24/836 AM.
Temperatures will remain above normal along the Central Coast at least through today and across all valleys and interior areas through this weekend. Coastal areas south of Pt Conception will be influenced by a stubborn marine layer that will keep temperatures on the cooler side until later in the week when increasing offshore flow returns to warm up those areas into the weekend.
(tdy-Thu), 24/849 AM.
***UPDATE***
Our forecast area currently occupies several differing weather regimes so the forecast is a little more complicated than usual. The Central Coast is still being influenced buy a moderate northeast offshore flow. Yesterday temperatures rose into the 80s and 90s and expecting that again today. The offshore flow there will weaken tomorrow bringing at least 5-10 degrees of cooling. However, models indicate another offshore push Thursday and Friday. This one, however, isn't quite as warm so temperatures will warm up but likely not as hot as the last couple days.
Coastal areas south of Pt Conception continue to be mired in a 1500' marine layer with a light onshore flow. This will continue at least through Wednesday and likely Thursday as well, keeping temperatures there generally in the 70s or lower 80s. Inland areas will be much warmer with minimal if any marine layer influence and temperatures in the 80s to low 90s, a solid 10-15 degrees above normal.
***From Previous Discussion***
Sort of an August like pattern over the next few days as the vlys and the interior will see above normal temperatures while the csts will be much cooler with plenty of marine layer clouds. The exception will be the Central Coast where decent offshore flow will bring much warmer than normal temperatures to the area.
There will be ridging over the area today and Thursday with a brief interruption Wednesday as a weak and dry trof moves through the center of the state. Hgts will be near 586 dam today, falling to 580 dam Wednesday with the trof and then rebounding to 584 dam on Thursday. Sfc grads in the E/W direction will cycle between weak onshore flow in the morning and moderate onshore flow in the afternoon. The N/S gradients will vary between weak offshore in the AM and weak onshore in the PM.
The marine layer is about 1200 ft deep with a strong capping inversion this will slow clearing and the moderate onshore push in the afternoon will bring the low clouds back in the early evening. Overnight a weak eddy will bring the low clouds into the lower vlys as well. The marine layer is deep enough to preclude widespread dense fog. This night through morning low clouds patter will continue through the short term.
There will not be too much change in temperatures today, maybe a little cooler over the csts and vlys and a little warmer for the interior. The Central Coast will remain well above normal and the heat advisory continue there through this evening. The offshore winds across the Central Coast will end Wednesday and this will bring 8 to 12 degree of cooling to the area and the heat threat will end. The rest of the area will not see much change. Max temps remain many degrees above normal away from the csts. Offshore flow will strengthen on Thursday and this will warm the csts/vlys by 2 to 4 degrees. The flow will also advect cooler air from the San Joaquin Vly and cool the interior by a couple of degrees.
(Fri-Mon), 24/217 AM.
Srn CA will be under gradually strengthening SW flow through the period. Hgts will slowly fall from 582 dam Friday to 568 dam on Monday as the upper high shifts to the east. The gradients will not change much on Fri and Sat but will become more and more onshore on Sunday and Monday.
Night through morning low clouds and patchy fog will continue through the period with better vly penetration on Sun and Mon.
Max temps are forecast to warm some on Friday although this is highly dependent on the actual gradients and marine layer. Not much change is forecast for Saturday. Noticeable cooling is likely on Sun and Mon as hgts fall and onshore flow increases. Monday's max temps should be in the 70s and lower 80s across the csts/vlys. Despite all the cooling Monday's max temps will end up 5 to 10 degrees over normal.
Both AI-Mdls (as they have for the past 6 days) show a system affecting the area sometime on 31st and 1st. It looks like it will be at least a half inch rain event although today's GFS-AI run was wetter. ***OF NOTE***
This has be a phenomenally warm month. Using the forecasted high temperatures for DTLA for today (the 24rd) to the 31st along with the max temps that have already occurred, the DTLA average max temp for the month would be 82.0 degrees. This would handily eclipse the previous record holders:
79.1 degrees in 2015 76.7 degrees in 2017 76.0 degrees in 1931 75.8 degrees in 1934 75.7 degrees in 1959
24/1152z.
At 0823Z at KLAX, the marine layer was 1300 feet deep. The top of the inversion was at 4600 feet with a temperature of 23 C.
High confidence TAFs for KPRB, KSBP, KSMX, KPMD & KWJF.
Moderate confidence in remaining coastal TAFs. Timing of CIG/VSBY restrictions may be off +/- 2 hours. Cig hgt could vary by +/- 200 ft.
Low confidence in KVNY TAF with a 40 percent chc of LIFR conds 13Z-17Z.
KLAX, Moderate confidence in TAF. There is a 30 percent chc of cigs OVC010-012 by 15Z. There is a 30 percent chc of VFR cond arriving at 20Z. There is a 20 percent chc that low clouds could return by 00Z. No significant east wind component is expected.
KBUR, Moderate confidence in TAF. VFR conds may not arrive until 17Z. There is a 30 percent chc of 2SM BR OVC004 conds after 25/11Z.
23/805 PM.
For the Outer Waters, moderate to high confidence in current forecast. Through Thursday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. For Wednesday, there is a moderate chance (30-50% chance) of GALES, likely to be focused during the afternoon thru overnight timeframe. Large seas of 10-14 feet are possible late Wednesday through early Friday. For the weekend, seas should generally remain below SCA levels with low to moderate chances for SCA winds.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. For Tuesday, there is a 40% chance of SCA winds. Followed by a 60-70% chance on Wednesday and Thursday. Winds will be strongest during the afternoon and evening hours.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For most of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Thursday. The only exception will be the western half of the Santa Barbara Channel where there is a 20-30% chance of SCA level winds focused during the afternoon and evening hours Wednesday and Thursday.
Dense fog is possible this week, focused in the late evening to early afternoon hours each day. Visibilities of one nautical mile or less can be expected.
Ca, Heat Advisory remains in effect until 8 PM PDT this evening for zones 340>342-346>348. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 9 AM PDT Thursday for zones 670-673. (See LAXMWWLOX).
