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
Tuesday, August 11, 2015
:
- Buoy 165 (Barbers Point): Seas were 3.5 ft @ 12.5 secs with swell 1.6 ft @ 13.1 secs from 178 degrees.
- Buoy 46025 (Catalina RDG): Seas were 2.3 ft @ 13.0 secs with swell 1.3 ft @ 14.3 secs. Wind variable 2-6 kts early. At Santa Barbara swell was 0.6 ft @ 14.4 secs from 183 degrees. At Santa Monica swell was 1.3 ft @ 14.5 secs from 203 degrees. Southward from Orange County to San Diego swell was 1.7 ft @ 13.9 secs from 202 degrees.
- Buoy 46012 (Half Moon Bay): Seas were 3.3 ft @ 14.0 secs with swell 1.7 ft @ 14.2 secs. Wind northwest 6-8 kts. Water temp 62.1 degs. Note: The hi-res Pt Reyes Buoy has been defunded and decommissioned. Funding comes from the CA Parks Dept. We're getting more info now to e.cgiore ways to reactive this buoy.
PACIFIC OVERVIEW
Current Conditions
On Tuesday (8/11) in North and Central CA local north windswell was producing surf in the knee to thigh high range and weak and heavily warbled from southerly wind with fog. Down in Santa Cruz surf was thigh high on the sets and clean with a little sun trying to peek through the upper fog. In Southern California up north there was no waves with surf knee or less high and clean early. Down south waves were knee high and weak but clean. Hawaii's North Shore was near flat and clean. The South Shore was getting bare minimal southern hemi background swell with waves occasionally waist high and clean. The East Shore was getting tradewind generated east windswell with waves waist to maybe chest high and chopped from east trades.
See QuikCASTs for the 5 day surf overview or read below for the detailed view.
Meteorological Overview
For the North Pacific no large scale swell producing weather systems were occurring. But, Tropical Storm Molave off Japan is forecast to regenerate while tracking towards the dateline (see Tropical Update below). And Hurricane Hilda is generating swell east-southeast of Hawaii pushing towards and hitting exposed shores there. Regarding windswell, relative to California high pressure was currently inactive but forecast to start generating windswell for the weekend. For Hawaii, windswell is in.cgiay mixing with tropical swell and forecast to hold till the early weekend. For the southern hemisphere a .cgiit upper level flow continues to suppress storm production over the bulk of the South Pacific with no swell in the waters and none forecast. Otherwise El Nino continues to develop, which should positively affect the Fall and Winter surf seasons for the North Pacific.
SHORT- TERM FORECAST
Current marine weather and wave analysis.cgius forecast conditions for the next 72 hours
North Pacific
Overview
Surface Analysis
On Tuesday (8/11) no swell producing fetch that wasn't tropical was occurring over the greater North Pacific. High pressure at 1024 mbs was in the Gulf of Alaska with a weak low pressure system between in and the coast just off Oregon setting up a light wind pattern locally offering no support for windswell development along the US West Coast. For Hawaii the same high pressure system was generating trades at 15 kts east and over the Islands, though most of that wind was caused by the interaction of Hurricane Hilda (east-southeast of the Big Island) and the high pressure system.
Over the next 72 hours very weak low pressure is to slowly sink south and east moving over and into North California holding high pressure at bay. Maybe some northerly winds to develop Fri (8/14) over Pt Conception to 15 kts, but no windswell is to result. Relative to Hawaii trades to hold at 15 kts east of and over the Islands through Thurs (8/13) producing more east windswell, then possibly building to 20 kts on Friday as the remnants of Hilda move west over and south of the Islands.
Of far more interest is to be the forecast track of Tropical Storm Molave, expected to gain hurricane strength briefly Thurs (8/13) while tracking east-northeast well off Northern Japan generating 65 kt winds and seas at 18Z to 32 ft at 37.5N 163E (303 degs HI, 295 degs NCal) and building to 35 ft at 06Z Fri (8/14) at 40N 167.5E (310 degs HI,296 degs NCal) . A quick fade is to follow. If this system were to do as forecast, small 15 sec period swell could result in Hawaii by Mon (8/17) and CA by Wed (8/19). Something to monitor. No other swell source was indicated.
North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height
Tropical Update (as of 12Z Tues 8/11)
Hurricane Hilda peaked on Saturday night (8/8) with winds 115 kts positioned 850 nmiles south-southeast of the Big Island. Swell from that has already passed the Big Island and Oahu. On Tues AM (8/11) winds were down to 75 kts positioned 250 nmiles east-southeast of the Big Island tracking west-northwest and steadily fading. the core of Hilda is to pass over the southern third of the Big Island on Thursday (8/13) morning with winds 35 kts then moving east from there passing 130 nmiles south of Oahu Fri (8/14) afternoon. Windswell from the interaction of Hilda and high pressure to the north to continue if not intensify some relative to the east shores of Maui and Oahu Friday (5.5 ft @ 8 secs (4.5 ft). Peak swell for Hawaii to occur just before the core of the storm moves onshore Thurs AM (8/13) (6 ft @ 9-10 secs (5.5 ft faces).
Tropical Storm Molave was positioned 300 nmiles southeast of Tokyo Japan tracking east-northeast with winds 45 kts and forecast to continue on that heading while building in strength, perhaps make hurricane strength late Wed (8/13) evening. See details above in the North Pacific Shore Term forecast.
On Sat (8/15) a pair of tropical systems are to develop in close proximity to each other in the far West Pacific 1800 and 2400 nmiles east of the Northern Philippines driven by westerly surface winds occurring south of there in the Kelvin Wave Generation Area. The GFS model suggests rapid development with both system on a west-northwest track. Something to monitor.
California Nearshore Forecast
On Tuesday (8/11) high pressure at 1026 mbs was in the Gulf of Alaska trying to push towards the Pacific Northwest but being held at bay by weak low pressure just along the Oregon/NCal coast. Winds were generally light along the CA coast. More of the same is forecast through Thurs (8/13). By later Friday 15-20 kt north winds are to rebuild nearshore from Pt Conception up to Cape Mendocino as the surface low dissipates, with northwest winds building and moving up to Cape Mendocino at 25 kts later Saturday driven by high pressure again building off Oregon. The gradient and north winds to hold into Sun AM, then start slowly fading as the high retrogrades. Light winds to be in.cgiay nearshore by Tues (8/18).
South Pacific
Overview
Jetstream
On Tuesday AM (8/11) the jetstream continued very .cgiit with the southern branch tracking from a position down at 69S running east from a point well south of Australia and over Antarctic Ice continuing that heading over the bulk of the South Pacific rising only to 65S at a point south of Chile. No troughs were indicated offering no support for gale development. The northern branch of the jet was tracking east as it has all summer from a point north of Northern New Zealand on the 30S latitude line with an embedded pocket of 150 kt winds north of New Zealand. A ridge was positioned south of Tahiti helping to drive the SOI up some with yet a stronger ridge off the Chilean Coast. No support for gale formation that could support swell production in lower levels of the atmosphere was indicated. Over the next 72 hours more of the same is forecast with the track of the southern branch of the jet if anything falling further south and into mainland Antarctica south of New Zealand on Fri (8/14), then lifting a little to the north once approaching South America but never escaping the grip of Antarctic Ice. In the northern branch a trough is to start developing south of Tahiti late Thurs (8/13) helping to form a cutoff low there and possibly driving the SOI a bit more negative (in the right direction relative to El Nino). Beyond 72 hours still no change is forecast relative to the southern branch of the jet. And in the northern branch the trough south of Tahiti is to start moderating on Mon (8/17) letting the SOI drift more towards neutral. But there's no support indicated for gale development for the South Pacific.
Surface Analysis
On Tuesday AM (8/11) high pressure at 1024 mbs was positioned between the .cgiit jetstream flow southeast of New Zealand ridging south to 65S driving the storm track south over Antarctic Ice. No winds of 35 kt or greater were occurring anywhere over the South Pacific except in the far Southeast Pacific, and they were aimed at Antarctica and over ice.
Over the next 72 hours more of the same is forecast. no gale lows of interest are forecast. Relative to the SOI, a broad cutoff low is to form south of Tahiti on Thurs (8/13) holding for 2 days perhaps helping the SOI to fall more negative, then moderating and falling southeast.
Small South Pacific Gale
A small gale developed Wed PM (8/5) southeast of New Zealand producing 40 kt west winds and seas to 28 ft at 58S 162W aimed east. Those winds started fading Thurs AM (8/6) from 35 kts with seas fading from 26 ft at 57S 150W.
Hawaii: Very low odds of background swell appearing on Fri AM (8/14) with period 15 secs Swell Direction: 182 degrees
California: Low odds of swell arrival on Sun mid-day (8/16) with period 15 secs. Swell Direction: 200 degrees
South Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height
LONG-TERM FORECAST
Marine weather and forecast conditions 3-10 days into the future
North Pacific
Beyond 72 hours high pressure is to start ridging into California as low pressure dissipates, and by late Fri (8/14) north winds to start building to 20 kts over the entire North and Central Coasts becoming consolidated over North CA on Sat (8/15) at 25 kts. Windswell to be building with winds holding into early Sunday AM (8/16), then fading fast Sunday afternoon as the gradient dissipates. A light wind pattern is to follow. Relative to Hawaii trades to rebuild east and north of the Islands after the passage of Hilda on Fri (8/14) at 15 kts, driven by the interaction of another tropical low further north and east of Hawaii and high pressure in the Gulf of Alaska. But locally winds are to be light. Otherwise no large scale swell production is forecast.
MJO/ENSO Update
Nino 3.4 Temps Peaking - Nino1.2 Temps Cooling - Subsurface Reservoir Rapidly Expanding/Warming
- Surface Counter-Current Beats '97, TS Molave Recuring ENE off Japan
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.cgianet, though most noticeable in the Pacific. 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. Prolonged and consecutive Active MJO Phases help support the formation of El Nino. During the Inactive Phase the jet stream tends to .cgiit 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).
Overview: As of Saturday (8/8) a strong El Nino is in development. It began its lifecycle in late 2013 as a primer WWB and Kelvin Wave developed. Then in early 2014 a historically strong push by the Active Phase of the MJO resulted in a large Kelvin Wave, and anomalies continued in the Spring into early Summer transporting more warm water eastward. But the cycle faltered in July due to a protracted bout of the Inactive Phase of the MJO which enabled the upwelling phase of the Kelvin Wave cycle to manifest driving cooler water east, muting warm water buildup along the Ecuador coast. Still the warm water pipe remained open, but surface temperatures near the Galapagos never recovered and any atmospheric momentum was lost. Then in early 2015, another historically strong push from the MJO occurred, effectively a repeat of the early 2014 event, invigorating the warm water transport process and, adding more heat to an already anomalously warm surface pool off Ecuador. That pool has been building steadily in spurts ever since. The paragraphs below describe the current status of various El Nino indicators, followed by a few paragraphs that tie all the pieces together and provide our analysis of what is to come.
(1st paragraph in each section is new/recent data and is typically updated with each new forecast. 2nd paragraph, where present, provides analysis and context and is updated only as required).
Southern Oscillation Index (SOI): As of Tues (8/11):
Daily SOI: Was holding at -4.60, ending a 17 day run of numbers below -10 with 10 days of reading below -20.
30 Day Average: Was holding at -18.37, responding to the 10 day negative dip. It was it's lowest point in years on 7/18/15 at -20.49
90 Day Average: Was stable at -12.44. It has been at or below -10.0 since early July.
Trend (looking for negative SOI numbers, indicative of the Active Phase of the MJO or El Nino): The near term trend based on the daily average was indicative of perhaps a building of the Inactive Phase of the MJO, though that is a reach since no real MJO activity was present. The longer term pattern was indicative of a steadily building El Nino base state.
SOI Analysis: Darwin (looking for high pressure here): Strong high was tracking east from the East Indian Ocean and is forecast to be pushing over Western Australia and into East Aus on Wed (8/12) peaking in Southeast Australia on Sat (8/15) at 1032 mbs. A slow fade is forecast setting in on Mon (8/17) with lower pressure building over East Aus into Tues (8/18).
