15/1138 PM.
Night through morning low clouds and fog will persist through the week. Afternoon temperatures will be near normal today and Wednesday but sharp cooling is forecast for Thursday and Friday with a more persistent marine layer. Warmer conditions are likely next week.
(tdy-Thu), 16/839 AM.
***UPDATE***
Pilot reports this morning show the marine layer depth is up to around 1500-1700 ft and morning visible satellite showing a very similar cloud coverage picture to the previous couple of days, with the exception of slightly further inland reach across the LA basin. Surface obs and traffic cams did not show any evidence of locally dense fog.
Forecast is still on track for similar high temperatures this afternoon to yesterday, if not 1-2 degrees warmer in a few spots. Breezy coastal and onshore winds are expected again this afternoon especially south of Point Conception.
***From Previous Discussion***
Very similar conditions today compared to ydy. Srn CA is under a weak ridge that is nosing in from the west with hgts near 590 dam. At the sfc there is moderate onshore flow both to the north and east. There is no eddy and with the higher than normal hgts overhead the marine layer will likely stay smooshed enough to prevent much valley penetration. 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). 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 strong onshore push to the east will bring near advisory level winds to the western Antelope Vly in the afternoon. 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.
(Fri-Mon), 16/250 AM.
Friday and Saturday are set to be peak June Gloom days. Broad troffing moves into and over the state and will provide the gentle lift needed for a deep marine layer. At the sfc there will be stg onshore flow esp to the east. Low clouds and fog should cover the csts and all vlys and will likely xtnd into the mtn passes. The stg onshore push to the east will likely generate advisory level gusts across the western Antelope Vly. 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 start to diminish Sunday 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)
16/0953z.
At 0832Z at KLAX, the marine layer was 1400 ft deep. The top of the inversion was near 2300 ft with a temperature of 23 C.
High confidence in KPMD & KWJF.
Fair confidence in TAF for KPRB with a 20 percent chc of no low clouds.
Moderate confidence in TAFs for KBUR and KVNY with 30 percent chc of IFR cig/vis 13Z-16Z.
Moderate confidence in remaining TAFs. Cigs may be off by +/- 300 ft and VFR transition could be 1 hour early or up to 2 hours late.
KLAX, Moderate confidence in TAF. There is a 30 percent chc that cigs will remain AOA 010. VFR conds could arrive as early as 17Z or as late a 20Z. No significant east wind component expected.
KBUR, Moderate confidence in TAF. There is a 30% chance for 2SM OVC006 conds 13Z-16Z.
16/251 AM.
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. However, winds may approach SCA levels with gusts 20 to 25 knots over portions of the waters at times this afternoon near and south of Point Conception and into the western Santa Barbara Channel.
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, NONE.
