16/1245 AM.
Look for partly to mostly skies with a chance of showers today. Afternoon highs will be well below normal. Another cooler system will bring rain to most of the area Monday with showers continuing into Tuesday. Wednesday will offer a brief respite from the rain with warmer temperatures. Another storms is slated to arrive next Thursday and linger into Friday.
(tdy-Tue), 16/303 AM.
An upper low currently over LA county will move to the NE this morning. Currently the low is producing numerous showers in its SE quadrant that are moving over the SE portion of LA county. Some of these cells put out enough rainfall (.32 inches in 15 minutes) over the bridge fire to create a high likelihood of flash flooding. Some shower activity was also moving across southern VTA county. Lighter wrap around showers were moving over the Central Coast from the north.
There will be a marked decrease in shower activity over the next few hours as the flow over the area transitions to entirely NNW. This downsloping less dynamic flow pattern will not allow for much shower development or enhancement. Most additional rain will fall this morning and additional rainfall totals will mostly be under a quarter inch with amounts up to a half inch possible over SLO county where the wrap around will be strongest.
The clouds will not be as thick today and there will be some peaks of sunshine, but the character of the day will be mostly cloudy. Max temps will warm a couple of degrees but will only end up in the lower 60s for most of the csts/vlys or 8 to 12 degrees blo normal.
Another upper low with an associated cold front will move into nrn CA later tonight. The front with its light rain will begin to move into the Central Coast in the predawn hours Monday. The front will sweep through forecast area during the day and will exit LA county in the early evening. There will likely be a 3 or hour period of rain with the front. This system is colder than the Fri/Sat storm and has no sup tropical moisture tap so the rainfall totals and intensities will be much less. Max rainfall rates will top out at a half inch per hour with quarter inch per hour rates much more common. Rainfall amounts will range from .75" to 1.5" with the highest amounts along the south facing coastal slopes. Snow levels will be above 7000 ft during the day over LA and VTA counties. The colder system, clouds and rain will all team up to lower cst/vly temps to within a couple degrees of 60.
Shower activity will continue overnight in the wake of the cold front. Snow levels will drop to 5000 ft and a couple inches of snow is possible above 6000 ft. Rainfall amounts will not be homogeneous at all but some areas could see a third of an inch of extra rainfall.
The upper low does not move much at all on Tuesday and will sit to the north of Kern county and spin some weak disturbances over the area. There will be 20 to 30 percent chc of shower through the day with partly to mostly cloudy skies. The best chc of showers will be across the north slopes, while places that have downsloping under north flow conditions (southern SBA county and southern VTA county) will see much less showers and rain. Rainfall totals should not add up to much. Hgts overhead will only be 550 dam and max temps will struggle to even reach 60.
(Wed-Sat), 16/106 AM.
All mdls and ensembles fcst a small ridge to ride over the area on Wednesday. In quite the change of pace the day will be dry and there will be sunshine. Hgts rise to 568 dam. Max temps will bump up 2 to 4 degrees across the area. Even with the warming max temps across the csts/vlys will only be in the lower to mid 60s or 8 to 12 degrees blo normal.
Another system is slated to affect the state on Thursday and/or Friday. There is still considerable disagreement on track and speed of this system. The GFS takes a slower more over water trajectory while the EC is faster and more inside. The EC-AI mdl has been performing the best over the last couple of weeks and it shows rain starting early Thursday and lasting into the evening with a dry Friday. It is forecasting a half inch to an inch of rain. The official forecast based on the entire ensemble based probabilistic spread, however, calls for a 40 to 50 percent chc of rain on Thursday and a 20 to 30 percent chc on Friday with rainfall amounts of a quarter inch to three quarters of an inch. This system is quite a few days away and is embedded in a fast moving storm track, so it is very likely that the forecast will change as the day draws nearer.
While the mdls forecast wildly different synoptic patterns next Saturday, almost all of the solutions are dry. Max temps should warm, but will likely still remain a few degrees blo normal.
16/1200z.
At 1008Z at KLAX, there was no marine layer. There was a deep moist layer up to at least 10000 feet.
Low confidence in TAFs through 20Z and then fair confidence. Multiple SCT-BKN layers in the low MVFR, high MVFR and low VFR categories will create variable cigs through 20Z along with a 25 percent chc of a shower.
Better confidence in TAFs aft 20Z with sct-bkn conds between 040 and 060.
KLAX, Low confidence in TAF through 20Z. Cig/Vis will likely vary frequently between BKN015, BKN025 AND BKN035 through 20Z. There is a 25 percent chc of brief -SHRA through 20Z. Better confidence in cig fcst after 20Z. Lower confidence in east wind fcst with a 30 percent chc of an 8kt east wind component through 16Z.
KBUR, Low confidence in TAF through 20Z. Cig/Vis will likely vary frequently between BKN015, BKN025 AND BKN035 through 20Z. There is a 25 percent chc of brief -SHRA through 20Z. Better confidence in cig fcst after 20Z.
16/328 AM.
For the waters from southwest through northwest of the Channel outside the southern California bight and the nearshore waters along the Central Coast, winds and seas will likely remain below Small Craft Advisory levels, then there is a likely (60-80 percent) chance of SCA conditions developing tonight through late Tuesday night. Winds and seas will likely fall below SCA levels for Wednesday and Thursday, then there is a moderate-to-high (30-50 percent) chance of SCA conditions developing on Friday.
Inside the southern California bight, winds and seas will likely remain below Small Craft Advisory levels through early Monday morning, then there is a moderate-to-high (30-50 percent) chance of SCA conditions developing on Monday and continuing through early Tuesday morning. Winds and seas will likely fall below SCA levels for Wednesday and Thursday, then there is a moderate-to- high (30-50 percent) chance of SCA conditions developing on Friday.
There is a 10-20 percent chance of thunderstorms across the coastal waters south of Point Conception through mid-morning this morning. Any thunderstorms that develop will be capable of producing brief heavy rain, small hail, dangerous cloud to surface lightning, gusty and erratic winds, locally rough seas, and possible waterspouts.
Ca, NONE. PZ, Small Craft Advisory in effect from 9 PM this evening to 9 PM PST Tuesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 9 PM this evening to 3 AM PST Wednesday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect from 3 AM Monday to 3 AM PST Wednesday for zone 676. (See LAXMWWLOX).
