248 FXUS66 KLOX 051210 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 410 AM PST Tue Dec 5 2017 .SYNOPSIS... Strong offshore winds have developed across much of Ventura and Los Angeles Counties and will continue through Friday. Winds will be strongest through this afternoon and again late Wednesday night through Thursday with damaging wind gusts expected in some areas. && .SHORT TERM...(TDY-THU) Strong offshore pressure gradients and good upper level support caused widespread strong to damaging winds to develop across much of Los Angeles and Ventura Counties last night and early this morning. Gusts over 70 mph have been reported in the mountains, with gusts between 50 and 60 mph in the valleys. The winds, very low relative humidites and very dry fuels caused rapid growth and spread of a large wildfire in western Ventura County, the Thomas Fire. As of early this morning, the fire had scorched 31,000 acres, and has destroyed at least 150 structures, including many in and around the city of Ventura. There were widespread power outages in Ventura County and even southern Santa Barbara County. Winds may actually increase a bit more for a few hours around or just after sunrise, then are expected to slowly diminish in the afternoon. Winds will likely drop below High Wind Warning levels in coastal and valley areas this afternoon. However, strong offshore gradients will continue across L.A. and VTU Counties tonight and Wed as strong surface high pressure settles into the Great Basin. A strong upper high just off the Pac NW will move slowly eastward through Wed. While winds and subsidence aloft will decrease some across the area tonight through Wed, causing the winds to abate a bit, still expect advisory level winds to continue in many coastal and valley areas of L.A. and VTU Counties through Wed evening, and Wind Advisories will likely replace the High Wind Warnings, once they expire. In the mtns of L.A. and VTU Counties, damaging gusts to 60 mph will likely continue through Wed. Max temps will be up a few degrees west of the mountains today, but little change or even some cooling is expected in the mountains and deserts. Additional warming is expected west of the mountains on Wednesday, with highs reaching 80 degrees in the warmest locations on the coastal plain and in the lower valleys. Tonight and Wed night will be very cold in wind sheltered locations, especially across SBA and SLO Counties and in the Ojai Valley. Freezes or hard freezes are likely across much of interior SLO and SBA Counties, and hard freezes are possible. Freezes are possible in the Ojai Valley, and on the Central Coast. A strong vort will drop southward through Utah and eastern Nevada Wed night and early Thu. This will cause upper level north to northeast winds to strengthen once again across the region, with another area of strong subsidence. In addition, the WRF shows offshore surface pressure gradients increasing once again, to an incredibly steep 11 mb between KLAX and KDAG. Expect winds to increase once again Wed night, then peak Thu morning into early Thu afternoon. Wind gusts may again reach 70 to 80 mph in the mountains of L.A. and VTU Counties, and 50 to 60 mph in the valleys and in coastal sections of VTU Counties. High wind warnings remain in effect for the mtns of L.A. and VTU Counties through Thu afternoon, and High Wind Watches may be needed for the valleys and the VTU County coast. With rising heights and thicknesses, expect some warming in most areas on Thu. While critical fire weather conditions are expected across much of L.A. and VTU Counties through Thu, there is a chance that Thu will have the most extreme conditions, due to a warmer and even drier air mass and similar wind conditions. .LONG TERM...(FRI-MON) The ridge will continue to build over the West Coast into Saturday then pretty much maintain that strength into early next week. Models don't really show any weakening through the end of next week with the only caveat being possibly another inside slider riding down the east side of the ridge axis. And all that would do would be to reinforce the pre-existing offshore flow, which now looks like it will be around for at least the next 10 days, though winds should drop below advisory levels by the weekend. So prepare for a very lengthy period of really dry/warm conditions. Not seeing any hint of precip through at least the middle of the month. && .AVIATION...04/0030Z... At 0000Z, there was no marine layer or inversion at KLAX. Good confidence in gusty offshore winds focused across many TAF sites south of Point Conception, with moderate confidence in timing and strength of increasing winds. There will be a brief lull in winds at some TAF sites around 14Z. Lower confidence exists in offshore winds for KSMO, KLAX, and KLAX after 14Z. KLAX...Good confidence in 18Z TAF through 12Z with lower confidence thereafter. There is a 40 percent chance of 09010KT+ for up to 3 hours sometime between 13Z and 18Z. KBUR...Moderate confidence in 18Z TAF. There is a 20 percent chance of brief 04022G32KT between 14Z and 17Z. && .MARINE...05/230 AM. Gusty northeast winds and choppy seas will continue Small Craft Advisory (SCA) conditions over the southern portion of the outer waters into midday. South of Point Conception, northeast Gale Force winds with gusts to 40 knots will continue through this afternoon in the nearshore waters from Ventura to Santa Monica. There is a 20 percent chance of SCA level gusts over nearshore portions of the Central Coast waters during this time. Northeast winds gusting to 30 knots will likely affect the San Pedro Channel out to Catalina Island during this time with short- period hazardous seas of 3 to 6 feet. The wind driven seas will cause boating hazards for east-facing harbors and inlets, such as Avalon Harbor and other offshore islands. The offshore winds will begin to diminish in speed this afternoon and fall below SCA levels by late tonight. A second burst of offshore winds will bring another round of SCA winds and seas across the inner waters south of Point Conception Wednesday night into Thursday and possibly continuing into Friday morning. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Freeze Watch in effect from late tonight through Wednesday morning for zones 34>36-38-44. (See LAXNPWLOX). Freeze Warning in effect until 8 AM PST this morning for zones 36-38. (See LAXNPWLOX). Hard Freeze Warning in effect until 8 AM PST this morning for zone 37. (See LAXNPWLOX). High Wind Warning in effect until 4 PM PST this afternoon for zones 40-44-45-88-547. (See LAXNPWLOX). Wind Advisory in effect until 4 PM PST this afternoon for zones 41-87. (See LAXNPWLOX). High Wind Warning in effect until 4 PM PST Thursday for zones 46-53-54. (See LAXNPWLOX). Red Flag Warning in effect until 6 PM PST Thursday for zones 240-241-244>246-253-254-288-547-548. (See LAXRFWLOX). PZ...Gale Warning in effect until 3 PM PST this afternoon for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PST this afternoon for zone 676. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK...(THU-MON) Strong Santa Ana winds are expected through at least Thursday or Friday across Los Angeles and Ventura Counties, along with critical fire conditions. && $$ PUBLIC...DB/MW AVIATION...Munroe MARINE...Kj SYNOPSIS...Kj weather.gov/losangeles