Now that it’s metrological summer, most get excited about the warmer weather, but not along the California coast where a June gloom dominates, keeping conditions cool and foggy. This phenomena happens every year and often peaks in activity in June, hence the phrase ‘June gloom.’
This gloom typically brings low clouds and fog to much of the Californian coasts most mornings. Then as the daytime heating kicks in, the fog lifts, allowing for sunshine during the afternoon. Meanwhile a few miles inland, the it’s full on sunny throughout the day. There’s a certain pressure pattern that is often present this time of the year which is responsible for the June gloom. The hot temperatures across the desert and interior of the Southwest forms a thermal low pressure, making for an offshore flow. The flow meets the onshore winds from the high pressure over the Pacific Ocean. This pressure gradient pushes the cooler air over the ocean waters into the immediate coastline, allowing for the marine layer to move inland at times.
Another phenomena present this time of year: stratocanes. This coastal eddy is known as the ‘stratocane’ because the low, thick stratus clouds take on the shape of a hurricane on satellite imagery with the distinct eye, or hole, through the cloud deck. Taking place at least once per week in the summertime, the flow of winds coming from the north paired with the stratus clouds causes spin when it hits the elevation of Channel Islands just a few miles off from the Southern California coast.
The most recent instance of this stratocane was this past Sunday, as the National Weather Service office at San Diego detected:
A good morning for “stratocane” development. Two of particular note are shown in this imagery spinning off of San Clemente and Catalina Islands through 9 AM PDT. Meantime, the stratus has cleared all land areas. #cawx pic.twitter.com/LQPgll8plY
— NWS San Diego (@NWSSanDiego) June 3, 2018