03/851 PM.
Cloudy and cool conditions will continue through Tuesday, with increasing chances of mostly light rain. Warming and drying to follow Wednesday through the next weekend, with high temperatures approaching 90 degrees in some areas by Friday.
(tdy-Wed), 04/1225 AM.
The marine layer is over 6000 ft deep and has produced a fairly high based (4000-6000ft) cloud deck of much of the area. Conditions are a little clearer over the Central Coast where the effects of the approaching upper low are mixing the atmosphere some.
Today's weather will come courtesy of a 560 dam upper low currently just to the SW of Monterey Bay. The upper low will move very slowly to the SE and will over SLO county later this afternoon. This is a fairly dry and non dynamic system, but it still will bring a 20-30 percent chc of rain to the area. The best chc of rain today will be south of Pt Conception where the flow will have the longest over water trajectory and the most PVA. There will also be a chc of showers over the mtns where there will be decent instability. SLO and SBA county will have a very slim but non zero chc of a TSTM as the core of the low moves overhead during peak afternoon heating. Rainfall amounts will mostly be under a tenth of an inch with plenty of locations not seeing any rain or just a trace but a few areas could see a quarter inch under a heavier shower. Rainfall rates should also not be a concern with the exception of any area affected by that 5 percent chc of a TSTM. Max temps will resemble January more than May with highs only in the 60s across the csts/vlys or 10 to 15 degrees blo normals away from the near shore areas.
Over night the low will spin over VTA county and the best chc of rain will shift to the mtns esp the north slopes.
On Tuesday the low is fcst to accelerate to the east and should be over the state line by mid afternoon. A 20 to 30 percent chc of showers will continue across the mtns of VTA and LA counties through the day. Elsewhere look for a decrease in clouds with the resulting increase in sunshine bringing a few degrees of warming to the area esp to SLO and SBA counties.
On Wednesday dry NNE flow will set up over the state as a ridge pushes into Bay Area. Hgts will rise quickly to 578 dam. There will be a little offshore push from the north in the morning while the onshore flow to the east will increase from weak to moderate by afternoon. Skies will be sunny. Coastal temps will warm 3 to 5 degrees tempered by the onshore flow. Away from the coasts, however, the sunshine and hgt rises will combine to bring a very noticeable 5 to 10 degree warm up with 10 to 15 degrees across mtns and far interior.
(Thu-Sun), 04/228 AM.
All signs pointing to an xtnd warm up for the long term. All mdls agree that the east Pac ridge will nose into the state from the west. Hgts will rise to 582 dam on Thu and stay there through Sat and then bump up a little to 584 dam on Sunday. The biggest question mark for the forecast will be the E/W sfc gradients. While there is decent agreement that there will be weak offshore flow from the north, there is considerable disagreement on what the E/W grads will do. About half the EC ensemble grads (which usually verify better than the GFS ensembles) are onshore in the mornings while the other half is offshore. The deterministic EC follow the mean pretty closely with its grads just a little onshore. For now will go with that, but have to keep an eye on this critical parameter because if it does go offshore the already warm temps will soar even higher.
Right now most areas are looking at 3 to 6 degrees of warming Thursday, 1 to 3 degrees Friday, 2 to 4 Saturday and 1 to 2 degrees on Sunday. Cst/Vly temps start out 2 to 4 degrees above normal on Thursday and rise to 5 to 10 locally 12 degrees on Sunday. The mtns and far interior will end up 15 to 18 degrees over normal on Sunday. On Sunday max temps across the near shore areas will be in the lower to mid 70s, the rest of the csts in the upper 70s and to mid 80s. The vlys will be mostly in the lower 90s. If the offshore flow from the east does develop these temps could be 4 to 8 degrees highers with some locations possibly hitting 100 degrees.
04/1002z.
At 0835Z at KLAX, the marine layer was 5600 ft deep with an inversion top at 6500 feet and a temp of 9 C.
Good confidence in TAFs with VFR cigs 040-060 through most of the period and then improving further. There is a 20-30 percent chc -SHRA along with a 5 percent chc of a -TSRA from 22Z-04Z.
KLAX, Fair confidence in TAF with only a 25 percent chc of BKN025 conds 08Z-16Z. There is a 20-30 percent chance of -SHRA 22Z-04Z. High confidence that any east wind component with be AOB 6kts.
KBUR, Fair confidence in TAF with only a 25 percent chc of BKN025 conds 08Z-16Z. There is a 10-20 percent chance of -SHRA 22Z-04Z.
04/150 AM.
For the nearshore waters inside the SoCal Bight, Small Craft Advisory (SCA) west winds are likely (40-60% chance) Tuesday afternoon and evening with a chance (30-40% chance) Wednesday and Thursday nights, mainly in the channel.
For the outer waters, SCA NW winds are likely (40-60% chance) for the waters near Point Conception to the northern Channel Islands, possibly extending south to San Nicolas island. Winds will increase again from the NW Wednesday night (for PZZ676) into Thursday for the remaining outer zones through Thursday night. Stronger winds will be possible Friday into the weekend.
Nearshore along the Central Coast there is a 30% chance for SCA NW winds Tuesday and Wednesday nights, with a 30 to 40% chance of SCA conds Thursday afternoon and night.
Ca, NONE. PZ, NONE.
