Swell Classification Guidelines
Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead).
Summer - Head high or better.
Advanced: Winter - Swell and period combination capable of generating faces 1.5 times overhead to double overhead (7-10 ft)
Summer - Chest to head high.
Intermediate/Utility Class: Winter - Swell and period combination generating faces at head high to 1.5 times overhead (4-7 ft).
Summer - Waist to chest high.
Impulse/Windswell: Winter - Swell and period combination generating faces up to head high (1-4 ft) or anything with a period less than 11 secs.
Summer - up to waist high swell. Also called 'Background' swell.
On Thursday (4/24) in North and Central CA local windswell was chest to shoulder high and a bit warbled with a light onshore winds and fairly foggy. Down in Santa Cruz surf was waist to maybe chest high on the sets and textured by northwest winds wrapping into the bay. In Southern California up north residual Gulf swell/windswell combo was producing surf to waist high and clean. Down south surf was in the chest high range and slightly textured but fun looking. Hawaii's North Shore was getting dateline swell with waves 1 ft overhead and clean. The South Shore was flat. Exposed breaks on the East Shore were getting east windswell at waist high and chopped from east trades.
See QuikCASTs for the 5 day surf overview or read below for the detailed view.
North windswell was the rule along the Central CA coast with wrap-around energy pushing into Southern CA mixed with limited small southern hemi background swell. Swell from a small gale that developed over the dateline Sun (4/20) with 28 ft seas was hitting Hawaii. Limited energy from this system is scheduled to arrive in Central CA for the weekend. Another small gale is forecast for the Northern Gulf of Alaska on Fri-Sat with seas to 26 ft mainly targeting British Columbia. Nothing else to follow for the North Pacific. Down south a broad gale built in the Southeast Pacific on Fri (4/18) with up to 40 ft seas on Sat (4/19) aimed best at Peru with sideband energy pushing towards Southern CA. And another small gale is forecast in the deep Southeast Pacific on Thurs (5/1) with up to 36 ft seas possible.
SHORT- TERM FORECAST
Current marine weather and wave analysis plus forecast conditions for the next 72 hours
Jetstream - On Thursday (4/24) the jetstream was split over Japan but consolidated just off the coast while ridging gently northeast with winds to 150 kts over the dateline reaching up to a point just south of the Eastern Aleutians. From there the jet fell southeast forming a gentle trough off the Pacific Northwest and pushing inland over Northern CA capable of supporting low pressure down at lower levels of the atmosphere. Over the next 72 hours winds to build to 170 kts in the jet over the dateline Friday (4/25) briefly as the trough off the Pacific Northwest starts to push inland reaching down to Central CA.The jet is to continue pushing inland but rising some into Sunday over the Oregon/Washington border. A disorganized split flow is to continue off Japan building east to the dateline. No support for gale development is indicated. Beyond 72 hours the jet is to remain weak and disorganized in the west and building east, fully taking over the North Pacific by late Wed (4/30). Almost no coherent flow is forecast by later Thurs (5/1). This looks to be the end of the Winter/Spring season.
Surface Analysis - On Thursday (4/24) swell from a gale that developed just west of the dateline last weekend was hitting Hawaii and bound for the US West Coast over the weekend (see Dateline Gale below). Otherwise weak but broad low pressure was circulating over the North Dateline region tracking east but had no fetch of interest. High pressure at 1028 mbs was lodged 1200 nmiles west of Central CA. Over the next 72 hours the North Dateline low is to build to gale status as it migrates to the Northwestern Gulf on Fri AM (4/25) with 35 kt westerly winds aimed at the Pacific Northwest resulting in 19 ft seas at 48N 167W. The gale is to proceed east unchanged in the evening with seas building to 21 ft at 49N 160W (306 degs NCal). 35-40 kt west winds to build into Sat AM (4/26) with 25 ft seas forecast at 49N 156W (307 degs NCal). The gale is to fade in the evening with winds barely 35 kts and seas dropping from 25 ft at 50N 152W (309 degs NCal). This system is to rapidly dissipate from there. Perhaps some 14 sec period swell is to result from the Pacific Northwest down into Central CA by early next week if all plays out as currently modeled.
Otherwise no swell producing weather systems of interest are forecast.
