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Pacific Storm and Surf Forecast
Updated: Monday, September 21, 2020 4:58 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
3.3 - California & 2.3 - Hawaii
Using the 'Summer' 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 9/21 thru Sun 9/27

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   

New Zealand Swell Weakly Hitting CA
Gales Building in Gulf and SPac

On Monday, September 21, 2020 :

  • Buoy 233 (Pearl Harbor Entrance)/Buoy 239 (Lanai): Seas were 3.2 ft @ 15.4 secs with swell 1.7 ft @ 15.1 secs from 191 degrees.
  • Buoy 106 (Waimea): This buoy is currently not operating (ceased service at 9/15 - 19Z). Water temp 81.0 degs.
  • Buoy 46025 (Catalina RDG): Seas were 2.1 ft @ 13.7 secs with swell 0.9 ft @ 19.1 secs from 178 degrees. Wind at the buoy was north at 0-2 kts. Water temperature 67.5 degs. At Harvest Buoy (071) primary swell was 3.2 ft @ 6.8 secs from 302 degrees. At Santa Monica (028) swell was 0.7 ft @ 20.3 secs from 215 degrees. At Oceanside (045) swell was 1.0 ft @ 20.2 secs from 200 degrees. Southward at Point Loma (191) swell was 1.0 ft @ 20.3 secs from 209 degrees.
  • Buoy 46012 (Half Moon Bay)/029 (Pt Reyes): Seas were 4.5 ft @ 6.7 secs with swell 3.8 ft @ 6.4 secs from 314 degrees and southern hemi swell 1.1 ft @ 19.8 secs. Wind at the buoy (012) was northwest at 14-16 kts. Water temp 55.0 degs (013), 59.7 degs (SF Bar) and 57.2 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 (9/21) in North and Central CA local northwest windswell was producing waves at thigh high on the sets and pretty junky and crumbled from northwest winds. Protected breaks were thigh to wiast high and clean but weak. At Santa Cruz waves were thigh to waist high on the sets and clean and lined up with fog on top. In Southern California/Ventura waves were waist to almost chest high on the sets and peeling but soft and weak. Central Orange County had set waves at waist to rarely chest high coming from the south and clean and soft. South Orange County's best summertime breaks had set waves at chest high and clean and peeling but soft. North San Diego had sets at waist high and clean and lined up with overcast early. Hawaii's North Shore was flat and clean. The South Shore was getting fading southern hemi swell with set waves waist high and lined up and clean but inconsistent. The East Shore was getting minimal east windswell with waves waist high and lightly chopped early from modest east trades.

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

Meteorological Overview
On Tuesday (9/21) no meaningful locally generated windswell was occurring in North or Central CA or along the East Shores of the Hawaiian Islands. Minimal small southern hemi swell was fading in Hawaii an trying to develop in California having been generated by a gale that tracked under New Zealand Fri-Sat (9/12) with up to 43 ft seas aimed east. And another system developed under New Zealand on Sat (9/19) tracking east through the deep Central and Southeast Pacific into Tues (9/22) producing seas up 41 ft aimed east. Up north a gale was starting to develop in the far northwestern Gulf Mon-Wed (9/23) with up to 28 ft seas projected aimed well east and southeast. And maybe another to follow behind it in the Northeast Gulf on Fri-Sat (9/26). And maybe another to follow. So there's hope both north and south but the focus is turning decidedly to the north.

See all the details below...


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

North Pacific

Surface Analysis
On Monday (9/21) swell was starting to be generated from a gale tracking through the Northwestern Gulf of Alaska (see northwestern Gulf Gale below).

Over the next 72 hours no additional swell production is forecast.

