SoCal Forecast
Updated most Sundays, Tuesdays, and Thursdays

Thursday December 3, 2020 6:00 AM
By Nathan Cool

Surf Charts for SoCal

Rincon | Ventura, C-St. | County Line | Malibu | Hermosa | Huntington Beach
Trestles | Old Mans | Oceanside | Beacons | Sunset Cliffs

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Today (Thursday) NW ground swell with exceptionally long periods is filling in today. This NW swell will peak Friday with notable size at many west facing breaks. A moderate NW teaser swell is due early next week. And then a significant NW ground swell is due Tuesday the 8th into Wednesday the 9th. Wind swell may trail that. The next NWer is being watched for the 14th. And something is showing up for potential on the 20th. Condition-wise: Santa Ana wanes over the weekend with another becoming likely early next week; the tide is still swinging wide; water temps remain fair; and advisories are in effect.

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Early this morning, periods were primarily running 13 seconds from 300°, but forerunners are coming in at 22 seconds from 295°.

Most west facing breaks were running chest high with occasional pluses at standouts early this morning; however, size should build later in the day, and rogue waves are highly likely as the day progresses. South facing breaks, relying on wrap, were mostly waist to chest early this morning.

Rip Current Advisory: The NW swell building today has elevated the risk of rip currents through Saturday, and then again early next week when a bigger swell is due. The NWS has issued rip current warnings and high surf advisories as well. Caution is advised.

Swell Forecast and Schedule
Buoys in the outer waters off SoCal were running 6-8'. Nearshore buoys were mostly 1.5-2.0'.

Tide levels are swinging wide from Monday's Full Moon but they will relax over the next couple days. Today we have a 3' low around 4:00 AM, a 5.7' high around 10:00 AM, a -0.3' low around 5:45 PM, and a 3.3' high after midnight.

Water temps were running 58-60° around much of OC and SD yesterday, although San Clemente reported warmer at 62°. In LA, most buoys were running 58-60°. In VC, Channel Islands Harbor reported 54° overnight. SB Harbor reported 58° last night.

Swell-wise: Today we're seeing initial swell from the Aleutian storm that peaked Sunday evening with seas reaching an incredible 52' (16 meters), as measured by NOAA's OPC below:

As you may recall from my earlier reports, that storm trekked through mid latitudes into the Gulf, so a good deal of swell has been sent our way. When this swell peaks Friday, most west facing breaks should see sets running 2-3' overhead with top spots seeing some DOH set waves at times. While Friday should see periods 18-20 seconds, we're seeing exceptionally long periods today coming through as rogue-wave forerunners. This will make today a precarious day to be in (or near) the water as rogue waves interrupt smaller sized sets with much bigger outsiders, scrambling the lineup farther out. Also, these rogue waves can rush far up on the sand, so keep an eye out for little ones playing by the water's edge.

This swell should linger to a lesser degree Saturday the 5th (head high with pluses at standouts), then drop off Sunday the 6th (chest high).

Next week has swell written all over it with an initial teaser swell Monday the 7th, and then something quite momentous Tuesday the 8th into Wednesday the 9th from this pair of storms shown on NOAA's OPC 72h model below:

The first, smaller system with 26' (8m) seas, should bring a swath of moderate NW ground swell Monday the 7th, enough to put most west facing breaks into chest to head high sets with swell angled from about 295-300°, and periods short in the 12-second range. On its heels though is something much, much bigger.

Tuesday the 8th into Wednesday the 9th should see swell from the second storm, which OPC's analysis says will house 52' (16m) seas, and at a fairly low latitude. If you remember from earlier reports this week, models had been spit on this, but all models have now aligned on this scenario; in fact, to get a visual on this, check out FNMOC's GFS WAM:

That monster fetch is impressive to say the least, and with models in agreement today it's safe enough to make a call with a fair amount of confidence. Running the numbers this morning, it looks like the peak impact would occur in the afternoon Tuesday the 8th into the very early AM hours Wednesday the 9th. The biggest waves may occur overnight. This means Tuesday the 8th would see swell build during the day with size changing drastically hour by hour, more so in the afternoon, starting out at head high in the early AM, and topping out at DOH overnight. DOH sets should still linger for the dawn patrols Wednesday morning. Max face heights are calculated at 14', but those would likely occur late evening Tuesday the 8th into pre-dawn Wednesday the 9th. Periods would initially run 22 seconds Tuesday the 8th and remain 18-20 seconds Wednesday the 9th. Swell should be angled from 290-295°.

