steadily decreasing as the community’s expertise has developed to a point that several European weather forecast agencies are currently planning operational attribution capabilities in the near future ( 12). While a human influence on the precipitation from individual extreme storms has been identified before ( 5, 6), Hurricane Harvey was the first true tropical cyclone to undergo these analyses ( 7– 11). Since the pioneering analysis of the 2003 European heatwave ( 3), substantial advancements in attribution statements about the influence of anthropogenic climate change on the frequency and magnitude of individual extreme weather and climate events have been made ( 4). Tropical cyclones, extreme temperature, drought, and severe weather account for most of the increasing damages and economic impacts in the United States ( 2). Change in extreme weather and extreme climate events is a principal way that society experiences the impacts of anthropogenic climate change ( 1).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |