13/1205 AM.
Scattered rain and mountain snow showers will continue at times through the afternoon, mainly over the interior and the Central Coast. Dry and warmer weather is expected the rest of this week.
(tdy-Wed), 13/847 AM.
***UPDATE***
The main story today is the potential for lingering showers and thunderstorms as a very cold (for mid April) upper low hangs nearby to the north.
Modest instability and strong mid level lapse rates support a 10-30 percent chance of thunderstorms this afternoon to early evening with the highest probability from the LA County mountains and Antelope Valley foothills west to the Ventura County mountains. Main storm hazards will be brief heavy rain, small hail, gusty winds, and cloud-to-ground lightning. Although a weak/brief tornado cannot be ruled out, especially across eastern LA County, focused across the mountains into the Antelope Valley. Storm motion will generally be south to east 10-30 mph following steering motion aloft, limiting localized flooding concerns, however a few storms could become anchored in place. Peak rainfall rates will generally be around a quarter of an inch or less per hour. However, any training of or anchored storms could produce very localized rates on the order of 0.5-0.75 inches in one hour.
***From Previous Discussion***
Brisk and dry westerly flow is over the area. There are clouds pushed up against the north slopes where some snow flurries may also occur. A weak convergence zone is also bringing some showers to the Long Beach area. Later this morning a weak impulse will move over the area. The high April Sun angle and mostly clear morning skies will bring low level heating to the area esp the mtns. The trof will bring cool air aloft and lift. These two things will combine to bring a chc of showers and slight chc of TSTMs late this morning and into the early evening. Additional rainfall will not be much except for isolated heavier amounts under any TSTMs that form. Snow levels will range from 4500 to 5000 ft today. The morning will see snow across the north slopes, but the afternoon will have the showers and TSTMs. These snow levels and the showers and TSTMs along with the gusty winds will create winter weather advisory conditions and the Winter Weather Advisory has been extended until 700 pm this evening. It will be breezier than normal esp in the Antelope Vly. The sunshine will overwhelm the cold air advection and max temps will rise 1 to 3 locally 4 or 5 degrees over most areas. Max temps will still end up 5 to 10 degrees blo normal.
Weak ridging will set up on Tuesday and continue into Wednesday. There will be onshore flow to the east. In the north south direction there will be weak offshore flow in the morning and weak onshore flow in the afternoon as the gradients follow the typical diurnal pattern. Skies will be at worst partly cloudy. Max temps will rise both days. Look for 3 to 6 locally 8 degrees on Tue with an additional 1 to 2 degrees on Wednesday. Wednesday's highs will top out in the upper 60s across the csts and in the lower to mid 70s across the vlys. Max temps will still be a couple degrees blo normal.
(Thu-Sun), 13/314 AM.
An inside slider is expected to work its way down the state line on Thursday, followed by dry NW to N flow on Friday. Thursday morning will feature onshore flow to the east and offshore flow from the north. On Friday there will be weak offshore flow from both the north and east in the morning.
There will not be much wind on Thursday, but Thursday night and Friday decent north flow will develop in the mtns with advisory level gusts likely through the I-5 corridor and the Santa Barbara county mountains.
Max temps will not change much on Thursday, but the offshore flow will bring 2 to 4 degrees of warming to most of the area on Friday.
On Saturday the upper flow turn westerly. There will still be some offshore flow at the sfc, but with no upper support it will only generate sub advisory canyon winds. Max temps will respond to the continued offshore flow and 3 to 5 degrees of additional warm seems likely. This will bring max temps up into the upper 70s to mid 80s for most of csts/vlys which is 4 to 8 degrees above normal.
Mdls are struggling a bit with the pattern for Sunday. All mdls show a large upper low spinning somewhere to the NW but there is massive disagreement on the location. For now the forecast is similar to Saturday with just a little cooling across the csts as the offshore flow weakens.
13/1511z.
At 1530Z at KLAX, there was no marine layer or inversion.
Overall, high confidence in 18Z TAF package as VFR conditions are expected for all sites through the period. There is a 20% chance of showers this afternoon/evening at KWJF and KPMD.
KLAX, High confidence in 18Z TAF as VFR conditions are expected through the period. No significant easterly wind component is expected.
KBUR, High confidence in 18Z TAF as VFR conditions are expected through the period.
13/811 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Friday, high confidence in Small Craft Advisory (SCA) level winds. On Thursday afternoon and Thursday night, there is a 30-40% chance of GALE force winds.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Thursday, high confidence in SCA level winds during the afternoon and evening hours. On Friday, the chances for SCA level winds drop to 30-40%. Thursday afternoon and Thursday night.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through tonight, there is a 60-80% chance of SCA level winds, especially across western portions. For Tuesday through Thursday, there is a 60-80% chance of SCA level winds across the western half of the Santa Barbara Channel, but only a 20-30% chance elsewhere across the southern Inner Waters. On Friday, high confidence in winds and seas remaining below SCA levels.
Ca, Winter Weather Advisory now in effect until 7 PM PDT this evening for zones 353-376>380. (See LAXWSWLOX). PZ, Small Craft Advisory in effect from 2 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Tuesday for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect from 1 PM this afternoon to 8 AM PDT Tuesday for zones 670-673-676. (See LAXMWWLOX).
