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Pacific Storm and Surf Forecast
Updated: Tuesday, December 18, 2018 5:21 PM
Buoys: Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Buoy Forecast:
Northern CA - Southern CA - Hawaii - Gulf of Alaska - Pacific Northwest
Pacific Links:  Atmospheric Models - Buoy Data - Current Weather - Wave Models
Forecast Archives: Enter Here
A chronology of recent Mavericks Underground forecasts. Once you enter, just click on the HTML file forecast you want to review (e.g. 073199.html equals July 31, 1999). To view the maps that correspond to that forecast date, select the html file labeled 073199 maps.html
5.1 - California & 4.2 - Hawaii
Using the 'Winter' Scale
(See Swell Category Table link at bottom of page)

Probability for presence of largest swells in near-shore waters of NCal, SCal or Hawaii.    

Issued for Week of Monday 12/17 thru Sun 12/23

Swell Potential Rating Categories
5 = Good probability for 3 or more days of Significant swell
4 = Good probability for 1-2 days of Significant swell
3 = Good probability for 3 or more days of Intermediate/Advanced swell
2 = Good probability for  1-2 days of
Intermediate/Advanced swell
1 = Good probability for 3 or more days of Impulse or Windswell
0 = Low probability for 1-2 days of Impulse or Windswell   

Swell #3 Fading in CA
Swell #4 Hitting Hawaii & Pushing East

On Tuesday, December 18, 2018 :

  • Buoy 233 (Pearl Harbor Entrance)/Buoy 239 (Lanai): At Barbers Point seas were 4.3 ft @ 18.2 secs with swell 2.7 ft @ 18.9 secs from 306 degrees.
  • Buoy 106 (Waimea): Seas were 6.8 ft @ 18.2 secs with swell 4.5 ft @ 19.0 secs from 327 degrees.
  • Buoy 46025 (Catalina RDG): Seas were 7.9 ft @ 17.2 secs with swell 5.8 ft @ 16.7 secs from 261 degrees. Wind at the buoy was southwest at 2-6 kts. Water temperature 62.4 degs. At Ventura (Buoy 111) swell was 3.8 ft @ 10.3 secs from 275 degrees. At Santa Monica (028) swell was 4.8 ft @ 17.4 secs from 263 degrees. At Oceanside (045) swell was 3.0 ft @ 14.9 secs from 264 degrees. Southward at Pt Loma (191) swell was 5.8 ft @ 17.1 secs from 275 degrees.
  • Buoy 46012 (Half Moon Bay)/029 (Pt Reyes): Seas were 13.1 ft @ 15.4 secs with swell 10.2 ft @ 14.8 secs from 290 degrees. Wind at the buoy (013) was southeast at 12-16 kts. Water temp 58.6 degs (042).

See Hi-Res Buoy Dashboards (bottom of the page)

Swell Classification Guidelines

Significant: Winter - Swell 8 ft @ 14 secs or greater (11+ ft faces) for 8+ hours (greater than double overhead).
- 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).
- 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.
- up to waist high swell. Also called 'Background' swell.

Surf Heights for Hawaii should be consider 'Hawaiian Scale' if period exceeds 14 secs.

Current Conditions
On Tuesday (12/18) in North and Central CA swell from Storm #3 was still hitting with waves 15 ft and cleaner and lined up with offshore winds at some breaks but still a little bit jumbled. Protected breaks were 3-4 ft overhead and pristine clean and closed out. At Santa Cruz surf was 3-4 ft overhead and sometimes bigger and clean and lined up. In Southern California/Ventura surf was the best it's been in a very long time with set waves 3 ft overhead and lined up and clean and racing down the point. In North Orange Co surf was 2 ft overhead and clean and lined up pushing hard out of the north. South Orange Country's best breaks were chest high and clean and lined up. In North San Diego surf was 3 ft overhead on the sets and clean and lined up. Hawaii's North Shore was getting new swell from Storm #4 with waves double overhead on the sets and clean and lined up. The South Shore was flat to thigh high and clean. The East Shore was getting wrap around northwest swell with waves chest to shoulder high and pretty clean with light east trades.

See QuikCASTs for the 5 day surf overview or read below for the detailed view.

