Bob Blog 23 Feb

WEATHERGRAM

YOTREPS

Compiled Sun 23 Feb 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

Latest cyclone activity report is at and TCFP tropical Cyclone Formation Potential at www.ssd.oaa.gov/PS/TROP/TCFP/index.html (but not this week).

It has been busy in the South Pacific recently with TC VICKY bothering mainly Niue and TC WASI now near Samoa and heading for Niue tomorrow (Sunday local date). Since these two features have been so close to each other, they have actually mitigated things and stopped something larger from forming.

 

After TC WASI there is expected to be a lull in cyclone formation in the South Pacific for few weeks.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to weaken this week and drift north, so mainly be from Tuvalu to Samoa to Niue and then fade off to the southeast.

 

Subtropical ridge (STR)

HIGHS, one well east of NZ and t’other in Tasman Sea, are expected to remain quasi-stationary and then fade by Wednesday. A new High is expected to develop east of the South Island on late Tuesday and then travel east along 40 to 45S.

Another High is expected to travel east over northern NZ from Thursday to Sunday.

Tasman Sea /NZ/Aus

Brief trough for southern NZ on Monday local, larger trough over South Island on Wednesday/Thursday, and another on Saturday followed by strong W to NW winds .

OK for Noumea to Australia.

As for sailing east across the Tasman: it may be possible south of 35S with a start on Monday or Tuesday. probably a no-go this week due to easterly winds.

 

From Panama to Galapagos/Marquesas:

Northerly winds to around 5N this week, the light winds to 4N, then SE winds to Galapagos.

The ITCZ has a gap in it between 85W and 79W, but doe s have outliers that reach as far south as Galapagos at times.

Winds are expected to be SE to north of Galapagos, so that’s an OK short cut to Marquesas this week, albeit showery at times.

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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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Bobgram 16 feb 2020

WEATHERGRAM

YOTREPS

Compiled Sun 16 Feb 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 TCFP tropical Cyclone Formation Potential at www.ssd.oaa.gov/PS/TROP/TCFP/index.html (but not this week).

 

Last week, Tropical Cyclone USEI managed to remain mostly offshore as it travelled south from west of Vanuatu, past NW New Caledonia, then south across the Tasman sea to the far SW of New Zealand (as a wet and windy mid-latitude low).

 

At present GABEKILE is in the mid-Indian Ocean. Tropical depression 93P is starting to form between Fiji and Samoa and may develop into a Tropical Cycle that may go SE and affect Samoa/Tonga Niue and Southern Cooks over the next few days. Keep checking.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active this week mainly from Fiji/Samoa to Southern Cooks, worth avoiding.

The cyclone risk remains high in the South Pacific.

 

Subtropical ridge (STR)

HIGH to east of NZ should remain slow-moving near 45S 160W until mid -week and then fade/go east.

Another High is expected in South Tasman Sea by the weekend.

 

Tasman Sea /NZ/Aus

Low is expected to deepen off Sydney area by Tuesday and move off to Se/S, feeding strong NW/westerly flow and large swells over southern NZ for Thursday /Friday.

 

OK for Noumea to Australia.

 

As for sailing east across the Tasman: probably a no-go this week due to easterly winds.

That mid-week trough does offer a brief gap in these, but maybe not long enough for sailing the whole way.

 

From Panama to Galapagos/Marquesas:

Northerly winds to around 4N, these may fade near 4N next week.

Forecast SW wind to north of Galapagos from 19-21 Feb so take the track south of Galapagos to get to Marquesas.

Weak ITCZ and variable winds from 3N to 1N. Then light to moderate S/SW winds to 3S.

 

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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 9 Feb

WEATHERGRAM

YOTREPS

Compiled Sun 09 Feb 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 MJO

The Madden Julian Oscillation is an occasional visitor to the Pacific (as a burst of extra convection that can trigger cyclones). It usually takes 10 to 20 days for the active part of an MJO event to travel across the Pacific

Another parameter that helps us watch convective patterns in the tropics is Outgoing longwave radiation or OLR. When the tropical convergence zones are active their cloud blocks radiation from escaping to outer space, and OLR is low, coloured blue (for bubbly). When skies are clear radiation can escape to outer space and OLR is high, coloured orange or (mellow) yellow.

A constructed analogue forecast of future values of the OLR, using the MJO, show that we are expected to have a phase of low OLR (blue values) over the next few weeks, and that means an active South Pacific convergence zone and increased cyclone risk.

Deeper blue indicates less OLR and that means MORE convective activity.

See www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml

 

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and TCFP tropical Cyclone Formation Potential at www.ssd.oaa.gov/PS/TROP/TCFP/index.html (but not this week).

 

Tropical Cyclone DAMIEN was very active when it made landfall near KARRATHA in NW of Australia and is now weakening as it moves inland.

