Marine Weather and Tide Forecast for Pasadena, CA

.SHORT TERM (TDY-FRI)...23/440 AM.

The latest fog product imagery shows low clouds and fog extending into the coastal slopes of the mountains across the Southland and into the interior valleys of San Luis Obispo County. Earlier AMDAR soundings from KLAX around 07Z indicated a marine layer depth near 2100 feet deep, but that was several hours ago, and the marine layer has deepened substantially since. From looks of the satellite imagery combined with NAM BUFR time height sections, the marine layer depth is close to 3500 feet deep currently. If NAM BUFR time height sections play out as advertised, the marine layer depth should top out around 4000 feet deep later this morning.
With the marine layer depth deepening substantially, drizzle is possible as weak dynamics with a shortwave trough move over the region and interact with the deep marine layer cloud deck this morning. Some rain gauges in southern Santa Barbara County are starting to pick up a few tips due to heavy drizzle.

A deep marine layer depth is likely to continue to remain in place over the coming days as broad troughing remains anchored along the California coast and strong onshore flow will remain intact. A cooler pattern will linger into late week with temperatures below seasonal normals. Weak dynamics aloft will continue to scrape the area and bring the possibility of night through morning drizzle.

Across the interior portions of the area, stronger onshore flow will bring much breezier to windier conditions during the afternoons and evenings. A wind advisory was added for the western Antelope Valley foothills for this afternoon and this evening where gusts up to 45 mph are possible. Isolated gusts to 55 mph cannot be ruled out near Lake Palmdale. With similar onshore pressure gradients developing over the coming days, additional wind advisory headlines may be needed.

By Friday, an elongating trough in the Gulf of Alaska will enter the region while splitting off from the flow aloft. This cutoff trough will likely deepen the marine layer depth between Friday and Saturday to turn it into a deep moist layer up to around 7000 to 8000 feet deep on Friday night. This will be plenty deep enough to produce night through morning drizzle or light rain across the region. Mountain showers seems to be a high probability given the pattern and favorable flow pattern.

.LONG TERM (SAT-TUE)...23/441 AM.

The cutoff trough will approach the California coastline on Saturday morning as the marine layer mixes out into a deep moist layer. The forecast ensemble members introduce a majority of the perturbations with light rain across the area. EPS members are the wettest relative to the GEFS and CMC ensemble members. Almost all of the EPS ensemble members have precipitation across the region with amounts lessening as one heads south. EPS QPF means suggest a quarter inch or less, with a high chance of values between 0.25 and 0.50 inch for San Luis Obispo County. Meanwhile, GEFS and CMC keep the forecast more inline with night through morning drizzle. Given the cutoff trough, the current forecast generally keeps NBM values for PoPs, while skewing PoPs higher along the coastal slopes of the mountains.

Temperatures will be much cooler than normal on Saturday with most areas being 5-12 degrees below normal. Temperatures in the mid 50s to mid 60s will be common across the coastal and valley areas.
Experimental data analysis on the NBM forecast suggests KLAX and KOXR potentially seeing record low maximum temperatures on Saturday. Local records versus the forecast indicate otherwise, but near record low maximum temperatures will be possible on Saturday.

A warming trend for much of next week is expected as cluster analysis still favors an upper-level ridge of high pressure building into the West Coast. Anomalously high heights seem more plausible across the Pacific Northwest, but the pattern will still likely create above normal temperatures with less marine layer low cloud coverage.

AVIATION
23/0103Z.

At 2315Z at KLAX, the marine layer was 1400 feet deep. The top of the inversion was 2500 feet with a temperature of 11 C.

High confidence in TAFs for KPMD and KWJF.

Moderate in remaining TAFs. Timing of flight cat changes may be off +/- 2 hours. There is a 30% chance for LIFR conds at KSMX tonight, and a 20% chance at KBUR/KVNY. There is a 20% chance of IFR conds at KSMO/KLAX/KLGB.

KLAX...Moderate confidence in TAF. There is a 25 percent chc of a 19Z VFR transition. There is a 20 percent chc of OVC008 conds 11Z-15Z. No significant east wind component expected.
KBUR...Moderate confidence in TAF. Cigs may arrive as early as 07Z. There is a 20 percent chc of OVC004 conds 11Z-15Z.

MARINE
22/920 PM.

For the Outer Waters, moderate to high confidence in current forecast. Through tonight, there is a 40-50% chance of Small Craft Advisory (SCA) level wind gusts across the northwestern portion PZZ670, mostly over far western portions. Therefore, holding off on issuing a SCA due to the localized nature of the winds. Conditions will remain below SCA levels across PZZ673/676 through tonight. For Wednesday through the weekend, northwest winds will increase with a 50-60% chance for SCA winds Wednesday afternoon and evening, and a 60-80% chance of SCA level winds Thursday afternoon through the weekend across all the Outer Waters.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Through tonight, high confidence in winds and seas remaining below SCA levels. For Wednesday, there is a 30-40% chance of SCA level winds in the afternoon and evening hours. For Thursday through the weekend, there is a 50-70% chance of SCA level winds, mainly in the afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Tonight through Wednesday morning, high confidence in winds and seas remaining below SCA levels.
There is a 30-40% chance for localized gusts to SCA levels over western portions Wednesday night. For Thursday and Friday, there is a 40-60% chance of SCA level winds across the western half of the Santa Barbara Channel. For Saturday and Sunday, there is a 60-80% chance of SCA level winds across western sections of the entire southern Inner Waters.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory in effect from noon today to 9 PM PDT this evening for zone 381. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Thursday for zone 670. (See LAXMWWLOX).