Meteorological Overview
On Tuesday (12/18) swell from strong Storm #3 was hitting California after previously tracking west over the dateline Thurs (12/13) with up to 44 ft seas aimed east then into the Western Gulf on Fri (12/14) with up to 49 ft seas then into the Central Gulf Sat (12/15) with seas 46 ft before fading Sun (12/16) with seas dropping from 40 ft. Large swell has resulted, but not as over the top as expected. And swell from another smaller but strong storm is starting to hit Hawaii after previously developing on the dateline on Sun (12/16) with 44 ft seas tracking over the dateline then east into the Western Gulf on Mon (12/17) with seas fading from 42 ft then dissipating 1100 nmiles off North CA on Tues (12/18) with seas dropping from 27 ft. After that a small storm is forecast for the Northern Gulf on Thurs-Fri (12.21) with up to 40 ft seas aimed east, then a break in the action. Maybe another system is to try and wind up in the Western Gulf on Tues-Wed (12/26). So the storm track to remain active, but not exceedingly so.

See all the details below...


Current marine weather and wave analysis plus forecast conditions for the next 72 hours

North Pacific

On Tuesday AM (12/18) the jet was consolidated with winds 170 kts pushing off Japan riding slightly over the dateline then falling into a trough in the Western Gulf of Alaska offering good support for gale development then tracking east and pushing into the CA-OR border with winds still in the 160 kts range. A solid jetstream follow was in effect. Over the next 72 hours more of the same is forecast with the trough pinching off and moving east to the Eastern Gulf on Thurs (12/20) with support for gale development fading. A new weaker trough is to try and develop while tracking east through the Northern Gulf on Thurs-Fri (12/21) offering some support for gale development. Beyond 72 hours the jet is to still be consolidated pushing the whole way across the North Pacific on the 35N latitude line with a trough developing on the dateline late Sun (12/23) and getting somewhat more organized into Tues (12/25) being fed by a weakening flow of 150-160 kts winds streaming off Japan. Support for gale development possible. Certainly there is no indication of the jet splitting or weakening as one would normally expect during the Inactive Phase of the MJO.

Surface Analysis
On Tuesday (12/18) swell from a strong storm that has pushed over the dateline and tracked through the Gulf was fading in California (see West Gulf Storm #3 below). And swell from another storm that previously pushed over the dateline was starting to show in Hawaii (see Storm #4 below).

Over the next 72 hours a new small storm is to develop in the Northwestern Gulf producing a small area of 50 kt northwest winds and seas 32 ft up at 49N 167W aimed southeast. In the evening northwest winds to be 45-50 kts targeting the US West Coast well with seas 40 ft at 48N 160W (357 degs HI, 305 degs NCal). The gale is to fade fast Fri AM (12/21) with west winds 40 kts targeting Vancouver Island and seas 36 ft at 48.5N 152.5W aimed east. This system to dissipate from there. Possible swell targeting mainly North CA and points north of there though energy will reach south to Pt Conception.


West Gulf Storm #3
A storm was building just west of the dateline Thurs AM (12/13) producing 55 kt west winds positioned decently to the south and tracking east with seas building from 38 ft over a small area at 42N 165E aimed east. In the evening 55 kt west winds were pushing east on the dateline and seas building to 44 ft at 42.5N 177E aimed east. The storm tracked east fast and building in the Western Gulf on Fri AM (12/14) with 50 kt west winds in it's core embedded in a broad area of 45 kt west winds and seas 44 ft at 42N 172.5W aimed east. In the evening northwest winds rebuilt to 50-55 kts over a solid area in the Central Gulf with 49 ft seas at 42.5N 160.5W. The storm is to be pushing east Sat AM (12/15) and fading with 45-50 kt west winds and seas 46 ft at 44N 152W aimed east. In the evening winds are to be fading and lifting northeast at 45 kts still over a solid area with 43 ft seas at 44N 147W. The gale is to be fading Sun AM (12/16) in the Northern Gulf with winds dropping from 35-40 kts and seas fading from 38 ft at 45N 144W. Large long period raw swell is possible for the US West Coast with more managed sideband swell for the Islands. Something to monitor.

