22/156 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.
(tdy-Wed), 22/156 PM.
Overall, 12Z models in good synoptic agreement through the short term period. At upper levels, high pressure will build over the area through Tuesday then weaken on Wednesday as weak low moves across the area. Near the surface, onshore flow will prevail to the east with some northerly offshore flow across the mountains.
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. By Wednesday with the upper level high weakening, all areas will cool a few degrees and no heat products will be expected on Wednesday.
As for winds, the northerly gradients will generate some gusty winds across the Interstate 5 Corridor and the Antelope Valley foothills tonight through Monday night. In these areas, gusts of 45-55 MPH will be likely. Therefore, will issue WIND ADVISORIES for the Interstate 5 Corridor tonight through Monday night. Elsewhere, no significant wind issues are anticipated.
Otherwise, there will continue to be a marine layer stratus/fog presence south of Point Conception today through Wednesday with the potential for some dense fog. Otherwise, skies should remain mostly clear through Wednesday.
(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
22/1729z.
At 16Z at KLAX, the marine layer was 1300 feet deep. The top of the inversion was at 3400 feet with a temperature of 22 C.
Moderate confidence for coastal TAFs SBA and south including KLAX. There is a 10-20 percent chance for brief to no clearing today near the the coast. 80-90 percent chance of LIFR or lower cigs/vsbys returning 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.
KLAX, 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).
