Point Piedras Blancas to Santa Cruz Island CA between 150 and 250 NM Offshore Forecast
|Tonight...N Winds 10 To 15 Kt. Seas 7 To 10 Ft.|
|Thu...N Winds 5 To 15 Kt, Becoming Ne. Seas 9 To 13 Ft.|
|Thu Night...N To Ne Winds 5 To 15 Kt. Seas 11 To 13 Ft.|
|Fri...Ne Winds 5 To 15 Kt, Becoming N 5 To 10 Kt. Seas 10 To 12 Ft.|
|Fri Night...N Winds 5 To 15 Kt, Becoming N To Nw 5 To 10 Kt. Seas 8 To 10 Ft.|
|Sat...Nw Winds 5 To 15 Kt. Seas 6 To 9 Ft.|
|Sat Night...N To Nw Winds 5 To 15 Kt. Seas 5 To 7 Ft.|
|Sun...N Winds 15 To 25 Kt. Seas 6 To 10 Ft.|
|Sun Night...N Winds 20 To 30 Kt. Seas 9 To 12 Ft.|
|Mon...N Winds 20 To 25 Kt. Seas 10 To 12 Ft.|
|Mon Night...N Winds 15 To 25 Kt. Seas 11 To 17 Ft.|
| Area Forecast Discussion|
...UPDATED National Weather Service Los Angeles/Oxnard CA
949pm PST Wednesday Dec 2 2020
Gusty northeast winds are expected through the rest of the week and continue into next week. Damaging gusts are likely over the mountains and foothills of Los Angeles and Ventura Counties on Thursday with critical fire weather concerns. It will remain dry across the region with temperatures above normal.
.SHORT TERM (WED-SAT)...02/925 PM.
The latest satellite imagery shows a tilted omega block ridge centered over the state and extending into the northern Intermountain Region. An upper-level trough on the front side of the ridge will dig south through Arizona through Thursday, while another trough near 44N and 144W slams into the back side of the ridge. A cold air mass dropping south with the trough to the east will tighten the offshore pressure gradient while adding some wind support for the strong Santa Ana wind event that is setting up. Winds have been picking up across Los Angeles and Ventura Counties this evening and a few locations are already pushing into damaging wind gust criteria. Local damaging wind gusts will become more widespread tonight across the mountains and the Santa Clarita Valley. Humidities and dewpoints are are crashing this evening as offshore flow strengthens and drier air spreads in. The current headlines look agreeable and no updates are planned at this time. The forecast will be updated to tweak temperatures slightly for Thursday.
Along the Central Coast, patches of stratus has pushed into the area as enough westerly flow remains. Any stratus that forms will likely form as dense fog tonight. The ridging building an offshore flow redeveloping along the Central Coast should wipe out stratus after midnight. If stratus does linger into sunrise Thursday, it should scour rather quickly as offshore winds will start to mix down.
An update will be issued shortly for stratus tonight along the Central Coast and to tweak temperatures on Thursday.
***From Previous Discussion***
As mentioned previously models have scaled back the offshore flow Thursday night and Friday and it's very unlikely we'll see warning level winds for a second night and day. In fact, many areas will likely drop below advisory levels Thursday afternoon and stay that way through Friday, though it will still be breezy at times, especially during the typical late night/early morning increase. No wind hazards are currently in effect for that period but it's possible a few low end advisories may be needed.
Temps warmed up nicely today at the coast with the offshore flow and Camarillo actually came close to tying a record with the 85 there. The cold advection coming in tonight should knock that down a few degrees Thursday with mostly 70s at lower elevations. And cold overnight again in wind protected areas like the Ojai Valley, SLO/SB Counties, and the Antelope Valley. Probably even colder Thursday night into Friday with less wind and even drier air. MOS guidance numbers in the teens for the AV and that looks reasonable so a Hard Freeze Watch has been issued to the extreme cold there and possibilty of damaged agriculture and pipes. And similarly cold temps expected again Friday night.
Offshore flow to continue into the weekend but gradients and upper support will continue to weaken so winds will be weaker and more isolated. Slightly warmer daytime temps, especially inland as cold air shifts east.
.LONG TERM (SUN-WED)...02/204 PM.
Sunday looks to be a fairly quiet weather day with light offshore flow, cool morning temps but mild in the afternoon. Then things get a little tricky Monday as both operational GFS/ECMWF (European Centre for Medium-Range Weather Forecasts) models now showing a back door upper low moving in from the north with the actual low center almost right overnight Monday morning. The models are dry with it at lower levels with just some high clouds. But the GFS generates a wide area of 50+ kt winds at 850mb and a LAX-DAG gradient of almost -7mb. The EC has a similar gradient but the EC ensembles are quite a bit weaker with the surface winds. So still some uncertainty and it's likely we'll still see quite a bit of model fluctuation in the track of that low as we get closer. But suffice it to say that it looks like there will be another increase in Santa Ana winds early next week, potentially to another strong event. Winds expected to drop off later Tuesday into Wednesday.