A gale developed just west of the dateline Sat PM (4/19) with a small area of 40 kt northwest winds building. By Sun AM (4/20) a moderate sized area of 40-45 kt northwest winds were west of the dateline with seas on the increase from 26 ft over a small area at 41N 166E (311 degs HI). By evening winds were already fading from 40 kts aimed to the east with seas peaking at 28 ft at 42N 173E (315 degs HI). Fetch held at 35 kts Mon AM (4/21) with the gale easing up to the dateline with seas holding at 26 ft over a modest sized area at 43N 178E (322 degs HI, 296 degs NCal). 35 kt west winds were fading in the evening and lifting north with barely 26 ft seas holding at 47N 178W (332 degs HI, 299 degs NCal). This system held with 35-40 kt west winds just south of the Aleutians Tues AM (4/22) with seas 24 ft at 48N 176W (304 degs NCal). 35 kt west winds to be fading into the evening with seas fading from 24 ft over a modest area at 48N 173W (304 degs NCal). This system to fade out after that. Some rideable 14-15 sec period swell is expected to result for Hawaii with perhaps a decent shot of 14 sec swell for the US West Coast.
Hawaii: Residuals on Friday (4/25) fading from 4.0 ft @ 12-13 secs (4.5-5.0 ft). Swell Direction: 315-320 degrees.
NCal: Expect swell arrival late Fri (4/25) with swell maybe 3 ft @ 16 secs by sunset with luck (4.5 ft). Swell peaking Sat (4/26) at 4.0 ft @ 14-15 secs (5.5-6.0 ft) early and inconsistent. Swell fading on Sun (4/27) at 4.5 ft @ 13 secs (5.5 ft). Swell Direction: 298-304 degrees
North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height
No tropical systems of interest were being monitored.
California Nearshore Forecast
On Thursday AM (4/24) low pressure at 996 mbs was pushing over British Columbia with high pressure at 1028 mbs displaced west and located 900 nmiles north of Hawaii generating a small area of 15-20 kt northwest winds over Pt Conception. Otherwise a weak wind flow was in control of the state. Light rain associated with a front was pushing south over Northern CA. 10 kt or less northwest winds are forecast early Friday building to 15 kts for the entire state including SCal late. Light rain down to Big Sur late. 12 inches of snow for Tahoe during the day if one is to believe the models. 20 kt northwest winds are forecast for all regions including SCal Sat AM (4/26). Light rain early for Southern CA. Another front is to push down the California coast late Saturday with light rain down to Monterey Bay early Sunday, dissipating through the day. Northwest winds forecast 10 kts nearshore Sunday everywhere but Southern CA (light winds there). 1 inch of snow for Tahoe to result Sun AM. 15-20 kt northwest winds projected building Monday over all of North and Central CA with rain to Pt Arena, then clearing Tuesday with 15 kt northwest winds for North and Central CA. Light winds for Southern CA. Light winds for everywhere on Wed except North CA (15 kts northwest) continuing into Thursday but building up north to 25 kt and pushing south as high pressure starts ridging into the Pacific Northwest.
Storm #1S - 4th Southern Hemi Gale of the Season
Surface - The first storm of the season developed Fri (4/18) in the Southeast Pacific resulting in a significant class swell pushing northeast (Swell #1S). Over the next 72 hours no swell producing weather systems are forecast in the grater South Pacific. Also a small system is modeled developing in the Tasman Sea on Sat (4/26) lifting northeast into Sun AM (4/27) with 36 ft seas targeting Fiji. Swell possible for that area.
A broad gale developed in the Southeast Pacific Fri PM (4/18) with a large area of 45 kt southwest winds taking hold targeting Peru. Seas were on the increase from 28 ft at 52S 142W (191 degs NCal, 195 degs SCal). 45-50 kt southwest winds continued into Sat AM (4/19) reaching storm status aimed well to the north-northeast with seas building to 40 ft at 53S 136W (188 degs NCal, 191 degs SCal). The Jason-1 satellite passed directly over this area at 12Z reporting seas of 35.1 ft with a peak reading of 39.1 ft where the model suggested 40 ft seas. The model was running on the high side. Another pass occurred at 18Z with seas 32.6 ft with one reading to 36.8 ft where the model suggested 30 ft seas. In this instance the model was running below expectations. Fetch was fading from 40-45 kts still aimed north northeast and tracking east in the evening with seas fading from 39 ft at 48S 127W (185 degs NCal, 186 degs SCal). Another Jason-2 pass occurred at 06Z with seas 34.8 ft with one reading to 41.1 ft where the model suggested 37 ft seas. The model was just 1-2 ft on the high side. By Sun AM (4/20) this system had only 35 kt southwest winds with seas fading from 34-36 ft on the edge of the SCal swell window 43S 120W (179 degs NCal, 181 degs SCal). The Jason-2 satellite passed directly over the core of the fetch at 16Z and reported seas 31.9 ft with one reading to 36.5 ft where the model suggested 31 ft seas. The model was one foot under the actuals. A secondary fetch of 40 kt southwest winds developed in the evening generating more 26 ft seas at 52S 125W (183 degs NCal, 185 degs SCal). This gale was mainly east of the SCal swell window by Mon AM (4/21) except for the secondary fetch which was generated 30 ft seas at 52S 121W (183 degs SCal, 180 degs NCal). By evening this system was gone.
