textproduct: Los Angeles

SYNOPSIS

24/158 AM.

Very hot conditions will dominate the week, with a high risk for heat illness. Patchy night through morning low clouds and locally dense fog will be confined to coastal areas, mainly north of Point Conception.

LONG TERM (THU-SUN)

24/158 AM.

Not much change in the upper levels on Thursday and Friday. The sfc gradient problem in the E/W direction remains with the EC remaining significantly offshore while the GFS keeps it onshore. Given how the NAM is tracking the gradients it seems the best bet is for onshore gradients, but weaker than the GFS is forecasting. All mdls show offshore flow from the north, but again the EC is much stronger.

Thursdays temps will be very similar to Thursday's with most max temps 10 to 15 degrees above normal. High confidence that all of the heat warnings and advisories will continue.

The current forecast for Friday shows some cooling. This is a low confidence forecast and depends on the gradient forecast. There is a very good chc that temps will be very similar to Thursday's values.

The overnight lows will continue 8 to 12 degrees above normal and this will greatly exacerbate the heat risk as there will be no time for people's body to release the heat stress.

Very hot sundowners across southern SBA county remain a concern as well. A decent N to S gradient will set up over the county each evening and gusty north canyon winds will develop. These hot winds could drive max temps into the 100-105 degree range and could also keep temperatures in the 80s until almost dawn.

Better confidence in a noticeable cooling trend for the weekend. Both the EC and GFS agree that troffing will move into the west coast and force the upper high to the east. Hgts will fall to 590 dam Sat and then to 588 dam on Sun. More importantly both mdls show a return to onshore flow from both the South and West. Look for 2 to 4 degrees of cooling on Saturday and an additional 3 to 6 degrees on Sunday. Even with the cooling, Sunday's max temps will end up 2 to 4 degrees above normal south of Pt Conception. The Central Coast will fall a few degrees blo normal.

AVIATION

24/0917Z.

At 0822Z at KLAX, the marine layer was 500 feet deep. The top of the inversion was at 2500 feet with a temperature of 30 C.

High confidence in TAFs for KPRB, KSBA, KOXR, KCMA, KSMO, KWJF and KPMD.

For KSBP and KSMX, timing of flight category changes could be +/- 2 hours of current forecast.

For KLGB, there is a 10-15% chance of LIFR/IFR conditions 12Z-16Z.

KLAX...Low confidence in TAF with a near 50 percent chc of no low clouds. No significant easterly wind component is expected.

KBUR...High confidence in CAVU TAF.

MARINE

24/158 AM.

For the Outer Waters, high confidence in current forecast. Today through Friday, Small Craft Advisory (SCA) winds are expected to continue although the winds will drop briefly across PZZ670 tonight and Monday. Short period SCA level seas (5 to 7 feet at 6-8 seconds) will continue along with the gusty winds. Wednesday into Thursday, larger seas approaching 7-9 feet are likely.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Monday night, high confidence in winds and seas remaining below SCA levels. For Tuesday through Friday, there is a 50-70% chance of SCA level winds each afternoon and evening.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Friday. The only exception will be the western half of the Santa Barbara Channel where there is a 60-80% chance of SCA level winds Monday through Friday, mainly in the late afternoon and evening hours.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory in effect until 10 AM PDT Tuesday for zones 38-87-88-349>358-362-366>376-378>380-548. (See LAXNPWLOX). Extreme Heat Watch in effect from Tuesday morning through Friday evening for zones 38-87-88-349>358-362-366>376-378>383-548. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 4 AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).