Dramatic warming is expected late this week for places away from the ocean, with above-normal temperatures Thursday through Saturday, peaking on Friday. Night through morning low clouds and fog will remain confined to the beaches Friday and Saturday.
The Central Coast is under the influence of an upper-level trough, within which a cut-off low has developed to our southwest. This low will slowly move southward off the Baja Peninsula before curving back north and eventually moving east on Monday.
Scattered high clouds currently cover much of the region, and low clouds were stubborn along the beaches, particularly along the Central Coast.
Warming Trend on the Horizon:
Starting Thursday and extending into the weekend, the low-pressure system to our south will separate from the main steering flow and stall off the coast of Baja California. Simultaneously, a broad ridge of high pressure will establish itself over the western United States. Regardless of the cut-off low's precise location, substantial warming is expected for Thursday and Friday. Light offshore winds will make Friday the warmest day, with temperatures around 10 to almost 20 degrees above normal.
Highs on Friday are likely to be in the mid-70s at the beaches, and 80s to mid-90s for warm coastal valleys. Inland San Luis Obispo County could see temperatures up to around 104 degrees. Gusty (but sub-advisory) north to northwesterly winds will occur tonight through Thursday night as the low passes by, most notably for southwest Santa Barbara County.
A Heat Advisory has been issued for Friday across interior San Luis Obispo and Santa Barbara Counties, valid from 11 AM to 8 PM.
Some calendar day records may be challenged on Friday, especially in Paso Robles, where the current daily record is 102 degrees. The high pressure aloft will compress the marine layer, largely confining clouds to the coastal plains on Friday. Dense fog is possible in this shallow marine layer, particularly Friday night into Saturday morning.
On Saturday, onshore flow will increase, leading to a widespread cooling but likely less than 10 degrees of cooler.
Moisture from the low to our south could lead to some cloud buildup over the mountains and potentially a few showers later in the day.
Extended Outlook:
From early Sunday through Monday, the cut-off low is favored to move northeast, crossing over land just south of our region.
Temperatures will cool Saturday through Monday, becoming widespread below normal on Monday, with strong onshore flow expected. We'll have to watch for rain potential as the cutoff low keeps drawing in moisture.
By Tuesday, overall low pressure will continue as an unseasonably strong trough is favored to drop into the region. The cooling trend will persist, with temperatures falling 5 to 10 degrees below normal. Gusty winds are likely with this pattern, rain can't be ruled out but isn't that likely locally.
On Wednesday, high pressure returns, kicking off a warming trend that should last from the mid to late points of next week.
