Marine Weather and Tide Forecast for Signal Hill, CA

.SHORT TERM (TDY-THU)...12/225 PM.

High confidence that a relatively strong trough for this time of year will continue to drop into California through Tuesday before departing, leading to remnant weak troughing and northwest flow aloft.

The main impacts of this system will be the wind with advisory level onshore to northwest winds continuing for southern Santa Barbara County and coastal Ventura County as well as the Antelope Valley into this evening where Wind Advisories are in effect.
There is a 20 percent chance that advisory level winds may continue overnight for interior mountains and deserts prone to northwest winds.

Northwest flow across the region will likely spin up an eddy with low clouds and drizzle down south again tonight into Tuesday morning. However, the northward extent is in question, so we have the highest confidence in low clouds with drizzle at times for much of Los Angeles County, we have lower confidence for Ventura County.

Rising 500 mb heights will support a warm up Wednesday into Thursday (highs generally 68-82 by Thursday, coolest near the coast), focused inland of a shallower marine layer where clouds may seasonally slow to clear each day. Weaker but still present Sundowner and inland onshore winds will peak each afternoon to evening, but should mostly be below advisory levels.

.LONG TERM (FRI-MON)...12/225 PM.

Below normal confidence for Friday through early next week with near equal odds of a repeat pattern like we are expected to experience through Tuesday or weaker northwest flow aloft more akin to what Wednesday/Thursday time frame look like with similar impacts possible. The repeat performance would be windier, colder, with drizzle or light showers, while the latter would be somewhat warmer, drier, with less wind. Either way significant impacts seem unlikely during this timeframe.

AVIATION
12/1637Z.

At 16Z over KLAX, the marine layer was 2400 ft deep. The top of the inversion was 4300 feet with a temperature of 14 Celsius.

There is a 10% chance of a light shower at KPRB KSBP 18-22Z today.
Otherwise, High confidence in VFR at KPRB, KSBA, KPMD, KWJF through Tuesday. High confidence that any airport currently with MVFR ceilings will clear by 20Z. High confidence that any ceilings that form tonight into Tuesday will be MVFR or VFR. Low confidence on ceiling coverage or timing however, and will likely be stratocu with patches of clearing instead of a solid blanket of clouds.

High confidence in stronger than usual onshore winds 21-04Z today, with gusts over 25 knots likely at all coastal and desert airports. Brief LLWS possible 18-20Z as the winds start shifting and increasing.

KLAX....High confidence in VFR conditions by 20Z. Low confidence on timing of ceiling return tonight, but high confidence in MVFR or VFR ceilings. Current southeast winds are honestly surprising at how strong and prevalent they are. Best estimate is for the winds to flip to onshore 1730-1830Z. West gusts 25-30 knots likely 21-03Z today. Another round of E-SE winds are likely tomorrow 13-17Z, with a moderate risk of 10+ knots.

KBUR...High confidence in VFR conditions by 20Z. Low confidence on timing of ceiling return tonight, but high confidence in MVFR or VFR ceilings.

MARINE
12/221 PM.

Winds are slower than expected in developing, but still expected to ramp up through this afternoon. Steep seas with widespread winds of 25 to 35 knots will be building through Tuesday, with generally hazardous conditions for most vessels each afternoon and evening. Current Small Craft Advisories and Gale Warnings look good. While some areas will see some lulls, steep seas will affect much of the area.

Moderate confidence in forecast for the next 3 days...winds plus or minus 5 knots and seas plus or minus 3 feet.

Gale Watch remains for waters south of Point Sal for Tuesday, including the Santa Barbara Channel (west and east portions). 60% chance of a lower-end Gale Warning needed. Decided to keep it a watch as the winds are slow to develop today which adds some uncertainty to tomorrow.

High confidence in improving winds and seas (heights remain elevated but periods lengthen) Wednesday through Friday.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory now in effect until 9 AM PDT Tuesday for zones 349-351-352. (See LAXNPWLOX).
Wind Advisory in effect until 9 PM PDT this evening for zones 350-354. (See LAXNPWLOX).
Wind Advisory remains in effect until 9 PM PDT this evening for zones 381>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 645-655-670. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 PM PDT this afternoon for zone 650. (See LAXMWWLOX).
Gale Warning in effect until 3 AM PDT Tuesday for zone 650. (See LAXMWWLOX).
Gale Watch in effect from Tuesday afternoon through Tuesday evening for zones 650-673-676. (See LAXMWWLOX).
Small Craft Advisory in effect until 2 PM PDT Tuesday for zones 673-676. (See LAXMWWLOX).