26/758 PM.
Substantial cooling is expected across the area Sunday and Monday. Beach impacts from Tropical Cyclones well south of the region are expected to peak Monday and Tuesday in the form of high surf, beach erosion, and possible coastal flooding. A significant warming trend is expected Tuesday and Wednesday.
(tdy-Tue), 27/1030 AM.
***UPDATE***
The biggest near term concern continues to be the surf and coastal flooding, see beached discussion below for details.
Mid-to-high clouds were streaming over Ventura and especially Los Angeles Counties this morning. Cannot rule out a shower or sprinkle with this activity through this evening focused across eastern LA County.
For Monday, breezy northwest to onshore winds ahead of a decent trough but dry trough for this time of year will mostly remain under advisory levels through the afternoon hours. However, Monday evening through Tuesday afternoon, there is a weak to moderate offshore push with a 40-50 percent chance of low end Wind Advisory winds focused across southern Santa Barbara (especially Santa Ynez range and foothills) and the mountains near the I-5 corridor. A weak sub-advisory) Santa Ana may follow Tuesday for the most prone mountains and coastal valleys of Los Angeles and Ventura Counties.
Heat may once again become the biggest concern mid-week and beyond, especially coastal valleys to coast, as week offshore flow may become entrenched for into at least early next week and join forces with persistent ridge.
***From Previous Discussion***
High clouds are slowly shifting to the south and will make their way mostly out of LA County by the afternoon. Currently, these high clouds are disrupting the formation of marine layer clouds for areas south of Point Conception, and any low clouds and patchy fog that forms will be pretty short-lived. North of Point Conception, low clouds and patchy fog are overspreading the Central Coast, and even into the Southern Salinas Valley. These low clouds are expected to burn off by the afternoon. Low clouds and fog are forecast to return to the Central Coast and possibly across the LA Coast tonight into Monday morning.
Guidance appears to be trending toward a drier solution for today and Monday, as this upper level low passing through appears to be moisture starved. Any showers (10 to 15% chance) that form should carry little to no impacts. However, additional clouds and colder temperatures will translate to 5 to 10 degrees of cooling Sunday/Monday. Weak northerly offshore winds start to develop early Monday, with some borderline advisory level Sundowner winds by Monday evening. Offshore gradients peak around 3.0 mb Tuesday morning, and still appear to favor a fairly northerly direction. This supports a 6 to 15 degree boost in Tuesday's high temperatures.
(Wed-Sat), 27/1030 AM.
Good confidence in high pressure and warmer temperatures Wednesday through the rest of the week. Current guidance has northerly onshore flow peaking Tuesday, then trending weaker each day. Offshore gradients look moderate at best, so coastal areas will likely begin to see some decent sea breezes by Wednesday. However, we could still see valley temperatures nearing 100 degrees later this coming week.
National Hurricane Center is tracking a developing disturbance south of the Gulf of Tehuantepec. Current projections indicate that this system will likely strengthen significantly. If this does occur, the upper-level ridging would steer this system west- northwest for quite some time putting it in a favorable position for southerly swell impacts for the beaches. We will have to keep an eye on this system because there is a chance it produces a building southerly swell which could result in impacts at the beaches. However, this is rather far out and would not see impacts until probably after October 4th.
27/1755z.
At 1716Z at KLAX, the marine layer was 1000 ft deep. The top of the inversion was at 1800 feet with a temperature of 23 Celsius.
High confidence in VFR TAFs for KBUR, KVNY, KWJF, and KPMD.
Moderate confidence in IFR conds at KSBP/KSMX with a 40% chance for brief LIFR conds. 20% change for no cigs.
Moderate confidence in VFR TAFs for remaining sites. Chance for IFR to MVFR conds arrivinig after 10Z at KPRB (30%), KSBA (15%), KOXR (15%), KCMA (15%), KSMO (20%), KLAX (30%), and KLGB (30%).
Gusty onshore winds expected after 18Z Mon. KLAX, Moderate confidence in VFR TAF. There is a 30% chance of BKN008-015 conds after 06Z Mon. If cigs form they may bounce between BKN and SCT frequently. High confidence in no significant east wind component. Gusty southwest winds expected after 18Z Mon.
KBUR, High confidence in VFR TAF.
27/820 AM.
High confidence in Small Craft Advisory (SCA) winds and steep seas affecting the outer waters through at least Tuesday night. Gale force gusts will be possible at times, especially Monday afternoon and evening across the outer waters south of Point Conception. Nearshore along the Central coast will see SCA winds and steep seas each afternoon and evening through Tuesday.
For the nearshore waters south of Point Conception, SCA winds may occur across western portions of the Santa Barbara Channel today, likely expanding across the entirety of the Santa Barbara Channel and portions of the inner waters adjacent to Los Angeles and Orange Counties on Monday, with moderate chances Tuesday.
Southerly swells from Hurricanes Odalys (SSW) and Polo (SSE) will continue to affect the region through Tuesday. These swells will create larger waves and surf nearshore, which could impact some harbor entrances.
Conditions are likely to improve to below SCA levels Wednesday into next weekend, except for occasional northwest SCA winds near Point Concpetion in the afternoon/evening hours.
27/830 AM.
Southerly swells from Tropical Cyclones Odalys and Polo will affect the waters through the middle of this week, with Hurricane Polo likely sending the more impactful swell from the SSE, affecting our coastline Monday and Tuesday. This swell timing will likely line up with very high tides Monday and Tuesday in the late morning hours. Lastly, some south-facing shores are more vulnerable because of the lingering erosion effects from Hurricane Marie earlier this month.
Surf heights across Los Angeles and Ventura Counties are likely to peak around 4-7 feet Monday and Tuesday, while the Santa Barbara south coast should see surf in the 3-5 foot range. High tides will steadily build and peak Monday and Tuesday, likely reaching around 7 feet (MLLW) in the late morning hours - which is higher by almost a foot over astronomical tides due to ongoing effects of El Nino.
While this swell is slightly smaller than the swell from Marie, there is a significant concern of Coastal Flooding over vulnerable south-facing beaches. 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. Minor tidal overflow is possible for west facing beaches due to the very high tides.
Beach Hazards Statements (BHS) are in effect for LA and Ventura coasts through early Monday morning, and for the Santa Barbara south coast into Wednesday. Then a Coastal Flood Advisory and High Surf Advisory are in effect for LA and Ventura Monday and Tuesday. A BHS may need to be issued for the LA and Ventura coasts for Tuesday afternoon through Wednesday (lining up with Santa Barbara) due to the very high tides.
Ca, Beach Hazards Statement in effect through late tonight for zones 87-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect from 5 AM Monday to 5 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect from 5 AM Monday to 5 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect through Wednesday afternoon for zones 349-350. (See LAXCFWLOX). PZ, Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Monday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from noon Monday to midnight PDT Monday night for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Tuesday for zones 670-673-676. (See LAXMWWLOX).
