06/719 PM.
Temperatures will cool some again on Tuesday with increasing onshore flow and areas of low clouds and fog near the coast. Warmer temperatures will return briefly Wednesday before a sustained cooling trend takes us into the weekend, along with a chance of rain.
(Mon-Thu), 06/908 PM.
***UPDATE***
A weak upper low brought cooling to the area today, aided by onshore flow along the coast. Most of the cooldown occurred west of the mountains, most notably along the Central Coast with highs down 7 to 10 degrees from Sunday. Elsewhere from the valleys to the coast, highs dropped by around 3 to 5 degrees.
Gusty, moderate northerly winds are currently affecting southwest Santa Barbara County, where a Wind Advisory is in effect through 8 AM Tuesday. Gusts thus far have been peaking near 45 mph but are expected to increase later this evening to up to 50 mph. Pressure gradient tables indicate similar to slightly stronger winds in this area again tomorrow night, and at that time an Advisory may be needed for the I-5 Corridor as well. For tonight, winds in the I-5 Corridor do not look to be quite strong enough. Meanwhile, southwest to west winds are affecting the Antelope Valley with gusts generally up to 30 mph. These onshore winds are also expected to increase during the afternoon tomorrow, as the LAX to Daggett gradients increase from around +6.2 mb to near 7 mb.
Low cloud cover is expected tonight into early Tuesday along most of the coast except for the Santa Barbara South Coast. Fairly extensive low clouds are likely over the Central Coast, with a chance of moving into the Santa Ynez Valley. More uncertainty exists with respect to the Oxnard Plain and LA Basin, but expect coverage to be similar or slightly more expansive than what was observed last night.
High temperatures on Tuesday will be in the 70s for most areas, except for low 80s in some of the warmer valleys, and in the Antelope Valley.
***From Previous Discussion***
Onshore pressure gradient are increasing this morning and will further increase across the region this afternoon, when LAX- Daggett pressure gradient could reach +5 to +6 mb range. This will generate increasing onshore winds across the interior this afternoon/evening, and this trend will continue the next few days. Also expecting northwest pressure gradients to increase tonight and the next few nights, with Santa Barbara-Santa Maria expected to reach around -4 mb. A wind advisory has already been posted for later today into tonight for the western Santa Ynez mountains and southwest Santa Barbara coast, with gusts in the 35 to 50 mph range. Winds will be strongest tonight from Gaviota to San Marcos Pass. A wind advisory may need to be expanded to include the I-5 corridor and western Antelope Valley foothills as early as tonight, with increasing probability for Tuesday night. In addition, the sundowner winds are expected to shift eastward into the eastern Santa Ynez range by Tuesday night, which may require wind advisories for that region as well. North gradients will peak Wednesday, and with an increase in support aloft and subsequent downsloping south of the mountains, temperatures are expected to rise anywhere from 3 to 6 degrees, making Wednesday the warmest day of this week.
(Fri-Mon), 06/255 PM.
Light rain will be possible starting Thursday night, particularly for areas north of Point Conception. By Friday, the cold upper low will enter the region, bringing cooler temperatures, rain and thunderstorms chances. Due to the cold and unstable nature of the storm, thunderstorms will be possible. Most rain is likely to fall between Friday and Saturday, with lingering chances for showers and thunderstorms on Sunday. Rain totals with this storm are likely to be between 0.25 inch and 1.0 inch, but locally up to 2 inches will be possible across some mountains and areas impacted by thunderstorms. Ensemble means over the last couple days have been fairly consistent with regards to average rain amounts and timing. However there remains a lot of spread in the exact rain totals between ensemble members, which suggests uncertainty in rain totals and a showery rain pattern that would yield variable rain amounts across the region. By early next week, a gradual warming and drying trend is expected, however at this point there is no strong signal for another storm or heatwave.
07/0249z.
At 2205Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was at 3400 ft with a temperature of 17 C.
Overall, moderate confidence in 00Z TAF Package. Timing of CIG/VSBY restrictions may be off +/- 2 hours and flight minimums by one category. There is a 30-40% chance for LIFR CIGs at KBUR & KVNY after 10Z.
KLAX, Moderate confidence in TAF. Arrival and clearing times of CIGs may be off +/- 2 hours. CIGs likely to range from IFR to MVFR. Any east wind component that develops is expected to be less than 5 kt.
KBUR, Moderate confidence in TAF. LIFR CIGs possible (40% chance) after 10Z.
06/904 PM.
Current Small Craft Advisories (SCA) look on track. SCA winds will continue across all Outer Waters through Wednesday. There is a 40% chance that a GALE Warning will be needed for the outer waters south of Point Conception Tuesday evening through the overnight hours. Another chance for outer water gales comes Wednesday evening for about the same area.
The Inner Waters will reach SCA levels at times mainly during the afternoon and evening hours - lower chances along the Central Coast later in the week. There is a 30% chance of GALE force winds Wednesday night across the Santa Barbara Channel and near the Channel Islands.
Winds will diminish later in the week with moderate chances for SCA winds lingering south of Point Conception on Thursday and possibly into Friday.
A storm system is expected to impact the coastal waters starting Thursday night lasting into the weekend bringing rainfall and the potential for thunderstorms. Confidence is low on exact timing and details for now.
Ca, Wind Advisory in effect until 8 AM PDT Tuesday for zones 349-351. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Tuesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 650-670-673-676. (See LAXMWWLOX).