Tropical Depression 06F is brewing west of Vanuatu, 994hPa tonight near 16S 163E, and likely to become a tropical cyclone going southwest and skirting the NW end on New Caledonia on Monday. The system is then expected to make a beeline SW and parallel to the Queensland coast passing by Brisbane on Friday and getting into the south Tasman Sea by the weekend.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active this week across the Coral Sea, Vanuatu, Fiji and Tonga.

I have already mentioned the tropical system near Vanuatu

The cyclone risk remains high in the South pacific and there may be another forming near Fiji /Tonga by the weekend. Take care and get updates if planning to Island hop.

 

Subtropical ridge (STR)

HIGH over southern Tasman Sea is expected to slowly travel NE across central NZ on wed /Thu.

Another High is expected to travel into south Tasman Sea on Friday heading for east of the South Island over the weekend.

 

Tasman Sea /NZ/Aus

Weak trough is expected to cross NZ on Thursday

As for sailing across the Tasman: probably a no-go this week due to possible cyclone

 

From Panama to Galapagos/Marquesas:

Northerly winds to around 4N.

Then a weak ITCZ and variable winds from 4N to 2N (will need some waypoints).

There is expected to be a slight change in a pattern in the wind direction north of Galapagos This is expected to swing from easterly to light to westerly from mid-week. There are some great west-going currents north of Galapagos, but once this wind direction change occurs we will need to try and go SW of Galapagos instead.

The main problem with the “SW of Galapagos” voyage is some southerly winds forecast between 2N and 2S. These will require waypoints.

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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 2 Feb

WEATHERGRAM

YOTREPS

Compiled Sun 02 Feb 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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REVIEW OF THE LAST MONTH (January 2020)

Sea Surface temperature anomalies as at start of January compared with the start of Feb may be seen at https://www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

The main changes are in the South Pacific Ocean, with the hot pool east of NZ fading, and the hot pool in the Tasman Sea intensifying

According to BoM (Australia) the Indian Ocean is going neutral – and since ENSO is also neutral, there are no major climate drivers active at present. That means that it is the short-term drivers (such as MJO) and ocean temperature that we need to watch to work out weather changes in advance.

During January there have also been some small changes in the pattern around South America, but anomolies in the North Pacific remain much the same.

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

The subtropical ridge in much the same place. The area below 1010hPa in the equatorial area has expanded around Indonesia and the Coral Sea but not advanced much further southwards.

There remains higher than normal air pressure over the Antarctic, but this is now retreating. In the Arctic, high anomolies have been replaced by low anomolies. High-anomaly zones have shifted all over the planet, and the one that was over SE-Australia a month ago is now in east Tasma Sea. maintaining a weak southerly anomaly flow over the North Island.

 

Zooming into the NZ area, and comparing monthly anomalies from last month with now, shows that the subtropical ridge STR has strengthened in the east of the South Pacific but weakened around and west of Australia--- and remains about the same in the Tasman Sea.

The 1010 isobar in the tropics has drifted south especially in the Coral Sea, and the 1010 isobar near NZ has also drifted south.

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The Tropics

The latest cyclone activity report is at tropic.ssec.wisc.edu and TCFP tropical Cyclone Formation Potential at www.ssd.noaa.gov/PS/TROP/TCFP/index.html (but not this week).

At present there is  no  cyclone in any basin.

There is a tropical depression in the Coral Sea near 10S 155E and its central pressure MAY deepen to 1000 h Pa as it travels south to just northwest of New Caledonia on Tue 4 Feb then west across the Coral Sea, slowly fading.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active this week from the Coral Sea across northern Vanuatu to Tuvalu and Samoa.

The low tonight over Southern cook is expected to move off to Se next few days.

Another weaker low is expected to travel south from Tuvalu to Fiji /Tonga from 6 to 8 February.

The outlook for next week is a possible tropical Cyclone developing for Vanuatu from 13 Feb, this will be reviewed next weekend.

SO,  if you are planning to Island hopping next few weeks, keep up to date and stay alert.

 

Subtropical ridge (STR)

HIGH is crossing northern NZ and moving off the east along 27S.

Another High from Bass strait on Tuesday is expected to travel east across Tasma Sea at 40S then skirt around south of the South Island on Friday then go NE across Chathams.

Third High is expected to move from wet into south Tasman at 45S on Saturday.

 

Tasman Sea /NZ/Aus

Active trough is expected to cross the South Island on Monday and weaken over the North Island on Tuesday and be followed by a brief slightly cooler SW flow.

As for Noumea to Australia: Mainly SE/E winds, so OK.

As for Sydney to NZ: will need to go SE to 40S to get a round Highs in the Tasman.

 

From Panama to Galapagos/Marquesas:

Northerly winds to around 4N. Then an active ITCZ and variable winds from 4N to 2N (will need some waypoints), and a good west -going current near 3N 83 to 85W, then S /SE winds as far as Galapagos area, As for getting to Marquesas, not enough data for entire voyage but what data we have is looking OK and goes past the north end of the Galapagos. .

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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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