Bob Blog 31 May

The state of the ENSO = neutral

 

It has been months since we have looked at ENSO, so here goes.

 

El Nino and La Nina are opposite ends of the swing of an identifiable tropical influence on our seasonal weather. The La Nina, caused by cooler than normal seas along the equatorial eastern pacific, shifts the subtropical ridge away from the equator, and the El Nino, with warmer than normal seas, draws the subtropical ridge closer to the equator. Their comings and goings can last several months, maybe over a year, and so their status can be used to help forecast the weather for the coming season.

 

The Atmosphere:

 

ENSO = El Nino/Southern Oscillation. The main parameter we watch from the atmosphere is the Southern Oscillation Index SOI (30 day running mean) as it sums up the whole weather pattern over the South Pacific in one number. It is based on the standardized difference in the barometer readings between Tahiti and Darwin, in other words it counts the average number of isobars between them on the weather map. When the SOI is more than plus one (standard deviation from its mean) for more than a month we call it a LA NINA event, and when it stays more than minus one we call it an EL NINO event.

 

Since a brief El Nino late in 2019 the ENSO has been neutral and the subtropical ridge line spent the Summer and Autumn moths mostly over central NZ, keeping troughs away from northern NZ (hence the droughts). This ridge line has recently become more variable and further north.

 

See  this at www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi&p=weekly

(Note that in this graph on the vertical axis 10= 1 standard deviation)

 

The Ocean:

The sea surface temperatures in the equatorial eastern Pacific has been warmish so far this year but now is showing a cooling ( La Nina) trend.

 

Sea temperatures, are seen at

www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

 

Seas

 

Seas have been warmer than normal in North Pacific Ocean, in swaths across Indian Ocean and Atlantic Ocean, an d from Fiji to the east of NZ Indian. There is a slight cooling in the eastern equatorial Pacific.

 

Also, Waters just beneath the surface are slightly cooler than normal. These trends are towards a La Nina.

 

 

The International Research Institute of the Climate Prediction Centre compiles data from several ENSO prediction models.

The model forecasts neutral condition s during our winter but the chance of a la Nina may rises to (a rather meger) 31% in our Spring ( with neutral chance dropping to 40%,and El Nino chance around 25%)

See CPC/IRI predictions from iri.columbia.edu/our-expertise/climate/forecasts/enso/current/

 

So the outlook is for a Neutral window, but we on watch for La Nina trends.

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

Quieter after MANGGA and a cold front combined over Perth early last week.

TD2 is affecting central America for now.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active around Solomon Island, over northern Vanuatu, Tuvalu, Samoa, and Tahiti.

A Tropical low may travel south over or south of the Tahiti area late in the week.

 

Subtropical ridge (STR)

HIGH 1034 east of South Island expected to travel east along 45S and grow to 1038hPa (wow) on Monday to Wednesday. -1028hPa is expected over Tasmanian on Monday, and should cross central and southern NZ on Thurs

Next HIGH 1026hPa is expected to move into central Tasman on Friday and ease to 1020 north of NZ over next weekend. n Thurs and cross southern NZ on Friday and then build to 1036hPa well east of NZ.

 

Tasman Sea /NZ/Aus

Low from the sub-tropics to travel south over North island from now to end of Monday(Queens Birthday holiday ).

Another active trough is likely to cross NZ on Tuesday night/Wednesday dripping to 996hPa SE of South Island, and followed on Thu by a strong southerly with large swells in the eastern Tasman Sea on Thu

 

From Panama: Not good this week, and maybe for the coming months. SW winds in Panama, and the ITCZ is visiting at times. It is most active/squally to3N. I reckon that the best way to tackle these SW winds is to go SSE then west.

 

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

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Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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Bob Blog 24 May

WEATHERGRAM

YOTREPS

Compiled Sun 27 May 2020

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

It was a busy week last week, with AMPHAN hitting NE India and Bangladesh hard , and an early Atlantic storm ARTHUR affecting eastern USA. Now MANGGA is threating Perth, Australia.

  

SPCZ=South Pacific Convergence zone.

The SPCZ is active around Solomon Island, building this week to north of Vanuatu and to N of Fiji, and then rather weak from Samoa to Tuamotu Islands.