This storm was solid for this early date and had a good footprint with fetch aimed mainly towards Peru but with good offband energy radiating north. Jason-2 data suggested this system was modeled maybe 1-2 ft on the high side, but still quite respectable. A solid pulse of southerly angled swell is likely for all of California with the leading edge possibly hitting Southern CA on Sat (4/26) with period 19-20 secs.
Southern CA: Expect swell arrival on Sat (4/26) before sunrise with period 20 secs and size small but building steadily through the day, reaching 3.6 ft @ 19 secs at sunset (6.8 ft faces with sets to 8.5 ft) but inconsistent. This might be a little on the generous side. Swell to continue overnight and still solid by Sun AM (4/27) with swell 3.6 ft @ 17-18 secs early (6.3 ft with sets to 7.5 ft) with period dropping to 16-17 secs late. Increased consistency. Swell fading Monday (4/28) from 3.3 ft @ 15-16 secs (5 ft with sets to 6 ft). Better consistency but less variability. Swell Direction: 191 degrees,
Northern CA: Expect swell arrival on Sat (4/26) just after sunrise with period 21 secs and size small but building steadily through the day, reaching 3.3 ft @ 20 secs at sunset (6.6 ft faces with sets to 8.0 ft) but inconsistent. This might be a little on the generous side. Swell to build some overnight and peaking near sunrise Sun AM (4/27) with swell 3.6 ft @ 18 secs (6.5 ft with sets to 8.0 ft) with period dropping to 17-18 secs late. Increased consistency. Swell solid but starting to fade Monday AM (4/28) from 3.3 ft @ 16 secs (5.3 ft with sets to 6.5 ft). Better consistency but less variability. Swell Direction: 186 degrees
South Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height
Marine weather and forecast conditions 3-10 days into the future
Beyond 72 hours no swell producing weather systems are forecast.
Note: The Madden Julian Oscillation is a periodic weather cycle that tracks east along the equator circumnavigating the globe. It is characterized in it's Inactive Phase by enhanced trade winds and dry weather over the part of the equatorial Pacific it is in control of, and in it's Active Phase by slack if not an outright reversal of trade winds and enhanced precipitation. The oscillation occurs in roughly 20-30 day cycles (Inactive for 20-30 days, then Active for 20-30 days) over any single location on the planet. During the Active Phase in the Pacific the MJO tends to support the formation of stronger and longer lasting gales resulting in enhanced potential for the formation of swell producing storms. During the Inactive Phase the jet stream tends to split resulting in high pressure and less potential for swell producing storm development. The paragraphs below analyze the state of the MJO in the Pacific and provide forecasts for MJO activity (which directly relate to the potential for swell production).
As of Thursday (4/24) the daily Southern Oscillation Index (SOI) was up to 20.55. The 30 day average was rising at 4.00 and the 90 day average was steady at -2.24. The near term trend based on the 30 day SOI was indicative of an Inactive Phase of the MJO. The longer term pattern was indicative of a weak Inactive Phase of the MJO. The 30 day SOI continued rising from the lowest point it's been since the El Nino of '09/10 and suggesting whatever occurred during the Jan-March timeframe (to push it negative) was over. The SOI tends to be a lagging indicator running a week behind surface level weather trends.
