13/807 PM.
Multiple periods of light to moderate rain is expected well into next week, with the first round ending by Saturday morning. There will be a break this weekend, with the next round set for around Monday, then the next around Thursday. The risk of significant impacts and flooding with any of these storms is low, with generally light to moderate rain. Temperatures will remain at or below normal. Very large surf will bring coastal impacts well into next week, largest on Saturday.
(tdy-Mon), 14/125 AM.
Overall, latest models in good synoptic agreement through the short term period. Basically, a cold front will move out of the area this morning with a weak upper ridge prevailing this afternoon through Sunday. However on Monday, another cold front will sweep across the area.
Forecast-wise, no major changes to previous thinking. Scattered showers will continue through this morning, but will end by this afternoon. At this time, based on current rainfall rates around 0.10 or less per hour, do not anticipate any significant hydrologic issues this morning. Additional rainfall accumulations will be under 0.25 inches. With the rain ending by this afternoon, skies will clear and high temperatures should be rather nice, topping out in the mid 60s to lower 70s.
For tonight and Sunday, the weak upper level ridge overhead will keep the area dry. High temperatures on Sunday will bump up a couple degrees with widespread mid 60s to mid 70s.
Beginning Sunday evening, the next cold front will approach the area. This front will sweep across the area Sunday night through Monday night. At this time, this front does not look too impressive. Current QPF forecasts are very meager with 0.25 inches or less expected across the area (with the best totals across northwest San Luis Obispo county). Snow levels look to drop to around 5000 feet Monday evening/night, so a dusting of snow would not be out of the question. Northwesterly winds are expected to increase across the I-5 Corridor and the Santa Ynez Range Monday night with a 30-40% chance of advisory-level winds (especially through the I-5 Corridor).
(Tue-Fri), 14/125 AM.
For the extended period, models continue to indicate an unsettled pattern for the area. On Tuesday, a flat upper level ridge will keep the area rain-free, but temperatures will remain on the cool side with coastal/valley area in the 60s.
For Wednesday and Thursday, models are in agreement with another system impacting the area. At this time, the ECMWF is a bit faster with the associated cold front than the GFS. So, confidence in timing remains low, but high confidence in measurable rainfall between Wednesday and Thursday night. Looking at QPF amounts, this particular frontal passage could be a bit more impressive with deterministic models indicating rainfall totals in the 1-2 inch range. Ensemble forecasts also seem to be leaning towards a bit more impressive frontal system than previous ones. Given the potential for some decent southerly flow, orographic effects could easily generate such totals across the foothills. Of course, a lot could change between now and then, so expected totals could change noticeably.
On Friday, there may be some lingering showers in the morning hours. However, the balance of the day is expected to be dry.
14/1024z.
At 1000Z at KLAX, there was no marine layer and no marine inversion.
For the 12Z TAF package, moderate to high confidence in current forecasts. Through 17Z, moderate confidence in forecasts as timing of flight category changes could be +/- 3 hours of current forecasts. After 17Z, high confidence in CAVU conditions for all sites.
KLAX, Overall, good confidence in 12Z TAF. Through 17Z, there is a 40-50% chance of MVFR CIGs. After 17Z, high confidence in CAVU conditions. No significant easterly wind component is expected.
KBUR, Overall, good confidence in 12Z TAF. Timing of dissipation of MVFR CIGs could be +/- 2 hours of current 15Z forecast. Otherwise, CAVU conditions are expected this afternoon through tonight.
14/854 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Wednesday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. Dangerously large seas are expected to peak today (18-25 feet, locally higher with a secondary peak expected on Monday (13-19 feet). Additionally, there is a 30-50% chance of Gale force winds on Monday and Tuesday - most likely south of Point Conception.
For the Inner Waters north of Point Sal, high confidence in current forecast. Today through Wednesday, a combination of SCA level winds and seas are expected. Dangerously large seas are expected to peak today (14-21 feet) with a secondary peak on Monday (11-16 feet).
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through this afternoon, high confidence in SCA level winds, mainly across western sections with SCA level seas developing. For Sunday, winds and seas are expected to drop below SCA levels. For Monday through Wednesday, high confidence in SCA level winds developing with a 50% chance of SCA level seas. Additionally, there is a 30-40% chance of Gale force winds developing.
With the expected large west-northwesterly swell this weekend, there is the threat of dangerous breaking waves at Ventura and especially Morro Bay harbor entrances. Refer to the Marine Weather Statement which has been issued (MWSLOX) for more details.
Periodic rain can be expected through the middle of next week.
14/854 AM.
A series of very large, long period west-northwesterly swells will impact the coastline of southwest California through at least Tuesday of next week, creating large surf and dangerous conditions at all coasts. Largest surf will be focused along west to northwest facing shores and surf is expected to peak today with a potential secondary increase Monday. Moderate to significant beach erosion and shallow flooding of sea water over low-lying beach walkways, parking lots, and roads is likely, especially in the morning hours near high tide. Large surf will create dangerous rip currents, along with strong long shore currents, potential sneaker waves, and large shore pound. Impacts will be less for south-facing shores.
The highest risk will be for the Central Coast with potential for localized damage to the most vulnerable areas - such as to piers, roads, and structures. High Surf and Coastal Flood WARNINGS are in effect for the Central Coast with impacts such as breaking waves at Morro Bay Harbor entrance and Pismo and Cayucos Piers, as well as widespread sandy beach flooding - including Oceano Dunes State Park and other vulnerable low lying areas (especially during high tide). Surf heights are expected to reach 18-25 feet, highest at west-northwest facing beaches.
For west-facing beaches in LA/Ventura counties, high surf advisories are in effect with high surf expected to continue through at least Tuesday. There may be a relative "lull" in the surf Sunday before the second swell arrives, but surf and rip currents will still be hazardous. Surf is expected to peak today and there is a low chance for WARNING level surf at Ventura County beaches. Hazardous breaking waves are expected at Ventura Harbor entrance today - refer to MWSLOX for more details. Additionally, moderate coastal flooding is likely today around high tide in the late morning, thus Coastal Flood Advisories have been issued.
Ca, Beach Hazards Statement in effect through Tuesday afternoon for zone 87. (See LAXCFWLOX). Coastal Flood Warning in effect until 6 PM PST this evening for zones 340-346. (See LAXCFWLOX). High Surf Warning in effect until 3 AM PST Sunday for zones 340-346. (See LAXCFWLOX). High Surf Advisory in effect until 4 AM PST Sunday for zones 349-350. (See LAXCFWLOX). Coastal Flood Advisory in effect until 4 PM PST this afternoon for zones 354-362-366. (See LAXCFWLOX). High Surf Advisory in effect until 3 PM PST Tuesday for zones 354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PST Wednesday for zones 645-670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Sunday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until noon PST today for zone 655. (See LAXMWWLOX).