Northwestern Gulf Gale
A low pressure system started traversing the far Northwest Pacific on Sat PM (9/19) tracking just south of the Aleutian Islands producing a small area of up to 27 ft seas at 51N 173W aimed east on Sun PM (9/20) but not getting interesting till Mon AM (9/21) when the low is to start falling southeast some over the Eastern Aleutians producing 35 kt northwest winds with seas building in coverage at 27 ft at 49.5N 167.5W aimed southeast. In the evening northwest winds to increase in coverage at 35 kts with seas building to 28 ft at 47.5N 161,5W aimed southeast. On Tues AM (9/22) the gale is to fall southeast over the Central Gulf of Alaska producing 35-40 kt northwest winds over a decent sized area with seas 28 ft at 45.5N 154.5W aimed southeast. The gale is to fade some in coverage in the evening while tracking east with 35 kt northwest winds and seas 29 ft at 45.5N 152W aimed southeast. More of the same is forecast Wed AM (9/23) with northwest winds 35 kts over the Central Gulf approaching the Pacific Northwest with seas fading from 27 ft over a solid area at 44.5N 148W aimed southeast. Fetch is to be fading in the evening from 30 kts with seas fading from 24 ft at 45.5N 144.5W aimed southeast. The gael is to dissipate from there. This forecast has held pretty decent for days now and is likely to produce swell.

North CA: Rough data suggests swell arrival late Thurs (9/24) building to 7.0 ft @ 15-16 secs (10.5 ft). Swell continues on Fri (9/25) at 7.5 ft @ 14-15 secs (10.5 ft). Residuals fading on Sat (9/26) from 5.2 ft @ 13 secs early (6.5 ft). More on Sun (9/27) Swell Direction: 300-305 degrees


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


Tropical Update
No tropical system are being monitored.

California Nearshore Forecast
On Monday (9/21) northwest winds were blowing at 15-20 kts limited to Pt Arena with northwest winds 10 kts south of there early. Northwest winds to build to 15+ kts everywhere in North and Central CA later. No meaningful windswell production is forecast. Tues (9/22) northwest winds are to be 15 kts for North CA and 10 kts for Central CA early and near 15 kts everywhere in the afternoon. Low pressure is to be filling the Gulf of Alaska. No windswell production is forecast. Wed (9/23) northwest winds to be 10 kts or less except 15 kts near Big Sur early building to 15-20 kts for all of Central CA in the afternoon. South winds to be building into the afternoon at 15-20 kts for Cape Mendocino. On Thurs (9/24) northwest winds are forecast at 15-20 kts for Central CA south of Monterey Bay early and northwest 10 kts for North CA early building to 15 kts for all of North and 20 kts for all of Central CA later. Rain for Cape Mendocino holding through the day. On Fri (9/25) northwest winds are forecast at 20 kts for all of North and Central CA early holding through the day. Sat (9/26) northwest winds are forecast at 20-25 kts for all of North CA early and 10 kts south of the Golden Gate holding all day. Sunday (9/27) northwest winds to be 20-25 kts streaming down North CA, but near calm all day over Central CA all day. Monday (9/28) north winds to be 20-25 kts for North CA early and fading in coverage later with light winds for Central CA all day building up to Pt Arena later.

Total snow accumulation for the week for Squaw Valley, Sugar Bowl, Kirkwood and Mammoth at 0, 0, 0 and 0 inches respectively. Freezing level down to 12,500 on 9/21-9/23, then above 14,000 ft after that.

Snow Models: (Scroll down for resort specific forecasts). Updated!


South Pacific

On Monday (9/21) the southern branch of the jet was pushing firmly east under New Zealand at 150 kts on the 58S latitude line clear of the Ross Ice Shelf and rising slightly northeast over the Central South Pacific forming a weak trough offering support for gale development. East of there the jet was falling southeast east of the California swell window pushing over Antarctic Ice offering no support for gale development. Over the next 72 hours that pocket of wind energy is to continue flowing mostly zonally west to east on the 57S latitude line over the entirety of the South Pacific on Tues (9/22) still supporting gale development, but with the focus moving east and effectively east of the Southern CA swell window on Wed PM (9/23) with support for swell development ending then. Beyond 72 hours the jet is to start falling southeast later Fri 99/25) pushing south of the Antarctic Ice Line offering no support for gale development with a full on ridge evolving over the Southwest Pacific on Sun (9/27) and sweeping east fast eliminating support for gale development over the entirety of the South Pacific. But on Mon (9/28) a new trough is to start building south of New Zealand with 110-120 kt southwest winds lifting northeast to 52S offering some support for gale development southeast of New Zealand. Something to monitor.

Surface Analysis
On Monday (9/21) swell from a New Zealand gale was tracking northeast and impacting California while fading out in Hawaii (see Stronger New Zealand Gale below). And another gael developed under New Zealand and was tracking east (See South Pacific Gale below).

Over the next 72 hours no swell producing fetch of interest is forecast.