Tahiti (looking for low pressure here): Modest high pressure was build south of Tahiti forecast to hold on Wed (8/12), then relenting as a new upper trough and lower pressure takes hold south of Tahiti Thurs-Sat (8/15), fading, then weak low pressure returning on Tues (8/18).
SOI 1 week Forecast: The net result is to be a rising SOI for 2 more days, then falling SOI numbers by Thurs (8/13) holding through the weekend, then loosing ground again next week.
Southern Hemi Booster Index (SHBI) Analysis: South winds are not in control today, offering nothing to support the SHBI (which is theorized to supercharge a developing El Nino). South and southeast wind anomalies have been building in this region off and on for weeks now (latest run starting 7/29-8/5). The next bout of south winds are forecast starting on Wed (8/12) continuing into Sat (8/15) then starting again on Tues (8/18).
The SOI tends to be a lagging indicator (atmospheric co.cgiing signal rather than a driver of oceanic change).
Equatorial Surface Wind Analysis & Short-term Forecast: As of Tues (8/11):
Analysis from TAO Buoys: Down at the surface the TOA array (hard sensors reporting with a 24 hr lag) indicated moderate west winds (not anomalies) at 160E-170E while the GFS model suggest southwest winds there at 16 kts. Strong anomalies continued from 165E to 170W in the heart of the KWGA, then fading at 155W. This continues impressive. These west anomalies are purely a function of the El Nino base state perhaps enhanced by a new small Rossby Wave moving into the area. Overall these anomalies have remained virtually unchanged for the past 23 days (7/19-8/11) and followed directly behind a very strong WWB burst (third of the year) that was associated with a robust Active Phase of the MJO (historically strong) 6/24-7/17.
1 Week Forecast: Solid west anomalies are to hold for the next 4 days (8/15) then weaken some but not quit. One model suggests a hint of some east anomalies developing in the Kelvin Wave Generation Area on 8/18. Something to monitor for.
A huge WWB occurred in March followed by a second smaller one (9 day duration) in early May with weaker but still solid west anomalies continuing after that through 6/10. Anomalies faded to neutral for 8 days through 6/18 as the Inactive Phase of the MJO interfered with the pattern (the first such event of the year), then weak westerlies started again on 6/18. A significant WWB, the strongest of the year so far, starting on 6/26 peaking near 7/4 but held nicely through 7/17, the result of another Active Phase of the MJO. A moderate westerly anomaly flow redeveloped thereafter until 7/29 when a Rossby Wave started interacting with the building El Nino base state, enhancing the westerly flow, developing a mini-WWB at 175E through 8/5. And westerly anomalies continue through today. The major June-July WWB effectively held for 26 days and has produced a strong Kelvin Wave, the third this year, and the strongest by far. West wind anomalies at the surface are the hallmark of the Active Phase of the MJO and El Nino and drive Kelvin Wave production.
Kelvin Wave Generation Area monitoring model here
Longer Range MJO/WWB Projections: As of 8/11:
OLR Models: Indicate a weak Active MJO signal over the West Pacific, but it is believed to actually not be MJO related. The Statistic model suggests a weak MJO pattern is to hold for the next 10 days with a weak Inactive signal 15 days out. The Dynamic model depicts effectively the same thing, but with no Inactive signal 15 days out. In essence no MJO influence is forecast.
Phase Diagrams (ECMF and GEFS): They suggest the Active Phase of the MJO is trying to redevelop weakly over the West Pacific, but is to collapse in the next 24 hours with no return forecast.
40 Day Upper Level Model: It depicts a modest Active MJO pattern in.cgiay over the dateline, forecast to east east through 8/28. A moderate Inactive Phase is to develop in the far West Pacific 8/21 tracking east through 10/20.
CFS Model (850 mb): Depicts a weak Inactive MJO influence fading out today. Another weak Inactive Phase is forecast 8/16-9/15, but westerly winds are to persist. A major push of the Active Phase of the MJO remains scheduled starting Sept 18 in the far West Pacific holding till early Nov. The CFS model does predict steady but weak westerly anomalies from now until the Active Phase returns. No easterly anomalies are forecast.
