Climatology and Ensemble Predictions of Nonconvective High Wind Events in the New York City Metropolitan Region

Abstract

Damaging wind events not associated with severe convective storms or tropical cyclones can cause significant problems with transportation, infrastructure, and public safety over the northeastern United States. These nonconvective wind events (NCWEs) are difficult to forecast in New York City and surrounding regions as revealed by the relatively poor probability of detection (POD) and false alarm ratio (FAR) in recent years. This paper investigates the climatology of NCWEs between 15 September and 15 May over 13 cool seasons from 2000/01 through 2012/13. The events are separated into three distinct synoptic patterns: precold-frontal (PRF), post-cold-frontal (POF), and nor'easter/coastal storm (NEC) cases. Relationships between observed winds and some atmospheric parameters such as 900-hPa geopotential height gradient, 3-h mean sea level pressure (MSLP) tendency, low-level wind profile, and stability are also presented. Overall, PRF and NEC have the largest FAR, because several events with a low-level jet at 1-2 km above the surface have relatively strong low-level stability that limits vertical momentum mixing. The POD is lowest for the POF events, which have a strong diurnal influence given the relatively deep mixed layer. Verification is also conducted over the cool seasons from 2009/10 to 2013/14 using the Short Range Ensemble Forecast (SREF) system from the National Centers for Environmental Prediction (NCEP). Both deterministic and probabilistic verification metrics are used to evaluate the performance of the ensemble during NCWEs. Although the SREF has more forecast skill than any of the deterministic SREF control members, it is rather poorly calibrated and exhibits a significant overconfidence given its positive wind speed bias in the lower troposphere.

A Review of Historical and Future Changes of Extratropical Cyclones and Associated Impacts Along the US East Coast

“…Milrad et al [19] suggested that along the east coast, extreme precipitation events are associated with nor'easters, while Sisson and Gyakum [20] suggested that over inland areas, heavy precipitation events are more related with cyclones from the southwest. Extreme wind events over the northeast are generally associated with storms from the southwest with the cyclone center to the west of the affected regions [21][22][23], while Colle et al [18] suggested that moderate storm surge events at New York City are mainly caused by nor'easters.…”

New York City Panel on Climate Change 2019 Report Chapter 4: Coastal Flooding

“…High winds during the cool season can be separated in pre-cold frontal (PRF), post-cold frontal (POF), and strong pressure gradients near a coastal northeast winter storm (NEC). Layer and Colle (2015) showed that NECs and PRFs peak in December, while POFs peak in January and February. During the warm season, there can be severe small-scale convective wind gusts (Colle et al, 2012), quasi-linear convective systems and squall lines (Lombardo and Colle, 2010), and tropical cyclones undergoing extratropical transition such as Sandy (2012; Colle et al, 2015) andFloyd (1999;Colle, 2003).…”

Short‐Term Forecasting of Wind Gusts at Airports Across CONUS Using Machine Learning

“…Near‐surface wind gusts are micro‐scale flow features typically resulting from downward entrainment of higher momentum air. They can be embedded within synoptic‐scale phenomena such as extra‐tropical cyclones (Earl et al., 2017; Layer & Colle, 2015; Letson et al., 2021), synoptic to mesoscale phenomena such as tropical cyclones (Shu et al., 2015; Sparks, 2003), be caused by topographically forced wave breaking or flow channeling (Letson et al., 2019; Ngo & Letchford, 2008), or result from meso‐to micro‐scale phenomena such as intense down‐drafts within deeply convective systems (Kuchera & Parker, 2006; Nakamura et al., 1996). While these parent phenomena are fully or partially resolved in most numerical weather prediction (NWP) and regional climate models, wind gusts themselves and the turbulent flow fields in which they are embedded are sub‐grid scale.…”