Cool-Season Dew Point Temperature and its Relationship With Atmospheric Rivers and Precipitation in the Northeast U.S.

Dew point is commonly used to measure atmospheric moisture and has been correlated with temperature and extreme precipitation. Atmospheric rivers (ARs) are narrow, horizontal channels of water vapor that are capable of producing extreme precipitation. Extensive research has not been conducted on dew point trends nor ARs in the Northeast U.S.. This study aims to create a 30-year dew point climatology (1988-2017) for the region and investigate how dew point impacts ARs and AR-caused precipitation in cool season (October-March). Extreme high dew points (99th percentile) primarily occur in July and August and extreme low dew points (bottom 1%) are observed most frequently in January. Additionally, dew point tends to decrease as latitude increases. Cool season ARs occur most often on days of extreme high dew points. More (less) ARs occur on days with higher (lower) dew points, top dew point days show a similar monthly frequency as AR occurrences, and ARs occur more frequently at locations with more extreme dew points. Furthermore, dew point is greater when an AR occurs with extreme precipitation, and while median precipitation is similar with and without an AR, more outlier precipitation values occur when an AR is present on days with dew point in the 95th percentile. Seasonal/latitudinal dew point trends indicate that higher temperatures can lead to higher dew points. These findings suggest that cool season ARs are capable of increasing atmospheric moisture during months that are typically cooler/drier. Consequently, a correlation exists between ARs, high dew points, and extreme precipitation.