The general consensus by the models is that we are to hold in a neutral to slightly Inactive MJO pattern for the next 5 weeks, then perhaps giving way to the Active Phase. In reality, a pure El Nino base state is at.cgiay driving current west anomalies and not expected to change much. Westerly anomalies, regardless of their source, are all that's required to push warm water to the east.
CFSv2 3 month forecast for 850 mb winds, MJO, Rossby etc
Surface Water Temps: 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.
Low-res imagery: On (8/10) first impressions continue indicating a moderate and somewhat decently defined El Nino pattern in.cgiace covering the entire equatorial Pacific. But compared to previous imagery (7/16), the pattern remains diffuse. There has been no increase in concentration of warm waters and if anything, the entire pattern looks less defined. Temperatures in the NINO1.2 region as of the latest image appear to be holding, but are not getting any warmer, but neither are they getting cooler. Along the West African Coast, cool water continues holding there. Very warm water continues off the US West Coast extending west the whole way to Japan but unrelated to this years El Nino, but possibly attributable to the building warm phase of the PDO. Slightly cool water is over Australia. Warm water continues near Madagascar.
TAO Data: +1.5 anomalies are in control over most entire equatorial Pacific, the warmest in years, presumably advecting west from the Galapagos covering the entire area west to the dateline except for a small break rising to +1.0-1.5 degs from 150W-165W. That break suggests a downgrade is occurring. There is an embedded area of +2.0-2.5 deg anomalies extending from the Galapagos to 145W with +1.5 deg anomalies reaching to 150W (contracting some) with a solo pocket at 170W. Overall the warm water signature is holding but not migrating west any.
Hi-res Imagery: (8/10) Warm anomalies are holding steady along the immediate coast of Peru and the coverage of pockets of +2.25 degs anomalies out to the Galapagos are unchanged. But temperature anomalies are less that what they were, peaking between the Galapagos and Ecuador on 7/14. Temps faded between 7/14-7/30 (and is reflected in the low res imagery too - see above). Since 7/31 temps between Ecuador and the Galapagos appear to have stabilized.
Galapagos Virtual Station: This station reported temps at +2.0 degs today (8/10). This is a major drop. A solid reading occurred on 5/23 at +4.59 degs suggesting the first Kelvin Wave generated in Jan-Mar had arrived, then built to +5.45 degs on 6/14. Temps faded from that high peak down to +4.1 degs in late June then rebuilt up to +4.94 on 7/17. Then a fade set in, down to +3.1 degs as of 7/31 and bouncing from +3.1-3.5 through 8/7, then falling dramatically to 2.0 on 8/10. This is not good. . Much more warm water is poised at depth just off Ecuador (see below).
Nino1.2 Index Temps: Temps are holding today at +1.9 degs. Previously temps hovered at +2.1 degrees early June then spiked reaching +3.0 degs on 7/3, faded then spiked again on 7/13 at +3.0 degs and yet again on 7/22. Temps fell to +1.9 degrees on 7/27 and have more or less stabilized now.
Nino 3.4 Index Temps: Temps are down some today at +1.76, having reached the all time peak (so far) for this year event on 8/10 at 1.8 degrees. Water temps previously held in the +1.0-1.3 deg range since mid-April, then started building pushing +1.5 degs on 6/30, held then crept up, peaking at +1.75 degs on 7/19 and +1.7 degs on 7/29 and the peaking at +1.8 of 8/10.
NINO 3.4 Temp Extent: Hi-res satellite images clearly depict unbroken +2.25 degs anomalies have encroached westward from the Galapagos to 149W today (8/10), the furthest west so far. Previously they reached to 133W as of 7/16 and then 138W (7/31) pushing to 149W on 8/10. This is advection west of warm water resulting from eruption of the 1st and 2nd Kelvin Waves earlier this year.
