827 FXUS66 KLOX 211312 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 512 AM PST Sun Nov 21 2021 .SYNOPSIS...21/331 AM. A warming trend will continue into Monday as an offshore flow regime remains in place across the area. Gusty offshore winds are likely for portions of the area, strongest across much of Ventura and Los Angeles Counties. Cooler and cloudier conditions are expected between Tuesday and Wednesday as a weak weather system moves over the region. Another Santa Ana wind event is possible beginning as early as Wednesday, possibly extending into Friday. && .SHORT TERM (TDY-TUE)...21/509 AM. Offshore flow is firmly in place this morning. Surface pressure gradient are trending more strongly offshore with KLAX-KDAG surface gradients showing a 7 mb offshore trend over 24 hours ago. KLAX-KTPH gradients are an impressive -11.5 mb currently. Skies are mostly clear across the region, except for patches of low clouds and dense fog for the interior San Luis Obispo County valleys and some reduced visibility in portions of the Los Angeles County coast. Gusty Santa Lucia winds have developed as forecast across western San Luis Obispo County with gusts generally between 35 and 45 mph. Local gusts to 53 mph have been observed at Whale Rock Reservoir. A wind advisory remains in effect through 8 am this morning. Winds do weaken somewhat late this morning through early this evening, but local 3-km WRF and HRRR solutions suggest winds resurfacing again this evening and continuing into Monday morning. Gusts will not be as strong, but the areal extent looks to be focused between San Simeon and Morro Bay and along the west facing slopes of the La Panza mountain range. Future shifts will need to ponder reissuing the wind advisory for tonight and into Monday morning as winds drop below advisory criteria for about 12 hours. A moderate to locally strong Santa Ana wind event is getting underway. Gusty northeast winds between 35 and 50 mph have already been observed. A few isolated gusts between 58 mph and 67 mph have been picked up in the windier peaks and valleys. With offshore trends increasing, the strongest winds are expected this morning, especially after daybreak. NAM-WRF solutions and EPS ensemble members continue to place this event in the moderate category, but sits on the fringes of high wind warning levels. NAM-WRF solutions suggest 950 mb winds increasing to around 45 knots and 850 mb winds around 40 knots. Local 3-km WRF solutions trend a little stronger closer to 55 knots at 950 mb across the Ventura County valleys. Local gusts to 65 mph would not be surprising at sites like Boney Mountain, Warm Springs, and Wiley Ridge. A majority of the EPS ensemble members keep K3A6 just below high wind criteria, but there are a few perturbations increasing winds to near 58 mph. Wind advisories remain in effect for much of Ventura and Los Angeles County, except for the San Gabriel and Antelope Valleys through Monday afternoon. High confidence exists in the timing at this point and no adjustments are planned at this time. With offshore flow in place, a warming and drying trend will establish today. As soon as the winds hit KCMA at between 2 am and 3 am, temperatures jumped from 47 degrees to 70 degrees. Temperatures are on track for daytime highs in the upper 70s to mid 80s today with much of the immediate coastal locales seeing the greatest warming and likely the hottest temperatures today. A warmer air mass will remain in place into Monday. The greatest warming occurring in the valley areas Monday. An upper-level trough of low pressure near 30N and 130W will get cutoff from the flow this evening as upper-level ridging to the north building into the North Coast of California and squeeze the broad troughing in place across the region. The ridge will build southeast into the Desert Southwest and cutoff the trough offshore. The upper-level trough will sit nearly stationary along the 130th meridian west through early Monday morning, then the trough will lift out to the northeast through Tuesday afternoon and move over the region. Deterministic NAM-WRF solutions continue to suggest some moisture moving back with the north, but model solutions do not accurately handle moisture parameters to the southwest of the region. The forecast leans in favor of CMC ensemble members relative to the EPS and GEFS as local knowledge suggest that the forecast should take a wetter stance. Slight chances PoPs remain in place for the Los Angeles and Ventura County mountains, but light rain or showers cannot be ruled out for southern Los Angeles County for Monday night and into Tuesday. .LONG TERM (WED-SAT)...21/508 AM. Gusty Santa Ana winds look to develop again for Wednesday. EPS ensemble members for K3A6 favor a weak to moderate Santa Ana wind event lingering into Thanksgiving Day, especially across the mountains and the higher terrain. EPS members are little more mixed for the coastal and valley areas such as KCMA, but there are a few ensemble members developing gusts between 35 and 40 mph at KCMA. Deterministic ECMWF solutions suggest a 5.4 mb offshore KLAX-KDAG surface pressure gradient developing. The forecast mostly leans towards NBM values, except for temperatures which were tweaked to bring lower to mid 80s into the forecast for the coastal and valley areas. In wind sheltered areas, clear skies will allow for more efficient radiative cooling processes to take place. Cold overnight temperatures