Improving Monsoon Precipitation Forecast in Northwestern Mexico and Southwestern US: A Project of Consortium of Arizona-Mexico Arid Environment 2017

C. Bayu Risanto, Christopher L. Castro, James M. Moker, Avelino F. Arellano

Department of Hydrology and Atmospheric Science

The University of Arizona

North American Monsoon Precipitation that annually occurs from early July to mid September impacts the water supply, severe weather, droughts, and wildfires in the arid regions of Southwestern US and Northwestern Mexico (Adams and Comrie 1997). The challenge has been how to better forecast the precipitation when the monsoon season comes. Consortium of Arizona-Mexico for Arid Environment (CAZMEX) conducted a field campaign in Sonora, Mexico from June to September 2017 by collecting meteorological data from 15 installed GPS meteorological sites. We look closely at two cases of precipitation, i.e. precipitation generated by inverted trough (27 to 28 July) and precipitation without inverted trough (9 to 10 August). We run WRF model for both cases with data input from GFS and NAM. For validation we use rain gauge data from 25 meteorological sites including our GPS sites in Sonora, four satellite products, i.e GPM-Early, GPM-Final, CMORPH, and PERSIANN, and radar data of NEXRAD in Tucson. The preliminary results show that GPM-Early has less bias against the rain gauge measurement, and WRF-NAM performs better than WRF-GFS in forecasting the 24 hour total of precipitation and hourly precipitation. Data assimilation is being conducted to achieve better forecast.