Stronger New Zealand Gale
A new gale started building southwest of New Zealand on Fri PM (9/11) producing 45-50 kt west winds over a decent sized area with seas to 43 ft at 56.5S 158E.5 aimed east (218 degs SCal, 216 degs NCal and shadowed by NZ for HI). On Sat AM (9/12) west-southwest winds were pushing east over a decent sized area at 40-45 kts with seas 44 ft at 57.5S 169E aimed east (213 degs SCal and shadowed by Tahiti, 212 degs NCal and unshadowed, 197 degs HI). In the evening fetch was aimed better northeast at 35-40 kts with seas fading from 39 ft at 58S 180W aimed east-northeast (209 degs SCal and still shadowed, 208 degs NCal and shadowed by Tahiti, 192 degs HI). On Sun AM (9/13) fetch was fading from 30 kts over broad area aimed northeast with seas fading from 33 ft at 57S 170W aimed northeast (206 degs SCal and unshadowed, 205 degs NCal and still shadowed, 186 degs HI). The gale was gone after that. Some small swell is possible for California with tiny sideband swell for Hawaii.

Hawaii: Expect swell arrival on Fri (9/18) building to 1.0 ft @ 20-21 secs late (2.0 ft). Swell peaking on Sat (9/19) at 1.2 ft @ 18 secs mid-day (2.0 ft). Swell fading on Sun (9/20) fading from 1.1 ft @ 16 secs (1.5-2.0 ft). Swell Direction: 200 degrees

Southern CA: Expect swell arrival on Sun (9/20) building to 1.3 ft @ 20-21 secs later (2.5 ft). Swell building on Mon (9/21) to 1.7 ft @ 19 secs (3.0 ft). Swell continues on Tues (9/22) at 1.8 ft @ 17 secs mid-day (3.0 ft). Swell fading Wed (9/23) from 1.7 ft @ 16 secs (2.5 ft). Swell dropping on Thurs (6/24) from 1.3 ft @ 15 secs early (2.0 ft). Swell Direction: 213 degrees

North CA: Expect swell arrival on Sun (9/20) building to 1.2 ft @ 20-21 secs later (2.5 ft). Swell building on Mon (9/21) to 1.6 ft @ 19 secs (2.5-3.0 ft). Swell continues on Tues (9/22) at 1.7 ft @ 17-18 secs mid-day (3.0 ft). Swell fading Wed (9/23) from 1.6 ft @ 16 secs (2.5 ft). Swell dropping on Thurs (6/24) from 1.3 ft @ 15 secs early (2.0 ft). Swell Direction: 213 degrees


South Pacific Gale
A gale started developing under New Zealand just off the Ross Ice Shelf on Sat PM (9/19) producing a 40-45 kt southwest winds resulting in seas at 38 ft aimed east at 59.5S 179.5W tracking east. On Sun AM (9/20) southwest winds were 40 kts over a solid area with seas building to 39 ft at 60S 172W aimed east-northeast. In the evening southwest winds built to 40-45 kts over a broad and solid area aimed east-northeast with seas 40 ft at 59.5S 162.5W aimed east-northeast. On Mon AM (9/21) 40 kt west-southwest winds were covering a large area with seas 40 ft at 59S 150W aimed east-northeast. Fetch is to start fading in the evening while pushing east at 40 kts from the west still over a solid area with seas fading from 37 ft at 57.5S 135.5W aimed east. On Tues AM (9/22) fetch is to be fading over the far Southeast Pacific and seas 34 ft at 58S 120W aimed east. In the evening a lingering fetch of west winds to to hold at 40-45 kts barely in the SCal swell window with seas 33 ft at 53S 120W aimed east. This system is to build some while tracking east offering energy only up into Chile. Something to monitor.

