Weather experts are keeping a close eye on an unusual severe-weather risk that’s expected to affect parts of Arizona and Southern California on Wednesday. The National Weather Service Storm Prediction Center has issued a marginal (Level 1 out of 5) risk warning, which includes cities such as Phoenix and Tucson. Additionally, there is a possibility of a brief and isolated tornado forming along Southern California’s immediate coastline.
These potential tornadoes could occur if rotating cells moving towards the coast spawn waterspouts. If such a waterspout makes landfall, it could cause tornado-like damage before dissipating within a short distance inland.
The underlying cause of this weather pattern is an upper-level low system. This involves a region of cold air, low pressure, and atmospheric spin at high altitudes.
On Tuesday, this system was situated offshore of Southern California, directing warm, moist air northward. The same conditions will also bring Pacific moisture into Arizona, prompting a flood watch for the region.
The air mass, now rich in moisture, will lead to showers and thunderstorms in the afternoon. There is a likelihood of severe thunderstorms, capable of dropping one to two inches of rain in a short time. This could result in localized flash flooding, particularly on Arizona’s sandy soils.
Some of these storms might evolve into supercells, characterized by rotating thunderstorms. The upper-level low pressure is affecting the jet stream, creating a trough with wind shear, or shifts in wind direction with altitude. Changing winds interacting with tall thunderstorm clouds can lead to rotation, slightly increasing the risk of tornadoes in a region not typically known for such weather events.
Leave a Reply