Los Angeles, CA 90036 Weather

Synopsis

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.

Short term (tdy-sat)

29/714 AM.

***UPDATE***

Latest satellite and surface observations indicate mostly cloudy skies across the area with a mix of stratus and cirrus clouds. Current sounding data indicates marine inversion in the 4000 to 4500 foot range. No significant winds are observed.

Forecast-wise for the immediate short term, no significant issues are expected. Current cloudy conditions will likely improve to partly cloudy levels this afternoon as stratus dissipates and high clouds thin out. However, it will likely "cloud up" again this evening. Given the cloud cover, temperatures will be a couple degrees cooler than Wednesday.

Overall, current forecast has good handle on the immediate short term. So, no significant updates are expected. For the afternoon forecast suite, attention remains focused on our weekend storm. As mentioned by the night shift below, it does seem to be trending on the "drier" side of things. Will have to see what the 12Z model runs think. Stay tuned.

***From Previous Discussion***

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.

Long term (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.

Aviation

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.

Marine

29/701 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 Today & Friday.

A storm system is likely to impact the coastal waters this weekend. However, guidance continues to shift to the south with some solutions with showers only as far north as the Channel islands. Regardless, there will be some gusty SCA NW winds behind the system on Sunday.

Watches, warnings and advisories

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.