textproduct: Los Angeles

SYNOPSIS

23/1251 PM.

Very hot temperatures are expected this week with highs 6-12 degrees above normal. Patchy night through morning low clouds and fog will be confined to coastal areas, mainly north of Point Conception.

LONG TERM (THU-SUN)

23/300 AM.

The only real question for the Wed through Fri forecast is: will it be very hot or extremely hot. This forceast problem is driven by a wide range of possibilities with the sfc gradients. The EC is show a fairly strong offshore push which would bring near record very dangerous heat to the area. The GFS keeps the E/W gradient onshore but even it has some offshore flow forecast from the north (just much less than the EC does). The upper high moves a little to the west but hgts really do not change much and should remain around 594 dam through the period.

Almost all of the vlys, lower mtn elevations and far interior will have temps between 100 and 110 degrees during this period. If the EC verifies Vly temps could end up 2 to 3 degrees warmer than the current forecast. The interior cst sections (such as DTLA) have a 15 percent chc of high temps of 100 to 103 degrees. The Central Coast will not be immune from the heat this time around. Offshore trends will lead to an 8 to 12 degree warm up on Wednesday leading to max temps in the upper 80s to mid 90s - there is a 10-20 percent chc that SLO could see 100 degrees.

In addition to the daytime highs overnight lows will be 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.

It is very likely that almost the entire forecast area will be blanketed by some combination of heat advisories and Extreme Heat Warnings starting Wednesday.

One additional local concern will be very hot sundowners across southern SBA county. 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.

Some cooling is forecast on Saturday, but in the past these heat waves have held on a little longer than forecast.

AVIATION

23/1615Z.

At 1600Z at KLAX, the marine layer was 500 feet deep. The top of the inversion was at 2700 feet with a temperature of 28 degrees Celsius.

For 18Z TAF package, high confidence in KPRB, KSBA, KOXR, KCMA, KSMO, KWJF and KPMD.

For KSBP, there is a 50% chance that CIG/VSBY restrictions do not develop tonight. For KSMX, timing of flight category changes could be +/- 2 hours of current forecast.

For KLAX and KLGB, there is a 10-20% chance of LIFR/IFR conditions 08Z-17Z.

KLAX...Overall, good confidence in 18Z TAF. There is a 10-20% chance of LIFR/IFR conditions 08Z-17Z. No significant easterly wind component is expected.

KBUR...High confidence in 18Z TAF.

MARINE

23/110 PM.

For the Outer Waters, high confidence in current forecast. Tonight through Friday, Small Craft Advisory (SCA) winds are expected to continue although the winds will drop briefly across PZZ670 tonight and Monday. Seas will be approaching SCA levels beginning on Wednesday.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Tonight 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 30% chance of SCA level winds late this afternoon and evening then 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 9 PM PDT this evening for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 4 AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).