North CA: Swell fading some overnight and dropping Tues AM (12/18) from 10.4 ft @ 15-16 secs (15.5-17.0 ft). Swell fading Wed AM (12/19) from 9.8 ft @ 13-14 secs (13 ft). Swell Direction: 292-295 degrees

Southern CA: Swell dropping Tues AM (12/18) 7.0 ft @ 17-18 secs (12 ft). Residuals on Wed AM (12/19) fading from 5.0 ft @ 15-16 secs (7.5 ft). Swell Direction: 299-302 degrees


Storm #4
Another strong storm started building west of the dateline Sat AM (12/16) with 45-50 kt northwest winds over a small area and seas building from 28 ft at 40N 166E aimed east. In the evening the storm was approaching the dateline with 50 kt west winds and seas building from 40 ft at 42N 174E aimed east. On Sun AM (12/16) 50 kt west-northwest winds were pushing east with 43 ft seas at 42N 178.5W aimed east. The storm tracked east in the evening and moderating with 45 kt west winds and seas 44 ft at 42N 170W aimed east. On Mon AM (12/17) the storm is to be down to gale status in the Western Gulf and fading with 40 kt west winds and seas fading from 41 ft at 41.5N 162.5W aimed east. In the evening the gale was fading with 35 kt west winds a bit off North CA and seas fading from 36 ft at 40.5N 154.5W aimed east. The gale was fading out Tues AM (12/18) with 35 kts west winds off Oregon and seas fading from 28 ft at 40N 146W aimed east mainly from previous fetch. Another bout of larger swell is possible.

Hawaii: Expect swell arrival on Tues (12/18) with swell building through the day peaking at 8.7 ft @ 17 secs (14.5 ft) just before sunset. Swell fading some over night and down Wed AM (12/19) to 8.4 ft @ 14-15 secs (12 ft) early. Residuals on Thurs AM (12/20) fading from 7.0 ft @ 12-13 secs early (8.5 ft). Dribbles fading on Fri AM (12/21) at 4.8 ft @ 11 secs (5 ft). Swell DIrection: 325 degrees moving to 350 degrees

North CA: expect swell arrival on Wednesday (12/19) just after sunset with period 20 secs and size building. Swell to build overnight peaking near 1 AM Thurs (12/20) at 9 ft @ 18-19 secs (16.5 ft). Swell fading at sunrise Thursday from 9.0 ft @ 16-17 secs (14-15 ft). Residuals on Fri AM (12/21) holding at 7.0 ft @ 13 secs (9.0 ft). Swell fading on Sat AM (12/22) from 4.8 ft @ 12-13 secs (5.5-6.0 ft). Swell Direction: 289-295 degrees

Southern CA: Expect swell arrival on at sunset on Wed (12/19) with period 22 secs and size barely noticeable. Swell builds as period hits 20 secs at 1 AM Thurs (12/20) and starting to peak just after sunrise at 4.2 ft @ 18 secs (7.5 ft). Swell holding through the day as period drops to 17 secs at sunset. Swell fading some on Fri (12/21) at 3.9 ft @ 16 secs all day (6.0 ft). Residuals on Sat (12/22) fading from 2.0 ft @ 13-14 secs (2.5 ft). Swell Direction: 293-300 degrees


  North Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height


Tropical Update
No tropical weather systems of interest are forecast.

California Nearshore Forecast
On Tuesday AM (12/18) a front is to stall over the Oregon-CA border with weak high pressure locked over San Francisco with south winds for Cape Mendocino at 20-25 kts but calm south of there but north 15 kts for Pt Conception. Light rain for Cape Mendocino all day reaching south to maybe Bodega Bay late. Wednesday (12/19) high pressure is to build north centered off Monterey Bay with light winds forecast for the entire coast but building south at 15 kts for Cape Mendocino late. Light rain for Cape Mendocino early. Thursday (12/20) a local low is to be pushing northeast into the Pacific Northwest with weak high pressure holding locally off Central CA and light winds for all of Central CA and south winds 15-20 kts for Cape Mendocino and 5-10 kts down to Pt Reyes later. Rain for Cape Mendocino reaching south to Pt Reyes late evening. Fri (12/21) north winds are forecast for Cape Mendocino early at 15 kts then building over all of North and Central CA to 15 kts at sunset. Light rain for Pt Arena to San Francisco early fading out by 10 AM. Light snow for Tahoe through 10 AM. Saturday (12/22) high pressure builds with north winds 10-15 kts for all of North and Central CA. Sunday (12/23) high pressure is to be weakly ridging into the SF Bay Area with light winds there but a front pushing into Oregon with south winds 15-20 kts for Cape Mendocino and north winds 15-20 kts for Pt Conception. Light rain down to Pt Arena. Monday (12/24) a new low is to be building just off the Oregon coast with southwest winds 15-20 kts from Pt Reyes and points north of there early turning to north winds 20-25 kts later reaching south to Pt Conception. Rain moderate to heavy for Cape Mendocino early building south to San Francisco mid day pushing to Pt Conception late. Heavy snow building for the entire Sierra mid-day peaking late afternoon and continuing but weaker through the evening. Tuesday (12/25) north winds to continue at 15 kts for the North coast and 20+ kts for the Central coast and 25 kts for South California and continuing through the day. Light rain for Pt Arena northward.

