02/934 AM.
Slightly cooler temperatures are expected today as offshore flow weakens. Another warming trend will kick off on Tuesday, with near record high temperatures possible by Wednesday along with moderate Santa Ana winds. Another more pronounced cooling trend to follow after Thursday.
(tdy-Wed), 02/944 AM.
***UPDATE***
Offshore flow has weakened considerably from the weekend and low clouds and fog were very close to Long Beach, Palos Verdes, and Catalina Island this morning. But clouds are clearing now and expecting sunny skies the rest of today. It will be cooler today thanks to an earlier arriving sea breeze but highs will still be 5-10 degrees above normal. May see some of those low clouds and fog returning to coastal areas south of Pt Conception this evening and overnight, but returning offshore trends will likely clear any clouds by mid morning Tuesday, if not sooner.
***From Previous Discussion***
The offshore flow will restrengthen on Tuesday and Wednesday with LAX-DAG sfc pressure gradients reaching around -6.0 mb on Wednesday and Thursday, and LAX-BFL reaching around -4.0 mb on Wednesday (and weaker on Thursday). The strengthen offshore flow paired with climbing 500 mb heights from 575 dam today to 582 dam Tuesday night through Wednesday, will lead to another round of drier and warmer conditions for the region Tuesday through Thursday morning, with gusty Santa Ana winds. As a result, high temperatures will increase across the region each day, with highs pushing into the 80s range across the coasts and coastal valleys of LA and Ventura counties, while the remainder of locations such as the Antelope Valley and Santa Barbara and San Luis Obispo Counties will mainly be in the 70s to low 80s. High temperatures will peak on Wednesday when the offshore flow and 500 mb heights peak, and highs across the warmest locations may even squeak into the low 90s. These temperatures will be 10-20 degrees above normal across the region for this time of year.
As for winds, because LAX-DAG sfc pressure gradient (west-east) is stronger than the LAX-BFL sfc pressure gradient (south-north), the strongest winds will be more focused from Santa Clarita Valley through the Oxnard Plains, rather than pushing into the eastern San Fernando Valley. Additionally, the Santa Ana winds will have better upper support this time, and like the temperatures will also peak on Wednesday. Gusts up to 50 mph will be common in the mountains and 25-40 mph elsewhere in the favored Santa Ana wind areas. Could see some isolated peaks around 60 mph in the San Gabriel Mountains and the Santa Monicas
(Thu-Sun), 02/256 AM.
The Santa Ana winds and warm temperatures will continue into Thursday as mentioned above, but will likely be slightly cooler with weaker winds as the 500 mb heights start to lower and the sfc pressure gradients will weaken as the high pressure aloft shifts eastward and another trough approaches the Pacific Northwest. There could still be some advisory level winds, mainly in the mountains and foothills, but upper support is weakening at that point.
The 500 mb heights start dropping rapidly from 582 dam on Wednesday to 574 dam on Friday, while the sfc pressure gradients weaken and switch onshore. This will result in more pronounced cooling on Friday with temps dropping back in the 70s (still 5-10 degrees above normal for this time though).
Beyond Friday, there is still some disagreement in the models. While the GFS and EC deterministic models suggest brief light rain on Saturday morning (certainly possible considering the rapidly decreasing 500 mb heights to 563ish dam as a trough approaches), their respective ensembles are staying dry until the deterministic and ensembles somewhat come to agreement on rain around the 10th through 12th. The aforementioned rain would be the result of a low pressure system dropping into the region, however amounts look to be under 1.00 inch at this time (which could certainly change in the next 8 days).
In the meantime, it looks like the most likely outcome for next weekend is continued dry weather with temperatures still well above normal and possibly another light to moderate Santa Ana wind event.
02/1351z.
Around 13Z at KLAX, there was no marine layer. There was a weak sfc-based inversion with a top at 900 ft and a temp of 17 C.
Moderate to low confidence in coastal TAFs south of Point Conception and KPRB, high confidence in remainder of TAFs.
There is a 30% chance of LIFR/VLIFR conds at KOXR, KCMA, and KSMO through 18Z Mon. There is a 50% chance of conds remaining VFR at KLAX and KLGB through the period. After 08Z Tue, there is a 30-40% chance of VLIFR/LIFR conds at KSMO, KLAX, and KLGB. For KPRB, vis may bounce cats through the morning.
KLAX, Low to moderate confidence in TAF. There is a 50% chance that conds remain VFR through 07Z Tue, but if cigs do arrive, there is a 50% chance of 1/4SM FG VV002 conds. After 08Z Tue, there is a 35% chance of 1/4-1SM FG/BR BKN002-004 conds through 16Z Tue. Good confidence in no significant east wind component.
KBUR, High confidence in TAF.
02/1237 AM.
For all the Outer Waters and the Inner Waters north of Point Conception, high confidence in current forecast. Expecting Small Craft Advisory (SCA) level winds to gradually decrease Monday, with SCA level seas lingering into Monday night. Tuesday through Thursday, offshore northeast winds will develop each morning, and there is a 30-40% chance for localized gusts near SCA levels for the near shore waters around Morro Bay and near the Channel Islands. Another round of SCA level winds and seas across the outer waters will be possible Friday into Saturday, and SCA winds may linger into the following week.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Tonight through Monday a moderately long-period W swell will bring seas of 4-8 feet to the southern inner waters. Then Tuesday night through Wednesday and potentially into Thursday morning, local areas of SCA level northeast winds will be possible from Ventura Harbor south through Malibu and off the coast of Orange County. Northwest winds should increase to SCA levels over the waters early next week, especially Tuesday.
Ca, High Surf Advisory in effect until 9 AM PST Tuesday for zones 340-346-354. (See LAXCFWLOX). Beach Hazards Statement in effect until 9 PM PST this evening for zones 362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 9 PM PST this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 2 AM PST Tuesday for zones 670-673-676. (See LAXMWWLOX).
