Flood watches cover several western states as a rare tornado threat looms. A storm approaching the West Coast on Wednesday is set to soak portions of California and the Intermountain West, with unusual severe thunderstorms and rough seas expected too.

Flood watches are in effect for portions of Southern California north of Los Angeles, as well as across much of Arizona, southern Utah, southwestern Colorado and western New Mexico as the slow-moving disturbance is expected to linger over the West through this weekend.

NOAA’s Storm Prediction Center described a “climatologically rare and a concerning/well-above-typical risk for severe storms” across the interior Southwest on Wednesday, with a risk for tornadoes, large hail and damaging winds.

That’s especially the case in a corridor from near Phoenix to Flagstaff in Arizona, where there’s an enhanced risk (Level 3 out of 5) for severe storms.

There’s even a tornado threat for coastal Southern and Central California, including Los Angeles. This latest round of significant weather follows a recent spate of wildfire activity in the region.

“Minor beach erosion and tidal overflows may occur across south-facing beaches especially along the Malibu Coast and in the Long Beach area,” wrote the National Weather Service in Los Angeles. That area was slammed by waves from Tropical Storm Rachel earlier this month — with wave heights and ocean temperatures being boosted by a Kelvin wave.

Record warm seas near Southern and Central California are also expected to add more moisture to approaching storms through winter.

This unsettled pattern is being influenced by a record El Niño in the Pacific Ocean, which is causing winds to strengthen in the upper atmosphere near Hawaii, signaling the emergence of a strong subtropical jet stream pattern that will probably fuel increasingly stormy weather like this across the United States during November. That’s why the approaching storm is probably just the start of something much bigger.