Severe Weather and Early Winter Weather in the West

An unseasonably strong upper-level trough that cuts off into a closed low in California tonight will bring quite the gambit of weather across the West in the next 24 to 40 hours. There will be everything from heavy storms bringing flash flooding, strong winds and even an isolated tornado to accumulating snowfall.

Strong Storms and Severe Weather:

There are two main time periods of severe weather, the most widespread being Saturday into Saturday night.

Late this afternoon and evening, scattered locally strong storms are likely to develop well ahead of the main trough. These will occur over parts of southeastern California and western Arizona north into southern Nevada, including the Las Vegas area, into western Utah. A surge of very moist air is being drawn north along the Colorado River as this forecast from the HRRR RAP shows.

This moisture along with heating of the day and some lift from the approaching trough will spark scattered thunderstorms. The biggest threat is from locally damaging wind gusts and heavy rain causing flash flooding.

Tomorrow and tomorrow night, more widespread heavy showers and thunderstorms are likely. A cold, upper-level low will be in Central California.

Early Season Snow:

With the cold low moving inland into California Saturday then slowly moving east into Nevada Sunday there will be accumulating snowfall in the high country of the Sierra. The snow will fall mainly above 7,500 feet but it will be cold, windy and wet much lower than that. Since this is so early in the season hikers, campers and hunters need to be prepared for this unusually cold weather. During the early season there are always people caught unprepared and this can be deadly with the potential for hypothermia. Snowfall will probably average 4 to 8 inches with locally higher amounts possible.

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