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.
Thursday, August 13, 2015
- Buoy 165 (Barbers Point): Seas were 3.7 ft @ 13.3 secs with swell 1.8 ft @ 13.3 secs from 178 degrees.
- Buoy 46025 (Catalina RDG): Seas were 3.6 ft @ 6.0 secs with swell 0.9 ft @ 14.5 secs. Wind northwest 4-10 kts early. At Santa Barbara swell was 1.1 ft @ 6.2 secs from 255 degrees. At Santa Monica swell was 1.0 ft @ 15.4 secs from 205 degrees. Southward from Orange County to San Diego swell was 1.2 ft @ 15.4 secs from 187 degrees.
- Buoy 46012 (Half Moon Bay): Seas were 2.0 ft @ 16.0 secs with swell 1.5 ft @ 14.5 secs. Wind north 2-4 kts. Water temp 63.7 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.
On Thursday (8/13) in North and Central CA at best breaks local north windswell was producing surf in the thigh high range and lightly textured with high fog. Down in Santa Cruz surf was thigh high on the sets and clean but weak and crumbled with some texture on it. In Southern California up north there were no waves with surf knee or less high and textured with chop lines running through it. Down south waves were thigh high and weak but clean breaking nearly on the beach. Hawaii's North Shore was flat and getting some sideshore wind bump on it. The South Shore was getting bare minimal southern hemi background swell with waves occasionally waist high or so and clean at best breaks. The East Shore was getting tradewind generated east windswell with waves waist high and chopped from east trades.
See QuikCASTs for the 5 day surf overview or read below for the detailed view.
For the North Pacific no large scale swell producing weather systems were occurring. But Tropical Storm Molave was mid-way between Japan and the dateline producing 21 ft seas aimed east (see Tropical Update below). The remnants of Hilda are dissipating southeast of the Big Island offering nothing more of interest. Regarding windswell, relative to California high pressure was currently inactive but forecast to start generating the usual pressure gradient and small north windswell over North CA by the weekend, then quickly fading. For Hawaii, east windswell continues but is expected to start fading some mid-weekend, but not gone till mid-next week. 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 the El Nino base state continues to develop. At this point we're just waiting for the first signs of Fall to kick in.
SHORT- TERM FORECAST
Current marine weather and wave analysis.cgius forecast conditions for the next 72 hours
On Thursday (8/13) no swell producing fetch that wasn't tropical was occurring over the greater North Pacific (see Tropical Update section below for details). High pressure at 1028 mbs was in the Gulf of Alaska while weak low pressure was between it and the coast just off North CA setting up a light wind pattern locally and 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 of and over the Islands, though much of that wind was attributable to the interaction of the remnants of Hilda (fading out southeast of the Big Island) forming a gradient with the above high pressure system well north of the Islands.
Over the next 72 hours relative to California the weak low pressure system just off the North Coast is to move inland and dissipate later Thursday with the Gulf high starting to ridge onshore Fri (8/14) forming the usual summer time pressure gradient generating 15-20 kt north winds over Central CA. That gradient is to lift rapidly north early Saturday taking shape over North CA waters generating 20-25 kt north winds with windswell on the increase later and holding through Sun (8/16). A rapid collapse of the gradient is forecast Monday AM with windswell from it fading as well. Relative to Hawaii trades to hold at 15 kts east of and over the Islands through Fri (8/14) producing more east windswell, driven by the interaction of the remnants of Hilda easing east and high pressure to the north. But on Sat (8/15) Hilda is to have dissipated south of the Islands with only high pressure driving the easterly flow now, getting less coverage as a result. Spotty east winds at 15 kts to continue through Sunday with windswell from it fading some.
Of some interest is the track of minimal Tropical Storm Molave, tracking east-northeast off Central Japan almost mid-way to the dateline. Winds are less than previously forecast, only at 40 kts generating 13 ft seas per the official forecast and 20 ft per the model at 35N 158. Winds to hold in the evening with seas to 20 ft at 36N 162E then fading from there. No swell of interest is to result for Hawaii or the US West Coast. Still, the track is encouraging and suggests El Nino is trying to feed the jetstream some, but not alot yet regardless of all the hype. As usual, hindcast data tells the real story, not modeled projections. No other swell source was indicated.
