04/746 PM.
Onshore flow will continue to bring low clouds to the coasts and coastal valleys each night through morning. Onshore flow will start to weaken Monday and cause decreasing clouds in the valleys and gradually warming temperatures. Expect a return to above normal temperatures early next week.
(Sat-Tue), 04/813 PM.
***UPDATE***
There is around a 5 to 10 percent chance of brief showers or thunderstorms this evening and overnight, mainly over areas north of Point Conception. However, there are non-zero chances over northern LA County and the Ventura Mountains as well. This is in response to subtropical moisture moving northward over the area, along with a weak disturbance aloft. Wetting rain (0.10 inch or more) is not expected, however there is a low risk of dry lightning and/or gusty erratic outflow winds.
The high clouds streaming over the area helped to disrupt the marine layer earlier today resulting in fewer coastal low clouds for Ventura and LA Counties. While a similar low cloud pattern is expected tonight into early Sunday, there is a chance that the upper disturbance will prevent any organized low cloud formation along the Central Coast.
As for temperatures, expecting a slight cool-down Sunday due to slightly lower heights aloft and increasing onshore flow. This will be followed by warming Monday and especially Tuesday through Thursday with strong high pressure building aloft and onshore flow weakening considerably. Heat Advisories will likely be needed for much of the area, especially Wednesday and Thursday. Highs in the 80s to mid 90s are expected away from the coast Sunday, rising into the 90s to above 100 degrees starting Tuesday.
Through Monday, onshore winds gusting up to 35 mph are expected for the Antelope Valley and Foothills, along with Sundowner winds Sunday through Wednesday, with peak gusts up to 40 mph.
(Wed-Sat), 04/1224 PM.
Above normal temperatures and dry weather are anticipated through the extended periods as high pressure strengthens aloft helping to aid in a continued warming trend across the region.
At this point, the upper level ridge looks to be centered across southern California over the Wednesday/Thursday time period, when afternoon temperatures should peak. The ridge is then expected to shift north and east by the end of the week and over next weekend, providing some minor relief to end the week. That said, temperatures are still expected to remain well above average to end the current forecast period, and likely beyond - with CPC outlooks continuing to favor above normal temperatures through at least week 2.
Given the anticipated warm up, there will be at least a minor to moderate heat risk each day, with about a 70% chance that heat advisories will eventually become necessary Tuesday-Thursday across mainly inland areas including the San Fernando and Santa Clarita valleys.
Finally, an increased surface pressure gradient early next week will also likely result in a return to modest sundowner winds both Tuesday and Wednesday nights.
04/2259z.
At 2200Z at KLAX, there was no marine layer. There was a surface based inversion that was 800 ft deep. The top of inversion was at 2500 feet with a temperature of 22 C.
High confidence in VFR TAFs for desert airfields (KWJF & KPMD).
Moderate confidence in remainder of TAFs. Timing of flight cat changes may be off by +/- 2 hours and CIG heights +/- 300 ft. There is a non-zero chance of a thunderstorm for KLAX, KBUR, KVNY KSMO, & KLGB through this evening.
KLAX, Moderate confidence in TAF. VFR conditions with widespread high clouds BKN100-150 through 05/06Z-07Z. Arrival and clearing times of 008-010 CIGs may be off +/- 3 hours. There is a non-zero chance of a thunderstorm through this evening. No significant easterly wind component expected.
KBUR, Moderate confidence in TAF. There is a 15% chance of BKN005-010 05/11Z-15Z. Otherwise, VFR conditions with no wind issues are expected.
04/836 PM.
For the Outer Waters, moderate to high confidence remains for the current forecast. High confidence in winds and seas remaining below Small Craft Advisory (SCA) levels through Sunday morning. For Sunday afternoon through Thursday, there is a greater than 80% chance of SCA level winds. Seas will begin gradually increasing Sunday and will reach advisory levels by Sunday evening. There may be a shower or two across the northern waters this evening.
For the Inner Water north of Point Conception, moderate to high confidence in current forecast. Winds and seas are expected to remain below SCA levels through Monday morning. There is a 40% chance of SCA level winds on Monday, 70% chance Tuesday & Wednesday, and a 60% chance on Thursday. Seas will begin gradually increasing Sunday and will near advisory levels for the start of the week.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. High confidence in winds and seas remaining below SCA levels through Sunday morning. From Sunday midday through Wednesday, there is a greater than 80% chance of SCA level winds and seas across the western portion of the Santa Barbara Channel. Local gusts could approach 22 kts during the late afternoon through evening hours near Point Dume and across the San Pedro Channel.
Ca, NONE. PZ, Small Craft Advisory in effect from 5 PM Monday to 5 AM PDT Tuesday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect from 5 PM Sunday to 5 AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).
