California Gets Chastisement From Hurricane Hillary

HEADLINE: Desperate Californians climb trees to escape floods and mudslides with many trapped in cars for hours after Hilary brings record rain: Palm Springs is submerged and 25M are now under flood warnings: Shock video shows earthquake rock at bar by Olivia Jones HEADLINE: Understanding The Weather Forecasts That Preceded The Maui Wildfires by Steven Businger  Essentially a high amplitude atmospheric wave forced by strong winds interacting with the mountains of northwest Maui produced powerful, dry downslope winds on the lee slopes of West Maui mountains. The sirens are for hurricanes and tsunami’s only. The community is told, if you hear the siren, you immediately get to higher ground. NWS forecasters are familiar with this weather pattern, which meteorologists refer to as a “downslope windstorm.” HEADLINE: The Real Cause of the Maui Wildfire Disaster by Cliff Mass Weather Blog A phenomenon skillfully predicted by modern high-resolution models, and thus a feature we could have warned Lahaina's population about.   A phenomenon that would have been picked up by surface weather observations, if only West Maui had invested in inexpensive weather stations. High pressure is centered north of Hawaii and this high pressure was far more intense than normal just north and over Maui (indicated by the orange, red, and brown colors).   The pressure anomalies due to the Hurricane Dora were very small in scale and limited to far south of Hawaii.  Last week, I asked David Ovens, a highly skillful atmospheric modeler in my group at the UW, to run a forecast of the Maui event using the WRF model at very high resolution (1.3 km grid spacing). I was stunned by the simulation, which revealed the real cause of the disaster:  a high-amplitude mountains wave with very strong downslope flow on the West Maui Mountains.