23/306 AM.
High temperatures will peak today, with highs 5 to 10 degrees above normal. The marine layer will shrink during this time, with overnight low clouds and fog limited to coastal areas through at least Thursday night.
(Wed-Sat), 23/836 PM.
***UPDATE***
Calm day with temperatures around 5 to 10 degrees above normal. Marine layer clouds at around 1000 feet are starting to fill in across the Central Coast and Los Angeles County and will likely be fairly widespread for the coastal areas by morning.
***From Previous Discussion***
Very quiet, though warm, weather pattern today and through the end of the week. Very little change in high temperatures expected through Saturday with highs 5-10 degrees above normal. 100 degree temps are still on the table for the warmer valleys, roughly a 20-40% chance, while Downtown LA has around a 60-70% chance of reaching 90 each of the next 3 days. Onshore gradients will remain light but there will be a slight increase in gradients over the next couple days, possibly resulting in couple degrees of cooling near the immediate coast, particularly along the Central Coast on Saturday. Some marine layer clouds are expected as well, again mostly confined to areas within a few miles of the beach.
(Sun-Wed), 23/128 PM.
A cooling trend will begin in earnest Sunday as a trough moves onshore over northern California. Confidence in the forecast beyond that remains murky as a tandem of two tropical systems jockey for position off the Baja coast. At this time there are exactly zero solutions that bring either of these systems to southern California. There are a couple of GEFS solutions that (out of many) that bring a much weakened Polo to the central part northern Baja, but the majority keep it over southern part of Baja. The track of Odalys is a little more uncertain but again all but one or two remain south of northern Baja. The message here is that the greatest threat to Southern California is again the beaches with periods of increasing south swells late Sunday and peaking Monday and Tuesday. Can't rule out a stray shower, however if the trough moves through as most of the models are suggesting then most of the moisture will be pushed south and east of LA County.
23/2335z.
At 2311Z at KLAX, the marine layer was 1200 ft deep. The top of the inversion was at 2100 feet with a temperature of 29 C.
High confidence in VFR TAFs for KPRB, KPMD, and KWJF.
Low confidence in TAFs for KBUR and KVNY, as there is a 30% chance of LIFR-IFR cigs with best chances 12Z-17Z. Low confidence on min flight cat if cigs arrive.
Good confidence in cigs arriving tonight at remaining coastal sites except lower for KSBP (30% chance for no cigs). Lower confidence in min flight cats at all sites. Flight cats may be off by one. There is a 40% chance 1/4SM vis at KSMX and KSBP when cigs are present.
KLAX, Moderate confidence in TAF. Cigs may arrive as early as 03Z with cig heights most like 007-012. No significant east wind component expected.
KBUR, Low confidence in TAF after 10Z with a 30% chance for LIFR-IFR cigs 12Z-17Z. Low confidence on min cig height.
23/830 PM.
Small Craft Advisory (SCA) northwest winds will linger around Point Conception until late tonight. Conditions will then drop below advisory levels for all waters through Thursday afternoon. SCA level winds are likely to return Thursday evening/night starting across far northern waters and locally near Point Conception. By Friday afternoon or evening, these winds will expand to cover the majority of outer waters and even reaching into the nearshore waters along Central Coast. Short- period steep, choppy seas most likely during this timeframe. Coverage and wind strength is likely to decrease some on Saturday with more focus near Point Conception. These SCA winds will expand in coverage again Sunday through early next week with increasing potential to reach into the Santa Barbara Channel.
23/214 PM.
The eastern Pacific is currently active with Hurricane Polo, Hurricane Odalys, and tropical depression Fifteen-E south of Hawaii. This discussion will focus on the potential impacts from the SSE swell generated from Hurricane Polo.
Uncertainty is still rather high regarding the evolution (track, intensity) of Hurricane Polo. Current trends in guidance have shifted eastward with more solutions turning north and east making landfall in Baja California Sur.
With these current projections here are the latest thoughts: Expecting elevated SSE swells from Hurricane Polo with elevated surf, with potential impacts peaking Mon-Tues. Confidence is high in tide predictions near 7 ft Mon-Wed in the late morning hours. Low to moderate confidence for surf which is dependent on Polo's track which has not be ironed out yet.
The Swell is likely to have a more SE direction compared to Labor Day weekend event. Areas of most concern: Long beach (Peninsula and Belmont shore), Avalon, Malibu, and possibly Santa Barbara Harbor.
Scenario 1 (Mon-Tues): Coastal Flood Advisories (High Chance) Shallow flooding of sea water of low-lying walkways, parking lots, and roads. Significant beach erosion possible.
Scenario 2 (Mon-Tues): Coastal Flood Warnings (Low Chance) Flooding of sea water impacting structures, walkways, parking lots, and roads. Significant beach erosion expected.
Ca, NONE. PZ, Small Craft Advisory in effect from 6 PM Thursday to 3 AM PDT Saturday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zone 673. (See LAXMWWLOX).
