SynthETC: A Statistical Model for Severe Winter Storm Hazard on Eastern North America

Abstract

13We develop, evaluate, and apply "SynthETC," a statistical-stochastic model of winter 14 extra-tropical cyclones (ETCs) over eastern North America. SynthETC simulates the 15 life cycle of ETCs from formation to termination, and it can be used to estimate the 16 probability of extreme ETC events beyond the historical record. Two modes of 17 climate variability are used as independent covariates: El Niño/Southern Oscillation 18 (ENSO) Niño3.4 and the monthly North Atlantic Oscillation (NAO). We use SynthETC 19 to estimate the annual occurrence rate over sites in eastern North America of 20 intense ETC passage in different ENSO and NAO states. Positive NAO is associated 21 with increased rates over the North Atlantic, while negative NAO is associated with 22 decreased rates over the North Atlantic and increased rates over northern Quebec. 23 Positive ENSO is associated with decreased rates over the North Atlantic, Ontario, 24 and the Canadian Maritime, while negative ENSO is associated with increased rates 25 over those regions, as well as the Great Lakes region. 26 27 28 3 Introduction 29 30Winter extra-tropical cyclones (ETCs) pose a major hazard to eastern North 31 America. These storms can cause damage through their precipitation, e.g., blizzards 32 and floods, and through their winds, e.g., extreme surface winds and storm surge. 33Heavy snowfall causes power outages, collapse of structures, and suspension of 34 travel and commerce. ETC winds sometimes reach hurricane force and drive 35 damaging coastal storm surge. Orton et al. (2016) found that in the New York City 36 area, ETCs are the dominant cause of surge events that have annual probability 37 greater than 1%. NOAA's NCDC estimated $40.9 billion in insured and uninsured 38 losses due to ETC events from 1980 to 2016 that caused more than one billion 39 dollars in damage each (www.ncdc.noaa.gov/billions/summary-stats; see also Smith 40 and Katz, 2013). 41 42ETCs are a dominant source of mid-latitude weather, and their varied formation and 43 evolution mechanisms have been studied using a wide range of observational, 44 theoretical, and modeling approaches (reviewed in Catto, 2016). The 45 characterization of ETC variability in the Northeast US has been documented for 46 some time (e.g. Miller 1946), and a climatology of northeast ETC tracks exists 47 (Hirsch et al. 2001). However, our understanding of the link between the storms' 48 variability, hazardous extreme events, and large-scale climate variability remains 49 incomplete (Colle et al. 2015). An examination of ETC tracks on seasonal timescales 50 suggests that there are a large set of forcing parameters, however the variance 51 4 explained by multiple predictors is less than 50% (DeGaetano 2008). 52Climatologically, ETC tracks have been used to identify a preferred track path for 53 storms that create wind hazards in the northeast (Booth et al. 2015). However, the 54 probabilistic analysis in that work is limited by the short time span of the reanalysis 55 utilized. A large body of w...

New York City Panel on Climate Change 2019 Report Chapter 2: New Methods for Assessing Extreme Temperatures, Heavy Downpours, and Drought

“…One reason for the uncertainty is the presence of modes of natural variability, such as the North Atlantic Oscillation, that affect precipitation in the New York metropolitan region. These can have strong interannual impacts on the location and the types of cyclones that generate at least half of the strong precipitation events for the region (see, e.g., Hall and Booth, ). Additionally, the issue of characterizing and projecting Northeast U.S. precipitation extremes and their relationship to natural climate variability has been found to be more complicated than understanding the cyclone tracks (Ning and Bradley, ).…”

“…It influences climate patterns in the Northern Hemisphere. types of cyclones that generate at least half of the strong precipitation events for the region (see, e.g., Hall and Booth, 2017). Additionally, the issue of characterizing and projecting Northeast U.S. precipitation extremes and their relationship to natural climate variability has been found to be more complicated than understanding the cyclone tracks (Ning and Bradley, 2014).…”

Atmospheric Research Over the Western North Atlantic Ocean Region and North American East Coast: A Review of Past Work and Challenges Ahead

“…Winter extratropical cyclones (ETCs) also pose a hazard to the U.S. East Coast (Hall & Booth, ). ETC winds can on occasion reach hurricane force and cause damaging coastal storm surges.…”

“…The National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC) estimated that from 1980 to 2016, major ETC events caused more than $1 billion in damage for each event (https://www.ncdc.noaa.gov/billions/summary-stats). The importance of ETCs has led to a series of studies evaluating the effect of El Niño Southern Oscillation and NAO indices on heightened ETC activity (DeGaetano et al, ), increases in likelihood of storm surge (Bernhardt & DeGaetano, ), and the probability of extreme ETC events (Hall & Booth, ).…”

The Relationship Between Extratropical Cyclone Steering and Blocking Along the North American East Coast

“…Previous studies have established an indirect link between extratropical cyclones and blocking via the North Atlantic Oscillation (NAO; Serreze et al, ; Woollings et al, ; Hall & Booth, ). During the NAO negative phase, blocking in the vicinity of Greenland occurs more frequently (Croci‐Maspoli et al, ), and cyclones tend to be steered eastward, and to a lesser extent northward, away from their climatological southwest to northeast path (e.g., Figure 6 in Serreze et al, ).…”