Precipitation response in mountainous and coastal regions of Northwestern Mexico under ENSO scenarios during the landfall of tropical cyclones

El Niño-Southern Oscillation (ENSO) tropical cyclones (TCs) are important moisture sources in semiarid, mountainous Northwestern Mexico. Studies conducted in this region have not expressed differences between coastal and mountainous regions under different ENSO scenarios, instead, changes have been explored in the entire region as a whole. Attempting to fill this gap, the present study conducted an analysis of observed changes in rainfall contribution of landfalling tropical cyclones under five scenarios: (1) El Niño, (2) La Niña, (3) El Niño to La Niña, (4) La Niña to El Niño, and (5) Neutral on mountainous, foothill and coastal regions. In addition, the changes observed were explored under five scenarios in monthly precipitation peak and seasonal cumulative precipitation, which are important characteristics during the North American Monsoon (NAM). The results indicate that most changes occur in the coastal region during La Niña, El Niño to La Niña and Neutral scenarios, where more than half of the stations recorded average precipitation above their regional climatology. Thus, six TCs made landfall with an average of 73% of stations that recorded accumulations above their regional climatology (i.e. NAM precipitation) mainly affecting the southern foothill region. Although the observed changes do not show a well-defined seasonal pattern distinguishing the three regions, changes may be identified and explained by the latitudinal gradient, relief and soil moisture characteristics strongly influenced by local factors. Unfortunately, these results make it difficult to forecast the precipitation response under the different scenarios.