09/521 AM.
A warming trend is expected today and Wednesday, and highs will run 5 to 10 degrees above normal midweek through the weekend. Patchy low clouds and fog will impact some beaches and coastal valleys, but will likely burn off by mid morning. Breezy northwest winds are expected along the Central Coast this afternoon and gusty conditions are expected across southwestern Santa Barbara County this evening into tonight.
(tdy-Thu), 09/903 AM.
***UPDATE***
Northerly winds reached advisory levels across the western Santa Ynez Range and the northern LA County mountains overnight and into this morning. Slightly stronger winds are expected this afternoon through tomorrow morning, and wind advisories are in place.
This northerly winds played a role in keeping most of the marine layer from reaching land this morning south of Point Conception. Expected even less marine layer cloud coverage tonight into Wednesday morning, with about a 50% chance of low clouds reaching the southern half of the LA Basin.
We're on track for at least a few degrees of warming across much of the region today, and still on track for a more significant increase tomorrow thanks to pressure gradients trending offshore while upper level ridging continues to build in.
***From Previous Discussion***
Today the synoptic pattern will shift, as the trough of low pressure exits the region making way for high pressure to build. Temperatures will trend a few degrees warmer today compared to yesterday (mid 70s to mid 80s common), and marine layer clouds will struggle to form, particularly for southern Santa Barbara County and Ventura County. Sundowner Winds are expected to redevelop this evening into tonight across southwestern Santa Barbara County, in addition to northwest winds across the I-5 Corridor. Wind Advisories will likely be issued for the aforementioned areas. This afternoon the strong northwest flow will also produce gusty but sub-advisory conditions along the beaches of the Central Coast.
By Wednesday morning, surface pressure gradients will become moderately offshore from the northeast across San Luis Obispo and Santa Barbara Counties (gusts around 25-40 mph across the mountains), which will reduce marine layer clouds and lead to a noticeable spike in temperatures for northern areas. Temperatures will be warmest across San Luis Obispo County, where highs between 80-90 will be common at the coast, and around 100 degrees is expected at Paso Robles. Much weaker offshore flow is expected for Ventura and Los Angeles Counties on Wednesday, but this will still cause warming temperatures and a reduction in morning cloud coverage. There continues to be a 20 percent chance of a Heat Advisory being needed for some coast/valley areas, most likely the southern Salinas (Paso Robles), Santa Clarita, and the western San Fernando Valleys. Additionally, with any clouds that do form there will be a chance of dense fog due to the high pressure aloft. Thursday offshore flow (if any) will be weaker and daytime highs will cool by a few degrees across the coasts and valleys and remain similar for inland desert areas.
(Fri-Mon), 09/518 AM.
Friday through the weekend there will be minimal temperature changes each day, followed by very minor cooling early next week. The synoptic pattern favors persistent high pressure and onshore flow at the surface, which will result in minor day to day chances. Highs through the weekend will be around 5 to 10 degrees above normal for this time of year, with minor to moderate HeatRisk impacts for much of the region. Morning low clouds and sometimes dense fog will occur across the beaches and coastal valleys, but will struggle to make it to the inland valleys and foothills. Ensembles still hint at at elevated mid-level moisture shuttling into the region from the southeast as early as Thursday afternoon and at least through the weekend. This will result in a small (~5 percent) chance of a thunderstorm occuring over the San Gabriel Mountains.
09/1729z.
At 1633Z at KLAX, the marine layer was about 2100 ft deep. The inversion top was at 3300 ft with a maximum temperature of 17 C.
High confidence in VFR TAFs for KPMD and KWJF, but winds may be off by 5 kt at times.
Moderate confidence in remaining TAFs. Timing of flight category changes may be off +/- 3 hours. Most cigs that form are scattering out or clearing. There is a 15-25% chance of MVFR cigs at KSMO, and KLAX between 13Z-15Z Wed, and a 50% chance at KLGB.
KLAX, Moderate confidence in TAF. Timing of flight category changes could be +/- 3 hours of current forecast, and there is a 25% chance of BKN015 cigs between 13Z-15Z Wed. Any east wind component is expect to be less than 6 kt.
KBUR, High confidence in TAF.
09/905 AM.
For the Outer Waters, moderate to high confidence in current forecast. High confidence in a combination of Small Craft Advisory (SCA) level winds and seas through Wednesday. Localized gale force gusts will be possible over all of the outer waters late this afternoon and early evening, with a 30% chance that a Gale Warning will be needed. Otherwise, SCA winds are likely to persist through Wednesday night, with much weaker winds Thursday through Saturday.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Through Wednesday, SCA level wind are expected, mainly in the afternoon and evening hours, with seas near or above SCA levels. Lighter winds are likely during the morning hours, then increasing again each afternoon. Thursday through Saturday, winds and seas are expected to remain below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. There is a 40% chance for isolated Gale force gusts over the west portion of PZZ650. For a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Friday. The exception will be the western half of the Santa Barbara Channel, with a SCA in effect through late tonight. Light winds are then expected Wednesday through Saturday.
09/340 AM.
A long period south swell will move through the waters Today through Thursday, with swell height building to 3 feet nearshore. Periods will initially be 21 seconds, decreasing to 15 seconds by Thursday. Surf is forecast to build to 3 to 6 feet with local sets to 7 feet along south facing shores of Los Angeles and Ventura Counties. There is a chance of more widespread surf of 4 to 7 feet with larger sets, in which case a high surf advisory will be needed.
Hazardous surfing and swimming conditions are expected due to the building surf, along with strong rip currents.
Ca, Beach Hazards Statement in effect through Thursday evening for zones 87-354-362-366. (See LAXCFWLOX). Heat Advisory in effect from 10 AM to 7 PM PDT Wednesday for zones 341-347. (See LAXNPWLOX). Wind Advisory remains in effect from 7 PM this evening to 7 AM PDT Wednesday for zones 349-351-378. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 5 PM PDT Wednesday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect until 8 AM PDT Wednesday for zone 676. (See LAXMWWLOX).