Thursday the 10th could then see an injection of wind swell into the mix; in fact, there is even the possibility of seeing wind swell accompany this swell as two cut-off lows are being bandied about on the models, like this GFS model by NOAA MAG:

In this scenario — which many models are in some level of agreement — strong high pressure (blue) would be interrupted by two lows (red) pinching off from the jetstream (green). Depending on where these lows track would mean wind swell (trekking along the coast), or strong offshore winds (trekking inland). Being cut-off lows gives these systems minds of their own, not easy to forecast being outside the more predictable guidance of the jetstream. I'll need to see how this plays out over the next few days.

Monday the 14th looks like our next window of NW swell opportunity. Most models show some kind of activity near the Aleutians in about five days, and all of those scenarios keep things moderate. This is on the long range, 160h+ models, so it earned a yellow pin in the charts for now and I'll see how models deal with it over the next few days.

Last and certainly not least is potential for waves and/or rain around the 20th; that is, if one can trust the super extended, 300h+ models like this GFS by NOAA MAG:

Unlike our current pattern that smacks of La Niña, with high pressure dominating the Gulf of Alaska and the American West, this scenario would drop a monster low pressure system southwestward through California. Rain becomes likely from this pattern, but if the jet stays farther north, then SoCal would stay mostly dry with notable NW swell. Being that far out on the long range though doesn't warrant any more of my ramblings right now, so I'll leave it as a footnote and see how it goes.

Here's how the day-to-day is breaking down so far, and an ad to help pay the bills:

Friday the 4th should run 2-3' overhead at most west facing breaks with DOH pluses at standouts at times.

Saturday the 5th should run head high to a couple feet overhead at most west facing breaks.

Sunday the 6th is expected to run chest high at west facing breaks with occasional pluses.

Monday the 7th should run chest to head high at west facing breaks.

Tuesday the 8th should see strong NW ground swell build during the day, starting out at head high around dawn and then DOH after nightfall. Bigger overnight.

Wednesday the 9th is expected to see DOH sets at west facing breaks for the dawn patrols. Swell should drop late in the day to a couple feet overhead.

Thursday the 10th, so far, is expected to run head high at most west facing breaks.

Friday the 11th, so far, looks about head high at west facing breaks.

Saturday the 12th, so far, looks about chest max at west facing breaks.

Sunday the 13th, so far, looks about waist to chest at west facing breaks.

Monday the 14th, so far, looks about chest high at west facing breaks.

Weather Outlook
High pressure will remain over SoCal through the weekend to keep skies clear, no marine layer, plenty of offshore flow, and max beach temps in the mid to upper 60s, possibly 70° at times at the warmest spots. Sunday looks a tad cooler, perhaps low to mid 60s at the coast as the Santa Ana temporarily wanes. Another Santa Ana is becoming likely early next week, but as noted above, it would be from one of the cut-off lows diving south, which can't be confidently forecast right now. This is also where the wind forecast gets tricky.

Wind Outlook
Winds at 6:00 AM were offshore in most spots to about 10 mph, but the wind-prone spots were much stronger; for instance, much of the VC coast reported NE winds 15-20 mph with stronger gusts, and parts of OC were about 15 mph. These offshore winds should peak by noon and then back off in the afternoon, likely 10-15 mph max at the wind-prone spots by early to mid afternoon, and 5-10 mph elsewhere along the coast — with stronger gusts at times. Friday should see tamer winds about 10-15 mph max offshore in the wind-prone spots and 5-10 mph elsewhere, with winds shifting lightly onshore Friday afternoon. Saturday and Sunday should see light offshores everywhere in the AM 5-10 mph, and lightly onshore in the afternoon to 10 mph. A Santa Ana is becoming likely for Monday, but with models in disagreement right now I'll need to wait until my Sunday report to see.


Until my next report (Sunday), take care, be safe, and smile in the lineup!


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