Hawaii: Expect swell arrival on Sat (9/26) building to 1.1 ft @ 19 secs late (2.0 ft). Swell building some on Sun (9/27) to 1.4 ft @ 17 secs (2.0-2.5 ft). Swell holding on Mon (9/28) at 1.5 ft @ 15-16 secs (2.0-2.5 ft). Swell Direction: 195 degrees

Southern CA: Expect swell arrival on Sun (9/27) building to 1.3 ft @ 23 secs at sunset (2.5 ft). Swell building on Mon (9/28) to 2.3 ft @ 20 secs later (4.5 ft). Swell Direction: 198 degrees

North CA: Expect swell arrival on Sun (9/27) but not rideable yet with period 23-24 secs late. Swell building on Mon (9/28) to 2.0 ft @ 21 secs later (4.0 ft). Swell Direction: 197 degrees


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 another small gale is forecast developing in the far Northeastern Gulf of Alaska on Sat AM (9/26) with 35-40 kt west winds and seas building to 20 ft at 51N 149W aimed east. The gale is to track northeast in the evening with 40 kt west winds and seas building to 26 ft at 53.5N 142W aimed east and moving east of the North CA swell window. The gale is to hold on Sun AM (9/27) off North Canada with 30 ft seas targeting British Columbia and maybe the Pacific Northwest. Something to monitor.


South Pacific

Beyond 72 hours no swell producing fetch is forecast.


MJO/ENSO Forecast


Cold Water and La Nina Building

MJO/ENSO Discussion
The Madden Julian Oscillation (MJO) 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.

And the El Nino/La Nino cycle (collectively know as ENSO - El Nino Southern Oscillation) is a less frequent (about once every 7 years) but more impactful cycle that affects world wide weather. Specifically, strong El Nino events promote storm production in the Pacific while La Nina events suppress storm production. These therefore have a significant impact on the production of swell and surf. The paragraphs below analyze the state of the MJO and ENSO in the Pacific and provide forecasts for upcoming activity (or inactivity depending on the state and interaction of these two oscillations).

Overview: A double dip La Nina was in control 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 to declare El Nino and not coupled with the atmosphere. In January 2019, those warm waters were fading, but then rebuilt late in Feb associated with Kelvin Wave (#3). But as of early June 2019 warm water was fading and by August a tongue of cool water was tracking west on the equator from Ecuador over the Galapagos reaching to a point nearly south of Hawaii. El Nino was dead. A bit of a recovery occurred during Fall of 2019, with weak warm water building in the Nino 1.2 region, but cool water held in a pool off Peru and had not changed until March 2020. By April the cool pool pushed east and by May subsurface cool waters erupted off Ecuador, forming a well defined cool tongue that looked like the start of La Nina, holding into July 2020.

Fall/Winter 2020/2021 = 3.0/3.5 (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: It is assumed the PDO has moved to the warm phase in 2014 and that a weak borderline El Nino from 2018 faded out in the Fall of 2019. A La Nina like ocean temperature pattern developed in the equatorial East Pacific in the summer of 2019, then faded and returned to a neutral if not weak warm status during the Winter of 2019-2020 only to return stronger in the Summer of 2020. We have been suspecting a turn towards a La Nina like atmospheric pattern to develop in the late Winter/early Spring of 2020. Our best hope is that moderation from the warm phase of the PDO might tamp down development of a full blown La Nina as we move into 2020. But at this time that does not appear likely. Given all that, for the 2020 there is decent probability for development of La Nina meaning a reduced number of storm days and storm intensity during the summer season, resulting in a below normal level of swell, with swell being below normal duration and period. And by the Fall and early Winter of 2020/21, the number of storm days, intensity and duration of those storms should fade even more, resulting in depressed swell production. This pattern is expected to hold through the Spring of 2021.

KWGA/Equatorial Surface Wind Analysis & Short-term Forecast (KWGA - Kelvin Wave Generation Area - The area 5 degrees north and south of the equator from 170W to 135E)
Analysis (TAO Buoys): As of (9/20) 5 day average winds were strong from the east over the Eastern equatorial Pacific continuing over the Central Pacific and strong from the east over the KWGA. Anomalies were moderate east over the East equatorial continuing over the Central Pacific and then building in coverage at moderate easterly over the KWGA. (Note: These are 5 day average winds, so they lag what is happening today by about 2 days).
1 Week Forecast (GFS Model): On (9/21) strong east anomalies were filling the KWGA today extending east to a point south of California on the equator. The forecast calls for east anomalies holding at strong status filling the KWGA through the end of the model run on 9/28. Support for energy transfer into the jet is weak and is expected to continue that way if not weakening more for at least the next week.

