SLO County forecast: Increasing cloudiness, chance of rain

·3 min read

Due to the incoming direction of the tsunami caused by the underwater volcano eruption off Tonga and the bottom topography of San Luis Bay, NOAA’s Port San Luis Tide Gauge reported a water-level of 8.8 feet on Saturday morning; the highest level above mean lower low water (MLLW) ever seen at that location. Other Central Coast tide gauges reported lower-water levels.

A 570-decameter upper-level low-pressure system 300 miles to the southwest of Central Coast will gradually move northward toward San Luis Obispo and Santa Barbara counties and strengthen to 563-decameters by Sunday. This upper-level low, cut off from the jet stream, will produce increasing mid to high-level clouds and a chance of sprinkles/rain showers on Saturday night into Monday.

Temperatures over this period will remain mild, with most locations ranging between the low to high-60s. Further inland, Tule fog is expected to develop in the Central Valley during the night and morning.

This weekend, the surface winds will be primarily out of the northeast, which will bring in a dry air mass. Consequently, much of the precipitation will evaporate (virga) near the earth’s surface before reaching the ground. Overall, rainfall amounts will only be a few hundredths of an inch for most locations this weekend. The greatest chance of rain will occur Saturday night into Sunday morning, and again on Monday as the winds turn out of the northwest and the upper-level low moves over the Central Coast. The European model is advertising up to a quarter of an inch of rain could fall on Monday, while the American model only shows a few hundredths of an inch.

Along with the possible rain, the gentle to moderate (8- to 18-mph) northwesterly winds on Monday through Tuesday will allow areas of low marine clouds with pockets of fog and mist to develop in the coastal regions during the overnight.

Wednesday, Thursday and Friday will see moderate to fresh (13 to 24 mph) Santa Lucia (northeasterly) winds and mostly clear and dry weather with near to slightly above-normal temperatures. The dry weather may continue through the following week as high pressure remains over the Central Coast with no signs of a pattern.

Surf report

Sunday’s 5- to 7-foot west-northwesterly (280-degree, deep-water) swell (with an 11- to 15-second period) will and remain at this level through Tuesday.

A 4- to 6-foot west-northwesterly (280-degree, deep-water) swell (with an 8- to 12-second period) is expected on Wednesday, decreasing to 3- to 5-feet (with an 11- to 15-second period) on Thursday into Friday.

Seawater temperatures will range between 55 and 57 degrees through Monday.

LOWS AND HIGHS, PASO ROBLES

SUN

MON

TUE

WED

THU

FRI

SAT

SUN

41, 63

40, 64

41, 65

39, 65

39, 69

42, 68

41, 68

42, 67

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUN

MON

TUE

WED

THU

FRI

SAT

SUN

48, 69

47, 64

46, 66

43, 72

45, 75

46, 74

45, 70

46, 71

PG&E safety tip

PG&E Safety Message: If rain showers develop on Sunday into Monday, the roads will be slippery due to the accumulation of oils. Please slow down and give yourself more time to reach your destination.

John Lindsey’s is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.

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