May 31—Final approach; A lot going on

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

We are updating frequently now, so best to download the KML file and update your Google Earth.

Jacob had been holding back waiting for better forecast before completing the last leg of his voyage, up to Flora Pass (160 nmi), though the Great Barrier Reef and on into Cairns. A total run of about 185 nmi.

That better forecast did not show up, so he has taken off now, with hopes of getting there before the worst of it. The video below goes over the route and mentions our study of the wind forecasts at

http://davidburchnavigation.blogspot.com/2019/05/tools-for-crucial-weather-routing.html

It is an interesting ongoing study of the models, hoping to learn which one was most successful in this difficult to forecast atmosphere.

Not mentioned in the video is our concurrent study of the scatterometer wind data from ASCAT and WindSAT. We look for cases where they are close passes and see if they read the same winds.  This is long overdue. If the WindSat data are reliable, this is another large set of real wind measurements sailors can use.

See http://davidburchnavigation.blogspot.com/2019/05/compare-ascat-and-windsat-scatterometer.html

We have half a dozen new samples that we will add on Friday May 31.

He is close enough now to look ahead to actual wx forecasts at Cairns, sort of equivalent to our VHF weather. Here is the latest report:

Weather Situation

A high [1035 hPa] over the Great Australian Bight extend a strengthening ridge along far northern Queensland waters with fresh to strong southeasterly winds developing.

Forecast for Friday until midnight

Strong Wind Warning for Friday for Cairns Coast

Winds

Southeasterly 20 to 25 knots, reaching up to 30 knots south of Cairns in the late afternoon and evening. Lighter southerly winds inshore south of Innisfail in the late morning.

Seas

1 to 1.5 metres, increasing to 1.5 to 2.5 metres south of Innisfail by early evening.

Swell

East to northeasterly around 1 metre outside the reef.

Weather

Cloudy. 80% chance of showers.

Saturday 1 June

Strong Wind Warning for Saturday for Cairns Coast

Winds

South to southeasterly 20 to 25 knots, increasing to 25 to 30 knots inshore north of Innisfail.

Seas

1 to 1.5 metres, increasing to 1.5 to 2.5 metres outside the reef.

Swell

Easterly 1 to 1.5 metres outside the reef.

Weather

Cloudy. 95% chance of showers.

Sunday 2 June

Winds

South to southeasterly 20 to 25 knots, reaching up to 30 knots at times north of Cairns.

Seas

1 to 1.5 metres, increasing to 1.5 to 2.5 metres outside the reef.

Swell

Easterly 1 to 2 metres outside the reef, decreasing to 1 to 1.5 metres during the morning.

Weather

Cloudy. 70% chance of showers.

So we see there are indeed strong winds forecasted for the moment. He would be there now on about June 3.

You can read the latest report online at http://www.bom.gov.au/qld/forecasts/cairns-coast.shtml

May 29—Waiting out the forecasts.

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

We are updating frequently now, so best to download the KML file and update your Google Earth.

Jacob is poised and ready to finish this epic voyage, but on hold due to the longer term forecasts. His next leg is a 160 nmi run to the NW to the entrance of Flora Pass, which takes him though the Great Barrier Reef, and then on to Cairns,  about 40 nmi from there.

The problem now is that last turn into Flora Pass and the passage through the Reef. The strong SE winds are excellent for running up to the Pass, but not good at all for turning to south of west to transit the Reef area. His large boat cannot be controlled with strong winds on or near the beam.

Details of the passage through the reef can be seen in the Google Earth overlay.

He has been watching this forecast now for several days, and it has not been very encouraging. First the winds are strong at the turning time (up to 28 kts, often to 20+) and second, the models do not agree on the forecasts.   We have an article in another blog that compares these models along with other models that even provide probabilities of winds.

In any event, it looks like the strong wind forecast is not going away anytime soon. It could be well into next week.  Furthermore, Jacob knows by direct hard first hand experience that these trades can crank up to 15+ and stay that way for weeks.   So this is a time for patience.

