Evaluation of atmospheric river predictions by the WRF model using aircraft and regional mesonet observations of orographic precipitation and its forcing

TitleEvaluation of atmospheric river predictions by the WRF model using aircraft and regional mesonet observations of orographic precipitation and its forcing
Publication TypeJournal Article
Year of Publication2018
AuthorsMartin A., Ralph FM, Demirdjian R., DeHaan L., Weihs R., Helly J., Reynolds D., Iacobellis S.
JournalJournal of Hydrometeorology
Volume19
Pagination1097-1113
Date Published2018/07
Type of ArticleArticle
ISBN Number1525-755X
Accession NumberWOS:000437725300001
Keywordscold-front; comparison; extratropical cyclones; extreme precipitation; forecasting; forecasts; inland penetration; Meteorology & Atmospheric Sciences; model; Model evaluation; northern california; Numerical weather prediction; Orographic effects; pacific-ocean; performance; precipitation; rainfall; signature; water-vapor; west-coast precipitation
Abstract

Accurate forecasts of precipitation during landfalling atmospheric rivers (ARs) are critical because ARs play a large role in water supply and flooding for many regions. In this study, we have used hundreds of observations to verify global and regional model forecasts of atmospheric rivers making landfall in Northern California and offshore in the midlatitude northeast Pacific Ocean. We have characterized forecast error and the predictability limit in AR water vapor transport, static stability, onshore precipitation, and standard atmospheric fields. Analysis is also presented that apportions the role of orographic forcing and precipitation response in driving errors in forecast precipitation after AR landfall. It is found that the global model and the higher-resolution regional model reach their predictability limit in forecasting the atmospheric state during ARs at similar lead times, and both present similar and important errors in low-level water vapor flux, moist-static stability, and precipitation. However, the relative contribution of forcing and response to the incurred precipitation error is very different in the two models. It can be demonstrated using the analysis presented herein that improving water vapor transport accuracy can significantly reduce regional model precipitation errors during ARs, while the same cannot be demonstrated for the global model.

DOI10.1175/jhm-d-17-0098.1
Short TitleJ. Hydrometeorol.
Student Publication: 
Yes
Student: 
sharknado