Kelvin Wave Generation Area wind monitoring model: West and East

Longer Range MJO/WWB Projections:  
OLR Models: (9/20) A weak Active MJO signal was over the KWGA today. The statistic model indicates the Active MJO pattern is to hold at weak status on day 5 fading to near neutral on day 10 then neutral on day 15. The dynamic model suggests the Active Phase is to hold a weak Active Status in the KWGA unchanged through day 15.
Phase Diagrams 2 week forecast (ECMF and GEFS): (9/21) The statistical model depicts the Active Phase was weak over the Maritime Continent today and is to collapse while tracking east into the West Pacific and near nothing at day 15. The GEFS model suggests the same thing but maybe the Active Phase at weak status on day 15 over the West Pacific.
40 day Upper Level Model (assumed to be a statistical mode and 1 week ahead of what is occurring at the surface): (9/20) This model depicts a strong Inactive MJO was pushing into and over Central America today. A weak Active pattern was over the Central Pacific and is to traverse east pushing into Central America on 10/18 having some limited benefit to storm production. A new weak to modest Inactive Phase of the MJO is to start building over the Maritime Continent 10/15 and tracking to the Central Pacific at the end of the model run on 10/30.
4 Week CFS Model (850 mb wind): (9/20) This model depicts no coherent MJO signal today but with moderate east anomalies filling the KWGA and all of the equatorial Pacific. The forecast indicates no MJO is forecast for the future with east anomalies steadily weakening over the KWGA through 8/29 then rebuilding to strong status starting 10/6 through the end of the run on 10/18. No real west anomalies are forecast in the KWGA other than a few days near 10/4. Overall a long run of easterly anomalies remain forecast in the KWGA.
3 Month CFS Model (850 mb wind): (9/21 - using the 4th/latest ensemble member): This model depicts a weak Active Phase of the MJO starting to build over the far west KWGA today with east anomalies from a previous Inactive Phase of the MJO over the eastern KWGA exiting to the east. The Active Phase is to weaken while pushing east and gone on 9/30 producing no west west anomalies. No MJO signal is forecast beyond to 10/22 with weak west anomalies in pockets in the Western KWGA and east anomalies on the dateline and points eastward. The Active Phase is to return in earnest on 10/23 coherently traversing the KWGA through 11/25 producing modest to strong west anomalies filling the KWGA and those anomalies moving over the East Pacific in the later part of that timeframe. Interesting. A strong Inactive Phase is to follow 11/8 tracking east through the end of the model run on 12/19 with modest west anomalies holding in the KWGA with east anomalies gone from the KWGA but holding over the East equatorial Pacific. This provides some hope. The low pass filter indicates a high pressure bias is firmly in control over the dateline today reaching east to a point south of California and is to hold in coverage through the end of the model run while perhaps easing east some. A second contour set up on 9/14 on the dateline and is to hold through the end of the model run. The western edge of the high pressure bias is to be slowly moving east through the period positioned on the dateline at the end of the model run. A single contour low pressure bias is over the Indian Ocean today and is to build in coverage through the end of the model run with its eastern periphery easing east to 160E at the end of the model run. But its core is to show no signs of moving east locked over the Indian Ocean. East anomalies that have been previously solid in the Indian Ocean for over a year are migrating east through the West Pacific today and should continue tracking east then stabilizing setting up over the East Pacific late Sept and holding for the foreseeable future. The trend is turning towards La Nina. The good news is that at least at this early date, this might end up being a short lived event.

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

Subsurface Waters Temps
TAO Array: (9/21) Today in the far West Pacific the 30 deg isotherm was gone. The 29 deg isotherm was stable at 165E today. The 28 deg isotherm line was easing east to 170W today. The 24 deg isotherm was stable at 133W today. Anomaly wise, warm anomalies +0-1 deg C were steady and perhaps trying to ease east some moving from the West Pacific 1to 155W at depth today. There was a large pocket of cooler anomalies at -2 degs filling the entire area east of there and bubbling up to the surface over that entire area. The hi-res GODAS animation posted 9/15 indicates the cool water bubble at depth was stronger and larger erupting to the surface from 160W eastward to Ecuador with a core to -4.5C but with cool anomalies even west to there to 170E. Warm anomalies were below the surface over the far West Pacific reaching east to 165W at depth (150m). The GODAS animation appears to be 1 week behind the TAO data but also is more detailed and accurately modeled.
Sea Level Anomalies: (9/15) Negative anomalies were forming a wave pushing west from the Galapagos to 160W with negative anomalies -5 to -15 cms. Negative anomalies were weak but still present along the coast of Peru up into Ecuador at -5 cms and then reaching north up to Baja and into Southern CA. No positive anomalies were over the equatorial Pacific, except from the dateline and points west of there.

