20/307 AM.
Light to moderate rain is expected late today through Tuesday, will the highest rain amounts expected for San Luis Obispo County and minimal impacts overall. Temperatures will be mild today, followed by much cooler weather Tuesday and Wednesday. Gusty southwest winds are expected through Tuesday, followed by west to northwest winds Wednesday through Friday.
(tdy-Wed), 20/303 AM.
Forecast-wise the primary focus remains on the cutoff low, forecast to bring some wet and unsettled weather to the area. Latest model data indicates nothing to really deviate from current forecast. Rain will begin across SLO county late this afternoon/evening, then will spread south and east tonight and Tuesday. By Tuesday evening, the rain will be tapering off, with dry conditions expected on Wednesday. Rainfall totals still look to be most impressive across SLO and SBA counties with widespread 0.50" to 1.00" totals and local amounts up to around 1.50" across some foothill areas. For Ventura and LA counties, the rain will lose some "oomph" with widespread totals of 0.33" or less with local amounts up to around 0.75 across the Ventura county mountains. Along with rain, there will be some increasing instability moving into northern areas on Tuesday. So, there will continue to be 15-20% chance of thunderstorms Tuesday, mainly across SLO county. Rainfall rates with this system are expected to be around 0.25" or less per hour. However, with any thunderstorm development, rates up to around 0.50" per hour will be possible. So, given the rainfall rates, no significant hydrologic issues are expected. Based on current snow level forecasts, no significant snowfall accumulation is anticipated in the local mountains.
As for winds, gusty southwesterly winds are expected today and Tuesday across interior sections and could flirt with advisory levels Tuesday afternoon/evening across the LA Mountains and Antelope Valley. On Wednesday, the winds will shift to a more west to northwest direction with advisory-level winds possible through the I-5 Corridor as well as the western half of the Santa Ynez Range.
As for temperatures, a noticeable cooling trend can be expected today and especially on Tuesday, with highs Tuesday about 4-8 degrees below normal for most areas. On Wednesday, temperatures will begin to rebound a few degrees, climbing to around normal levels.
(Thu-Sun), 20/328 AM.
Near normal to slightly below normal temperatures are expected for Thursday and 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. Starting on Saturday, another low pressure system may impact the region, and rain will be possible again over the weekend. At this point, rain totals, if any, are likely to be light across the area (<0.5 inches). Current model projections of the low pressure system show southwest flow, which would lead to orographic enhancement in rain totals across south- facing foothill slopes.
20/1724z.
At 1630Z at KLAX, the marine layer was 1500 feet deep. The top of the inversion was 2000 feet with a temperature of 14 degrees Celsius.
For 18Z TAF package, moderate to high confidence in current forecast. Through 05Z, high confidence in VFR conditions for all sites. After 05Z, a front will begin to move into the area, bringing CIG/VSBY restrictions as well as rain. 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 and KSBP.
KLAX, Overall, moderate confidence in 18Z 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. No significant easterly wind component is expected.
KBUR, Overall, moderate confidence in 18Z 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.
20/717 AM.
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. Additionally, there is a 20-30% chance of GALE force winds south of Point Conception.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Tuesday, there is a 20-30% 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.
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.
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, NONE. PZ, NONE.