If one is to make a direct comparison of the 2015 event to '97 at this time of year based on water temp alone, there is no comparison. '97 imagery leaves this years event in the dust. This is not unexpected given the freight train consistency of WWBs leading up to the '97 event. This years event is building, but at a slower pace and in fit's and starts, but with an underlying deliberateness just the same. Total coverage of warm waters in the current imagery still remains respectable, but the depth of concentration is not in the league of '97. And of late, the data suggests a significant downgrade is occurring in the Galapagos area, as evidenced by the apparent drop-off of NINO 1.2 water temps and the Galapagos stations data. This is likely the result of a pause in upwelling of warm water in that region, a break between the first Kelvin wave eruption and the second poised just off Ecuador. We're beginning to think a true Upwelling Phase of the Kelvin Wave cycle might be setting in. These cooler water will advect west and eventually negatively impact temps in the NINO3.4 area, driving it down too. There appears to be.cgienty of water poised in the subsurface reservoir, and if anything, is building driven by the strength and duration of the most recent WWB (late June) when the resulting Kelvin Wave hits (peak temps in Nino 1.2 expected 10/4). Still given the current pause in warming near the Galapagos, no additional expansion of the warm pool is expected in the short term. This is the opposite of what would be expected if one were trying to compare 2015 to '97. Still, this pause is temporary, with much warming, the biggest yet of this event, still in the pipe.
Subsurface Waters Temps
TAO Array: (8/11) On the equator and under the dateline (160-180W) temperature anomalies have rebuilt significantly. 29 deg temps are between 160E to 135W with a pocket of 30 deg temps pooled up at 152W 50 meters down. +2.0 degs anomalies are fully bulging from the dateline eastward and +4 deg anomalies taking root from 152W eastward (expanding), the direct effects of the July massive WWB. A large warm reservoir at +5-6 deg above normal is poised to erupt into Ecuador. That reservoir is holding coverage with +7 degs anomalies centered at 110W (major increase in temp this report) and extending east from 141W to Ecuador (an expansion today). This pocket is a mixture of warm water from a WWB in early May merging with water from the most recent strong WWB in late June-July. So the pipe is open with more warm water rushing in and very warm water poised to erupt into the Galapagos.
Sea Surface Height Anomalies (SSHA): Data from 8/6 depicts 0-+5 cm anomalies over the entire equatorial Pacific starting at 175E with a core at +15 cm from 110-150W (expanding). This is most impressive. All this is indicative of a wide open pipe with a large Kelvin Wave in flight in the mid-Pacific poised to merge with a subsurface reservoir poised off Ecuador. This is a classic major El Nino setup, not a standard El Nino.
Upper Ocean Heat Content: As of (8/6) this data drives the point home. It indicates +0.5-1.0 deg anomalies are tracking east between 178E and the Ecuador coast (expanding). +1.0-1.5 degs are from 170W eastward. +1.5 deg anomalies are doing the same easing east from 160W. All these sectors are sliding east slightly. A pocket of +2.0 degs anomalies are at 152W-->108W (easing east) with a large pocket of +2.5 deg anomalies between 146W-->120W (expanding). A pocket of cooler 0.5-1.0 degs anomalies is holding between the Galapagos and Ecuador (from 91W-80W) and not moving east.
A strong Kelvin Wave impacted the Ecuador Coast in May-June with a second somewhat weaker one impacting it in June. And now a third is setting up, the strongest of all an getting stronger with each update. The pause in warming near Ecuador is evident in the subsurface data too, suggestive of a break between successive strong Kelvin Waves. And that gap is not getting smaller (i.e. moving east). If anything, it is holding, and appears to be influenced by backdraft from the expanding 3rd Kelvin Wave developing west of it. We're beginning to be disposed to say that a Upwelling Phase of the Kelvin Wave cycle is occurring. Still no 'cooler than normal' waters are expected to result, just a pause in the steady incremental increase in surface warming. But that could have an affect on the overall heat signature at the surface longer term. Regardless, the subsurface configuration suggests there are 2.5 months of warm water in this reservoir (till Nov 1) and some of that water is extremely warm. And more warm water continues downwelling on the dateline. This is a great setup if we can just get through the short term 'pause'.
North Pacific Jetstream: As of Tues (8/11) a weak flow was continuous across the North Pacific roughly centered at 48N. This is not impressive but suggests some weak influence by El Nino is occurring. More of the same is forecast over the coming week but with a ridge building in the Gulf of Alaska by Sat (8/15) pushing the jet there up to 58N on Mon (8/17). Overall it's unremarkable.