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: (9/21) The latest images indicate cold anomalies were on the equator from Ecuador west to the dateline and solid in density over that entire and large area. Markedly cold anomalies were imbedded between the Galapagos to 135W. Cool anomalies were also holding along the coasts of Chile and Peru. This clearly indicates a well developed version of La Nina. Warm water was all but gone off Central America north of the equator. Overall the cool pool on the equator was unmistakable and starting to show signs of rebuilding after previously being stalled.
Hi-res 7 day Trend (9/20): A weak cooling trend was positioned from just west of Ecuador over the Galapagos and west to 165W, perhaps building some compared to days past. 2 pockets of warming were interspersed from Ecuador to 140W but not of interest.
Hi-res Overview: (9/18) A stream of consistent cool water is well entrenched from Chile up to Peru and Ecuador then tracking west on the equator out to the dateline. A clear La Nina signal is depicted.
Nino1.2 Daily CDAS Index Temps: (9/21) Today's temps were rising slightly to -1.731 degs after previously reaching a momentary low of -2.138 on 8/13. The trend has been steady but quite cold since June.
Nino 3.4 Daily CDAS Index Temps:
(9/21) Temps were falling hard today dropping to -0.926, the lowest so far in the La Nina event. The previous low was -0.733 on 9/10. Temps have been on a steady decline since 7/25. Before that temps were stable between 6/27-7/24 at near 0.0. And before that temps were rising after bottoming out down at -0.595 on 5/27. Overall the trend appears to be in a steep decline.

Click for Full Sized Image Click for Full Sized Image

CFSV2 Forecast for Nino3.4 Sea Surface Temp (SST) Anomalies & Current SST Anomalies

SST Anomaly Projections
CFSv2 Uncorrected Data (9/21) Actual temperatures were in the +0.65 deg range early this year through March, then started falling down to -0.20 in late-May before stabilizing near neutral into late June. They began falling again in July down to -0.80 mid-Aug. The forecast depicts a steady downward trend from here reaching down to -1.75 degs in late Nov holding in early Dec then beginning to rise in later Dec, rebuilding up to +0.00 degs in May. We think the dynamic models might be overstating the magnitude of the coming cooling trend for the equatorial Pacific, but maybe not too much.
IRI Consensus Plume: The August 21, 2020 Plume depicts temps are at -0.52 degs today, and are to fall in early Nov to -0.60 degs then moderating and starting to rise some to -0.35 by Jan 2021 and then neutral by March. The low outlier is a dynamic models (NASA GMAO). But a good plethora of models are now suggesting a developing modest La Nina. See chart here - link.

Atmospheric Coupling (Indicating the presence of El Nino in the atmosphere driven by the ocean):
Southern Oscillation Index (SOI) (negative is good, positive bad - this is a lagging indicator) (9/21): The daily index was positive today at 14.32. The 30 day average was rising some to +9.01. The 90 day average was rising to 6.37, suggesting a neutral ENSO pattern was in control and trending towards La Nina. This index is a lagging indicator.
ESPI Index (like SOI but based on satellite confirmed precipitation. Positive and/or rising is good, negative and/or falling is bad): June -0.67, May -0.46, April 2020 -0.69, March -0.09, Feb +0.65, Jan +0.42, This index was steady positive Aug 2018 through Feb 2020, and now is steady negative, but only weakly so.

Pacific Decadal Oscillation
Per NOAAs index recent values: Jan 2018 +0.29, Feb -0.19, Mar -0.61, April -0.89, May -0.69, June -0.85, July -0.09, Aug -0.43, Sept -0.46, Oct -0.75, Nov -0.78, Dec -0.12, Jan 2019 -0.18, Feb -0.50 Mar -0.23, April +0.10, May +0.14, June -0.11, July +0.44, Aug -0.14, Sept +0.05, Oct -0.96, Nov -0.28, Dec +0.01, Jan 2020 -1.17, This continues to look like the warm phase of the PDO. No consistently solid negative readings have occurred since Feb 2014
The Washington/JISAO index (Jan-Dec): Jan 2018 +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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