25/854 PM.
High temperatures will remain above normal through Saturday with areas of low clouds and fog in the morning. Substantial cooling is expected Sunday and Monday. Beach impacts from Tropical Cyclones well south of the region will be possible Monday and Tuesday in the form of high surf and possible beach erosion. A significant warming trend is expected Tuesday and Wednesday.
(Fri-Mon), 25/851 PM.
***UPDATE***
Highs today rose into the 90s over the interior, with 80s to low 90s for the valleys, and cooler 70s at the coasts. Clouds lingering along the western Santa Barbara and San Luis Obispo County coasts limited warming, where some areas struggled to rise out of the 60s. Tonight, expecting another return of marine layer clouds, and the addition of some high clouds that may limit warming over Santa Barbara and San Luis Obispo Counties Saturday.
Current guidance is picking up on an upper level low, forecast to move through southern California late Sunday into Monday. This combined with additional moisture from the tropical systems to the south is creating potential for showers over the area as early as Sunday morning. Currently, there remains quite a bit of disagreement in just how much atmospheric moisture we will recieve from the south, with models producing a wide range of PWAT values from 0.8 inches up to near 2 inches. Should showers form, amounts below 0.20 inches appear to be the most likely solution at this time. Showers favor areas south of Point Conception, and may be spotty in nature, leaving plenty of areas remaining dry or only seeing light, brief sprinkles. This system will also lead to cooler temperatures Sunday and Monday, and plenty of mid to high clouds for the region.
There remains quite a bit of uncertainty in the forecast Sunday through early next week due to the two strong hurricanes (Polo and Odalys) in the eastern Pacific and the uncertainties with their evolution and respective tracks. While most of the hurricane models are in pretty good agreement keeping the storms well south of California, there is a window of opportunity Sunday night into Monday for some mid level moisture to move into the area and create a few light showers south of Pt Conception. The biggest impacts locally are still expected to be confined to the beaches with increasing swells from the hurricanes, though this is also quite uncertain pending the ultimate track of both hurricanes.
(Tue-Fri), 25/208 PM.
Pretty big uncertainty in the weather forecast Tue and beyond. More than 50% of the models are indicating high pressure building over the state with a fairly substantial warming trend through at least Thursday. There's at least a 30-40 percent chance of near 100 degree temperatures in the valleys and similar chances for Downtown LA and San Luis Obispo reaching 90 or higher. There's also a lower but still significant chance of temperatures 5-10 degrees cooler than that. Will have to wait to see how the hurricanes track before having much confidence in the longer range.
26/0141z.
At 2212Z over KLAX, the marine layer was 1050 ft deep. The top of the inversion was at 2900 feet with a temperature of 25 Celsius.
High confidence in VFR conditions through at least Saturday for KPRB, KPMD, and KWJF. For tonight into tomorrow: LIFR/IFR conditions possible at KSBP, KSMX, and KSBA. IFR/MVFR conditions possible at KOXR, KCMA, KSMO, KLAX, and KLGB. There is a 20% chance for short-lived IFR/MVFR cigs at KBUR and KVNY. Moderate confidence in timing (plus or minus 3 hours).
High confidence in typical winds.
KLAX, There is a 70% chance of OVC008-012 tonight, low-moderate confidence on timing. High confidence in any east winds staying under 8 knots.
KBUR, High confidence in VFR conditions through at least 10Z. There is a 30% chance of IFR ceilings 12-16Z on Saturday.
25/808 PM.
Through this weekend, moderate to high confidence in Small Craft Advisory (SCA) winds and steep seas affecting the outer waters off the Central Coast to near Point Conception. The SCAs currently go through late Sunday night but will likely be extended through Tuesday night. SCA conds are also forecast over the waters southward to San Nicolas Island (PZZ676) starting late Saturday afternoon. Gale force gusts will be possible at times, especially Monday afternoon and evening across PZZ676. Nearshore along the Central coast will see SCA conditions through around midnight and short period seas (7-8 feet at 7 seconds) will likely persist through late tonight extending the SCA conds there.
Moderate to high confidence in widespread gusty winds Monday into Tuesday extending into the nearshore waters at times, with the highest confidence in the Central Coast waters and Santa Barbara Channel. SCA conds over PZZ655 may be limited to Monday afternoon and evening.
Southerly swells from Hurricanes Odalys (SSW) and Polo (SSE) will affect the region this weekend through the middle of next week. These swells will create larger waves and surf nearshore, which could impact some harbor entrances, especially Sunday through Tuesday.
Some dense fog is possible on the Central Coast this weekend.
25/819 PM.
Southerly swells from Hurricanes Odalys and Polo will affect the waters this weekend through the middle of next week. This is a complex scenario with two hurricanes so close in proximity, with one of them (Odalys) poorly handled by our computer models. Another complexity is the relatively short window of time that Polo is far enough west for its waves to have a clear path to southern California. This means that the swells will have a narrow window of time to line up with the high tides. Lastly, some south-facing shores are extra vulnerable because of the lingering erosion effects from Hurricane Marie earlier this month.
While the surf heights will likely range in the 4 to 7 foot range for south facing beaches Sunday through Tuesday, there is a plus or minus in that potential of 2 feet or so due to the complications mentioned above. High tides will steadily build each day and peak Monday and Tuesday, likely reaching around 7 feet (MLLW) - which is higher by almost a foot over astronomical tides due to ongoing effects of El Nino.
There is a significant concern of Coastal Flooding over vulnerable south-facing beaches as a result, but the magnitude is still uncertain. The areas of most concern include Avalon, Long Beach, Malibu and Santa Barbara. The reasonable worst-case scenario is for impacts similar to those from Hurricane Marie, but the most likely outcome is for impacts to be a step less. The one exception being Avalon on Catalina Island, as the swells from Hurricane Polo will be more from a southeasterly direction than with Marie, which they are more exposed to. The same goes for Santa Barbara Harbor where the risk is less but still present.
South-facing beaches should plan for shallow flooding of seawater over low lying beach walkways, parking lots, and roads as well as potential for significant beach erosion. Very localized damage to structures is also possible in the most vulnerable areas. With all that stated, there is a potential that impacts will be minimal if the lower-end surf outcome materializes.
Due to rather high uncertainty, have gone with Beach Hazard Statements through Wednesday afternoon. This covers the coastline from Santa Barbara South coast down to LA county, including Catalina island. A decision to upgrade to Coastal Flood Advisory will be made Saturday or Sunday. Refer to CFWLOX for more details.
Ca, Beach Hazards Statement in effect through Wednesday afternoon for zones 87-349-350-354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Saturday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM Saturday to 3 AM PDT Monday for zone 676. (See LAXMWWLOX).