A TROUGH may form around Fiji early next week.

 

Subtropical ridge (STR)

HIGH 1025-1028hPa is expected over Tasmanian on Monday, and should cross central and southern NZ on Thurs

Next HIGH 1028hPa is expected to cross Tasmania on Thurs and cross southern NZ on Friday and then build to 1036hPa well east of NZ.

 

Tasman Sea /NZ/Aus

A low is expected to cross northern and central NZ on Mon and then deepen to 950 hPa well off the SE of NZ, with up to 10m swells offshore.

Another low in the north Tasman Sea may bring wind and rain to northern NZ this weekend and Mon next week.

 

From Panama:

Not good this week, and maybe for the coming months. SW winds have arrived in Panama, and, although reasonably clear tonight, the ITCZ visits at times. It is most active/squally between 6 and 3N. I reckon that  the best way to tackle these SW winds is to go SSE then west.

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 If you would like more detail for your voyage, then check metbob.com to see what I offer.

Or Facebook at /www.facebook.com/metbobnz/

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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Bob Blog 17 May

WEATHERGRAM

YOTREPS

Compiled Sun 17 May 2020

 

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

Jetstreams

If you are having problems with working out where and when the systems on the (surface-based) weather map are going next, then it is worthwhile to check out the jetstream.

Jetstreams are rivers of wind found in the upper atmosphere where jets fly. They snake eastwards around the earth faster the earth’s normal eastward rotation, and often look like large waves marking passing troughs, and sometimes can have small buckles that play with the local weather below.

On average, there are TWO mains jetstreams affecting NZ weather-- the polar jet that is sometimes south of us and sometimes on top of us, especially when we have passing troughs. The other is a subtropical jet, sometimes just to north of us, but sometimes on top of us, especially when anything come to NZ from the tropics.

 

Jetstreams can tell us about development (invigoration) and decay (weakening) of surface weather.

In the southern hemisphere, expect development at the surface slightly north of a jetstream- entrance and south of jetstream-exit. Expect decay at the surface slightly south of a jetstream-entrance and north of a jetstream-exit.

 

As for a steering field for surface features, well, there are stagnant areas in the jetstream which indicate where surface weather may be stalling. However, for a better surface-steering indicator, go to windy,com and dial that height/altitude bar to around 850 maybe 800 or 700hpa.

 

The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

Today’s map shows TC AMPHAN in Indian Ocean heading north towards Bangladesh.

Also, a weakfish tropical depression of eastern USA.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ stretches from Solomon island to north of Fiji to norther Tonga for much of this week.

 

A LOW is predicted to form south of Tonga on Thursday and then go south, accentuating a squash zone of strong winds and swell between Fiji and NZ from Tuesday (between High to south and trough to NE).

 

Subtropical ridge (STR)

HIGH 1030hPa is expected to enter Tasman sea tonight and cross central NZ mid-week then go off east along about 40 to 35 S.

Next HIGH is expected to enter South Tasman Sea this weekend.

 

Tasman Sea /NZ/Aus

Trough over South Island Mon, North Island Tues.

Squash zone is expected between NZ and Fiji from Tuesday, travelling southeast on Thursday and south from Friday.

Low expected to form off Queensland this weekend and bring wind and rain to North island next week.

 

From Panama:

Not good this week, and maybe for the coming months. The SW winds arrive in Panama this week, and the ITCZ visits at times. I suppose the best way to tackle these SW winds is to go SSE then west

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

Or Facebook at /www.facebook.com/metbobnz/

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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bob Blog 10 May

WEATHER

YOTREPS

 

Compiled Sun 10 May 2020

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no cyclones around at present , and none are expected this week.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is slowly recovering after being drawn off to the east last week. It stretches from Solomon islands to N Vanuatu to Fiji to south of Tonga.

A LOW south of Fiji tonight is travelling SE next few days then south along 170W for  several  days.  On  Friday  it’ll likely be 996 hPa.

 

Subtropical ridge (STR)

HIGH 103hPa east of southern NZ tonight is moving off to the east. Likely to be a squash zone on its northern side.

