Objective Verification of the Weather Prediction Center's Mesoscale Precipitation Discussions

Mesoscale Precipitation Discussions (MPDs) are issued by the National Oceanic and Atmospheric Administration’s Weather Prediction Center (WPC) as short-term guidance for forecasters to determine areas where a flash flooding threat exists. MPDs, unlike outlook products issued by WPC, are created for smaller spatial and temporal scales and are typically only valid for up to 6 hours. These discussions include a summary of both the meteorological and hydrological conditions that are in place in a given region of interest, providing further information for local forecasters to apply as they monitor the situation. However, until the fall of 2022, there had been no objective verification of the MPD product since the Meteorological Watch Desk (MetWatch) began issuing them in April of 2013. This study provided the first objective verification to serve as a baseline for future studies of the evolution of the MPD and its skill in various situations. MPDs issued between 2016 and 2022 were analyzed and used to create a climatology and determine skill scores for the product. Additional analysis was completed dividing the MPDs by the region or season in which it was issued, revealing some patterns based on the dominant convective regimes of each grouping. There has been a remarkable improvement in the skill of MPDs issued on the West Coast of the United States and those issued during the winter months (December, January, and February). This suggests that additional experience with issuing MPDs related to atmospheric rivers since the task was assigned to them in November of 2015 provided the forecasters the ability to increase the skill in their MPDs over the years. The Southwest region remains a challenging forecast area for the forecasters. Monsoon rainfall can be difficult to forecast, especially when large-scale forcing is absent or weak. This leads to large MPDs with lower skill. Future work includes assessing the MPDs based on other categories.