Area Forecast Discussion
Issued by NWS Los Angeles, CA

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966 FXUS66 KLOX 152209 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 309 PM PDT Sat Jun 15 2024 .SYNOPSIS...
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15/137 PM. Warm to hot conditions are expected today, with slight cooling each day through Monday or Tuesday. Temperatures will then trend upwards by the end of the upcoming week. Gusty north to northwest winds will affect portions of the region, including southern Santa Barbara County, the Interstate 5 cooridor, Antelope Valley, and the Central Coast, through Monday morning.
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&& .SHORT TERM (TDY-TUE)...
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15/308 PM. The upper level pattern features a broad upper level trough that will intensify with the base lowering over the region into Monday. Upper level heights are expected to trend downward through Monday and hold constant for Tuesday. At the surface, north-to- south pressure gradients will be strong into Monday (LAX-BFL onshore peaking around 3 to 4 mb in the mornings). This northerly pressure gradient combined with some upper level wind support and cold air advection will continue the gusty to damaging northerly to northwesterly winds. Winds are expected to strengthen for wind- prone locations through this afternoon and evening, including Southern Santa Barbara County, the I-5 cooridor, the western Antelope Valley and foothills, and the mountains of Santa Barbara and Ventura Counties. Gusts of 45 to 65 mph will be common, and winds will be strongest in the evenings through the mornings. The widespread and long duration of the Sundowner winds in southern Santa Barbara county will make this a rather rare event for this time of year. The combination of gusty winds, warm temperatures, and low humidities will bring elevated to brief critical fire weather conditions to southern Santa Barbara county, mountains, interior valleys, and Antelope Valley through Monday (please see fire discussion for more details). This pattern of winds, including warning level gusts, is expected to continue through Monday mornings. In fact, latest model runs show an upward trend in wind speeds for Sunday night through Monday morning, and this period may see the strongest wind of the event. This is due to the dropping of the upper level trough over the region, which allows for better upper level support as pressure contours become more alighted through the atmosphere. Late this afternoon and evenings, the eastern portions of Santa Barbara County will see gusty Sundowner winds, including Montecito Hills and the Botanical Gardens in Mission Canyon. While winds will continue to be strong elsewhere, the period for warning level winds for this area will be confined to tonight. The compressional heating from the offshore flow has created pockets of very high temperatures, that rose rapidly this morning. Expect daytime highs to top out in the upper 90s (possibly up to 100-102) today for the foothills of the western San Fernando Valley, the Santa Clarita Valley, and the Ojai Valley. Due to the highly localized heat, no additional heat products are expected for today. Temperatures have peaked today for Los Angeles and Ventura Counties coastal plains, as the seabreeze has reached these areas. For the Santa Barbara South Coast, highs overall will in the 80s to low 90s today, followed by a few degrees cooler tomorrow. Due to the consistently cool and cloudy conditions thus far this season at this location, heat impacts are expected to be significant. In addition, because downsloping winds will persist all night, overnight lows will be very elevated and offer little relief. Heat awareness and precautions are advised through the weekend. The widespread downsloping flow from the north have driven away marine layer clouds, and stratus will likely be confined to coastal Ventura and Los Angeles Counties. Temperatures will largely trend downwards for the region by several degrees each day. .LONG TERM (WED-SAT)...15/308 PM. There is good agreement among the GFS and ECMWF that the trough will persist over the region through Thursday, and that upper level heights will trend upwards through Friday. Late Friday into the weekend there is greater uncertainty in the upper level pattern, with the potential for a weak ridge to begin to build. Daytime highs are expected to slowly trend upwards Thurday through the weekend, crossing over to above normal for much of the region on Friday. The north-to-south gradient is expected to weaken Wednesday and even flip to onshore at times. Onshore flow (both from the west and south) is generally expected to be dominant through the period, and thus morning low clouds and fog are likely. However with rising upper level heights, the marine layer depth, and thus the inland extend of stratus will be limited to the coastal planes and will at times struggle to reach the coastal valleys. Clouds may cling to some beaches all day, especially in Los Angeles and Ventura Counties. Even with less dramatic pressure gradients than in the short term, gusty northerly-to-westerly winds will continue during the evenings for some wind- prone locations (e.g., the I-5 cooridor, the Antelope Valley and foothills, the Santa Barbara Southwestern coast). At this time, wind in the extended period are likely to be much lower impact than in the short term.
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&& .AVIATION...