Outer Waters... Good confidence that Small Craft Advisory (SCA) level hazardous seas of 10 feet will develop by mid-morning Thursday across the northern portions before spreading to NW of San Nicolas Island by late Thursday morning or early afternoon. Hazardous seas will then likely last through Friday afternoon. Otherwise, seas should lower to below SCA (Small Craft Advisory) thresholds through early next week.
Inner Waters north of Point Sal...SCA (Small Craft Advisory) level hazardous seas are likely to develop Thursday morning and continue through Friday afternoon. Winds are not expected to reach SCA (Small Craft Advisory) thresholds. Peak seas will likely reach 10 feet. The combination of a long periods swell, could cause some higher steep waves near shore.
Inner Waters S of Point Conception...For the waters near shore from Point Mugu to Santa Monica gusty NE winds are expected through Thursday evening and will likely reach as far offshore as the Channel Islands. There is a chance that gusty NE winds may impact east-facing harbors such as Avalon Harbor and Two Harbors on Catalina Island Thursday morning.
A storm across the Northern and Central Pacific earlier this week has produced a large swell that will affect the Central Coast by Thursday morning through Friday evening. The combination of the northwest swell of around 8-10 feet with a long period between 17-20 seconds will bring high surf 10 to 14 feet to the Central Coast starting early Thursday morning and continue through Friday evening. There could be local sets to 17 feet at times for NW to W facing beaches. A High Surf Advisory remains in effect from early Thursday morning through Friday evening.
Some of the swell energy is likely to refract across portions of the Santa Barbara Channel and should bring some elevated surf up between 4-6 feet across exposed west facing beaches from Santa Barbara to L.A. County by Friday.
There is an increased risk for ocean drowning. Rip currents can pull swimmers and surfers out to sea. Large breaking waves can cause injury, wash people off beaches and rocks, and capsize small boats near shore.
The forecast remains on-track for red flag conditions starting this evening across Ventura and Los Angeles Counties through Friday evening for the coasts and valleys, and through Saturday evening for the mountains and Santa Clarita Valley. Humidities did not recover last night and remain between 8-14 percent ahead of the expected high winds and even drier air later tonight and Thursday. The LAX-DAG pressure gradient forecast for Thursday morning remains near 9 mb which will result in peak northeast wind gusts of 60-70 mph in the mountains and 35-50 mph in the lower elevations. Winds will be decreasing Thursday afternoon, however, humidities will also be dropping into widespread single digit values. Timing for the particularly dangerous situation of very dry air and strong winds remains between 6am and 3pm Thursday for the mountain areas. Santa Ana winds will be much weaker (advisory levels) Thursday night and Friday as offshore gradients decrease to 5-6 mb and we lose upper level wind support. However, relative humidities will remain bone dry in the single digits through Friday and Saturday with minimal overnight recoveries. Northeast wind gusts of 25 mph will be common in the valleys and 35-45 mph in the mountains for the duration of the red flag warning on these days.
The prolonged period of dry offshore flow will continue to bring elevated to brief critical fire weather conditions at times across much of Southwest California Sunday through at least next Tuesday or Wednesday.
We are urging the public to be extremely cautious with anything that can start a fire. Some ignition sources are obvious (campfires, welding equipment, cigarettes, fireworks) but others are less so (lawn trimmers, dragging trailer chains, firearms). Those living in wildland interfaces and areas vulnerable to wildfire should have a plan and be ready to evacuate if a fire starts. Any wildfire that starts has the potential to spread rapidly and exhibit extreme fire behavior due to the combination of very dry fuels, low humidity, and strong gusty winds.
.LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect from 6am Thursday to 10pm PST Friday for zones 34-35. (See LAXCFWLOX). Wind Advisory in effect until 3pm PST Thursday for zones 40-41-44-45-547. (See LAXNPWLOX). High Surf Advisory in effect from 2pm Thursday to 2am PST Saturday for zones 40-41-87. (See LAXCFWLOX). Wind Advisory in effect until 10pm PST this evening for zones 46-53-54-88. (See LAXNPWLOX). High Wind Warning in effect until 3pm PST Thursday for zones 46-53-54-88. (See LAXNPWLOX). Hard Freeze Watch in effect from Thursday evening through Friday morning for zone 59. (See LAXNPWLOX). Red Flag Warning in effect until 6pm PST Friday for zones 240-241-244-245-547-548. (See LAXRFWLOX). Red Flag Warning in effect until 10pm PST Saturday for zones 246-253-254-288. (See LAXRFWLOX). PZ...Small Craft Advisory in effect from 9am Thursday to 6pm PST Friday for zones 645-670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect until 8pm PST Thursday for zones 650-655. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK (SAT-WED).
Periods of offshore winds and dry conditions could lead to brief critical fire weather conditions Saturday and again early next week. High surf or strong rip currents may create hazardous ocean conditions early next week. Overnight lows in the teens in the Antelope Valley Saturday morning could cause damage to agriculture and exposed pipes. Near freezing conditions over coastal Santa Barbara and San Luis Obispo Counties may damage sensitive plants and crops this weekend.