Current equatorial surface wind analysis indicated modest west anomalies extending from the Eastern Maritime Continent reaching almost to the dateline. Neutral anomalies developed east of there and continued south of Hawaii reaching into Central America. A week from now (5/2) near neutral anomalies are expected to take hold over the Philippines reaching to the dateline, then turning to weak westerly anomalies extending from the dateline south of Hawaii and into Central America. In all this suggests the Active Phase of the MJO is weakening in the West Pacific and is to continue fading and easing east over the next week. Looking back the most recent westerly wind event started 4/7 and held through 4/20, and was strong enough to be considered a minimal Westerly Wind Burst WWB) likely continuing warm water transport feeding a pre-existing subsurface warm pool. Some degree of very weak westerly anomalies are to continue for the coming week, so this event is not over yet, just weakening. Previously a pattern of multiple strong Westerly Wind Bursts occurred Jan-March, but then moderated in late March, but never gave way to a fully Inactive Phase (and no hint of easterly anomalies developing west of the dateline). This is great news with westerly anomalies in play for nearly 4 months now. Longterm this signal (suppressed trades in the far equatorial West Pacific) will have to hold into at least August with warm water building greater than 0.5 deg C over the tropical East and Central Pacific (120W to 170W) before one could declare the development of El Nino. And there is much unknown as we traverse the Spring 'Unpredictability Pattern" (mid-March through early June). The whole pattern could collapse and return to a neutral pattern like last year. It's just too early to know. But the further into the unpredictability barrier we get, and with west anomalies continuing, the lower the likelihood of a total collapse becomes.
A previous WWB created a large Kelvin Wave tracking towards South America in January (starting 1/8, peaking 1/28 then fading the first week of Feb) followed by a second strong WWB in Feb-Mar (as strong as the first one starting 2/15 and peaking 2/20-3/2 then fading 3/10) setting up and offering yet more reinforcing transport warm water east. And then a third weak westerly wind burst developed (starting 3/12 and faded out by 3/28). As of right now this series of events is significant and is certainly something to monitor, but does not mean El Nino is in-play. And now with yet a fourth westerly wind anomaly event still in-play, the pattern has become more than coincidental and strongly suggests some degree of pattern change has developed for the tropics. Of historical note: The big El Nino's of '82/32 and '97/98 both started forming in the February timeframe and progressed non-stop through the Summer and Fall months. A article presenting a Comparison between the genesis of the 1997 El Nino and this 2014 WWB event has been posted here.
The longer range models (dynamic and statistical) run on 4/22 are in general consensus. They both suggest the Active Phase of the MJO was fading over the West Pacific. The core of the Active Phase was over the Eastern Maritime Continent with it's leading edge on the dateline but loosing coverage. The Active Phase is to continue holding over the far West Pacific 5 days out but steadily loosing coverage and is to continue that trend 10 days out before dissipating completely 15 days out per both the statistic and dynamic models. Both models depicts a weak to modest Inactive Phase building in the West Pacific 15 days out. The ultra long range upper level model suggests the current Active Phase is to slowly fade while tracking east into Central America through 5/7. A moderate Inactive Phase is to build over the West Pacific 5/5 tracking east while slowly fading pushing into Central America 5/19. Behind it a somewhat stronger version of the Active Phase is to develop about 5/17 pushing towards the east reaching the East Pacific 6/4. The upper level model tends to be a leading indicator, with surface level anomalies lagging behind 1 week or more.
The more warm water in the equatorial East Pacific means more storm production in the North Pacific during winter months (roughly speaking). Cold water in that area has a dampening effect. Regardless of what the atmospheric models and surface winds suggest, actual water temperatures are a ground-truth indicator of what is occurring in the ocean. As of the most recent imagery (4/24), a thin but distinctly warm water regime has taken over the entire equatorial Pacific now extending east of the Galapagos and ranging in the +0.5-1.0 deg C range with one pocket south of Mexico to +1.5 degs C. This pattern started in earnest on 3/29 and has been continuing and solidifying it's grasp every since. It would be best if it could increase its areal coverage 3-4 more degrees further south, especially in the area bound by from 90-140W. A small isolated cool upwelling flow previously east of the Galapagos is gone and is now turning to positive anomalies. We are expecting the arrival of a large Kelvin Wave in the East Pacific any day now, with a pronounced increase in surface anomalies over a short time span (not just the subtle warming that has been occurring). We'll continue monitoring daily values to identify the exact arrival date. Elsewhere the entire North Pacific Ocean is full of warmer than normal water as is the West Pacific (north and south). There are no signs of high pressure induced upwelling streaming southwest off California either as would be expected for this time of year. The only cool water present is streaming off Southern Chile pushing west almost reaching up to the equator, but getting shunted south by the warm water developing on the equator. But overall the total amount of warmer than normal water in the North Pacific is impressive. The next big development, will be the breech of warm water along the western coast of the Galapagos announcing the arrival of a massive Kelvin Wave currently positioned under the Central Equatorial Pacific (possibly occurring now).
