Marine Weather and Tide Forecast for Atascadero, CA

.SHORT TERM (TDY-SAT)...21/819 AM.

***UPDATE***

Cooling is certainly ongoing today across coast and valleys with some areas along the Central Coast running 20 degrees below yesterday at this time. Marine layer stratus returned to the Central Coast and in a few areas south of Pt Conception. Expecting more of that Friday and through next week and reaching the valleys as soon as tomorrow morning. Overall a very low impact period of weather the next several days, with aviation services being the focus as the marine layer returns and creates some minor impacts at airports.

***From Previous Discussion***

Overall, 00Z models in good synoptic agreement through the short term period. At upper levels, weak low, currently spinning southwest of the Channel Islands will move southeastward into northern Baja by Friday with a weak ridge nosing across the area on Saturday. At the surface, moderate onshore flow is expected through the period.

Forecast-wis, no significant issues are expected through the short term. With the increasing onshore pressure gradients and some lowering of H5 heights, the marine layer should become more established with increasing areal coverage from day-to-day.
However, the inversion will likely stay on the shallow side, so most any stratus/fog will likely be confined to the coastal plain with some patchy dense fog possible. Other than any marine layer stratus, skies are expected to remain mostly clear through Saturday.

As for temperatures, the combination of increased onshore flow, marine layer influence and some lowering of thicknesses will bring a cooling trend for all areas through the period. By Saturday, high temperatures will be hovering around seasonal normals for all areas.

Finally with respect to winds, no significant winds are anticipated. With the moderate onshore pressure gradients, there will be some gusty southwesterly winds across interior sections each afternoon/evening. However, speeds are anticipated to remain below advisory levels.

.LONG TERM (SUN-WED)...21/126 AM.

For the extended, models continue to exhibit decent synoptic agreement. At upper levels, weak low will move across the area on Sunday then general troughing will remain over the area Monday through Wednesday. At the surface, moderate to strong onshore pressure gradients are expected.

Forecast-wise, very benign and typical May weather can be expected. The combination of the upper level pattern and the onshore surface flow will allow for the marine layer to deepen and stratus/fog to become more widespread each day, pushing into the coastal valleys next week. Other than the marine layer stratus, skies are expected to remain mostly clear through the middle of next week. As for temperatures, there will be a cooling trend for all areas through the period with the increased marine influence and lower thicknesses/H5 heights.

As for winds, will expect continued onshore flow through the period. Given the forecast strength of the onshore pressure gradients, southwesterly winds across interior sections could reach advisory level each afternoon/evening by Tuesday and Wednesday.

AVIATION
21/1129Z.

At 1100Z at KLAX, the marine layer was 900 feet deep. The top of the inversion was 2700 feet with a temperature of 23 degrees Celsius.

For 12Z TAFs, high confidence in KPRB, KVNY, KBUR and KPMD.

For coastal sites, moderate confidence in 12Z TAFs as timing of flight category changes could be +/- 2 hours of current forecasts.

KLAX...Moderate confidence in 12Z TAF. Timing of flight category changes could be +/- 2 hours of current forecasts. There is a 30% chance that CIG/VSBY restrictions do not develop this morning. No significant easterly wind component is expected.

KBUR...High confidence in 12Z TAF as CAVU conditions are expected through the period.

MARINE
21/752 AM.

For the Outer Waters, moderate to high confidence in current forecast. Through this weekend, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels.
Increasing chances for SCA level winds will return next week.
Seas will gradually build possibly nearing SCA levels by mid to late next week.

For the Inner Waters north of Point Sal, high confidence in current forecast. Today through Monday, winds and seas are expected to remain below SCA levels. Thereafter, chances for SCA level winds will return; highest during the afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Through this weekend, winds and seas are expected to remain below SCA levels. On Monday, there is a 20-30% chance of SCA level winds in the afternoon and evening hours across the Santa Barbara Channel; 50-60% chance of SCA level winds on Tuesday.

LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.