05/219 PM.
Night through morning low clouds and fog will be common over coastal areas and the coastal valleys through at least this weekend, with clearing each afternoon. Hazardous heat will occur through this weekend over interior areas. Aside from a couple mountain showers possible on Sunday, dry conditions will prevail.
(Wed-Sat), 05/847 PM.
***UPDATE***
Little day to day change from yesterday, with minimal changes expected over the next few days. Heat continues for the interior, mountains and valleys, with coastal clouds and fog reoccurring each night. Onshore flow is expected to trend a little weaker each day, which could allow the coasts and coastal plains to trend a bit warmer. A warming trend is also supported by gradually rising heights, which should compress the marine layer and limit clouds closer to the coasts. Minimal changes to the forecast were needed, but the Central Coast was cooled for Thursday and Friday given ongoing onshore flow and coastal clouds.
***From Previous Discussion***
Not much synoptic change at all through this weekend, as a 595 dam upper high sits over AZ with 594-595 dam hgts over Srn CA. There will be mdt-stg onshore flow to the east and weak-mdt onshore flow to the north.
The marine layer will be near 1400 ft and night through morning low clouds and fog will affect not only the csts but also some of the lower coastal vlys each day. Clearing will be slow in nearshore areas in the afternoon due to the strong onshore flow.
There will be a slow warming trend through the period and by Friday most max temps will be 4 to 8 degrees above normal. Lower confidence in the warming trend for the coasts and the onshore flow and marine layer could easily defeat any other warming effects. While all areas will have above normal temps only the interior sections will be warm enough to support heat warnings and advisories, which run through the weekend.
One more thing will be the increase in humidity as monsoon moisture move in under the upper high and into Srn CA. The increased humidities will make the daytime highs feel worse and will hinder the overnight cooling. It will produce a non zero chc of afternoon convection over the mtns -- highest on Sunday.
The strong onshore flow in the afternoon will produce stronger than normal sea breezes and gusty afternoon winds in the interior. The gusty winds in the interior in combination with the hot and dry conditions will produce elevated fire weather conditions.
(Sun-Wed), 05/218 PM.
The pattern will remain similar through Sunday. Max temps will remain 4 to 8 degrees above normal, min temps will remain 3 to 6 degrees above normal and humidities will also be above normal. Heat Advisories and Extreme Heat Warnings have been extended into Sunday.
The western edge of a monsoonal moisture surge will bring slight chances (around 15%) for showers over mountains of Los Angeles and Ventura Counties into nearby deserts on Sunday.
The ridge is expected to begin to break down on Monday, continuing into the middle part of next week. This should lead to a cooling trend and an elimination of the need for heat products next week.
05/2346z.
At 2223Z at KLAX, the marine layer was 1200 feet deep. The top of the inversion was at 2300 feet with a temperature of 26 C.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Low to moderate confidence in remaining TAFs. Timing of flight cat restrictions may be off +/- 3 hours, and CIG heights by +/- 200 ft.
KLAX, Low to moderate confidence in TAF. Arrival time of CIGs may be off +/- 3 hours and clearing times +/- 2 hours. CIGs likely to range 008-012 through early morning. No significant east wind component expected.
KBUR, Good confidence in TAF. There is only a 15% chance of BKN/OVC006-010 conditions 12Z-16Z.
05/713 PM.
Winds and seas are expected to remain below Small Craft Advisory (SCA) criteria into this weekend, with the exception of northwest winds locally gusting to 20-25 knots in typically windy areas around and to the south of Point Conception each afternoon and evening.
Dense fog may affect portions of the coastal waters each night through morning into this weekend, especially across the waters north and west of Point Conception.
Ca, Extreme Heat Warning in effect until 8 PM PDT Sunday for zones 38-377-381>383. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT Sunday for zones 344-345-353-375-376-378>380. (See LAXNPWLOX). PZ, NONE.