Total snow accumulation for for the week for North Lake Tahoe 16-20 inches and 4-6 inches for Mammoth.


South Pacific

Surface Analysis  
No swell of interest was in the water.

Over the next 72 hours no swell producing weather systems of interest are forecast.


South Pacific Animations: Jetstream - Surface Pressure/Wind - Sea Height - Surf Height




Marine weather and forecast conditions 3-10 days into the future

North Pacific

Beyond 72 hours a broad area of generic low pressure is to be developing between the Kuril Islands and the dateline on Fri (12/21) generating 35 kt west fetch and no particular seas of interest. That low is to push east and start redeveloping in the Northwestern Gulf of Alaska on Mon (12/24) lifting quickly northeast with a secondary larger fetch building behind on the dateline on Tues (12/25) with with 35-45 kt west winds over a solid sized area on Tues AM (12/25) with seas 30-35 ft in two pockets at 44N 167W and 40N 180W and 20+ ft seas connecting them. Something to monitor.


South Pacific

Beyond 72 hours no swell producing weather systems of interest are forecast.


MJO/ENSO Forecast


Atmosphere Continues ENSO Neutral - Sea Surface Slowly Warming

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 equator it is in control of, and in it's Active Phase by slackening if not an outright reversing trade winds while enhancing 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, 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 in the Pacific help support the formation of El Nino. During the Inactive Phase the jet stream tends to split resulting in high pressure and less potential for swell producing storm development. Wind anomalies in the Kelvin Wave Generation Area (KWGA) are key for understanding what Phase the MJO is in over the Pacific. The KWGA is located on the equator from 135E-170W and 5 degs north and south (or on the equator from New Guinea east to the dateline). West wind anomalies in the KWGA suggest the Active Phase of the MJO in the Pacific, and east anomalies suggests the Inactive Phase. In turn the Active Phase strengthens and the Inactive Phase weakens the jetstream, which in turn enhances or dampens storm production respectively in the Pacific.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: La Nina started developing in early 2016, but westward displaced and generally weak. And by March 2017, it was gone with suspicious warming developing along South America and over the Galapagos to a point south of Hawaii. By May the atmosphere returned to a neutral configuration but then in July east anomalies started building in the KWGA and have not stopped, with cold water upwelling over the the Nino1.2 and 3.4 areas, indicative of La Nina. A double dip La Nina was in control and continued through the Winter of 2017-2018. But warming started building along the South and Central American coast in early March 2018 associated with two upwelling Kelvin Waves, and continued trying to build over equatorial waters over the Summer and Fall, but not enough yet to declare El Nino and not coupled with the atmosphere.

Fall/Winter 2018 = 6.0 (California & Hawaii)
Rating based on a 1-10 scale: 1 being the lowest (small and infrequent surf conditions), 5 being normal/average, and 10 being extraordinary (frequent events of large, long period swells)

Rationale: Assuming the PDO has moved to the warm phase and that El Nino does not develop as strong as previously forecast, and assuming and an ocean-atmospheric coupling becomes weakly established in the January timeframe and ocean temperature anomalies in Nino3.4 build to the +0.6 deg range, there is good probability for slightly enhanced storm production in the North Pacific starting in the late Nov timeframe (specifically the Gulf of Alaska and Dateline regions) with slightly increased intensity in number of storm days and storm intensity, resulting in slightly increased odds for larger than normal swell, with increased duration and higher than normal period. This should be significantly better than the past 2 winter seasons.

