04/1006 AM.
Seasonably warm weather will continue away from the immediate coast, while far interior areas will continue to bake under triple digit temperatures all week. Along the coast low clouds and locally dense fog will develop and could linger into the afternoon in some areas.
(tdy-Thu), 04/1008 AM.
A 597 dam upper high will sit over AZ through the short term 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 1000 ft and night through morning low clouds and fog will affect the csts each day. Some nearshore areas will see slow clearing in the afternoon due to the strong onshore to the east.
Max temps will be pretty close to normal across the csts and vlys. Since it is August "close to normal" in the vlys still means 90 to 101 degrees and mid to upper 80s in the inland cstl sections. The lower mtn elevations and far interior sections will not feel the effects of the onshore flow and max temps will range from 100 to 109 degrees or 5 to 10 degrees above normal.
The upper high moves to the west on Friday and hgts bump up to 596 dam and remain there through Saturday. At the same time there is a monsoon push and PWs rise to about 1.25 inches. Max temps will only rise a degree or two, but the increased humidity will increase the heat risk as well as keeping the overnight lows well above normal. The combination of well above normal highs and lows as well as increased humidities will continue to support moderate to high heat danger to interior mountains and valleys where HEAT ADVISORIES and WARNINGS have been extended through Saturday. As the weekend approaches a suite of heat advisories will likely (40-60 percent chance) be issued for many vly areas. As long as the marine layer remains in place coastal areas may mostly be heat advisory/warning free. One wrinkle is that monsoon moisture can disrupt the marine layer, so there is a 10-20 percent chance of advisory level heat with temperatures 4-8 degrees warmer than forecast on any given day Friday and beyond.
Otherwise, onshore flow will continue and this will keep the night through morning low clouds going through the period. The very high hgts will keep the marine layer under a 1000 ft with patchy dense fog possible near the coast. The vlys will remaining mostly clear.
There is little to no risk for monsoon showers or thunderstorms with only a 5-10 percent chance for the mountains and deserts of eastern LA County Thursday and especially into Friday and beyond.
Hot, dry and locally breezy conditions will continue to support high fire danger inland and above the marine layer through the week. Please take care with or avoid fire ignition sources such as possible dragging chains beyond vehicles, lawn care equipment, and campfires.
(Fri-Mon), 04/1008 AM.
Starting Sunday and continuing into Monday the upper high will weaken and the onshore flow will increase to almost 10 mb onshore to the east. Max temps are forecast to cool 1-2 degrees Sunday and 2 to 4 more degrees on Monday.
We will continue to be on the western edge of the monsoon with a 5-10 percent chance of showers or thunderstorms again focused across interior Los Angeles County mountains and deserts.
04/1717z.
At 1659Z at KLAX, the marine layer was 1800 feet deep. The top of the inversion was near 2700 feet with a temp of 27 C.
High confidence in VFR conds for KPRB, KPMD and KWJF. For sites with cigs forecasted, timing may be off by 2 hours and off by 1 category at times. There is a 20% chance for brief LIFR conds at KPRB/KBUR/KVNY between 12Z and 16Z Wed.
KLAX, Moderate confidence in TAF. Timing of flight category changes may be off by 2 hours, greatest this evening. No significant east wind component expected.
KBUR, High confidence in TAF. There is a 10% chance for BKN005-BKN010 cigs from 12Z-16Z.
04/908 AM.
Winds and seas are expected to remain below Small Craft Advisory (SCA) criteria through the week, 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 through much of the week, especially across the waters north and west of Point Conception.
Ca, Extreme Heat Warning in effect until 8 PM PDT Saturday for zones 38-377-381>383. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT Saturday for zones 344-345-353-375-376-378>380. (See LAXNPWLOX). PZ, NONE.
