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.
20/0822z.
At 07Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was 1500 feet with a temperature of 15 C.
High confidence in CAVU conditions for KPRB, KBUR, KVNY, KPMD and KWJF. For KSBP and KSBA, there is a 30% chance of IFR/MVFR cigs from 10Z-16Z. For all other sites coast and valley sites, cigs may bounce between categories due to high clouds with a 20% chance of mainly VFR conditions through the period.
KLAX, Moderate confidence in TAF. There is a 20% chance of mainly VFR conditions through the period, if cigs do form they may scatter and reform. No significant easterly wind component is expected.
KBUR, High confidence in TAF.
20/123 AM.
A storm system will move over the coastal waters this afternoon through Wednesday morning, bringing a chance of showers to much of the area. Cannot rule out a thunderstorm or two across the northern waters Tuesday morning.
SCA level southerly winds are expected to increase ahead of the cold front, and while SCA level winds are not forecast, there is a 20-30% chance that SCA gusts could occur at times this afternoon and evening, and possibly again Tuesday afternoon. Tuesday evening winds will shift to the northwest behind the front, increasing to SCA level NW winds Wednesday afternoon. These winds will likely expand to include the majority of waters by Thursday afternoon. Wednesday night there is a 40% chance of Gale Force gusts over the southern waters, including portions of the nearshore waters inside the SoCal Bight, especially the Santa Barbara Channel. SCA winds may persist into the weekend at least for some waters.
Ca, NONE. PZ, NONE.