KWGA/Equatorial Surface Wind Analysis & Short-term Forecast:
Analysis (TAO Buoys): As of (12/17) 5 day average winds were strong from the east over the Eastern equatorial Pacific to the dateline, then fading over the Eastern KWGA with light to moderate west winds over the Central KWGA. Anomalies were neutral over the far East equatorial Pacific turning strong easterly near the dateline then weak westerly in the core of the KWGA.
1 Week Forecast (GFS Model): On (12/18) strong east anomalies were over the dateline and in the eastern KWGA with moderate west anomalies in the mid-KWGA. The forecast is for this situation to generally hold into 12/22, then the east anomalies on the dateline are to vaporize while west anomalies remain solid in the western KWGA and those anomalies are to start migrating slowly east almost filling the KWGA at the end of the model run on 12/25. Support for storm development appears to be limited to the far West Pacific for the next 4-5 days with the Inactive MJO in control.

Kelvin Wave Generation Area wind monitoring model: West and East

Longer Range MJO/WWB Projections:  
OLR Models: (12/17) The Inactive Phase of the MJO was over the dateline with the Active Phase over the Maritime Continent trying to push into the far West Pacific. The statistical model indicates the Inactive Phase is to ease east and near out of the dateline region at day 5 and then gone after that with the Active Phase moving fully into the KWGA at day 10 holding into day 15. The dynamic model indicates the same thing initially but with the Inactive Phase not moving as fast to the east and still partially lingering over the dateline at day 15 while the Active Phase slowly builds in the far West Pacific. The 2 models are generally in sync.
Phase Diagrams 2 week forecast (ECMF and GEFS): (12/18) The ECMF model depicts the Active Phase of the MJO was moderately strong over the Western Maritime Continent. It is to track east steadily at moderate strength then stalling over the Eastern Maritime Continent then fading some there 2 weeks out. The GEFS model depicts the same thing but with the MJO holding strength. The 2 models are generally in sync.
40 day Upper Level Model: (12/18) This model is an outlier depicting a different situation than any other model. It shows a modest Active Phase of the MJO over the dateline moving east and inland over Central America on 1/7. An Inactive signal is to set up over the far West Pacific 1/4 tracking east and is to move over the East Pacific and into Central America on 1/27. A very weak Active Phase of the MJO is to build in the West Pacific 1/19 tracking east over the dateline at the end of the model run on 1/27/19.
4 Week CFS Model (850 mb wind): (12/17) This model depicts modest west anomalies were over the western KWGA with solid east anomalies on the dateline and those east anomalies are to fade over the next 5 days. After that modest west anomalies to hold in the heart of the KWGA building to strong status during the 2nd week of January as the Active Phase rebuilds through the end of the model run on 12/14.
3 Month CFS Model (850 mb wind): (12/18) This model depicts weak west anomalies were over the core of the KWGA with east anomalies on the dateline. The Inactive Phase of the MJO was past its peak in the KWGA and expected to fade some through 12/23 with east anomalies on the dateline dissipating too. After that a stronger Active MJO pattern is to develop 12/24 through 2/4 with west anomalies building in coverage filling the KWGA, possibly to o WWB status 1/8-1/21. A moderate Inactive Phase to follow starting 1/27 through 2/25, followed by the Active Phase holding through the end of the model run on 3/17 but with west anomalies still in control. The low pass filter indicates a low pressure bias is fully in control of the KWGA centered on the dateline reaching east over California and forecast holding through the end of the model run. A third contour line is fading 12/17 and to remain suppressed through 1/17, then reappearing thereafter. It appears from this model that El Nino is in control, but we know from other data this is not the case. The atmosphere and ocean are trying to become coupled towards El Nino in the Pacific Ocean, but there's no objective evidence of it occurring yet. If coupling has not happened yet (by Dec 15), it's doubtful there will be significant weather influence, even if it does develop during this winter cycle. And this model is not suggesting they will become coupled, with the MJO cycle active, and not muted as it would be during a strong El Nino. Still this pattern is to slowly become more favorable to support storm production in the Pacific regardless of whether El Nino develops, because the atmosphere is still turning from a La Nina pattern (that has been entrenched for the past 2 years) at a minimum towards a neutral one. Our assumption is a normal Winter pattern will result, or perhaps slightly enhanced, but nothing more.