Pacific Counter Current: As of 8/6 the current continues solid and building. The current is pushing strongly west to east over the west equatorial Pacific filling the Kelvin Wave Generation Area then lifting a bit north of the equator and still solid from 160W to 120W before fading out. A pocket of modest east anomalies was over the immediate Galapagos. Anomaly wise - Strong west anomalies were spread on the equator over the West Pacific to the dateline, then lifting a bit north of the equator from the dateline to 130W, then fading but continuing to 100W. Light west to east anomalies were also south of the equator from the dateline to 110W. This is fairly impressive, suggesting this event is getting legs. Compared to the '97 El Nino at this time, todays image actually beats the imagery for '97. This is the first time this has happened.
SST Anomaly projections (CFSv2 model - PDF Corrected): For the model run 8/11 for the Nino 3.4 region, peak temperatures have stabilized. It suggests water temps are at +1.5 deg C (verified at 1.76 degs today) and are to steadily warm continuing to +1.85 degs by Oct peaking at barely +2.0 degs by Nov, then dropping off. Even given the current pause occurring In Nino1.2, and considering the size of the new Kelvin Wave forming subsurface, we suspect this projection is on the low side.
The mid-July consensus Plume suggests development of a strong El Nino with peak temps (depending on model type) spread between 1.5-2.0 degs above normal. See the chart based version here - link.
Analysis: In late 2013 into 2014 the Active Phase of the MJO and successive Kelvin Waves warmed waters over the Eastern equatorial Pacific and primed the atmosphere out of a 15 year La Nina biased pattern that had been in.cgiay since the demise of the '97-98 Super El Nino. It is assumed some greater force was dictating the change from a cool regime to warmer pattern, (the PDO). This warming and teleconnection continued building in 2015 with two Kelvin Waves arriving in Ecuador warming surface waters well into El Nino territory and a third, the strongest so far, in flight now. Preceding this Kelvin Wave is a pocket of less warm water. But with a large warm reservoir lodged just west of the Galapagos and the third Kelvin Wave directly behind, warming is expected to resume shortly. At this time we believe the classic El Nino feedback/teleconnection loop is in effect, with the atmosphere and the ocean are well co.cgied.
A si.cgie glance at the SST Anomaly charts suggest a well developed El Nino pattern is in.cgiay. The big question then becomes: How strong will this El Nino become? That is purely a function of the strength and duration of westerly anomalies in the Kelvin Wave Generation Area. And the frequency of those events is dictated by the character of the El Nino. All El Nino events are different. The pace of the WWBs and Kelvin Waves, their duration, depth and speed all help to define any given ENSO event. The '97 event was fast paced and furious, with no breaks, transitioning from La Nina to the strongest El Nino ever (by some measures) in a quick 7 month window starting 4/23 peaking on 11/26 (+2.69 deg). The '82 El Nino took longer to build starting in May and peaking in late Jan of '83 (+2.8 degs) (data OISSTv2). Other strong events in '72, '86, and '91 had dissimilar profiles. The point being, there is no exact te.cgiate for a strong El Nino other than they tend to form in the Spring and peak during the following Winter. And regarding the exact micro-details of each WWB, the resulting Kelvin Wave speed and arrival time in Ecuador etc, all vary though fall into the general guidelines established above. Given the false start of this El Nino in 2014 (and for that matter the other false start in 2012), this event has taken it's sweet time getting organized. But it's been struggling against an atmospheric bias towards La Nina driven by the cool phase of the PDO. We believe the atmosphere is trying to transition to the warm phase of the PDO, but is still fighting momentum from the cool phase, hence elongating this El Nino's lifecycle. And regarding the 'warm blob' off the Pacific Northwest, we believe that is more a symptom of the developing warm PDO, and will get punctured by incoming storms once El Nino gets traction and the jetstream energizes in the late Jan/early Feb 2016 timeframe. Winds from storms cause mixing and upwelling, which in turn cool surface waters. Of course that assumes this El Nino event develops into at least Strong if not Super status.
