06/237 PM.
Strong northerly wind will pick up Wednesay evening through Thursday evening, strongest across the mountains but gusty conditions reaching the coast. Mostly dry conditions are expected for the next week. Friday through the weekend, warmer conditions are expected with moderate Santa Ana winds.
(tdy-Fri), 07/921 AM.
***UPDATE***
Calm weather expected today, before winds start to pick up tonight. Partly cloudy skies with lots of sunshine will be common, and highs will mostly be in the 60s (just slightly below normal). Wind and hazard products for tonight through at least Friday will be the focus area of the forecast this afternoon.
***From Previous Discussion***
The upper level low has started to move to the east. The northern edge of it will brush the Long Beach area later this morning and will bring clouds and a slight chc of rain. Clouds have also advected into the Paso Robles area and the Cuyama Vly. Aside from these morning clouds skies will be sunny today. Hgts will rise slowly to 562 dam today. Cool air advection from the interior will bring several degrees of cooling to SLO county and northern SBA county. More sunshine and very weak offshore flow will bring 1 to 3 degrees of warming to the rest of the area. The warming will not be enough to bring max temps up to normal levels. Most max temps across the csts/vlys will end up in the mid 60s.
To night a mostly dry trof will pass over the area. It will bring quite a bit of cloudiness to the north slopes some of which will spill into the Cuyama Vly. More importantly it will bring increasing offshore flow from the N and cold air advection both of which will team up to bring warning level (60 mph) gusts to the VTA mtns and the i-5 corridor. Advisory level gusts (45 to 55 mph) will develop across the rest of the LA county mtns and the SBA county mtns as well as the Santa Ynez range and the SBA south coast. Overnight lows in wind sheltered areas will be below normal as well.
The northerly winds will bring a good amount of upslope flow to the north slopes. There will be just enough moisture around to bring a 30 percent chc of showers Thursday morning to the north facing mtn slopes. 1 to 3 inches of snow is possible above 5000 feet and a dusting will be possible as low as 4000 feet.
The cold air advection will really dominate the weather on Thursday. It will drive advisory level gust out of the mtns and into the LA county Vlys (save for the San Gabriel), the Calabasas area, the eastern Santa Monica Range, Malibu and the VTA vlys near the LA county line. Unlike most wind events the peak winds will occur around noon as opposed to the more typical early to mid morning peak. The compressional warming driven by the downsloping winds will be totally overwhelmed by the cold air advection and max temps will (under sunny skies) plunge 4 to 8 degrees and end up in the upper 50s to lower 60s. There is also a chc that mtn wave activity will develop to the lee of the San Gabriels. Please see the product LAXNPWLOX for all of the wind related details.
Sfc high pressure quickly builds into NV Thursday night. This will create about 5 mb of offshore flow from the east. At the same time there will remain about 4 mb of offshore flow from the north. The winds will respond by healing over to the NE and this will kick off a long duration Santa Ana Wind event. Advisory level gusts (35 to 45 mph) will likely develop through the Santa Ana wind corridor. The offshore flow and reduction of cold air advection will allow 2 to 4 degrees of warming for most of the area, although the SBA county mtns, the northwestern VTA mtns and the Cuyama Vly could see up to 10 degrees of warming. Max temps, however, will remain 3 to 6 degrees blo normal.
One big item of note: Due to all the recent rains, there is a greater risk of downed trees and powerlines.
(Sat-Tue), 07/1234 AM.
High pressure aloft will continue through Tuesday. 578 dam hgts on Saturday will rise to 582 dam by Sunday and will then not change much through Tuesday. At the sfc there will be 4 to 6 mb of offshore flow from both the N and E through the period. Santa Ana winds will be present all 4 days of the xtnd fcst. Saturday is the only day with upper support and advisories look likely then, but the gusts should be below advisory criteria for the rest of the period.