North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height
Tropical Update (as of 12Z Thur 8/13)
TS Hilda was fading 150 nmiles southeast of the Big Island with winds 35 kts and no central dense overcast (clouds) left with the core totally exposed. A quick fade is forecast while it's remnants track west-southwest. Winds to be fading from 25 kt on Fri AM (8/14) with the core 170 nmiles south of the Big Island. No swell production is forecast other than windswell relative to the southeast shore of the Big Island.
Tropical Storm Molave was tracking east-northeast off Central Japan almost mid-way to the dateline. See details above in the North Pacific Shore Term forecast.
The models continue to hype development of a pair of tropical systems in close proximity to each other in the far West Pacific. On Sat AM (8/15) they are to be getting decently defined positioned 1600 and 2400 nmiles east of the Northern Philippines fueled by westerly surface winds occurring south of there in the Kelvin Wave Generation Area. The GFS model suggests rapid development with the west most one taking a west-northwest track bound for somewhere near Taiwan while the more easterly system grows to large proportions pushing well into hurricane force status and turning north at 26N 155E with 57 ft seas. Not believable but something to monitor.
California Nearshore Forecast
On Thursday (8/13) high pressure at 1028 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 North CA coast. Winds were generally light nearshore in CA. More of the same is forecast early Friday but later 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 ridging into the Pacific Northwest. The gradient and north winds to hold Sunday at 25-30 kts with a weak eddy flow nearshore south of Pt Reyes, then starting to slowly fade Monday as the high retrogrades with north winds down to 20 kts late. High pressure is to still be influencing the picture Tues (8/18) with north winds 15 kts Tues-Wed (8/19) for North and Central CA with the high surging east Thursday and the gradient rebuilding over Cape Mendocino at 25+ kts with 20 kt north winds down to Pt Conception. Balmy water temps to take a little hit if this north wind event develops next week as forecast.
On Thursday AM (8/13) the jetstream continued very .cgiit with the southern branch ridging hard south pushing into Antarctica south of New Zealand then running east slowly rising but never escaping Antarctic Ice even as it passed south of South America. 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 winds building to 180 kt winds northeast of New Zealand. A bit of a trough was trying to form southwest of New Zealand supporting formation of cutoff low pressure at the surface there and helping drive the SOI down some. From there the northern branch fell southeast forming a ridge well off 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 but with the track of the southern branch of the jet moderating some over time and lifting north to 68S, but still totally over Antarctic Ice running due east and tracking under the southern tip of South America. Ice. A trough is forecast forming south of Tasmania on Sun (8/16) pushing well to the north but with no real wind energy in it offering little to support gale formation. In the northern branch the cut off trough south of Tahiti is to wash out late Fri (8/14) with high pressure south of Tahiti the likely result (driving the SOI up some). Beyond 72 hours the trough south of Tasmania is to quickly get undercut on Mon (8/17). But a more energetic trough is forecast developing under New Zealand on late Tues (8/18) fed by 150 kt winds and trying to make progress into the greater Southwest Pacific late Wed (8/19) but quickly moderating while a big ridge develops east of there pushing the southern branch well into Antarctica. Low odds to support gale development in the New Zealand trough. No real change is forecast in the northern branch either save for a small trough south of Tahiti on Wed (8/19) again perhaps supporting weak low pressure down at the surface nudging the SOI down some.
On Thursday AM (8/13) high pressure at 1028 mbs was still positioned between the .cgiit jetstream flow southeast of New Zealand ridging south to 63S 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, where 35-40 kt southwest winds were east of the South CA swell window associated with a building low there and starting to get some traction on ice free waters but targeting only Chile and Peru. Otherwise a broad cutoff low was between the .cgiit jetstream flow south of Tahiti helping to push the SOI into negative territory.