The longer it takes El Nino to develop, the thought is it will take proportionally longer to dissipate. That is, once El Nino atmospheric momentum takes hold, and if it takes longer to make that transition, it will be more stubborn and take longer to dislodge. There is no scientific data to support that thesis, it's just an opinion. But if the Active Phase of the MJO does develop in the Sept/Oct timeframe as predicted by the CFS model, and if a significant Kelvin Wave results, it would not arrive in Ecuador till ~Jan 1, 2016, and not disburse till a month later (Feb). That said, the character of this event is not at all like '97, but is starting to show signs of developing slower, like '82. And that would not be a bad thing, in that it could slow the inevitable transition to La Nina until later in the winter of 2016-2107.
Finally the discussion of 'atmospheric co.cgiing' needs to be considered. How much affect is El Nino having on the atmosphere? That is ultimately what impacts the jetstream and fuels winter storm development. The SOI is one such indicator. Changes in surface wind in the equatorial West Pacific another. But it is the total effect of El Nino on a wide variety of indicators, and the weighting of those indicators into a single number that can be used to track this event against others. This approach provides a clearer picture, where tracking an individual condition in the absence of others leads to a less comprehensive view. NOAA has developed just such an index, the Multivariate ENSO Index. It is used for research purposes, but is useful for our need too. It is conservative, has a pedigree, and has been hindcast tested against previous ENSO events. Per the MEI, the top 5 events since 1950 in order are: '97, '82, '91, '86, and '72 with '97 and '82 classified as 'Super El Nino's' because they reached 3 standard deviations (SD) above normal. '91 and '86 were at about 2.2 and 2.1 respectively with '72 peaking at 1.8 SD's above the norm. The current ranking (July) for 2015 is 1.97 SD (65). At this same time in '97 the ranking was 2.85 SD (66) and in '82 it was 1.7 SD (61). So we're slightly above the '82 event but well below '97, or comfortably on track for this time of year to move into Super El Nino territory. And even more interesting, the MEI for July actually went down (0.09 SD) from last month. Suffice it to say were are somewhere between '82 and '97 in term of of atmospheric co.cgiing.
So where does it go from here? Having a MEI that today is equivalent to two other Super El Nino events is no guarantee that this years event will eventually evolve into a Super El Nino. We still have 1.0 SDs to go. Though looking at the record back to 1950 for other events that have similar values in July, the odds favor that outcome. Still, the argument goes back to monitoring WWB and Kelvin Waves. That ultimately is the best leading indicator of what's to come. The more west anomalies, the more warm water gets pushed down into the pipe and the rest turns into an assembly line process with a more or less fixed outcome. Said another way, it appears an evolving El Nino base state is in control and building which in turn should dampen any future Inactive Phases of the MJO cycle and/or potential for easterly anomalies. This is required for a major El Nino to develop. So the current concern is focused on the pause in warming in the Nino 1.2 region and it's eventual impact as it advects into the Nino3.4 region. But again, with a very vigorous Kelvin Wave locked and loaded in the pipe, and a large warm reservoir preceding it poised to erupt near Ecuador in the next few weeks, it seems the nearterm outcome is certain. The future concerning more and stronger WWBs is unknown, but we are betting on the CFSv2 being largely on the right track with the El Nino base state slowly having greater influence over time and being enhanced by the MJO and Rossby Waves at times. And that doesn't count the change of seasons scheduled to start in early Sept, again favoring enhancement of the El Nino base state and the MJO.
So for now we're somewhere between the 82' and '97 event, with very good atmospheric momentum in.cgiay, and that's a good.cgiace to be. We'll continue monitoring the North Pacific jetstream and will be looking for tropical activity in the West Pacific to recurve northeast moving towards the Gulf of Alaska (like TS Molave is Forecast to do), and for swell to result from such systems in later August and Sept. To us, those are the sure signs of deep changes in the atmosphere influenced by El Nino. Until then, continue on your training routines and complete.cgians to procure additional boards. And if you own beachfront property in California, pay your insurance premiums.
See imagery in the ENSO Powertool
South Pacific
Beyond 72 hours no gale formation is forecast in the Hawaii or California swell window.
Details to follow...
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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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