16/812 PM.
Dangerously hot temperatures are expected this week, peaking Wednesday through Friday. There is a HIGH risk for heat illness this week, with conditions remaining warm overnight adding to the heat risk.
(Mon-Thu), 16/812 PM.
***UPDATE***
The first day of the heat wave ended with several new high temperature records, most notably at the Burbank Airport and Woodland Hills, with highs of 92 and 97 respectively. Many locations had temperatures rise 10 to 15 degrees above Sunday's highs, and some as much as 15 to 20 degrees. For the most part, the beaches (and Antelope Valley) had more modest warming of around 5 degrees. The big exception is along the Santa Barbara South Coast where some of the biggest temperature rises were observed.
A Heat Advisory will remain in effect tonight and tomorrow. Offshore breezes that help enhance the daytime heating will persist overnight. Although these winds will be relatively weak, in the 15 to 25 mph range, they will help to maintain warm temperatures tonight in many areas except for the more wind sheltered valleys. All the hills and mountains will see overnight lows in the 70s to lower 80s, giving Tuesday a head start on the heating. Similar warming of daytime highs, of 10 to 20 degrees across the area, is expected.
Starting Wednesday, under very high pressure aloft and continued offshore flow, many areas will see an Extreme Heat Warning come into effect and persist through Friday evening.
***From Previous Discussion***
***DANGEROUS LONG TERM AND RECORD BREAKING HEAT WAVE THIS WEEK, PEAKING TUESDAY THROUGH FRIDAY***
Models continue to advertise record level heat this week, and in some cases not only breaking daily temperature records, but even breaking record monthly highs with temperatures in the upper 80s and 90s. There is even around a 30% chance of 100 degrees in the coastal valleys as well as Downtown LA which would be roughly 35 degrees above normal. A super anomalously strong upper level high of 596dam will move right over southern California starting Tuesday and only slowly moving east through the week. In addition, a light offshore flow will be in place which will allow areas near the coast to heat up as well. Heat advisories and extreme warnings are in place for all areas except the far interior.
Not only will there be record temperatures at the surface, based on RAOB sounding climatology at SPC, temperatures at 700mb (roughly 10,000 feet) will be higher than ever before measured in March over southern California.
On top of all that, overnight lows, especially in the lower mountain areas below 4000 feet such as the Santa Monica mountains, the Santa Ynez Range, the Santa Lucias, and the lower San Gabriel mountains, will not drop below the mid 70s to mid 80s. This will significantly limit the amount of overnight relief in those areas. Elsewhere, lows will be in the upper 50s and 60s which will provide at least a few hours of relief from the heat. It's imperative that outdoor activities this week are minimized as much as possible and confined to early morning or evening periods.
Very little change in this pattern through the week.
Record highs for Downtown LA this week are as follows:
Today: 91 in 1914 Tuesday: 94 in 1914 Wednesday: 87 in 1997 Thursday: 97 in 1997 Friday: 93 in 1997
(Fri-Mon), 16/215 PM.
Little or no change in the pattern Friday with all advisories and warnings remaining in effect.
Saturday and Sunday, models suggest that the high pressure will start to flatten out, and temperatures will finally start to decrease again. For Saturday, there is a 50% chance that some heat products will need to extended through the evening hours, mainly inland from the beaches. However by Sunday, things should cool down rather noticeably. Therefore, no heat products are anticipated.
As for rain chances, deterministic models (and their respective ensembles) indicate some possibility of light showers after the 25th. However, no significant storms are indicated for Southern California through the end of the month.
16/2133z.
Around 20Z at KLAX, the marine layer was 400 ft deep. The top of the inversion was at 1100 ft with a temperature of 26 C.
Moderate confidence in coastal TAFs KSBA to KLGB including KLAX 00Z-15Z with a 20-30 percent chance of LIFR or lower cigs/vsbys. High confidence in VFR otherwise and elsewhere with generally light winds.
KLAX, Moderate confidence 00Z-15Z with a 20-30 percent chance of LIFR or lower cigs/vsbys.
KBUR, High confidence in VFR TAF.
16/850 PM.
Winds are expected to mostly remain below Small Craft Advisory levels for the week with small seas. There is potential for some offshore gusty winds at times across for the near shore waters by Morro Bay and from Ventura to Point Dume Tuesday morning. Some gusty onshore winds are also possible Tuesday night and Wednesday night. Moderate chances for SCA level winds starting either Thursday or Friday across the northernmost outer waters, potentially becoming more widespread into the weekend.
Dense fog is possible at times this week.
Ca, Heat Advisory in effect from 10 AM Tuesday to 8 PM PDT Friday for zones 38-343-344. (See LAXNPWLOX). Heat Advisory remains in effect until 10 AM PDT Tuesday for zones 87-88-340>342-345>358-362-366>376-378>380-548. (See LAXNPWLOX). Heat Advisory remains in effect from 10 AM Tuesday to 8 PM PDT Friday for zones 87-340-341-346>350-354-355-362-366-367-549-550. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM Tuesday to 8 PM PDT Friday for zones 88-342-345-351>353-356>358-368>376-378>380-548. (See LAXNPWLOX). Beach Hazards Statement in effect through Wednesday evening for zones 354-362-366. (See LAXCFWLOX). PZ, NONE.
