Swell Matrix

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard Ca

958 pm PDT Tue Jun 15 2021

Synopsis

15/720 PM.

A dominant ridge of high pressure will continue to bring hot temperatures Wednesday. A very warm air mass will linger across the region through Saturday. Gusty north winds and critical fire weather conditions will affect southern Santa Barbara County through early Wednesday. A cooling trend is expected to begin by Saturday and continue into early next week.

Short Term

(Tue-Fri), 15/957 PM.

Strong and dominant high pressure remains anchored over the Four Corners Region this evening. Hot temperatures materialized across the inland areas as a very warm air mass settled into the area. Onshore flow stayed in place enough to keep temperatures moderated at beaches. A complex pattern is setting up as ridging aloft remains anchored in place, but onshore flow will make a good push in the wake of the ridge axis on Wednesday. Generally, some cooling should be expected along the coast and into some of the lower valleys for Wednesday. The forecast is problematic as forecast guidance is suggesting a coastal eddy circulation developing overnight. Winds at KSAN are indicative of an eddy developing currently, but a cyclonic wind pattern along the southern California coastline has yet to show itself. Some patches of stratus along the San Diego County coastline should push north overnight and could make it into Long Beach and the Los Angeles Harbor area. Some high resolution model solutions suggest stratus filling in along the coastal waters and hugging the coastline by Wednesday night, but confidence is moderate at best in that scenario. Given it is June, one would think that to be most plausible scenario, but this is a more typical weather pattern of July. For now, the forecast keeps the similar idea. A few tweaks were made to warm the interior slightly and bring it inline with the latest data.

Gusty Santa Lucia winds are forecast to develop tonight and marginally reach advisory levels. KSMX-KBFL surface pressure gradients are trending strongly offshore this evening which should be a prelude of the winds developing overnight. A wind advisory has been added for the San Luis Obispo County coast.

A wind advisory remains in place for southern Santa Barbara County this evening, but a High Wind Warning is being considered at this time. KSBA-KSMX surface pressure gradients are sitting at -5.6 mb and KSBA-KBFL surface pressure gradients near -7.1 mb, both of which are increasing the likelihood of damaging wind gusts across the South Coast of Santa Barbara County. For now, observations will be monitored and the forecast will wait on more data to arrive.

***From Previous Discussion***

Still looking like coastal areas south of Pt Conception will see several degrees of cooling Wednesday as a weak eddy circulation develops and onshore flow increases. There's even about a 50/50 chance of some dense fog moving into the Long Beach area early Wednesday morning. Cooling also expected for the coastal valleys, still hot enough for excessive heat warnings. Mountains and deserts will likely be even warmer Wednesday and with increasing onshore flow the addition of gusty late afternoon winds and the low humidities the fire weather concerns will be even greater. There will be some high clouds at times but likely not thick enough to have any significant impact on temperatures.

Onshore flow continues to increase Thu/Fri, though 950mb temps rise slightly Thursday. Expecting to see more marine layer stratus over the southern coastal waters (Ventura south) but still very shallow and confined to within a few miles of the coast. Beyond that, still quite hot, especially far inland areas. Given the increasing onshore flow there's a chance that coastal valley temps could drop enough to be in more of a heat advisory category so will leave those areas as a watch for now and see how tomorrow's temperatures do.

Long Term

(Sat-Tue), 15/145 PM.

Increasing onshore flow and slowly weakening high pressure aloft will start/continue the cooling trend over the weekend into early next week. It's possible far interior areas could need some sort of heat hazards for Saturday but by Sunday those should all be done. Temps still above normal but only by 5-10 degrees or so with the biggest anomalies in the interior valleys. Marine layer stratus will become more widespread along the coast but likely staying out of the valleys through the weekend.

Cooling trend to continue Monday and Tuesday, though the magnitude of which is somewhat uncertain. Some of the ensemble solutions stall the arrival of a trough into northern California and keep things warmer, those most favor temps dropping to near or slightly below normal by Tuesday with a strong onshore flow in place and marine layer clouds working their way farther inland.

Aviation

16/0212z.

At 01Z, the marine layer depth was around 600 feet deep at KLAX. The top of the inversion was around 1750 feet with a temperature near 37 degrees Celsius.

Moderate-to-high confidence exists in the current forecast. Less confidence exists in flight categories for coastal terminals between 08Z and 16Z. VFR conditions will likely persist through the period, except for low-to-moderate chance of LIFR conditions at Central Coast and Los Angeles County coastal terminals between 08Z and 16Z. Periods of moderate turbulence are possible through 16Z at Santa Barbara and San Luis Obispo County terminals.

KLAX, There is a 30 percent chance of LIFR conditions between 08Z and 16Z. There is a 30 percent chance of southeast winds 7 to 10 knots between 10Z and 17Z.

KBUR, VFR conditions are expected through the period. No wind impacts are expected at this time.

Marine

15/1235 PM.

For the Outer Waters, moderate to high confidence in current forecast. High confidence in Gale force winds continuing through tonight and the GALE WARNING will remain in effect. From Wednesday through Wednesday night, high confidence in Small Craft Advisory (SCA) level winds continuing. On Thursday and Friday, winds and seas are expected to remain below SCA levels although there is a 30-40% chance of SCA level winds across PZZ670 on Thursday. For Saturday and Sunday, there is a 50% chance of SCA level winds.

For the Inner Waters north of Point Sal, high confidence in current forecast. SCA level winds are expected in the afternoon and evening hours both today and Wednesday. For Thursday through Sunday, winds and seas are expected to remain below SCA levels.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. SCA level winds are expected across western sections of the southern waters this afternoon and tonight. For Wednesday through Saturday, winds and seas are expected to remain below SCA levels. On Sunday, there is a 50% chance of SCA level winds across the western half of the Santa Barbara Channel.

Watches, Warnings, Advisories

Ca, Wind Advisory in effect until 9 AM PDT Wednesday for zones 34-39-52. (See LAXNPWLOX). Excessive Heat Warning in effect from 10 AM to 9 PM PDT Wednesday for zones 34-35. (See LAXNPWLOX). Excessive Heat Warning in effect until 9 PM PDT Wednesday for zones 36-44>46-88-547. (See LAXNPWLOX). Excessive Heat Watch in effect from Wednesday evening through Friday evening for zones 36-44>46-88-547. (See LAXNPWLOX). Excessive Heat Warning in effect from 10 AM Wednesday to 9 PM PDT Friday for zones 37-38-51. (See LAXNPWLOX). Excessive Heat Warning in effect until 9 PM PDT Friday for zones 52>54-59. (See LAXNPWLOX). Red Flag Warning in effect until 6 AM PDT Wednesday for zones 239-252. (See LAXRFWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 645-650-655. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX).

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