14/143 PM.
Seasonal June conditions will continue through the first half of this week as at least weak to moderate onshore flow continues, with night through morning low clouds and fog across most coastal areas. Near to slightly above normal temperatures will continue through early next week as well, with minor afternoon heat impacts, before cooling down heading into the second half of the week.
(tdy-Wed), 14/141 PM.
Persistent weak synoptic flow continues along the West Coast, with subtle cyclonic circulation seen on wv satellite over central CA. This is imparting light 900-400mb southwesterly flow over the area and surface pressure gradients continue to support at least light to moderate onshore flow with gusty onshore winds expected again heading into the afternoon. Marine layer stratus had notably lower coverage over the LA basin this morning, compared to previous days, and cleared up quickly, while it was more expansive for most areas north of Point Conception. The marine clouds were sticking close to a few coastal areas through midday from Oxnard/Ventura northward, which may keep afternoon temperatures a touch cooler than forecast.
Midday temperatures were running 1-5 degrees cooler than the same time yesterday, which is consistent with the forecast trend of minimal day-to-day cooling that was expected late last week through this weekend. Despite the slow cooling we have seen, most areas will still experience near or above normal temperatures this afternoon, up to 5-10 degrees above in some interior valleys. High temperatures will mostly reach the upper 70s to upper 90s this afternoon away from the coast and 60s to low 70s along the coast.
Slight offshore trends and enhanced ridging aloft will bring a few degrees of warming into Monday and Tuesday with the potential for moderate heat impacts to expand for warmer coastal valleys and the interior. Although above normal temperatures will increase heat stress during the day for those interior areas, good cooling trends in the evening and especially overnight should limit overall impacts and therefore the need for heat products. However, those sensitive to the heat may want to consider avoiding peak heat of the day and hydrate often.
The marine layer and associated night-to-morning low clouds may be similar tonight-Monday morning with similar overall conditions to last night-this morning if not a slight weakening of the onshore flow and a deepening of the marine layer as pressure level heights rise. There is a chance for the low stratus to progress through some coastal valleys, like up into the Burbank area, but after the low coverage this morning, confidence is to low to include the stratus in this area. Hi-res models also support a low chance of low stratus and fog progressing up the Salinas Valley again toward San Miguel and Paso Robles. The marine layer clouds may become more squashed to mainly coastal areas heading into Tuesday with limited to no valley penetration, contributing to the aforementioned warming trends most notably for coastal valleys. Fog may become more widespread within the marine layer albeit with limited concern for dense fog given continued onshore flow and only weak ridging/height rises aloft.
A slow-developing trough offshore over the East Pacific will likely build into region toward late week, but begin bringing moderate cooling trends away from the coast starting Wednesday, reducing heat risk even to warmer interior areas. Night to morning low clouds will likely continue, but start to expand further into the coastal valleys and possibly some lower foothills as southwest flow increases.
(Thu-Sun), 14/156 PM.
A slow-developing trough over the East Pacific will become more organized and should build into the region by the end of the week, and carry a cooling trend into next weekend, with the most notable cooling away from the coast. This will significantly reduce heat risk even to warmer interior areas and latest guidance has afternoon high temperatures up to 5-10 degrees below normal. Night to morning low clouds will likely push further into the coastal valleys and possibly some lower foothills as southwest strengthens. There will also be increased odds for some drizzle within the marine layer in the mornings.
The associated onshore push will support gusty onshore to northwest winds nearing advisory levels for the interior, possibly extending to southwest Santa Barbara. There may be a period of enhanced fire weather concern on one or both of those transition days (Wed/Thu) for far interior areas and maybe especially at high elevations, which would be situated above the expanding marine layer influence.
Looking further out, there's a 50-60 percent chance of above normal temperatures returning and perhaps becoming more widespread during the early to middle part of next week as a ridge potentially builds into the region.
14/1804z.
At 1708Z at KLAX, the marine layer was 1000 ft deep. The top of the inversion was near 3000 ft with a temperature of 23 C.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Low to moderate confidence in remaining TAFs. Timing of CIG/VSBY restrictions may be off 3 hours and flight minimums by one category.
KLAX, Low confidence in TAF. Intermittent CIGs around 008 are possible from 14/18Z-14/23Z as stratus hangs along coastline. Thereafter, IFR CIGs 005-007 should arrive 15/05Z (+/- 2 hours). Stratus could hang along coastline again 15/18Z - end of fcst pd. No significant east wind component expected.
KBUR, Moderate confidence in TAF. High confidence in VFR conditions through 15/08Z. 30% chance of LIFR CIGs 12Z-16Z.
13/821 PM.
Moderate to high confidence in current forecast. Conditions are generally expected to remain below Small Craft Advisory (SCA) levels across the coastal waters through the forecast period.
Local gusts could reach 21 kts during the afternoon and evening timeframe across the western Santa Barbara Channel, Santa Monica Basin, and nearshore Los Angeles Harbor into the San Pedro Channel.
Patchy dense fog with visibility 1 NM or less is possible each night to morning through at least Monday.
Ca, Beach Hazards Statement in effect through Monday evening for zones 349-350-354-362-366. (See LAXCFWLOX). PZ, NONE.