Subsurface waters temps on the equator remain impressive. Of great interest is a large area of warm +3-5 deg C above normal water in-place and tracking east with it's core 150 meters down somewhere between 160W and 100W. Some sites are reporting water temps in excess of 6.0 degrees C, but the location of those readings are not near active TOA array sensors and are projections from models rather than the ground truth. Current data suggests it's leading edge is just off the Ecuador coast at 80W (+6 deg C) and beyond the east most line of buoys in the TOA array (95W), right on the cusp of erupting to the surface. Given the lack of sensors between 155W and 110W, exact details concerning the core remain sketchy. Regardless, a large Kelvin Wave has been generated by 24 days of modest to strong westerly anomalies west of the dateline in January (a Westerly Wind Burst) and reinforced by a second WWB in Feb-Mar with yet a third in March with trades suppressed since then. And yet a 4th but weaker WWB developed in April. The hope is the Kelvin Wave under the mid equatorial Pacific will fuel to what is the start of at least a small warm event. The Kelvin Wave has also been confirmed via satellite in the form of increased surface water heights at +10 cm (one small pocket at + 15 cm just west of the Galapagos on 4/18), suggesting warm water at depth is displacing the surface upwards. Surface heights have rebounded some on the dateline but are falling between 170W to 150W, suggesting the core of the warm water pool is now migrating into the East Pacific.
Based on previous history the evolution pattern is that when this large Kelvin Wave erupts along the South American coast, the increase in water temps should reduce trades above it (by reducing surface air pressure), which in turn could support yet more warm water building (heated by the sun and through reduced upwelling). Aided by yet another WWB in the West Pacific and more eastward moving warm subsurface water, a feedback loop could develop, reinforcing the warm water flow and buildup off Central America into the Fall. But we're a long ways from that occurring just yet. What is needed is another Westerly Wind burst or at least continued westerly anomalies. Anything that reduces or suppresses trades in the equatorial West Pacific will suffice to continue the transport mechanism. Out-and-out west surface winds are not required. And anything that reduced trades in the east (like increasing water temps) will continue to stabilize the warm pool that is hopefully evolving there.
Projections from the CFSv2 model run 4/24 have backed off slightly. The model had been continuously suggesting some form of warming starting in March 2014 (which did occur) with temps reaching +0.5 in the Nino 3.4 zone by April 1 (also occurred). It now suggests water temps building to +1.0 deg C by early Sept peaking at +1.5 deg C by Nov 2014. Our guess is that some form of El Nino warning could be declared in the late May/early June timeframe if all stays on track. For reference, the big El Nino of '82/83 was at +2.0 degs and '97/98 was +2.2 degs at their respective peaks). The El Nino of 09/10 was +1.4 degs.
Overall the immediate outlook remains unchanged, but potentially trending towards something that would be considered warm by June 2014, assuming one is to believe the models and the subsurface water configuration. At a minimum the ocean is in recharge mode, with cold water from the 2010-2011 La Nina dispersed and temperatures on the rise in fit's-and-starts. Regardless of the WWBs etc, we are in a neutral ENSO atmospheric pattern at this time with neither any form of El Nino or La Nina present or imminent. Given all current signs, warming could start developing by May in earnest over the equatorial Pacific possibly increasing during the summer, intensifying into Fall. Monitoring the affects when and if the Kelvin Wave arrives along the equatorial East Pacific will be key to the potential evolution of a warm event. Still there remains 6 months ahead where any number of hazards could derail this event. But this is a better place than previous years (2010-2011, 2011-2012 and 2012-2013) under the direct influence of La Nina. And it seems apparent we've finally recovered from the 2009-2010 El Nino. In a normal situation one would expect there to be at least one or two years of neutral temperatures ultimately converging in a stronger warmer pattern and possible El Nino 2-3 years out (2015 or 2016). Historically, this is the 'normal' pattern (a few years of false starts post La Nina before a legit El Nino forms). We've turned the corner, but it is still unknown what impact it will have on the atmosphere especially in light of what appears to be a decadal bias towards a cooler regime (since 1998).
See imagery in the ENSO Powertool and more details in the El Nino Update Updated 12/4/13
See a 'Comparison between the genesis of the 1997 El Nino and the 2014 WWB Event' Here (posted 4/5/2014)
Beyond 72 hours no swell producing weather systems of interest are forecast.
Details to follow...
External Reference Material: El Nino Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), Kelvin Wave
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Surf Height-Swell Height Correlation Table