During major synoptic-scale cold trough events in complex terrain, it is often extremely difficult to forecast the transition between heavy rainfall and heavy snowfall. This project will entail performing a series of very high resolution numerical experiments and asynoptic validation studies using the WRF model to simulate a record-setting storm that occurred in the Sierra Nevada mountains on 4-5 January 2008. The model grid resolution will be reduced until the narrow cold frontal rainbands (NCFR) disappears due to truncation. The goals of the research are to determine what scale leads to1) NCFR formation, 2) NCFR juxtapositioning relative to the transition from rain to snow in complex terrain, 3) how the extraordinary warming develops ahead of the NCFR and 4) how the operations models can be used to anticipate NCFR development even when they may not explicitly resolve them.