Powerful SLO County storm to bring heavy rain and wind gusts up to 80 mph

Two storms, a 988-millibar low-pressure system 150 miles west of San Francisco and a 990-millibar low-pressure system centered 300 miles west of Point Conception, will move northeastward and merge into a 984-millibar system off the Northern California coastline on Sunday.

This complex storm system will create strong to-gale-force (25 to 38 mph) southeasterly winds by Saturday afternoon, increasing overnight, peaking at strong gale-force-to-storm force (47 to 63 mph) levels along the coastline on Sunday.

As you move inland, the winds will be less dynamic; however, wind gusts on top of the coastal mountain ridges could reach 80 mph. Along with the southerly winds, rain will reach the Central Coast by Saturday evening, becoming heavy at times with a chance of thunderstorms on Sunday.

This system will have a moist subtropical tap (atmospheric river); consequently, snow levels will remain above 6,500 feet.

Total rainfall amounts on Sunday are expected to range between 2 to 4 inches throughout the Central Coast, with higher amounts in the coastal mountains.

On Monday, this storm will weaken to 998 millibars and become nearly stationary off Point Mendocino. This condition will allow the southeasterly winds to decrease to fresh to strong levels (19 to 31mph) levels; however, the associated cold front will continue to produce rain on Monday.

Total rainfall amounts on Monday will range between 0.75 and 1.50 inches.

Due to the abundant moisture in the atmosphere, partly cloudy to mostly cloudy skies, scattered rain showers, and gentle to moderate (8 to 18 mph) wins are our forecast on Tuesday.

Strong to gale-force (25 to 38 mph) northwesterly winds, cooler temperatures, and partly cloudy skies are forecast for Wednesday into Thursday morning.

Another storm is expected to arrive Thursday night into Friday with fresh to strong (19 to 31 mph) southerly winds and rain. This system is expected to produce between 0.75 and 1.25 inches of rain, with snow levels dropping to 3,500 feet.

After that, a period of dry weather is expected to start next Saturday and continue through Valentine’s Day.

Surf report

Increasing southerly winds will generate a 6- to 8-foot southerly (190-degree, shallow-water) seas (with a 3- to 5-second period) Saturday night, building to 15 to 17 feet (with a 4- to 7-second period) on Sunday. These southerly seas will lower to 6 to 8 feet on Monday.

A 5- to 7-foot northwesterly (295-degree, deep-water) swell (with an 18- to 20-second period) is forecast on Tuesday, becoming a 5- to 7-foot northwesterly (300-degree, deep-water) sea and swell (with a 7- to 17-second period) on Wednesday into Thursday.

Seawater temperatures will range between 58 and 60 degrees through Tuesday, decreasing to 57 to 58 degrees on Wednesday into Saturday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

John Lindsey is a retired PG&E marine meteorologist. Email him at JohnLindseyLosOsos@gmail.com or follow him on Twitter @PGE_John.