20/717 PM.
Light to moderate rain is expected late today through Tuesday, although locally heavier rain is possible over the northern area. The highest rain amounts are expected for San Luis Obispo County, however with minimal impacts. Much cooler weather is on tap for Tuesday and Wednesday. Gusty southwest winds are expected through Tuesday, followed by west to northwest winds Wednesday through Friday.
(Mon-Thu), 20/818 PM.
***UPDATE***
A moderate late season storm will move across Southwest California tonight through Tuesday. Most of the rain will occur late this evening through Tuesday evening, however some light showers may linger over the northern mountain slopes Tuesday night into early Wednesday. The highest rain amounts will cover San Luis Obispo and Santa Barbara Counties, as the front will weaken as it moves over Ventura County and especially Los Angeles County. There will be a slight chance of thunderstorms from 400 AM Tuesday through the afternoon hours over San Luis Obispo County. While there is a chance of locally heavier rain at times across much of the area, this will be enhanced over SLO county due to the convective chances.
Rainfall totals will range from one quarter of an inch to around an inch for San Louis Obispo (except for 1.5-2 inches for the coastal hills) and Santa Barbara Counties, to 0.5 inch in the Ventura Mountains, to one third of an inch or less elsewhere. Brief heavy downpours, gusty winds up to 40 mph, and cloud-to- ground lightning are the most likely hazards with any thunderstorms. Peak rainfall rates will be around a quarter of an inch per hour or less, although rates up to 0.5 inches per hour many occur in any thunderstorms or along the frontal boundary. Minor flooding is possible if these rates occur, especially in low lying urban areas or near recent burn scars.
As for winds, gusty south to southwest winds are expected ahead of and near the front, generally 20 to 40 mph. Stronger SW winds will affect the Antelope Valley and San Gabriel Mountains from around 10 AM Tuesday through Tuesday evening. After this time, winds will shift to the west to northwest and remain gusty into Thursday. These winds will be strongest over the mountains and interior, but may affect some coastal sections at times.
(Fri-Mon), 20/1222 PM.
Near normal temperatures are expected Friday when most highs will be in the low to mid 70s. Then temperatures will fall to several degrees below normal over the weekend, with highs in the 60s common. There is a 30-50 percent chance of mainly light rain focused across the foothills to interior sometime this weekend thanks to moist upslope flow over the mountains and limited instability. The storm energy is coming from the southwest to west and is weak so significant wind concerns are unlikely, but it does lend itself to below normal forecast confidence.
An active pattern (for April) may continue into early next week as another weak storm is possible.
21/0144z.
At 2209Z at KLAX, the marine layer was 1300 feet deep. The top of the inversion was 3100 feet with a temperature of 14 degrees Celsius.
For 00Z TAF package, moderate to high confidence in current forecast. High confidence in VFR conditions for all sites through 05Z, then moderate to low confidence from north to the south as the the front approaches. Timing of rain and flight category changes tonight and Tuesday morning could be +/- 3 hours of current forecasts. There will be a 10-15% chance of thunderstorms Tuesday morning at KPRB, KSBP, and KSMX.
KLAX, Overall, moderate confidence in 00Z TAF. High confidence in CAVU conditions through this evening. Overnight, high confidence in return of CIG/VSBY restrictions, but timing of flight category changes could be +/- 3 hours of current forecasts. Timing of light rain could also be +/- 3 hours of current forecast. There is a 30% chance for an easterly wind component of around 5-6 kt from 13Z to 18Z.
KBUR, Overall, moderate confidence in 00Z TAF. High confidence in CAVU conditions through this evening. Overnight, high confidence in return of CIG/VSBY restrictions, but timing of flight category changes could be +/- 3 hours of current forecasts.
20/1203 PM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Tuesday, there is a 20-30% chance of Small Craft Advisory (SCA) level southerly winds. For Wednesday through Friday, high confidence in combination of SCA level northwesterly winds and seas with a 20-30% chance of GALE force winds south of Point Conception Wednesday night. For Saturday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Tuesday, there is a 20% chance of SCA level southerly winds. For Wednesday through Friday, there is a 60-80% chance of SCA level northwesterly winds, mainly in the afternoon and evening hours. On Saturday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through Tuesday, high confidence in winds and seas remaining below SCA levels. On Wednesday, high confidence in SCA level northwesterly across all the southern Inner Waters with a 20% chance of GALE force winds. For Thursday through Friday, winds and seas are expected to remain below SCA levels for most areas. The only exception will be the western half of the Santa Barbara Channel with a 60-80% chance of SCA level winds. On Saturday, high confidence in winds and seas remaining below SCA levels for all of the southern Inner Waters.
A cold front will sweep across the coastal waters tonight and Tuesday. With this frontal passage, there will be a 20% chance of thunderstorms across the coastal waters north of Point Conception. Any thunderstorms that develop may produce brief heavy rain, gusty winds and locally rough seas.
Ca, Wind Advisory in effect from 10 AM to 10 PM PDT Tuesday for zones 378>383. (See LAXNPWLOX). PZ, NONE.
