10/219 PM.
A significant warm up is expected to start on Wednesday, likely lasting well into next week.
(tdy-Fri), 10/217 PM.
Enjoy the last day of mild temperatures as we likely enter into what may be an extremely rare prolonged (6-10 days) March heatwave with MODERATE TO HIGH heat impacts likely at times Thursday through at least the middle part of next week! A HEAT ADVISORY has been issued for Thursday and Friday and with additional heat products likely needed sometime this weekend into the first half of next week.
High pressure aloft will be building over the area as well leading to what may be just the beginning of a significant and POTENTIALLY DANGEROUS HEAT WAVE Thursday and Friday with highs expected to be in the 90s for all coast and valleys and even isolated areas possibly touching 100 degrees which would be 20-30 degrees above normal. There will almost certainly be numerous broken daily records area- wide and some locations may even break the all time record for the month of March.
Weak to moderate offshore flow developing this evening and continuing through at least Friday will also play a role in the heat by pushing the marine layer near if not offshore. There is a 30-50 percent chance that the offshore flow is not strong or persistent enough to remove the marine layer completely from coastal areas, which could result in daytime highs right near the coast only in the 60s and 70s. Either way dense fog could become more widespread during the marine layer retreat, especially Wednesday night into Thursday morning.
The offshore flow will likely support marginal advisory level winds above and inland of the marine layer through Wednesday, making a run towards prone coastal valley areas into Thursday, but those will probably fall shy of advisory levels.
(Sat-Tue), 10/219 PM.
Over the weekend the ridge will briefly break down while the offshore flow from the north will weaken and the onshore push to the east will increase. Look for a couple of degrees of cooling each day with max temps still 15-25 degrees above normal with still moderate heat impacts.
Most of the ensemble members show the high pressure system aloft rebuilding again next week and lasting potentially into next weekend, resulting in an unprecedented stretch of moderate to extreme heat for this time of year across all of southwest California. Highs all week are expected to be in the mid 80s to mid 90s with a 20-30% chance of an isolated 100 in the warmer valley areas. It's possible that any daily or monthly records set before this weekend will be broken again next week.
The one saving grace is that overnight lows are expected to be mostly in the upper 50s and 60s, which is still well above normal, but at least there will be several hours overnight relief.
Little to no chance of any rain for the next two weeks.
10/0856z.
Around 07Z, the marine layer depth was around 1100 feet deep at KLAX. The top of the marine inversion was near 1700 feet with a temperature around 14 degrees Celsius.
IFR to MVFR conditions are expected at coastal and valley terminals through at 16Z, possibly lingering at coastal terminals into the afternoon hours. There is a moderate to high chance that no clearing will occur at coastal terminals south of Point Conception, highest at Ventura County coastal terminals and KOXR. An early return of IFR to MVFR conditions should be expected for coastal terminals this evening.
KLAX, IFR conditions will improve to the MVFR category as soon as 11Z, or as late as 16Z. VFR conditions should develop as soon as 20Z, but more likely around 22Z. There is a 30 percent chance that KLAX will not clear at all. A return of MVFR conditions should occur as soon as 01Z, or as late as 06Z. Any easterly winds should remain less than 7 knots.
KBUR, There is a 60 percent IFR to MVFR conditions developing between 13Z and 16Z, and clearing by 18Z. Otherwise, VFR conditions should persist through at 05Z Wednesday. IFR to MVFR conditions should move into KBUR between 05Z and 10Z Wednesday.
10/203 PM.
Moderately high confidence in the current forecast.
For the waters southwest through northwest of the Channel Islands and the nearshore waters along the Central Coast, borderline Small Craft Advisory (SCA) winds will persist until at least early Thursday morning, especially beyond 30 nautical miles offshore of the Central Coast down past Point Conception to San Nicolas Island. Additionally, more widespread advisory conditions are expected to develop each afternoon and evening. There is a high to likely (40-60 percent) chance these gusty winds will extend into the nearshore waters along the Central Coast, with the highest likelihood occurring this afternoon and evening. There is a low to moderate (20-30 percent) chance of SCA level northeast to east winds for the nearshore waters each night between Wednesday and Friday.
Inside the southern California bight, winds and seas should remain below SCA levels through the period, except for a low to moderate (20-30 percent) chance of SCA level west to northwest winds developing Wednesday afternoon and evening across the Santa Monica Bay and into the San Pedro Channel, and in the Santa Barbara Channel.
Dense fog may become fairly widespread Wednesay night into Thursday morning.
Ca, Heat Advisory in effect from 10 AM Thursday to 8 PM PDT Friday for zones 88-340>342-346>352-354>358-362-366>375-548. (See LAXNPWLOX). Wind Advisory remains in effect until 9 AM PDT Wednesday for zones 352-353-376>378-381. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zone 676. (See LAXMWWLOX).
