16/835 PM.
Steady cooling through Thursday with below normal temperatures through Saturday or Sunday. Ample low clouds each morning through the weekend, with patches of drizzle possible Thursday and Friday. Gusty onshore winds will impact interior areas through the week. A significant warming trend remains on track for next week.
(Tue-Fri), 16/835 PM.
***UPDATE***
Forecast is on track. Made a few changes for the low clouds and fog pattern based on current trends on Satellite. June Gloom will bloom to close out the week.
***From Previous Discussion***
Very similar conditions this afternoon to yesterday with moderate onshore flow both to the north and east. Srn CA is under a weak ridge that is nosing in from the west with H5 hgts near 590 dam. Max temps will come in within a degree or two of ydy's readings. The csts will mostly be in the 70s and the vlys in the 80s (the western San Fernando Vly will soar into the 90s again). Most areas, save for the beaches, will have above normal temps.
Slight cooling is on track for Wednesday. The ridge will weaken and hgts will fall a few dam. Onshore flow will increase and the marine layer will deepen some. More of the vlys will wake up to low clouds. All of this will translate to about 3 to 6 degrees of cooling across the board.
A switch to cyclonic flow aloft along with a substantial increase in onshore flow will bring a deep marine layer that will cover almost all csts/vlys with marine stratus. Strong onshore flow (~9mb) to the east will bring slow clearing to all areas with no clearing likely for some beach and nearshore areas. The deepening marine layer may support spotty offshore and some coastal drizzle in the mornings Thursday and Friday. The strong onshore push to the east will bring near advisory level winds to the western Antelope Vly in the afternoons, likely peaking on Friday as the trough axis pushes inland. The deep marine layer and strong onshore push will drop temperatures away from the csts by 5 to 10 degrees (csts will only cool 1 to 3 degrees). This cooling will bring upper 60s to mid 70s to the csts and upper 70s and lower 80s to the vlys. These vly temps are 4 to 8 degrees blo normal.
(Sat-Tue), 16/143 PM.
The end of this week through at least Saturday is set to be peak June Gloom. Broad troffing will persist over the state through the weekend and will provide the gentle lift needed for a deep marine layer. At the sfc there will be stg onshore flow to start the weekend, esp to the east. Low clouds and fog should cover the csts and all vlys and will likely xtnd into the mtn passes. The low clouds will be slow to clear and early to return. Some, perhaps many, coastal locations will see little if any clearing. Max temps will only be in the mid and upper 60s across nearshore locations with only 70s across the rest of the csts/vlys. Most max temps will end up 5 to 10 degrees blo normal.
The trof will then diminish heading into Monday and the onshore flow will subside somewhat. This will lead to a lessening of the amount of morning low clouds, esp in areas like the Santa Clarita Vly, and an earlier and more complete afternoon burn off. Look for 1 to 2 degrees of warming on Sun and 2 to 3 degrees on Monday.
Looking further ahead into the middle of next week there are good indications of a strong upper high building into the area which would lead to well above normal temps for the vlys and inland areas (continued onshore flow will moderate the heat for the csts). There are already low probabilities (10-30%) for major heat risk for the warmer inland valleys beginning Wednesday next week. The heat next week, if it comes to fruition, may pose significant impacts to residents and especially for out of towners.
17/0018z.
At 23Z at KLAX, the marine layer was 1200 ft deep. The top of the inversion was near 3000 ft with a temperature of 24 Celsius.
High confidence in KPMD & KWJF in VFR and gusty southwest winds.
High confidence in ceilings at all other airports. Moderate confidence in timing (+/- 3 hours) and flight categories (+/- 500 feet ceilings).
KLAX, High confidence in IFR/MVFR ceilings for the majority of the night. Moderate confidence in timing (+/- 3 hours). No significant east wind component expected.
KBUR, Moderate confidence in IFR ceilings forming tonight with slightly stronger than usual onshore winds in the afternoon and evening hours.
16/846 PM.
Moderate to high confidence in current forecast. Conditions are generally expected to remain below Small Craft Advisory (SCA) levels across most of coastal waters through the forecast period. However, Small Craft Advisories were issued for the the waters from Point Sal southward to Point Mugu including the Channel Islands due to SCA level wind gusts.
Wednesday, local gusts could reach 21 kts (30-40% chance) during the afternoon and evening timeframe for the waters south of Point Conception, especially for western portions of the Santa Barbara Channel and southward to San Miguel Island. Breezy conditions will be ongoing for the waters south of Point Conception each afternoon/evening through Friday, with another chance for SCA gusts Friday afternoon. Lower confidence from Saturday onward, with a chance for widespread SCA conditions Sunday night.
16/821 PM.
A long period southerly swell (14 seconds and 18 seconds) will continue to affect the coastal waters through at least Friday. A Beach Hazard Statement is in effect through Wednesday evening due to elevated surf of 3 to 6 feet on south-facing beaches of Ventura County Beaches, Malibu Coast, Los Angeles County Beaches, and portions of the Southern Santa Barbara County Beaches.
Tides of 7.0 to 7.4 feet are predicted to peak around 10 PM to 11:30 PM tonight (Tuesday Night), and will reach 6.6 to 6.9 feet around the same time Wednesday night. The combination of the unusually high tides with elevated surf could result in minor to locally moderate coastal flooding along south exposed coasts, especially near Malibu and Long Beach. In addition, there is along potential for sneaker waves. Stay tuned for updates and refer to CFWLOX for additional details.
Ca, Beach Hazards Statement in effect through late Wednesday night for zones 349-350-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect until 2 AM PDT Wednesday for zones 362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 2 AM PDT Wednesday for zones 650-673. (See LAXMWWLOX).
