The extremely damaging Hurricane Sandy (2012) is noteworthy for the significant track bifurcation among several forecast models approximately 6-7 days before landfall. The operational versions of the European Center for Medium-Range Weather Forecasting (ECMWF) and Global Forecast System (GFS) models exemplify this difference over their runs early in Sandy's life cycle, as the former routinely forecast a storm which would make a U.S. landfall, while the latter routinely forecast a track toward the central North Atlantic. This was also generally true of their respective ensemble members. This paper demonstrates that these differences were caused not by resolution or initial condition differences but rather due almost exclusively to choice of cumulus parameterization. Simulations performed with the Weather Research and Forecasting model using an ECMWF-like cumulus parameterization in conjunction with GFS initial conditions yield forecasts whose accuracy is similar to that of ECMWF forecasts at extended time ranges (up to 1 week before landfall).

The New York State Mesonet (NYSM) is a network of 126 standard environmental monitoring stations deployed statewide with an average spacing of 27 km. The primary goal of the NYSM is to provide high quality weather data at high spatial and temporal scales to improve atmospheric monitoring and prediction, especially for extreme weather events. Compared with other statewide networks, the NYSM faced considerable deployment obstacles with New York’s complex terrain, forests, and very rural and urban areas; its wide range of weather extremes; and its harsh winter conditions. To overcome these challenges, the NYSM adopted a number of innovations unique among statewide monitoring systems, including: (1) Strict adherence to international siting standards and metadata documentation; (2) A hardened system design to facilitate continued operations during extreme, high-impact weather; (3) A station design optimized to monitor winter weather conditions; and (4) a camera installed at every site to aid situational awareness. Completed in spring 2018, the network provides data and products to a variety of sectors including weather monitoring and forecasting, emergency management, agriculture, transportation, utilities, and education. This paper focuses on the standard network of the NYSM and reviews the network siting, site configuration, sensors, site communications and power, network operations and maintenance, data quality control, and dissemination. A few example analyses are shown which highlight the benefits of the NYSM.

Hurricane Sandy (2012) is known as an incredibly destructive storm and one defined meteorologically by its large size, and its significant forecast track spreads among various operational models roughly 1 week before landfall. While the operational European Centre for Medium-Range Weather Forecasts model accurately depicted a northeastern United States landfall, the Global Forecasting System (GFS) model consistently forecast a track toward the North Atlantic Ocean. Using a Weather Research and Forecasting (WRF) model framework, Bassill (2014) suggested that these differences were primarily a function of differences between the two models' cumulus parameterization (CP). This study also uses a WRF model framework to examine the simplified Arakawa Schubert CP used in the GFS model. It is found that increasing the deep convective entrainment coefficient produces more realistic forecast tracks for forecasts initialized roughly 1 week before landfall. This occurs through a reorientation of the precipitation (and associated latent heating) around Sandy during a critical time period in which it was interacting with a series of upper troughs to its west and northwest. Reorienting the latent heating reshapes the upper tropospheric steering pattern toward the one that is more negatively tilted and consistent with observations.

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