CFSv2 3 month forecast for 850 mb winds, MJO, Rossby etc - Alternate link

Subsurface Waters Temps
TAO Array: (12/18) Today in the far West Pacific water temps are 30 degs and loosing some coverage (after previously reaching east to 175W on 12/11) reaching east today to 179W. The 28 deg isotherm line had retrograded west to 160W mid-Nov, then moved east and walled up, but has retrograded again today at 159W. The 24 deg isotherm was 125 meters deep at 140W then getting shallower east of there but pushing into Ecuador 25 meters down. Anomaly wise, warm anomalies are filling the entire subsurface Pacific with temps rebuilding in the Central Pacific at +4 degs at 150W (Possible Kelvin Wave #3). And temps are now stable at 3 degs east of there the whole way into Ecuador. It appears Kelvin Wave #2 is pushing into Ecuador and all but gone with new Kelvin Wave #3 west of the dateline. We were thinking the peak of the Kelvin Wave cycle for this supposed El Nino has already occurred associated with Kelvin Wave #2, but upwelling over Ecuador looks poised to continue nonstop for the next 4 months with the development and merging of Kelvin Wave #3 with Kelvin Wave #2. So there's great surface oceanic warming potential to feed jetstream core energy through the entirety of the 2018/2019 winter cycle. The hi-res GODAS animation posted 12/14 paints the same picture with the Kelvin Wave #2 in the East Pacific at +5 degs at 100W starting at 125W pushing into Ecuador and modest warming building at +3 degs under the dateline associated with Kelvin Wave #3. Kelvin Wave #2 was breaching the surface from 90W to 155W solidly with secondary warm anomalies west from there to 165E. The GODAS animation appears to be 1 week behind the TAO data but also is more detailed and accurately modeled.
Sea Level Anomalies: (12/14) Positive anomalies were solid from the interior Maritime Continent tracking east at 0 to +5 cms, then continuing east over the equator north of New Guinea at +5 cms extending steady into Ecuador.

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. All data is from blended infrared and microwave sensors.
Satellite Imagery
Hi-res Nino1.2 & 3.4: (12/17) The latest images (1.2 3.4) indicate temps were warm in a Kelvin Wave pattern straddling 5 degrees north and south of the equator from Ecuador west to the dateline, with a slightly warm imbedded pocket on the dateline and another building stronger today from Ecuador to 110W. Otherwise just generic steady warming was indicated. There is a stream of moderate warming along the immediate coasts of Chile and Peru and Ecuador and building in coverage. And the warming also extends north to Central America and Mexico and generally looked to be building in coverage. It's not a strong trend towards El Nino, but appears to be trending in that direction. But a pocket of cool waters was solid and steady elongated east to west off Peru to 130W. Overall the pattern looks weakly like El Nino, but also like lingering La Nina (given the cool pockets off Peru). In all this developing El Nino is weakly in control but still a bit fragile in the East Equatorial Pacific, but more stable than weeks past.
Hi-res 7 day Trend (12/17): A building broad area of warming water was developing on the equator from the Galapagos to 100W. A broad area of warming was fading along the coast of Chile and Peru.
Hi-res Overview: (12/17) Weak warm water was along the immediate coast of Chile and Peru. But more important, moderate warm water was on the equator from Ecuador over the Galapagos building out to the dateline. We have turned the corner from a cool regime a year ago to a warm regime now. And one could kinda think we are moving towards a El Nino pattern just looking at the surface temps. But that would be a false conclusion because the warm signal on the surface should be much stronger at this time of the year if El Nino were truly developing. We are in an ENSO neutral pattern biased warm and likely only going to move to a minimal warm regime, likely not reaching full El Nino status this winter.
Nino1.2 Daily CDAS Index Temps: (12/18) Today's temps were steady at +1.155 after falling to +0.212 on 12/3, after they built to +1.534 on 11/27. That peak on 11/27 was the all time high for this event in this region. A warming trend is steadily building.
Nino 3.4 Daily CDAS Index Temps:
(12/18) Today temps were stable at +0.539 after having previously risen to +1.050 degs on 12/6 but previously in the +0.5-+0.6 range since 11/12. The all time high for this event was +1.45 on 11/5, beating the previous peak temps of +0.795 on 10/9, and +0.649 on 9/27, and that beating the previous peak at +0.490 on 7/2. Overall temps are noodling around at +0.5 to +0.9 degs above normal adding suggesting some sort of minimally weak El Nino is trying to develop, but nothing serious.

