09/1148 PM.
A cooling trend will continue through the weekend. A couple storms will move through the area today through Monday with showers and thunderstorms possible. Dry and warmer weather expected the rest of next week.
(tdy-Sun), 10/1233 AM.
An upper high to the NW of the Bay Area will push up to the NE during the day today. It will bring a front through the state as it does. Since the upper low will be so far to the north of Srn CA it will not have much of a punch and will mostly affect areas north of Pt Conception. Showers should arrive in the morning across the Central Coast. In the afternoon showers will likely continue across SLO county where there will be just enough instability to bring a slight chc of a TSTM. Elsewhere there will be a 50 percent chc of showers across SBA county and just a 20 percent chc over VTA county. Rainfall amounts, if any, will be a tenth of an inch or less for most areas except for far NW SLO county and a few areas in the SLO/SBA mtns. Onshore flow, partly to mostly cloudy skies and falling hgts will all gang up and lower max temps by 2 to 4 degrees across the csts, 3 to 7 in the vlys and 8 to 10 degrees for the mtns and far interior. Today's max temps will mostly be 4 to 6 degrees blo normal.
There will be a 30 to 40 percent chc of rain this evening across most of the area as the front washes out over the area. Rainfall totals overngiht will not amount to more than a tenth of an inch except for the NW tip of SLO county where an additional quarter inch of rain could fall.
Most of the area will be in between storms during the day Saturday. A more vigorous cold front will approach the Central Coast later in the afternoon. Rain will likely develop across SLO county by evening with a chc of rain reaching as far south as Pt Conception. Again rainfall totals for the rainy areas will be under a tenth with the standard exception of the NW tip of SLO county where a quarter inch could fall. Max temps will cool another 2 to 4 degrees and most cst/vly max temps will end up in the mid 60s to lower 70s.
A cold (esp for April) 537 dam low will sweep into the Bay Area Saturday night and will drive a vigorous cold front through Srn CA. Rain is a near certainty for the area overnight. This system will bring dynamics and instability with it and there is a chc of TSTMs across the area but with the best chc focused north of Pt Conception where the best instability will occur. There will be just enough twist within the atmosphere to also bring a small threat of a waterspout or small tornado. Overnight rain totals will likely range from a half inch to an inch with greater amounts across the coastal slopes and any area affected by TSTMs. Peak rain rates expected to range from 0.25-0.50" per hour with isolated stronger storms as high as 0.75" per hour. Snow levels will be between 6000 and 7000 ft and several inches of snow is possible above 7000 ft.
Showery activity will persist through Sunday and even into the evening and overnight hours as the front finishes moving through the area and several post frontal impulses move across the area. Another quarter to half inch of rain is possible but rainfall totals will likely be less homogeneous as the showers will be more random. It will feel more like January with max temps only in the mid 60s
Snow level levels will lower to around 5000 ft Sunday night and the top of the Tejon Pass may see some snow will less than an inch accumulations.
(Mon-Thu), 09/227 PM.
The upper low is expected to pass through southern California Monday morning, with scattered showers and snow levels dropping to around 4500-5000 feet. Chances for any snow accumulations on the Grapevine are less than 10% but there could be some flurries or mix of rain and snow on the summit Monday morning. There is a chance of showers across LA County through Monday afternoon if the low is a little slower leaving the area. Otherwise, drying conditions expected Monday night and dry and warmer weather the rest of the week.
10/1210z.
At 0818Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was at 2000 ft with a temperature of 17 C.
Overall, moderate confidence in TAF (Good confidence in TAFs for KPMD and KWJF) Package. There is a 30 percent chc that sites with only MVFR in the afternoon could have periods of VFR. Flight Cat transitions could be off by as much as 90 minutes. There is a 20 percent chc of -RA over KSBA, KOXR and KCMA this afternoon. There is a 20 to 30 percent chc of rain at all sites from 04Z-12Z tonight.
KLAX, Moderate confidence in TAF. There is a 30 percent chc of SCT conds 18Z-01Z. There is a 20 percent chc of rain aft 04Z. No significant east wind component expected.
KBUR, Moderate confidence in TAF. There is a 30 percent chc that cigs will be AOA 010.
10/332 AM.
A weak Cold Front will move across the coastal waters today into Saturday morning bringing showers and a slight chance for a thunderstorm north of Point Conception.
A second system will arrive later on Saturday into Sunday with a more traditional cold front. This stronger front will bring numerous showers and a slight chance for thunderstorms across all waters. Potential hazards include: heavy downpours, dangerous cloud to ocean lightning, small hail, and erratic gusty winds. Boaters, especially those with small vessels should avoid these conditions.
Ca, NONE. PZ, NONE.
