Marine Weather and Tide Forecast for Vandenberg AFB, CA

.SHORT TERM (TDY-SUN)...08/1212 PM.

Temperatures continue to trend down today as onshore flow returns.
The cooling will continue through the weekend an upper low moves into California. All heat hazards will be discontinued this evening as highs Saturday are expected to be at least 5-10 degrees cooler.

The main forecast issue moving forward is the uncertainty with the the track of Rachel and the potential impacts. Swells have already started to arrive on our southern beaches and impacts will increase through Sunday. The last few tracks of Rachel have trended farther south but most of the ensemble solutions indicate at least some tropical showers south of Pt Conception by Sunday, and around 10% of the solutions show over an inch of rain. The more likely outcome is amounts between a tenth and a quarter inch, though locally higher in the mountains. Temperatures will be mostly in the 70s, but a significant increase in humidity is expected with the arrival of Rachel moisture so it will likely feet quite a bit warmer. Also, can't rule out a thunderstorm or two though models are indicating those will remain farther east and south.

Later Sunday into Monday an upper low will move south into southern California and possibly interact with lingering tropical moisture to generate additional shower into Monday.

.LONG TERM (MON-THU)...08/1213 PM.

On Monday the upper low will move into the vcnty of SBA county with 557 dam hgts. The low will bring clouds and chc of rain to the entire 4 county forecast area from midnight to midnight. Since most of the moisture will be to the east of the area rainfall totals will not be that great most areas can expect to recieve a tenth to a quarter inch of rainfall. Max temps will fall further to the mid 60s to lower 70s.

There is some disagreement on how fast the upper low will move out of the area. Enough solutions keep the upper low around long enough to keep a 20 to 30 percent chc of rain in the forecast.
Even if it does rain there will not be much additional rainfall.

Aside from a small chc of a mtn shower Wednesday should be dry as drier NW flow moves into and over the state. Sunnier skies and rising temps will bring 3 to 6 degrees of warming. Even with the warming max temps will end up about 6 degrees blo normal.

AVIATION
08/1751Z.

At around 17Z at KLAX, the marine layer was 500 feet deep. The top of the inversion was 1700 feet with a temperature of 28 C.

High confidence in VFR conditions at KPRB, KVNY, KBUR, KPMD, and KWJF, with a 10% chance of brief LIFR conds 13Z-17Z at KPRB/KVNY/KBUR.

Moderate confidence in remaining TAFs with slightly higher CIGs compared to last night. Min cig height may be off +/- 300 feet and arrival may be off 2 hours. There is a 20% chance KSMX/KSBP remain above VLIFR conds tonight. 10% chance for 1/4SM FG at KOXR/KCMA.

KLAX...Moderate confidence in TAF. Gusty onshore winds will be common this afternoon/evening. CIG heights may be off +/- 300 feet and cigs may arrive as early as 06Z. No significant easterly wind component is expected.

KBUR...High confidence in VFR TAF with a 10% chance for LIFR conds 13Z-17Z.

MARINE
08/852 AM.

Relatively quiet conditions are expected across the coastal waters through much of Saturday. Localized Small Craft Advisory (SCA) gusts may occur each afternoon and evening between Point Conception and San Nicolas Island. Night through morning dense fog may affect portions of the coastal waters adjacent to the Central Coast and south to San Nicolas Island.

Northwest to southwest winds will increase to at least 20-30 knots by Saturday afternoon/evening, becoming much more expansive all of Sunday and into Monday morning. There is a 40-50% chance of Gale Force winds on Sunday, primarily focused across the nearshore waters adjacent to Los Angeles and Orange Counties.
Large, steep, and choppy seas will develop Saturday, continuing through at least Monday. This fairly rapid and significant change in the winds is due to a very complex situation as an unseasonably cold trough drops down the California Coast, interacting with remnants of Tropical Storm Rachel, which will soon turn northeast and move towards the California/Mexico Border coastline over the next couple of days.

In addition the the increasing gusty winds, widespread light to moderate rainfall is likely late Saturday-Tuesday, with highest confidence for Sunday-Monday. There is a 10% chance of thunderstorms during the same timeframe. While rain/thunderstorms are possible anywhere, highest chances exist south of Point Conception.

As this is a complex and evolving situation, please continue to monitor the forecast.

BEACHES
08/941 AM.

The Coastal Flood Advisories continue into Tuesday afternoon.
Southerly swells, including from Tropical Storm Rachel, will continue to impact the LA/VTA coastline. 160-190 degrees at 12 seconds will pose the most risk from Malibu to Ventura through Friday. The Long Beach area is also at a relatively higher risk due to vulnerabilities from previous coastal events. The morning and evening high tides will remain similar in height at 6.5-7.0 ft through tonight, with a 0.3 ft reduction in the evening tides on Friday.

Meanwhile, Tropical Storm Rachel is expected to turn northeast, likely making landfall on Saturday night through Sunday somewhere in northern Baja California or in the vicinity of the Mexico- United States border (potentially as a post-tropical system).

As for impacts, deviations in the final track could influence the magnitude of impacts for the area. If Rachel takes a more northerly track, the combination of the increased wind wave and lower SFC pressure would result in higher tides, which are already expected to increase to 7.0 to 7.5 feet (1 to 1.5 feet higher than astronomical tides) over the weekend.

As of now, the most reasonable outcome for LA/Ventura and Catalina Island is flooding of sea-water over beach roads and paths, as well as significant beach erosion, with isolated damage possible. The time window for most concern is Sunday, especially during the morning high tide.

For the Central Coast, high surf advisories will likely be needed Saturday through Monday. In addition, there is a moderate risk for some beach erosion and isolated, minor coastal flooding.

Coastal flooding concerns will continue into early next week Refer to CFWLOX for more details and please continue to monitor the forecast for the latest information.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Extreme Heat Warning in effect until 8 PM PDT this evening for zones 38-87-88-349>358-362-366>375-548-550. (See LAXNPWLOX).
Coastal Flood Advisory in effect until 2 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX).
Heat Advisory in effect until 8 PM PDT this evening for zones 340>348. (See LAXNPWLOX).
PZ...NONE.