11/345 PM.
Minor to moderate coastal flooding is likely continue to through at least Tuesday. Periods of light to moderate rain and a low chance of thunderstorms will persist through Monday with below normal temperatures. Beginning Tuesday and continuing through the end of the week, weak to moderate offshore flow will bring warm and dry conditions to the area.
(tdy-Wed), 12/252 AM.
A highly amplified upper level pattern has developed over the eastern Pacific and it appears southwest California will be experiencing quite a range of temperatures and weather conditions over the next couple of weeks. The upper low over the area yesterday and today that has brought scattered light showers and much cooler temperatures will evolve into our first real Santa Ana wind event of the season later in the week. For today though, highs will mostly be in the 60s which is 10-20 degrees below with some off and on light showers, mainly in the morning.
As the upper low slowly moves into the Great Basin, onshore pressure gradients will be weakening and a light northeast flow aloft will develop over the area as early as Tuesday afternoon. Not expecting any winds of significance Tuesday but high temperatures will warm up 4-8 degrees area-wide as the air mass dries out and heights rise at least 10dam from Monday.
Wednesday will be noticeably warmer and drier as offshore gradients continue to increase across the area heights climb another 10dam. Still not expecting any significant winds yet except possibly some northeast winds in the San Gabriel mountains up to 35 mph.
(Thu-Sun), 12/339 AM.
Santa Ana winds will really pick up Thursday into Friday as all the ingredients appear be in place and properly aligned. We're still well outside the boundaries of the high res models but given the amplified upper level pattern, confidence is higher than usual at this early stage that a Santa Ana Wind event of at least moderate strength will develop during this period. The latest ensemble pressure gradients indicate that the peak offshore gradient will occur Friday morning somewhere in the 5-7mb range. Couple that with 50kt winds at 850 mb and very strong upper level subsidence, that should result in peak winds of 50-70mph in the San Gabriel mountains and 35-55mph across the LA/Ventura valleys as well as the Ventura County coastal areas and Santa Monica mountains. The ECMWF is already showing peak winds between 25 and 40 mph in Camarillo Thursday and increasing to 35-50 on Friday. As a reminder, Santa Ana winds typically do not impact the LA Metro area and LA coast.
Temperatures will be peaking during these days as well with highs in the upper 80s and 90s across all coast and valleys, including the Central Coast. There is a very strong chance (60-80%) that heat advisories will be needed for coastal areas Fri and Sat. However, mid 90s in the inland areas would not likely meet criteria there.
Temperatures are expected to remain well above normal through Sunday but slowly cooling into next week. And looking out a little further there is fairly high agreement in the models that another cold upper low will move into the area the middle of next week.
12/0535z.
At 06Z at KLAX, there was neither a marine layer nor a marine inversion. A moist layer was present around 4000 to 5000 feet.
Overall, low to moderate confidence in TAFs. There is a threat of sprinkles or very light showers at all sites, but higher chances for LA coast and valley TAF sites. There will be 20-40% chance of MVFR CIGs at all sites.
KLAX, Moderate confidence in TAF. Short periods of sprinkles or light showers are possible into Monday morning. There is a 30% chance of MVFR CIGs anytime during the TAF period. No significant easterly winds are expected.
KBUR, Moderate confidence in TAF. Short periods of sprinkles or light showers are possible through Monday morning. There is a 40% chance of MVFR CIGs anytime during the TAF period.
11/813 PM.
For the Outer Waters, moderate to high confidence in current forecast. Through Monday afternoon, high confidence Small Craft Advisory (SCA) level seas but winds will be below SCA levels except for near Point Conception in Zone PZZ673. On Tuesday, there is a 40-60% chance of SCA level winds, again mainly around Point Conception. For Wednesday through Thursday, high confidence in winds and seas remaining below SCA levels. Seas of 10+ feet will slowly diminish through late Monday afternoon.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Winds are below SCA levels but SCA seas of 10+ feet are likely through late tonight. For Monday, high confidence in winds and seas remaining below SCA levels. For Tuesday through Thursday, there is a 30-40% chance of SCA level winds in the afternoon and evening hours, except a 50% chance Wednesday evening.
For the Inner Waters south of Point Conception, moderate confidence in current forecast. Conditions are below SCA levels, but choppy seas between 4 to 6 feet are likely through late tonight. For Monday through Wednesday, high confidence in winds and seas remaining below SCA levels for most area, but the only exception is the western half of the Santa Barbara Channel where there is a 50% chance of SCA level winds Tuesday afternoon and evening. On Thursday and Friday, there is a 30-40% chance of SCA level northeast winds from Ventura south to Santa Monica.
Periods of light to moderate showers are likely through Monday, mainly during the overnight to morning hours. There is a 10% chance of thunderstorms during the same time frame. While showers or thunderstorms are possible anywhere, the highest chances exist south of Point Conception.
Long period swell from the west and the south are affecting the coastal waters, and can create a confused sea state. This can make boating more challenging and dangerous, especially for small vessels.
Ca, Coastal Flood Advisory in effect until 2 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect until 10 PM PDT this evening for zones 340-346-349-350. (See LAXCFWLOX). High Surf Advisory in effect until 10 PM PDT this evening for zones 340-346. (See LAXCFWLOX). Beach Hazards Statement in effect through Tuesday afternoon for zones 349-350-354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 5 PM PDT this afternoon for zones 670-673-676. (See LAXMWWLOX).