Over the next 72 hours the low off South Chile is to generate 45 kt west winds Fri PM (8/14) producing seas to 37 ft at 59S 90W targeting only extreme Southern Chile. The cutoff low south of Tahiti to produce a tiny fetch of 40-45 kt southeast winds and barely 28 ft seas at 18Z Fri (8/14) over a tiny area at 47S 152W obliquely targeting Tahiti. from a broader perspective this low is to mainly help drive the SOI negative through Fri (8/14). After that it is to collapse with weak high pressure building south of Tahiti and a rising SOI likely.
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
Marine weather and forecast conditions 3-10 days into the future
Beyond 72 hours high pressure in the Gulf of Alaska is to start retrograding away from the Pacific Northwest Coast on Monday (8/17) with the North California pressure gradient and north winds there fading from 25 kts, barely 20 kts late. Generic 15 kt northwest winds are forecast for the Central Coast Tuesday building to 20 kts on Wed (8/19) then regrouping to the north on Thurs (8/20) generating a small gradient and 25 kt north winds over Cape Mendocino area resulting in better defined north local windswell. Relative to Hawaii spotty trades to hold at 15 kts east and north of the Islands Mon (8/17) fading more Tues (8/18) then gone. No windswell generation potential is expected after that through at least Thurs (8/20) with high pressure too far to the north and no other tropical influence forecast in vicinity of the Islands to set up a pressure gradient.
Beyond 72 hours no gale formation is forecast in the Hawaii or California swell window.
Details to follow...
Subsurface Reservoir Anomaly Temps Pushing +7 deg
Westerly Anomalies Continue Strong In Kelvin Wave Generation Area
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: A strong El Nino is developing. 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).
Atmospheric Co.cgiing Index's (lagging indicators rather than driving oceanic change): As of Thurs (8/13):
Daily Southern Oscillation Index: Was falling at -19.50, coming 3 days after a 17 day run of numbers below -10 with 10 days of that below -20.
30 Day Average: Was falling from -18.48, 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 -12.11. 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 a building El Nino base state. The longer term pattern was indicative of a steadily building El Nino base state.
SOI Trend - Darwin (looking for high pressure here): High pressure was over Central Australia on Thurs (8/13) forecast 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 on Thurs (8/20).
SOI trend - Tahiti (looking for low pressure here): A new upper trough and lower pressure was taking hold south of Tahiti Thurs-Sat (8/15), then expected to be r.cgiaced by weak high pressure Sun-Mon (8/17) fading, with weak low pressure returning on Tues-Thurs (8/20).
SOI 1 week Forecast: The net result is to be a steady but negative SOI into the weekend, then rising Sun-Tues (8/18) before falling again through Thurs (8/20).
SOI Analysis: During El Nino, the SOI functions as a measure of how well the ocean and atmosphere are co.cgied. Current numbers suggest good but not great co.cgiing. that will likely change for the better as the El Nino base state builds as we move into Fall.
Southern Hemi Booster Index (SHBI) Analysis: South winds have again returned to East Aus offering some support for 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 7/29-8/10). South winds are forecast continuing into Sat (8/15), fading, then redeveloping on Mon-Thurs (8/20). The SHBI appears to positively influencing El Nino development, but we have no hard numbers to confirm.
ESPI (like SOI but based on satellite confirmed cloud cover): (8/13) Todays value is +2.59 and has been steady for the past few days. We just started following this index this week. Historically the peak of the '82 El Nino was +2.2 and the '97 event +2.85. This suggests the '15 El Nino is already very well co.cgied with the atmosphere.
Equatorial Surface Wind Analysis & Short-term Forecast: As of Thurs (8/13):
7 Day Models: Models are not updating. Owner is working to rehost on a new server
Analysis from TAO Buoys: Down at the surface the TOA array (hard sensors reporting with a 24 hr lag) indicated strong south winds (not anomalies) at 160E giving way to modest west winds on the dateline. The GFS model suggest south winds at 19 kts near 150E giving way to calm winds east of there. Anomaly wise - Strong southwest anomalies continued from 165E to 180W in the heart of the KWGA, then turned to moderate to strong west anomalies from there to 160W. This west winds pattern continues impressive. These west anomalies are purely a function of the El Nino base state enhanced by a new small Rossby Wave developing near 165E but tracking west out of the area. Overall these anomalies have remained virtually unchanged for the past 23 days (7/19-8/13) 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 (nearly 2 months of west anomalies or stronger).
