Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000 FXUS66 KLOX 222235 AFDLOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 235 PM PST Wed Feb 22 2017 .SYNOPSIS...
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Gusty winds and possible precipitation for the mountains into Thursday morning. Elsewhere the clouds will decrease into Friday and temperatures should stay below normal into Tuesday. One low will arrive by Saturday night with precipitation into Sunday. Then another low moves in on Monday and will continue the precipitation into Tuesday.
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&& .SHORT TERM...
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(TDY-SAT) Strong northwesterly flow is highlighted well on visible satellite with streams of cloud development pushing up against the mountains of the southern San Joaquin Valley. A good illustration as well of the high moisture level of that air mass. It helps support the forecast of mountain showers for this evening and overnight. Updated model runs... though... have not only kept the high humidities in the region but have also shown a much colder airmass moving through tonight through Friday. This will drop snow levels much lower than previously thought and will likely bring snow down to the Grapevine section of Interstate 5 (the Tejon Pass). There are indications of possibly one to two inches of snow at pass level overnight. This will bear close watching and it is entirely possible that a Winter Weather Advisory will need to be issued this evening for the likelihood of snow through the Tejon Pass. While the possibility of snow below the Tejon Pass level is still developing... the likelihood of strong and gusty winds through the mountains through late Thursday morning looks more certain. The strong winds are in part due to the cold dense airmass that would be squeezing through the passes and canyons. The affected mountains are the Santa Barbara... Ventura... and Los Angeles County Mountains. In addition... strong and gusty winds are expected in the Antelope and Santa Clarita Valleys and below passes and canyons along the Santa Barbara South Coast this afternoon and tonight. Areas along the Central Coast will be affected primarily this afternoon and evening prior to the winds turning more northerly. Winds and mountain showers may linger a bit on Thursday and there may be elevated winds through the Los Angeles County mountains Thursday evening. However wind advisories are not expected at this time. Conditions will continue to improve into Friday and much of Saturday and though below normal... temperatures will be warmer on Friday and Saturday. The next storm system will begin to move into the region on Saturday along the Central Coast. There may be a few periods of light rain after midday but most of the precipitation should hold off until Sunday. .LONG TERM...(SUN-WED) Precipitation will develop over the region on Sunday but there continues to be uncertainty regarding how much and when. The probability of rain has decreased across the region in general though it still looks as though most locations should get wet. Precipitation would begin along the Central Coast then move southward through the day. However there had been a chance of an extra shot of precipitation in the afternoon and evening into Ventura and Los Angeles Counties and that is what has diminished with recent model runs. The low appears to get hung up off shore and then brings the extra shot of moisture in with the Monday storm system instead. This would be helpful to the Academy Award event planned for Sunday afternoon and evening but would make Monday a messier weather day. Will need to see if this change gets carried through into later model runs before making major adjustments to the forecast package. After a wet Monday and early Tuesday... a weak ridge will help bring drier and warmer conditions to the region on Wednesday.
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&& .AVIATION...22/1800Z. At 1632Z, there was no marine inversion at KLAX. Poor confidence in the 18z TAFs. Some TAFS will have ceiling changes this afternoon as a layer of stratocumulus develops in some of the valley locations. Skies should clear out after dark. KLAX...Moderate confidence in 18Z TAF. After 20Z, moderate confidence in VFR conditions prevailing. This evening, after 02Z, there will likely be some northerly cross winds with a 30% chance of cross winds exceeding 25 knots. KBUR...Moderate confidence in 18Z TAF. After 20Z, poor confidence in VFR conditions. There is a 40 percent chance of sct v bkn ceilings. There is a 30% chance of light turbulence/LLWS developing after 02Z. && .MARINE...
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22/200 PM... For the Outer Waters, high confidence in current forecast. Northwest winds will increase today, reaching Small Craft Advisory (SCA) levels, with the SCA level winds continuing through Thursday night. Winds and seas will diminish on Friday, but southerly winds will increase on Saturday/Sunday with a high likelihood of SCA conditions developing. For the Inner Waters, high confidence in current forecast. West to northwest winds will increase today, reaching SCA levels, with the SCA level winds continuing through Thursday evening. On Friday, winds and seas will diminish below SCA levels. However on Saturday, southerly winds will increase to SCA levels north of Point Sal with southeasterly winds increasing to SCA levels south of Point Conception on Sunday.
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&& .LOX WATCHES/WARNINGS/ADVISORIES...
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CA...High Surf Advisory in effect until 3 PM PST this afternoon for zones 34-35. (See LAXCFWLOX). Wind Advisory in effect until 9 PM PST this evening for zones 34-35. (See LAXNPWLOX). Wind Advisory in effect until 10 AM PST Thursday for zones 39-52>54. (See LAXNPWLOX). High Surf Advisory in effect until 9 PM PST Thursday for zones 40-41-87. (See LAXCFWLOX). Wind Advisory in effect until 3 AM PST Thursday for zones 59-88. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 PM PST Thursday for zones 645-670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Thursday for zones 650-655. (See LAXMWWLOX).
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&& .HAZARD POTENTIAL OUTLOOK...
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(SAT-WED) Precipitation and wind are expected Saturday through Tuesday.
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&& $$ PUBLIC...Kj AVIATION...Sweet MARINE...Sweet SYNOPSIS...STu weather.gov/losangeles

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