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15/2110Z. At 2000Z at KLAX, the marine layer was 800 ft deep. The top of the inversion was at 3700 ft with a temperature of 27 C. Overall, moderate to high confidence in TAF package. CAVU conditions are anticipated at most locations through the period. However, CIG/VSBY restrictions in a returning marine layer will likely affect coastal LA County tonight and Sun morning (60-80% chance), including KLAX and KLGB. Onset timing of CIG/VSBY restrictions may vary by +/- 2 hours from current forecasts. Gusty northerly winds will continue developing today and continue through the TAF period, and there could be some light turbulence/LLWS across the mountains and foothills. KLAX...Moderate to high confidence in TAF. There is a 40% chance that CIG/VSBY restrictions do not develop. No significant easterly wind component is expected. KBUR...High confidence in TAF as CAVU conditions are anticipated through the period.
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&& .MARINE...
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15/210 PM. For the Outer Waters, high confidence in current forecast. Winds have increased to Gale force levels and will remain at Gale force levels through Monday. So, GALE WARNINGS will remain in place through Monday (with a 20% chance of Storm force winds through Sunday night). Seas will peak in the 12 to 15 foot range through Monday. For Tuesday through Wednesday, winds will subside, but remain at Small Craft Advisory (SCA) levels while seas drop below 10 feet. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. There is a 60-80% chance of Gale force winds through Sunday and a GALE WARNING remains in effect. Seas will peak in the 10 to 13 foot range through Sunday. For Monday through Tuesday, there is a 60-80% chance of SCA level winds. On Wednesday, 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. For the western Santa Barbara Channel, high confidence in Gale Force Winds continuing at Gale force levels through Sunday with a GALE WARNING remaining in effect. For Monday through Wednesday, there will be a 60-80% chance of SCA level winds across the western half of the Santa Barbara Channel. Elsewhere across the southern Inner Waters, there is a 20-30% chance of SCA level winds today through Sunday with high confidence in winds and seas remaining below SCA levels Monday through Wednesday. Across all of the coastal waters, steep and dangerous seas can be expected this weekend into at least early next week.
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&& .BEACHES...
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15/210 PM. Short-period wind waves, due to gale force winds over the nearby coastal waters, will generate significant surf conditions along the local beaches today through Monday. High surf, 4 to 7 feet, will impact the beaches of Ventura county. For the beaches along the Central Coast as well as Los Angeles county, elevated surf conditions will continue through Monday. Along with the surf conditions, dangerous rip currents can be expected through the weekend.
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&& .FIRE WEATHER...
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15/130 PM.
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&& Gusty northwest to north winds are expected to continue through early next week, peaking in intensity through tonight with a secondary peak late Sunday into early Monday. Wind gusts of 30 to 50 mph will be common at times through the period for the Central Coast, mountains of Santa Barbara, Ventura and northwest Los Angeles County as well as Antelope Valley (strongest in the mountains and deserts). Isolated gusts to 65 mph will be possible in the strongest periods of wind across the Santa Ynez Range and I-5 corridor. Meanwhile, the air mass will warm and dry, with widespread 8 to 15 percent humidities in the mountains and deserts. High temperatures between 90 and 100 will be common inland of the beaches. Poor overnight recoveries in the foothills are also expected. This warm and dry air will descend into some coastal foothills, including southern Santa Barbara County. As a result, there is an elevated risk for fast growing grass fires over much of the area, that could transition into wildfires where the fuel beds are most abundant and dry. && .LOX WATCHES/WARNINGS/ADVISORIES...
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CA...Beach Hazards Statement in effect through Monday evening for zones 87-340-346-362-366. (See LAXCFWLOX). Wind Advisory remains in effect until 11 AM PDT Sunday for zone 88. (See LAXNPWLOX). Wind Advisory remains in effect until 8 PM PDT this evening for zones 340-341-346-347. (See LAXNPWLOX). High Wind Warning now in effect until 11 AM PDT Monday for zones 349-351-353-376>378-381. (See LAXNPWLOX). Heat Advisory remains in effect until 8 PM PDT Sunday for zones 349>352. (See LAXNPWLOX). Wind Advisory remains in effect until 6 PM PDT this evening for zones 350-352. (See LAXNPWLOX). High Wind Warning remains in effect until 11 AM PDT Sunday for zones 350-352. (See LAXNPWLOX). High Surf Advisory in effect until 7 PM PDT Monday for zone 354. (See LAXCFWLOX). Wind Advisory in effect until 3 AM PDT Sunday for zones 356-383. (See LAXNPWLOX). PZ...Gale Warning in effect until 2 AM PDT Monday for zones 645-650. (See LAXMWWLOX). Gale Warning in effect until 7 PM PDT Monday for zones 670-673-676. (See LAXMWWLOX).
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&& $$ PUBLIC...Schoenfeld/Gomberg AVIATION...Cohen/RAT MARINE...Cohen/RAT BEACHES...RAT/Cohen FIRE...Munroe/Gomberg SYNOPSIS...DB/RS weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox