22/753 PM.
Warmer than normal conditions are expected to persist through the week, peaking on Tuesday. Low clouds and dense fog will continue to impact some coastal areas each night and morning. Also, there will be some gusty northerly winds across the mountains through the week.
(Sun-Wed), 22/815 PM.
***UPDATE***
After a relatively cool weekend, a broad ridge of high pressure will build over the region, becoming over SW California early Tuesday morning. The ridge will then shift further east to the Four Corners area on Wednesday, with a weak closed low approaching the So Cal Bight.
Significant warming is expected to occur on Monday for the coast and coastal valleys, especially along the Central Coast where a Heat Advisory is in effect from Monday morning through Tuesday evening. Highs along the Central Coast and adjacent valleys (and down to the Santa Barbara South Coast) will be between 15 to 25 degrees warmer than today (Sunday). For LA and Ventura Counties west of the mountains will see warming between around 5 to 15 degrees. East of the mountains, little change to slight cooling is expected. This pattern will persist into Tuesday, with a bit of cooling on Wednesday as the high shifts east.
Gusty northerly winds are also expected Monday and Monday night, mainly affecting the I-5 Corridor and the western Antelope Valley Foothills with gusts 45 to 55 mph. Gusty west to north winds are then expected at times through Thursday.
Marine layer clouds and fog are expected for near-coastal areas from the Santa Barbara South Coast and southward, with a good chance of patchy dense fog during the night to morning hours.
***From Previous Discussion***
Forecast-wise for the short term, two main issues are temperatures and wind. With respect to temperatures, the building upper level ridge will bring a warming trend to the area through Tuesday. By Tuesday, high temperatures will peak in the mid 80s to mid 90s with warm overnight lows. Looking at the Heat Risk, widespread MODERATE HEAT RISK is likely across the Central Coast Monday and Tuesday, but remain more localized south of Point Conception. So, will issue HEAT ADVISORIES for the Central Coast Monday and Tuesday with the afternoon forecast. Future shifts will need to monitor the potential for additional advisories across the valleys of Ventura/LA counties on Tuesday.
(Thu-Sun), 22/156 PM.
For the extended, 12Z models continue to exhibit decent synoptic agreement. The upper level will weaken and shift eastward through the period, keeping the area in a southwesterly flow aloft as a trough lingers over the Eastern Pacific. At the surface, weak to moderate onshore flow will continue to the east with some weak northerly offshore flow.
Forecast-wise for the extended, no significant issues are expected. Temperatures will fluctuate up and down a couple degrees through Saturday, but temperatures will remain 10 to 18 degrees above normal for most areas. By Sunday, widespread slight cooling is expected, but temperatures will still remain at least 6-12 degrees above normal. Looking at the Heat Risk, do not anticipate any need for heat products during the extended period.
As for clouds and weather, skies will generally remain mostly clear to partly cloudy, depending on the amount of high clouds drifting overhead. with more widespread cooling on Sunday. Marine layer stratus/fog will remain an issue for coastal areas south of Point Conception through Friday. By Saturday and Sunday, anticipate that the marine layer will expand in coverage, affecting most coastal and coastal valley areas.
As for rain, things look dry through the end of the month. However for the first week of April, models remain consistent, indicating the return of some rain. At this time, ECMWF ensembles indicate a 40-60% chance of rain totals greater than 0.50 inches the first week of April while the GFS ensembles indicate a 20-40% chance of 0.50 inch totals or greater. The chances for totals greater than one inch are less than 20% on all models.
***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
23/0150z.
At 0108Z at KLAX, the marine layer was 1100 feet deep. The top of the inversion was at 2100 feet with a temperature of 23 C.
Moderate confidence for coastal TAFs SBA and south including KLAX, LIFR or lower cigs/vsbys are expected to return tonight between 00Z-12Z.
Low confidence for KBUR, KVNY, and KSMX with a 30-50 percent chance of at least brief IFR or lower cigs vsbys 08Z-16Z Mon.
KLAX, Moderate confidence in forceast with a 40% chance of 1/4-2SM vsby possible from 02-017Z Mon. No significant easterly wind component is expected.
KBUR, Low confidence in TAF between 12-17Z with nearly equal chances of IFR or lower or VFR conds.
22/116 PM.
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. For today 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, Heat Advisory in effect from 10 AM Monday to 8 PM PDT Tuesday for zones 340>342-346>348. (See LAXNPWLOX). Wind Advisory in effect from 3 AM Monday to 3 AM PDT Tuesday for zones 378-381. (See LAXNPWLOX). 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).
