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Meteorological data is one of the critical items needed to execute an air dispersion modeling analysis; without this data, the air dispersion models will not run. Historically, Arizona agencies have allowed the use of either one (1) year of site-specific meteorological data or five (5) years of National Weather Service (NWS) data. Therefore, sites without access to representative NWS data, which is a common occurrence in Arizona, have historically been required to install on-site monitoring equipment and collect one (1) year of meteorological data prior to conducting an air dispersion modeling analysis. The upcoming Arizona Department of Environmental Quality (ADEQ) modeling guidelines will provide applicants with a third option through the use of "Prognostic Meteorological Data" if NWS data are not available and it is infeasible to collect site-specific data.

Prognostic Meteorological Data makes use of nationwide datasets for the years 2013 through 2015 and combines these datasets with regional Arizona data. The objective is to tailor the national data to reflect Arizona-specific meteorological conditions such that it is representative for modeling at the local level. Due to the extensive programs and subroutines involved with processing the data, the generation of Prognostic Meteorological Data can be time and cost intensive and will require case-by-case approval from Arizona agencies. However, the associated costs for producing these data are significantly lower than installing and operating on-site monitoring equipment. Additionally, producing these data can eliminate the one (1) year period required for on-site data collection that may be needed otherwise. Therefore, this development has the potential to dramatically improve project costs and timelines for cases where this new option may be used.