21/1137 PM.
Warmer than normal conditions will persist through the week, likely warmest Tuesday through Thursday. Dense fog will affect some coastal areas today and Monday. Breezy north winds will affect some areas by Monday.
(tdy-Tue), 22/817 AM.
***UPDATE***
Latest satellite and surface observations indicate some low clouds and fog across the coastal plain south of Point Conception as well as some clouds/fog in the Santa Maria/Lompoc area. Otherwise, mostly clear skies prevail. Current sounding data indicates marine inversion in the 1000-1500 foot range. Some northerly winds, gusting 20-30 MPH, are observed across the mountains.
Forecast-wise for the immediate short term, no significant issues are expected. Current stratus/fog should dissipate by afternoon, but some clouds/fog could linger near the beaches through the afternoon hours. Otherwise, skies will be mostly sunny. As for temperatures, expect cooler conditions today with cooler boundary layer and a bit stronger onshore pressure gradients. Current forecast temperatures for today match up pretty well with TEMP STUDY data. As for winds, there will continue to be some locally gusty northerly winds across the mountains today, but speeds will remain below advisory levels.
Overall, current forecast has good handle on the immediate short term. So, no significant updates are expected.
***From Previous Discussion***
The marine layer is a little deep today (about 1000 ft) this will allow a little better coastal coverage and will reduce the amount of dense fog. Flat flow with 584 dam hgts are overhead. At the sfc there will be weak onshore flow to the east while weak offshore flow will develop from the north. The capping inversion is quite strong so while there will be good clearing later this morning the low clouds will only retreat to a a mile or so off the shore. Easterly flow across the Central Coast will keep that area mostly cloud free. Max temps will be similar to ydy xcp for the SBA south cst where north flow off of the Santa Ynez range will bring 2 to 4 degrees of compressional warming. The interior of SLO and SBA will lower a few degrees as cool air advects in from the San Joaquin Vly. Despite all the cooling ydy and little change today, today's max temps will end up 10 to 15 degrees above normal.
Continued onshore flow to the east will likely bring an early return of the low clouds to the csts south of Pt Conception. Building hgts will smoosh the marine layer some and this will likely create some dense fog.
A little stronger offshore push from the north will being faster marine layer stratus clearing in the morning. The E Pac upper high will begin to reassert itself and hgts will climb to 586 dam. This will kick off another warming trend of 4 to 8 degrees for the csts and vlys south of Pt Conception. Stronger offshore flow north of Pt Conception will result in 8 to 12 degrees of warming across the Central Coast. Max temps will mostly be in the 80s across the csts and the lower 90s in the vlys. The csts and cstl vlys of SBA county will be flirting with heat advisory numbers.
Tuesday looks like the warmest day as hgts rise to 588 dam. This will not be anywhere near as hot as last weak as the hgts are lower and there is onshore flow to the east. Look for max temps to rise 1 to 3 degrees which will bring some 90 or 91 degree readings to interior cstl sections. These numbers are close to advisory levels with just a degree or two of additional warming needed for advisories.
(Wed-Sat), 22/309 AM.
Wednesday and Thursday will be very warm days, but will not be record breaking like last week's. The upper high will not be overhead and hgts will be a few dam lower. Additionally while there will be offshore flow from the north there will be onshore flow to the east. Highs will continue in the 80s and 90s or 15 to 20 degrees above normal. There may be a need for heat advisories in some of the vlys but no warnings are anticipated.
The ridge weakens some on Friday/Saturday and the onshore push to the east increases. There is a decent chc that the marine layer clouds will reform as as well. This will likely bring 3 to 5 degrees of cooling to the csts and 1 to 3 degrees in the vlys. Even with this cooling max temps will be 12 to 18 degrees higher than normal.
There is growing confidence that the rest of the month will be dry. The AI-mdls (esp the EC-AI)still show some chc of rain at the beginning of April.
***OF NOTE***
This has be a phenomenally warm month. Using the forecasted high temperatures for DTLA for today to the 31st along with the max temps that have already occurred DTLA average max temp for the month would be 83.9 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
22/1015z.
At 0837Z at KLAX, the marine layer was 1200 feet deep. The top of the inversion was at 1700 feet with a temperature of 24 C.
Good confidence in TAFs for vly and inland TAFs as well as KSBP and KSMX.
Moderate confidence in remaining TAFs. Cig hgts could be off by as much as 300 ft. Clearing times could be off by 2 hours.
KLAX, Moderate confidence in TAF. There is a 30 percent chc of OVC010 cigs by 1330Z. Clearing may not occur until 19Z (25 percent chc) or 20Z (10 percent chc). Low clouds may arrive as early as 03Z this evening. No significant easterly wind component is expected.
KBUR, High confidence in VFR TAF.
22/857 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Thursday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. For Wednesday, there is a moderate chance of GALES. Likely to be focused during the afternoon thru overnight timeframe, and across western portions. Large seas of 10-14 feet are possible late Wednesday through early Friday.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Conditions will remain below SCA levels through Sunday morning. For Sunday through Thursday, there is a 50-70% chance of SCA level winds 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 today through Thursday, focused during the afternoon and evening hours.
Dense fog is possible this week, focused in the late evening to early afternoon hours each day. Through at least Monday morning it appears to be mostly focused inside the southern California bight. Visibilities of one nautical mile or less can be expected.
Ca, NONE. PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Tuesday for zones 670-673-676. (See LAXMWWLOX).