New HIGH moving into central Tasman Sea on Friday and across central NZ for the weekend 1028 hPa

 

Tasman Sea /NZ/Aus

Passing trough over South  Island  on Monday and North  island  on  Tuesday/Wednesday,  then light to moderate SW to SE flow for the remainder of the week.

 

From Panama:

Light wind in Panama but the SW winds are expected from 7N to 3N then S to SE winds North of Galapagos. ITCZ is coming and going over Panama.

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

Or Facebook at /www.facebook.com/metbobnz/

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

Bob Blog 3 May 2020

WEATHERGRAM

YOTREPS

 

Compiled Sun 03 May 2020

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

 

COVID19  restrictions in NZ have dropped to  Alert  level 3

The national state of emergency remains in force. (It may now expire at 12.21pm Wednesday 6 May 2020.)

Yacht arrivals

Arrivals on superyachts and pleasure craft are not exempt from the current border closure. 

 New Zealand’s border is currently closed to almost all travellers to help stop the spread of COVID-19. Effectively, the New Zealand border is closed for all but essential travel. Only New Zealand citizens and residents, as well as some other specified travellers, are permitted to enter New Zealand without having to apply for an exception.

Visa waiver crew (including Australian citizens not resident in New Zealand) travelling on superyachts and pleasure craft are not exempt from the closure of New Zealand’s border, and current immigration instructions state they must be refused entry permission unless they meet one of the exceptions.

Border Advisory 19 is at: www.health.govt.nz/system/files/documents/pages/border_advisory_19_-_24_april_2020.docx

Border Controls are at: wwww.health.govt.nz/our-work/diseases-and-conditions/covid-19-novel-coronavirus/covid-19-current-situation/covid-19-border-controls

The MNZ COVID 19 response team is contactable via MNZCovid-19@maritimenz.govt.nz ; please contact via this email address with any concerns or questions.

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REVIEW OF THE LAST MONTH (April 2020)

Sea Surface temperature anomalies as at start of May can be seen at https://www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

Looking at the SST during the past few months we see a continuing warm pool in the Indian Ocean/Tasman Sea hot pool. This means a NEGATIVE Indian Ocean Dipole is possible later this year over Australia with above -average winter spring rainfall over parts of Southern Australia, perhaps.

 

According to BoM (Australia) ENSO (El Nino/southern Oscillation) is neutral and SAM (Southern Annular Mode) is currently negative but will go neutral so there are no major climate drivers active at present. That means that it is the short-term drivers (such as MJO) that we need to watch to work out weather changes in advance.

 

To see how the annual weather cycle and the seasons are working out, we can check the average isobar maps for past 30 days and their anomaly from  www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

 

There is now a belt of low pressure near 40-50S from south of South Africa to the east of NZ. This indicates that the subtropical ridge is lingering around 20-30 South and also increases the troughs over NZ.

 

Zooming into the NZ area, and comparing monthly anomalies from February with now, shows that the subtropical ridge STR has strengthened (as far as the 1015 isobar is concerned) but hasn’t shifted much. The 1010hpa isobar remains in much the same place.

A HIGH over Antarctic and its easterly winds may play with SAM.

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no cyclones around at present

 

Extended weather models no longer show a Tropical Depression near coastal Queensland in early May (as was mentioned last week).

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ spent the last few days visiting Southern Cooks/Tahiti, an d this week is expected to form again over PNG to New Caledonia to south of Fiji.

Tropical low expected to travel south east then south from between Fiji and Vanuatu on Thu 7 May to be east of NZ on Tue 12 May.

 

Subtropical ridge (STR)

HIGH 1030 moving into Tasman sea on Monday is expected to cross central NZ 1024hPa on Friday/Saturday. and then move off to the south east.

 

Tasman Sea /NZ/Aus

Passing squally trough over NZ on Monday then strong southerly flow on Tuesday, easing Thursday followed by incoming HIGH

Increasing NW winds over southern NZ on Saturday.

 

From Panama:

Northerly to light winds to 4:30N this week, ITCZ from 7N to 4N then light to moderate SW to S to SE winds to 2N NW of Galapagos then gradual swing to SE trade winds.

 

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If you would like more detail for your voyage, then check metbob.com to see what I offer.

Or Facebook at /www.facebook.com/metbobnz/

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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