are forecast for the interior portions of the area, including the Antelope and San Luis Obispo County valleys. Frost and freeze headlines could be needed for these days, and cannot be ruled out for some other valley areas such as the Cuyama, Ojai, and Santa Ynez Valleys and along the Central Coast. Overnight low temperatures break away from NBM values to accurately represent the cold air mass across the interior. Temperatures for the interior during this period trend toward CMC ensemble means for KPRB, KPMD, and KWJF with spatial adjustment toward climatological spreads in offshore flow. && .AVIATION...21/0614Z. At 0518Z at KLAX, there is a surfaced based inversion with a top around 1900 feet with a temperature of 20C. Moderate confidence in the 06Z TAFs. There is a 30% chance of of MVFR conditions forming at KPRB. There is a 20% chance of VFR conditions returning before 08Z at KSMO, KLAX, KLGB. Gusty NE winds will affect the mtns and valleys of L.A. and VTU Counties with mdt turbulence and some LLWS. KLAX...Moderate confidence in the 06Z TAF. There is a 20% chance of VFR conditions returning before 10Z. There is a 20% chance that there will be an easterly wind component up to 10 kt through early Sunday morning. KBUR...Moderate confidence in the 06Z TAF. Mdt turbulence and some LLWS possible. && .MARINE...20/1018 PM. For the outer waters, fairly high confidence in the forecast. There is a 30% chance of Small Craft Advisory (SCA) level NE winds across portions south of San Miguel Island and north of San Nicolas Island on Sun. Otherwise, SCA conds are not expected Sun thru Mon. SCA level NW winds are likely Tue thru Wed, with a 20% chance of seas reaching SCA levels Tue night through early Wed morning. For the inner waters north of Pt. Sal, moderate confidence in the forecast. There is a 20-30% chance of SCA level NE winds near shore late tonight Sun morning. SCA level NW winds are expected Tue, then there is a 40% chance of SCA level NW winds Wed. For the inner waters south of Pt. Conception, moderate to high confidence in the forecast. Late tonight and Sun, and again late Sun night/Mon morning, SCA level NE winds are likely from the eastern Santa Barbara Channel south to Santa Monica. There is a 20-30% chance of SCA level NE winds affecting Avalon Harbor. There is a 40% chance of SCA level W-NW winds across western SBA Channel Tue afternoon and evening. Otherwise, winds and seas will remain below SCA levels Mon afternoon thru Wed. && .FIRE WEATHER...21/341 AM. A Red Flag Warning remains in effect through Monday afteroon across much of LA/Ventura counties due to high confidence of Red Flag conditions for these areas. There will be elevated to brief critical fire weather conditions across San Luis Obispo and Santa Barbara counties today into early Monday. Northeast to east Santa Ana winds are increasing this morning. The peak winds expected later this morning and afternoon. During this peak, offshore wind gusts of 35 to 55 mph are expected across Los Angeles and Ventura Counties, except isolated gusts up to 60 mph in favored mountains and foothills. In addition, wind gusts of 25 to 45 mph are expected across San Luis Obispo and Santa Barbara Counties. Gusty Santa Ana winds are expected to continue into Monday morning, however wind gust speeds are expected to be 5 to 10 mph less than today. Humidities are expected to fall to around 15 to 20 percent by mid morning today, potentially lowering to between 7 and 15 percent by this afternoon and evening, and again on Monday. Very poor humidity recoveries expected across most windy locations on tonight, generally remaining in the 10 to 20 percent range. Temperatures generally look to peak between 75 and 85 degrees on Sunday and Monday. The potential for Red Flag conditions is above 80 percent for Los Angeles and Ventura Counties, resulting in the Red Flag Warning for those areas. There will be an increased risk of wildfire ignitions on Sunday and Monday across the region. Areas in a Red Flag Warning will have an increased risk for fires with rapid spread, long range spotting, and extreme fire behavior, especially considering the dry fuels in place across the region. Conditions are expected to improve Monday night into Tuesday. There is the potential for another round of weak to moderate offshore winds and low humidities Wednesday through Friday. The focus of this event will once again be Los Angeles and Ventura counties, with a chance of Red Flag conditions. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory in effect until 8 AM PST this morning for zone 34. (See LAXNPWLOX). Wind Advisory in effect until noon PST Monday for zones 40-41. (See LAXNPWLOX). Wind Advisory in effect until 3 PM PST Monday for zones 44>46-53-54-88-547. (See LAXNPWLOX). Red Flag Warning in effect from 9 AM this morning to 3 PM PST Monday for zones 240-241-244>246-253-254-288-547-548. (See LAXRFWLOX). PZ...Small Craft Advisory in effect until noon PST Monday for zones 650-655. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK (TUE-SAT). Another Santa Ana wind event is possible beginning on Wednesday and continuing into Thanksgiving Day. Gusty winds and critical fire weather conditions are possible across some areas. Cold overnight temperatures are forecast across the interior portions between Wednesday night and Friday. && $$ PUBLIC...Hall AVIATION...Lund/Sirard MARINE...Lund/Sirard FIRE...Hall/Gomberg SYNOPSIS...Hall weather.gov/losangeles