The combination of increased hgts, offshore flow and copious sunshine will bring 4 days of warming to the area. Look for 3 to 6 degrees of warming Sat; 2 to 4 degrees Sunday and 1 to 3 degrees both Mon and Tue. Max temps will remain blo normal on Saturday but will increase to above normal on Sunday. By Tuesday max temps will be 3 to 6 locally 8 degrees above normal with cst/vly temps in the upper 60s to mid 70s.
Early morning lows will remain blo normal in the wind sheltered areas through the entire 4 day period. Freezing and near freezing conditions are likely for the far interior and possible in the some the vlys.
Looking at the long range AI mdls, the next chc of rain will occur between the 17th and 20th of the month.
07/1643z.
At 1630Z at KLAX, there was a surface-baased inversion. The top of the inversion was 700 feet with a temperature of 14 degrees Celsius.
For 18Z TAF package, high confidence in all TAFs except for KPRB. For KPRB, there is a 50% chance that VLIFR conditions do not develop after 11Z.
Increasing northerly flow late in the TAF period will generate some LLWS and turbulence across the mountains and foothills.
KLAX, High confidence in 18Z TAF as VFR conditions are expected through the period. No significant easterly wind component is expected. However, there is a 60% chance of NNW winds gusting 15-20 knots in the 13Z-20Z time frame.
KBUR, High confidence in 18Z TAF as VFR conditions are expected through the period.
07/843 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Friday night, high confidence in a combination of Small Craft Advisory (SCA) level northwesterly winds and seas (peaking in the 14-18 foot range). Additionally, there is a 50-705 chance of Gale force winds late tonight through Thursday evening, with the highest chances south of Point Conception. For Saturday through Sunday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Friday night, high confidence in a combination of SCA level winds and seas developing. Additionally, there is a 20-30% chance of Gale force winds on Thursday. For Saturday through Sunday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through Thursday night, there is a 60-80% chance of SCA level northwest winds developing across western sections with winds and seas remaining below SCA levels elsewhere. For Friday through Sunday, there is a 60-80% chance of SCA level northeasterly winds from around Point Mugu south to Santa Monica and across the San Pedro Channel.
07/311 AM.
A moderately large northwest swell will build over the coastal waters through Friday. There is a moderate to high (30-50 percent chance that surf could reach high surf advisory criteria between late Thursday night through Friday evening. The highest chances will be for west and northwest facing shores along the Central Coast.
Ca, Beach Hazards Statement in effect from late tonight through Friday evening for zones 87-354-362-366. (See LAXCFWLOX). Wind Advisory in effect from 4 AM to 9 PM PST Thursday for zones 88-362-370>372-374-375. (See LAXNPWLOX). High Surf Advisory in effect from 4 AM Thursday to 9 PM PST Friday for zones 340-346. (See LAXCFWLOX). Wind Advisory in effect from 10 AM to 9 PM PST Thursday for zones 346>348. (See LAXNPWLOX). Wind Advisory in effect from 2 PM this afternoon to 9 PM PST Thursday for zones 349-351-352. (See LAXNPWLOX). Wind Advisory in effect from 1 AM to 2 PM PST Thursday for zone 353. (See LAXNPWLOX). High Wind Warning in effect from midnight tonight to 2 PM PST Thursday for zones 376>378. (See LAXNPWLOX). Wind Advisory in effect from 1 AM to 9 PM PST Thursday for zones 379-380. (See LAXNPWLOX). High Wind Watch in effect from Thursday evening through Friday morning for zones 379-380. (See LAXNPWLOX). High Wind Warning in effect from 4 AM to 2 PM PST Thursday for zones 381-383. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 PM PST Friday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 2 PM this afternoon to 9 PM PST Thursday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 PM PST Friday for zone 655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Saturday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 2 AM PST Thursday for zones 673-676. (See LAXMWWLOX). Gale Watch in effect from late tonight through Thursday evening for zones 673-676. (See LAXMWWLOX).