1 Week Forecast: Solid but decreasing west anomalies are to hold for the next 4 days (8/17) then fade out. The CFS model hints at some east anomalies developing in the western Kelvin Wave Generation Area on 8/17 for 3-4 days associated with a Inactive Rossby Wave, but west anomalies to continue from the dateline eastward. 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 (22 days), the result of another Active Phase of the MJO and produced a strong and large Kelvin Wave, the third this year and the strongest by far. 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 (8/13). That is nearly 2 months of non-stop anomalies if not out and out west winds (6/26-8/13). 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 8/13:
OLR Models: Indicate a weak Active MJO signal over the West Pacific, but it is believed to actually not be MJO related (insufficient filtering). 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 a weak Active signal 15 days out. In essence no MJO influence is forecast.
Phase Diagrams 2 week forecast (ECMF and GEFS): They suggest the Active Phase of the MJO is weak and collapsed and is to not return.
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 8/23 tracking east through 9/22. This makes sense given the CFS forecast for weak east anomalies in the far west KWGA for the next few days. Maybe a little bit of destructive interference regarding surface west anomalies to result from this weak Inactive Phase.
CFS Model starting 1 week out (850 mb): Depicts a weak Inactive MJO influence forecast 8/17-9/2, but westerly winds are to persist. A weak push of the Active Phase might starting 9/7 but fade, with a major push of the Active Phase of the MJO remains scheduled starting Sept 18 in the far West Pacific holding till 10/31. Some constructive Rossby Wave interference to add to the westerly mix in between. 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 4-5 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 (8/13) 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 weakly loosing concentration, but not getting cooler. Along the West African Coast, cool water continues holding there. Very warm water continues off the US West Coast and if anything building while 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. Slightly 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 (holding) with a solo pocket at 170W. Overall the warm water signature is holding but not migrating west any.
Hi-res Imagery Nino1.2: (8/12) Warm anomalies are holding steady along the immediate coast of Peru and Ecuador. But a pocket of decreased of +2.25 degs anomalies is working it's way west over the Galapagos and tracking west from there. Peak temps occurred between the Galapagos and Ecuador on 7/14, then 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.
Hi-res Imagery NINO 3.4: (8/12) Hi-res satellite images clearly depict unbroken +2.25 degs anomalies advecting west from the Galapagos reaching to 151W today, the furthest west so far. but there's some sense that the total thickness of the stream (coverage) is slightly less than days past (i.e. the stream is getting stretched while moving west with no backfill from the Galapagos occurring). 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.
Galapagos Virtual Station: This station reported temps at +2.5 degs today (8/13) increasing from the low point of 2.0 degs on 8/10. Previously 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. Much more warm water is poised at depth just off Ecuador (see below) and required immediately.
Nino1.2 Index Temps: (8/13) Temps faded some today at +1.8 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 at +3.0 degs 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 +1.62, 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.
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 and second Kelvin wave eruptions and the third 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
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 will likely have an affect on the overall heat signature at the surface, reducing it some in the short term (as is currently occurring in Nino1.2). 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'.
TAO Array: (8/13) 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 (holding), the direct effects of the July massive WWB. A large warm reservoir at +5-7 deg above normal is poised to erupt into Ecuador. That reservoir is holding coverage with +7 degs anomalies centered at 110W (holding) and extending east from 141W to Ecuador (holding). 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. 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.
North Pacific Jetstream: As of Thurs (8/13) a weak flow was continuous across the North Pacific roughly centered at 48N. A bit of a .cgiit was occurring from the dateline westward. This is not impressive but suggests some weak influence by El Nino is occurring by virtue of the jet being present at all south of the Aleutians. More of the same is forecast over the coming week but with a ridge building in the Gulf of Alaska Sun-Mon (8/17) pushing the jet there up to 58N) then falling back to 55N. 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 8/13 for the Nino 3.4 region, peak temperatures have stabilized. It suggests water temps are at +1.6 deg C (verified at 1.62 degs today) and are to steadily warm continuing to +1.9 degs by Oct peaking at +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.
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.
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.
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, 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
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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