textproduct: Los Angeles

SYNOPSIS

02/711 PM.

Expect cooler conditions for the coast and coastal valleys through much of this coming week, but with continued hot conditions for the interior as above-normal temperatures continue. Dense fog will affect some coastal areas.

LONG TERM (THU-SUN)

02/1254 PM.

After Tuesday temperature trends are expected to level off and possibly increase a degree or two as high pressure over AZ nudges west again through next weekend. In addition, there are some signals in the ensemble pressure gradients indicating some light offshore trends towards the end of this coming week that could result in warming temperatures across the coast and valleys as well. And as mentioned, it will remain very hot over the interior and would estimate at least a 60% chance of extended the desert Extreme Heat Warning through the end of the week and around a 20-30 percent chance of at least heat advisories for the coastal valleys. One factor that will need to be monitored is models are still indicating increasing monsoon moisture later in the week, especially by the weekend, that could introduce another heat risk factor with higher humidities and in turn warmer overnight lows.

AVIATION

03/0616Z.

At 0512Z at KLAX, the marine layer was 1000 ft deep. The top of the inversion was near 3100 feet with a temp of 27 C.

High confidence in VFR conds for KPRB, KBUR, KVNY, KPMD and KWJF.

Moderate confidence with the remaining TAFs. VFR transition timing may be off by +/- 90 minutes. KSBA and south cigs may be off by +/- 300 ft. There is a 30 percent chc of VLIFR conds at KSMX and KSBP through 15Z.

KLAX...Moderate confidence in TAF. VFR conds could arrive as late as 1730Z. No significant east wind component expected.

KBUR...High confidence in CAVU TAF.

MARINE

02/847 PM.

For the inner waters north of Point Sal, there is a 40% chance of SCA winds during through late tonight, highest along the Central Coast. Otherwise conditions are expected to remain below SCA levels across all nearshore waters.

For the Outer Waters, Small Craft Advisory (SCA) winds and seas will continue through tonight before beginning to subside early this coming week. There is a 30% chance that SCA winds will resume near and south of Point Conception.

Seas of 6-9 feet will impact the outer waters through tonight, due to a combination of long-period southerly swell and shorter- period northwesterly swell/wind- waves. Seas will begin to subside as the winds weaken late tonight into early next week.

Dense fog will affect some of the coastal waters each night and morning through much of the week.

FIRE WEATHER

02/323 PM.

Today through Saturday, widespread elevated to brief critical conditions will be common across the interior valleys, mountains, and deserts due to hot, dry, and breezy onshore conditions with an increased risk for large plume dominated fire behavior and rapid fire growth due to deep mixing heights. For much of this week, deep mixing heights of 10,000 to 17,000 feet can be expected across the interior, with peak heights likely by mid to late week as the atmosphere becomes slightly more unstable. If any fire ignitions occur across the interior, these deeper mixing heights will allow for large vertical plume growth, especially in the mountains and foothills, where Live Fuel moisture levels are approaching critical levels.

Other factors that will add to the fire weather risk across the interior this week will be southwest to northwest winds 10 to 25 mph with gusts 20 to 35 mph, as well as widespread and long duration single digit humidities. As a result, expecting at least a few hours of wind/RH overlap to reach brief critical fire weather conditions across many interior areas each afternoon and early evening. There is a 20-30 percent chance of Red Flag durations being reached (6+ hours) across portions of the interior sometime between Tuesday and Saturday. The highest risk areas include San Luis Obispo county interior mountains/valleys, Cuyama Valley, Santa Barbara county interior mountains, Ventura county interior mountains, and I-5 corridor. Hot-Dry-Windy index ensemble solutions showing several model members exceeding 95th percentile for multiple days across interior San Luis Obispo, Santa Barbara county interior mountains, Ventura county interior mountains, and I-5 corridor. In addition, there will be very poor to poor overnight humidity recoveries, especially in the mountains and foothills where some locations may continue to have humidities in the teens.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Extreme Heat Warning in effect from 10 AM Monday to 8 PM PDT Tuesday for zones 38-377. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Monday to 8 PM PDT Wednesday for zones 344-345-353-375-376-378>380. (See LAXNPWLOX). Extreme Heat Warning in effect until 8 PM PDT Wednesday for zones 381>383. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).