Here is this week’s weather forecast by PG&E meteorologist John Lindsey.
After a reprieve last week, the marine low clouds “May Gray” will return to coastal regions early this week and the North County later this week. In the North County, strengthening high pressure Monday into Tuesday will continue to create warm conditions with widespread mid-90-degree readings from Santa Margarita to San Miguel and all locations in between.
Along the coastline, fog with areas of mist will develop as a strong temperature inversion layer develops. Morning temperatures will range between the low 50s at sea level along the beaches and just a short distance away, but at 1,200 feet up, the top of the Irish Hills will see mid-80s and under clear skies.
An approaching upper-level trough will nudge the ridge of high pressure eastward Tuesday night, signaling an end to the recent stretch of above-normal inland temperatures. More importantly, this condition will produce a deepening marine layer. As the marine layer increases in height Tuesday night into Friday, heavy mist and drizzle will develop along the coast and will progressively move farther inland each night, reaching the North County by Thursday morning.
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If the numerical weather models are accurate, between a few hundreds and a third of an inch of precipitation (mist an drizzle) could accumulate along the coastline over this period. Dreary conditions indeed! Needless to say, widespread cooling will spread across the entire Central Coast as persistent onshore flow will continue to pump chilly marine air into interior valleys and the atmosphere cools from the top down.
The Eastern Pacific high will strengthen off the California coastline this upcoming Memorial Day weekend. This condition is expected to produce strong to gale-force (25 to 38 mph) northwesterly winds, warmer conditions and mostly clear skies as the marine layer is mixed out of atmosphere.
Monday’s 2- to 4-foot northwesterly (305-degree, deep-water) swell (with an 8- to 10-second period) will remain at this height and period into Tuesday. A 3- to 5-foot northwesterly (310-degree, deep-water) swell (with an 8- to 12-second period) is forecast along our coastline Wednesday into Friday.
Strong to gale-force (25 to 38 mph) northwesterly winds will generate a 3- to 5-foot northwesterly (310-degree, deep-water) sea and swell (with a 4- to 9-second period) Saturday, increasing to 4 to 6 feet (with a 4- to 6-second period) on Sunday. Combined with Monday’s northwesterly swell will, it be a 1- to 2-foot Southern Hemisphere (190-degree, deep-water) swell (with a 14- to 16-second period).
Seawater temperatures will range between 50 and 52 degrees through Wednesday. Seawater temperatures will increase to 51 and 53 degrees Thursday into Friday.
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At PG&E, the safety of our customers and employees is our top priority. Areas of dense fog with mist and drizzle this week will reduced driver visibility and may produce slippery road conditions. Please slow down on the road and give yourself extra time to reach your destination.
John Lindsey’s Weekly Forecast is special to The Tribune. He is PG&E’s Diablo Canyon Power Plant marine meteorologist and media relations representative. Contact him at email@example.com. Follow him on Twitter @PGE_John.
This week’s temperatures
LOWS AND HIGHS, PASO ROBLES
LOWS AND HIGHS, SLO AND COASTAL VALLEYS