Near-Real-Time Data Impact Studies for Extreme Precipitation Events during Atmospheric River Reconnaissance Program using NCEP Operational Global Forecast System

The Atmospheric River Reconnaissance Program has been developed as a collaborative effort to fill observation gaps for ARs and to improve forecast skills of landfalling ARs and the associated precipitation events. During AR Recon 2022 there were 25 successful Intense Observing Periods (IOPs) using 21 Air Force WC-130J flights and 11 NOAA G-IVSP flights. Dropsonde data collected from these recon missions are sent in real-time for operational use at NCEP. The Global Data Assimilation System (GDAS) and the Global Forecast System (GFS) have assimilated these special dropsonde observations along with flight level data, potentially contributing towards more skillful forecasts of ARs and their impacts along the US west coast. Conducting data denial experiments is one essential step to assess the impact of these unique datasets. Near-real-time (NRT) data denial experiments were carried out for AR Recon 2022 to assess data impact on precipitation forecasts, especially for those events that were impacted by landfalling ARs. Results from these experiments compared against operational GFS forecasts will be presented along with evaluation of data impacts for specific case studies related to extreme precipitation events.