29/235 AM.
Gradual cooling will continue through the week as will coastal flooding issues due to very high tides. The next storm system is expected to bring rain to the area from as early as Friday through Sunday, likely peaking Saturday evening into Sunday morning.
(tdy-Sat), 29/235 AM.
One, probably two, days of cloudy but benign weather on tap for the area as the stage gets set for rain event. Today and Friday the flow aloft will get stronger and stronger and will shift from the WSW to the SW. Plenty of mid and high clouds will stream overhead and skies will be mostly cloudy to overcast through the period. On Friday a stray shower or two may develop just about anywhere west and south of the mtns. Rainfall amounts, if any, will be less than .05 inches. Max temps across the csts/vlys will be in the 70s today falling to mostly the upper 60s to mid 70s on Friday. These max temps are 5 to 10 degrees blo normal.
The upper low responsible for the SW flow will elongate down the coast during the day Saturday and then sweep a trof or a weak cut off low into and over Srn CA Saturday and overnight into Sunday. Current blended mdl solutions are now showing a little more northward progression of the moisture plume moving in the SW and are showing likely pops (~70%) for most of the area including points north of Pt Conception. Rain (unfortunately for Trick or Treaters) will peak Saturday evening and continue overnight. Rain will quickly taper off from the west to east Sunday morning and by Sunday afternoon only eastern LA county will have a chc of rain.
There is still a wide range or rainfall solutions for this system. this is not surprising as forecast mdls struggle with systems coming in from the SW. The current official forecast indicates that this system will not be a super soaker with the current high chc of rain forecast only slated to produce a quarter to half inch of rain over most areas (less than a quarter north of Pt Conception and up to three quarters of an inch across SE LA county. There is still a 30 percent chc of this being a 1 to 2 inch storm (south of Pt Conception) and a 10-15 percent chc of it only producing a couple tenths.
All this said, these forecasts are based on longer range mdls using spectral physics. This system is now coming into the forecast window of the shorter range higher resolution sigma physics based mdls and there is a noticeable forecast difference. Both the NAM and the RRFS show a much later arrival time of the rain and in the NAM's case a much more southerly focused one. So perhaps Saturday and Saturday evening will be drier than the official forecast indicates.
Max temps for the csts and vlys will only be in the 60s on Saturday, but will rise into the lower 70s Sunday due to clearing skies in the afternoon.
(Sun-Wed), 29/235 AM.
Ridging and weak offshore flow move into the area on Monday and continue into Tuesday. The offshore flow will not be too strong and there will only be local sub advisory winds below the passes and canyons. Max temps will rise 3 to 6 degrees Monday and an additional 1 to 2 degrees Tuesday. Despite the warming max temps will end up 2 to 3 degrees blo normal.
Tuesday night and Wednesday the ridge will be pushed to the east by a trof and a 15 to 30 percent chc of rain will develop across the Central Coast. Wednesday, otherwise, will be partly cloudy and a couple of degrees cooler.
29/0952z.
At 0832Z at KLAX, the marine layer was 3600 ft deep. The top of the inversion was at 5800 ft with a temperature of 12 C.
High confidence in VFR TAFs for KPMD and KWJF.
Moderate confidence in remaining TAFs with VFR mid and high level clouds likely through the period. Periods of SCT-OVC 020-030 are possible through the TAF period, mostly thru 18Z for coastal and coastal valley sites.
KLAX, Moderate to high confidence in TAF. BKN to OVC020-030 cigs possible through the period, mostly thru 18Z. Any east wind component is expected to remain under 8 kt.
KBUR, Moderate to high confidence in TAF. BKN to OVC020-030 cigs possible through the period, mostly thru 18Z.
29/235 AM.
Conditions are expected to remain below Small Craft Advisory (SCA) levels through Saturday. Southwest flow aloft will produce chances for drizzle and isolated light rain showers Friday.
A storm system is expected to impact the coastal waters this weekend. There is a wide range of outcomes, but there is at least a low threat of a 12-24 hour period of strong winds and steep seas. Worst conditions will be focused south of Pt Conception.
27/652 AM.
Very high tides between 7.5 and 8.0 feet (roughly 1.0-1.5 feet above astronomical predictions) are expected during the morning hours through Thursday over all coastal areas, with the highest towards Los Angeles County. Through Wednesday, the tides may remain near record. In fact, at San Pedro, a new record tide of 8.02 feet was set on Monday morning.
Minor coastal flooding is likely purely based on the high tides. While these tides might be the highest of all-time, similar extreme tides in the past tell us that coastal communities should expect shallow flooding of harbor walkways, beach parking lots and bike paths. With swells and surf on the lower-end during these extreme tides (2-3 feet), the threat of more significance/damaging impacts should be limited to the most vulnerable areas that have little-to-no sandy beach left and have already seen water damage.
With that said, these is a small change for more elevated surf on south-facing shores around Wednesday as waves from a southern Hemisphere storm arrive. The majority of computer projections keep this wave energy on the small side, but a couple are a little larger.
With all of these considerations in play, Coastal Flood Advisories are in effect today through Thursday. There is a low potential for targeted Coastal Flooding Warnings if a larger swell develops and produces elevated surf on top of the very high tides.
Ca, Coastal Flood Advisory in effect until 2 PM PDT Friday for zones 87-340-346-349-350-354-362-366. (See LAXCFWLOX). PZ, NONE.
