LOS ANGELES — California braced Thursday for the overnight arrival of a powerful Pacific storm that is expected to bring widespread rain and snow to the drought-stricken state desperately in need of water but that also threatened flooding and mud flows in communities near areas scarred by wildfire.
Despite sunny blue skies behind a short-lived smaller storm, mandatory evacuation orders were issued for about 1,000 homes in two of Los Angeles’s eastern foothill suburbs beneath nearly 2,000 acres of steep mountain slopes left bare by a January fire.
For days, the cities of Glendora and Azusa have made extensive preparations. Residents built barriers of wood and sandbags to keep debris flows in streets and out of homes.
In Glendora, Dana Waldusky, 22, hurried to evacuate the family home, which backs up against the burned area.
She, her parents, and sister had made sure they had important documents, photos, medicines, and their toothbrushes packed, but timing was tight.
‘‘We have an hour to get evacuated,’’ she said. ‘‘We’re just boarding up all our doors.”
While concern was highest in the Glendora-Azusa area, meteorologists also posted flood watches for many other areas denuded by fires over the past two years. The National Weather Service warned of possible rainfall rates of 1 to 2 inches an hour as well as waterspouts offshore and small tornados.
Even as some Californians feared the precipitation, others were hoping for more.
The state Department of Water Resources took a new survey of the Sierra Nevada snowpack and found the water content at only 24 percent of average for the date. The northern and central Sierra snowpack normally provides about a third of the water used by California’s cities and farms.