There are two things the forecasters at WeatherOptics are watching this week in the western US: a warm up and the risk for fires in Southern California.
Millions of people will feel an early winter warm up across the large majority of the West this week into next week while a trough brings cold air to the East. We’re going to see a trough build into the East through this week, forcing a dip in the jet stream. What goes up must come down—that dip will lead to a rise over the West, allowing for warm air to surge into the region.
It may still be on the cool side to start the week, but Wednesday will be the turning point with above-average temperatures beginning to invade most of the West. However, it’s not until the weekend and into next week when I predict highs will reach well above-average (at least ten to twenty degrees, if not up to thirty degrees). That’s because the ridge as well as the positive PNA pattern will become stronger. Below, you’ll find the overall pattern from the European ensembles model, highlighting a ridge over the West and a significant trough to the east. You’ll also find the temperature anomalies for this coming weekend on the map to the right.
With the increase in temperature often comes a risk for wildfires. On top of this, relative humidities will be very low through this week (on average between 5% and 20%), thus making conditions prime for fires. Winds will also be gusty due to the development of the Santa Ana winds, which is an offshore, warming wind. This combination will make for a dangerous threat of wildfires, so if these fires start, they may be difficult to put out.
The Storm Prediction Center is highlighting an extreme and critical fire risk for today, and that will likely through continue the rest of this week for coastal Southern California.