02/100 AM.
Stagnant pattern through Friday with below normal temperatures, occasional patchy marine layer clouds, and weak to moderate Sundowner winds. Several potential scenarios exist for the Labor Day weekend, with anything from benign conditions to tropical rain, or even hot offshore winds.
(tdy-Fri), 02/820 AM.
***UPDATE***
Latest satellite and surface observations indicate clear skies across the area, except for some patchy stratus/fog across the Central Coast and over the Bight. Current sounding data indicates marine inversion in the 1500-2000 foot range. Some lingering northerly winds, gusting 30-35 MPH, continue across the western half of the Santa Ynez Range.
Forecast-wise for the immediate short term, no significant issues are expected. Current patchy stratus/fog will dissipate by late morning with sunny skies expected for all areas this afternoon. Based on morning TEMP STUDY data, high temperatures today will be similar to Tuesday with most areas several degrees below seasonal normals. As for winds, the northerly winds across southern Santa Barbara county will weaken later this morning. However, high resolution models indicate an uptick in northerly offshore gradients this evening. So, there is a good chance of widespread advisory level winds across the western half the Santa Ynez Range this evening and wind advisories will be considered.
Overall, current forecast has good handle on the immediate short term. So, no significant updates are expected.
***From Previous Discussion***
Expecting more or less the same weather each day through Friday thanks to a relatively unchanging upper level pattern as the trough in the PNW will sag down south slightly along the west coast. The weather will remain rather benign through Friday as the precipitation and gusty wind impacts will stay well north of us. Temperatures will remain relatively unchanged each day, with max temps generally 5-10 degrees below normal for early September. This still isn't cold by any stretch, but it is a welcomed change for many after months of warm and humid weather.
The marine layer continues to be the most difficult aspect of the forecast through Friday (definitely not the most difficult for this weekend). So far it has decided to take the morning off as there is virtually no marine layer stratus across the coastal waters from San Francisco down to San Diego. Really not expecting any sort of solid marine layer to form tonight, but there indications that tomorrow may be more solid, especially along the Central Coast. Safe to say confidence is very low in how the marine layer will behave and if/where it will form. If it does decided to form, there is potential for morning drizzle across coasts and coastal slopes, especially along the Central Coasts as the trough sags the furthest south.
As far as winds are concerned, the most significant winds will continue to be Sundowner winds, which will continue each night over southwest Santa Barbara County and flirt with an Advisory each time. Another round of near-Advisory strength Sundowners is expected this evening, and another Wind Advisory may be issued later today.
(Sat-Tue), 01/932 PM.
For the long term period, an upper low is forecast to wobble over and around the Pacific Northwest through the Labor Day weekend. Models vary on the exact path of the wobble, but cyclonic flow aloft will remain over the area through early next week. At the surface, focus remains on current Tropical Storm Marie. While some more models/ensemble members are starting to come into agreement with a more northwestward track away from SW California, still quite a bit of uncertainty in exact details for impacts across the region this weekend.
Currently, Marie is located between 15N and 20 N, and around 110W. The latest forecast from the National Hurricane Center has Marie intensifying to hurricane strength early this morning, following a track to the northwest through the Labor Day weekend. The chances of Marie directly hitting Southern California as a hurricane or tropical storm remain VERY LOW (with only a few ensemble members from the models indicate any track close to Southern California).
However, despite the HIGH likelihood of Marie maintaining a west to northwest track away from the West Coast, there still be some noticeable impacts for the area from this storm. With the upper level pattern, moisture from Marie will be advected over the area during the Labor Day weekend, but the amount of moisture will be greatly impacted by the exact track of the hurricane. At this time, there is a 50-60% chance of widespread light rainfall (amounts 0.10-0.50 inches) Sunday through Tuesday and about a 10-15% chance of heavy rainfall and thunderstorms. As for winds, there will be about a 10-15% chance of moderate to strong easterly winds ahead of any rainfall, which could produce some fire weather concerns. Finally, there is high confidence in significant coastal risks which are detailed in the Marine and Beaches segments of this discussion.
Needless to say, the weather for the upcoming Labor Day weekend may by highly dynamic. A minor change in the track of Marie could result in significant changes to the current forecast. So, given the uncertainty with this pattern, stay tuned and monitor the latest forecasts.
02/1111z.
At 0716Z at KLAX, the marine layer was 1300 feet deep with an inversion at 2400 feet and 20 degrees C.
High confidence on VFR TAFs at KPRB, KSBA, KOXR, KCMA, KBUR, KVNY KWJF, and KPMD. 10% chance for very brief MVFR cigs at coastal sites sometime between through 17Z.
Moderate confidence in BKN LIFR-IFR conds through around 17Z at KSBP/KSMX, but cigs may SCT at times. Moderate confidence in TAF for KLAX/KSMO with a 20% chance for brief IFR-MVFR cigs between 14Z-17Z. Low confidence in TAF for KLGB with a 50% chance VFR conds prevail.
Moderate confidence in return of LIFR-IFR cigs at KSBP/KSMX tonight within 3 hours of forecast. Low confidence in return of IFR-MVFR cigs across LA County coastal sites and KPRB sometime after 10Z/03.
KLAX, Moderate confidence in TAF. There is a 20% chance for brief BKN008-012 cigs developing sometime from 14Z-17Z. Low confidence in cigs of similar height returning after 10Z/03. No significant east wind component expected.
KBUR, High confidence in TAF, with a 10% chance for brief BKN0008-12 cigs from 14-16Z. 20% chance for IFR cigs after 12Z/03.
02/820 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Friday, high confidence in Small Craft Advisory (SCA) level winds across PZZ673/676, with a 20-30% chance of SCA level winds across PZZ670. For Saturday through Sunday, there is a 30-50% chance of SCA level winds across all of the Outer Waters.
For the Inner Waters north of Point Sal, moderate confidence in current forecast. Today through Sunday, there is a 30-50% chance of SCA level winds in the afternoon and evening hours.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For a majority of the southern Inner Waters, there is a 20-30% chance of SCA level winds today through Sunday, mainly across western sections. For the western half of the Santa Barbara Channel, there is a 60-80% chance of SCA level winds in the late afternoon through overnight hours today through Thursday with a 30-40% chance of SCA level winds Friday through Sunday.
Expecting increasing southerly swell Friday through Labor Day Weekend weekend due to tropical activity to the south. The details and timing are very much dependent on the track of soon to be Hurricane Marie, but confidence is high in larger than normal southerly swell through the holiday weekend and into Tuesday.
02/1258 AM.
While there remains a range of outcomes in terms of the track of son to be Hurricane Marie, SoCal is likely to see an increasing south-southeasterly swell Friday into Tuesday. The most likely scenario would result in elevated surf with possible high surf advisories for south facing beaches during a very busy holiday weekend, with very strong rip currents. Peak timing is still somewhat unclear, but Sunday through Monday appear to be the window of peak swell.
Additionally, evening high tides are expected to be around 7 feet during portions of the event. As a result, there is an increasing chance of moderate coastal flooding of low- lying areas and significant beach erosion. There is a chance that coastal flood advisories will be issued.
Some areas that may be most susceptible to impacts from the combined elevated surf and high tides are Avalon, Long Beach (Alamitos Peninsula), Malibu, Point Mugu, and potentially portions of Santa Barbara (if the swell directions ends up being 160-170 degrees).
Ca, NONE. PZ, Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Thursday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).