Click for Full Sized Image

CFSV2 Forecast for Nino3.4 SST Anomalies

SST Anomaly Projections
CFSv2 Uncorrected Data (12/18) The model indicates temps were at +0.85 degs in early Dec (which wasn't even close to reality - they were actually about +0.6) then forecast rising some to +1.35 degs by Feb 1 holding to early May 2019, falling to +1.20 degs into July 2019 and down to 1.0 degs in Sept. If one is to believe the model then one would assume that El Nino is to build in the Winter of 18/19. But given all the data we've seen, we believe odds of weak El Nino are more likely. Most models are suggesting a turn to weak El Nino conditions by late Fall. It's not certain we're there yet.
IRI Consensus Plume: The mid-Nov Plume depicts temps are to slowly rise from here, to +1.00 degs in November and +1.0-+1.1 degs through Feb 2019, then slowly fading to 0.71 in July. See chart here - link. There's a 90% chance of a weak El Nino developing through January.

Atmospheric Coupling (Indicating the presence of El Nino in the atmosphere driven by the ocean):
Southern Oscillation Index (SOI) (negative is good, positive bad) (12/18): The daily index was rising to +21.90. The 30 day average was rising at +7.89 suggesting a neutral MJO. The 90 day average was rising some at 1.49, rising the past 3 weeks and no longer negative and the highest its been in months. The 90 degree average turned negative for the first time in a year on 6/30 suggesting a neutral ENSO pattern was building in the atmosphere. Unfortunately we have made no progress from there towards a negative El Nino pattern and if anything, have moved back to a positive regime.
ESPI Index (like SOI but based on satellite confirmed precipitation. Positive and/or rising is good, negative and/or falling is bad): (12/18) The index has risen slightly from at +0.03 on 12/3 to +0.28 on 12/15 and down today to +0.22, just barely positive and not as strong as it should be if El Nino were developing. Typically El Nino peaks in late December. If that is the case in this years event, then there's no way we're going to move into a legit El Nino this winter. It was down to -0.22 the week of 10/22, after having risen to +0.39 on 10/10, the highest so far this event. This suggests that precip and evaporation are normal, and not above normal as one would expect if El Nino were in play. We are in an ENSO neutral pattern. The reading from 8/14 (+0.11) was the first time it's turned positive in a year.
Pacific Decadal Oscillation: The PDO is weakly positive, even though La Nina is in play.
Per NOAAs index recent values: June 2017 +0.21, July -0.50, Aug -0.62, Sept -0.25, Oct -0.61, Nov -0.45, Dec -0.13, Jan 2018 +0.29, Feb -0.19, Mar -0.61, April -0.89, May -0.69, June -0.85, July -0.09, Aug -0.42, Sept -0.42. This continues to look like the warm phase of the PDO, even with La Nina, because the warm PDO appears to be dampening the effects of La Nina. No consistently solid negative readings have occurred since Feb 2014
The Washington/JISAO index (Jan-Dec): June 2017 +0.79, July +0.10, Aug +0.09, Sept +0.32, Oct +0.05, Nov +0.15, Dec +0.50, Jan +0.70. Feb +0.37, Mar -0.05, April +0.11, May +0.11, June -0.04, July +0.11, Aug +0.18, Sept +0.09. No real negative readings have occurred since Dec 2013
The PDO turned from a 16 year negative run (Jan 98-Feb 2014) in early 2014 and has been positive ever since (other than a few months of negative readings in Fall 2016, the result of a turn towards La Nina). Looking at the long term record, it is premature to conclude that we have in-fact turned from the negative phase (La Nina 'like') to the positive phase (El Nino 'like'), but the data strongly suggests that could be a possibility. By the time it is confirmed (4-5 years out), we will be well into it.

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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