Below are weather maps from BOM that show the source of these strong trades.

We see that the isobars where we care about are affected by the High over AU as well as fronts moving around to the SE of AU.

I am not sure if models used by BOM are independent of the ones we follow in the link above, but here is what they forecast for this period... we are using 12z on Fri as a benchmark. These are taken directly from our Google Earth overlay on Jacob's track. The data are from BOM.

 

Here are now the maps from Thursday May 30:

We see the main problem by looking at the 1016, 1020, and 1024 isobar as they approach Queensland from offshore.  They get closer together and that is what makes this strong wind near the coast. There is some indication here that this is weakening on June 3, but we have to wait and see.

May 26—Back on Course, 280 nmi to go, another challenge on the horizon.

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

We are updating frequently now, so best to download the KML file and update your Google Earth.

With such great progress under the belt now, it is easy to forget that any ocean voyage is not complete until the boat is tied up at the dock.  All looks great for the moment, but there is a forecast for strong winds right at the finish line, about 8 or 9 days out now, which i am sure Jacob is thinking about already. The forecast might not pan out; this is a change 5 days out, so that would not be a surprise, but this is a classic case of spotting something early, and then watching it at every forecast until decision time arrives.  

On present schedule he would turn north on Wed 30th UTC, then the wind starts to build on Thursday or Friday. Here is the meteogram from LuckGrib.

We will watch this forecast every 6 hr going forward. We are using the FV3 GFS model, which will become the official US GFS model on June 12.  After that, there will not be two models, just GFS.

We note in the video below that the ASCAT data is gone missing. Something is wrong. We can see the data at KNMI, but not at the OSWT site that we rely on.

Here is a video discussion with nautical charts...

May 25—Good progress continues.

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.
We are updating frequently now, so best to download the KML file and update your Google Earth.

Good progress continues. We added the Navy WindSat scatterometer (on satellite Coriolis) to the ASCAT scatterometer (on the satellite Metop-A). It is not often we can compare the data for the same time exactly, but we will try to do that when possible.

Here is a preliminary comparison.

and then the ASCAT data 14 hr later...

Blue is under 15 kts; green is over 15 kts. We see he is still right on that edge of just about 15 kts, which is indeed the climatic expectation for this location and month.  You can view the climatic winds in the KML file. Please update that for latest components.

We have also added  new range rings at 100 nmi, and shut off in default  mode the 400-mile rings.  He is now well under 350 nmi to go, which could seem  like a lot until we remember he has rowed something approaching 9,000 miles!

Check back later for a video discussion and demo to date... discusses charts and lights, as well as relative climate... ie Cairns is "south of Jamaica."  [This has been postponed till tomorrow's post.]

We will also be adding shortly a note and video on how to track the scatterometer satellites to predict future passes.

May 23—Congratulations Jacob! Major Accomplishment.

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

Please download a new copy of the KML file. We have added several features, including WindSAT scatterometer data and new charts,

Jacob has gotten around the Lihou Reef which was a tremendous amount of work for him, fighting the 25 + kt SE trades.  This has lightened up as forecasted, thank goodness, and now he is doing well on course to meet the next one: Tregrosse Reefs, which are about 60 miles off, which is a bout a day and a half.

Wind forecast is favorable for this, but it is still a lot of work in rowing this big boat of his.  A LuckGrib meteogram assuming 1.6 kts on the indicated course is below.

We see the wind staying below 15 kts which is manageable.  You can view the climatic winds at the Google Earth posting, which we home maintain or go lighter for the duration of the voyage.

We will post shortly a new tool for noting if Jacob is in daylight or darkness. Plus we have to make a post on a fantastic new source of nautical charts.

Here is a short audio discussion.

Here is a WindSat image from our GE overlays that was valid at 21z on May 23. This was not processed yet at the time this note was originally posted. It could be the WindSat data takes longer to process than the ASCAT. I need to check that. We do get good wind data this way in most cases. I think if the WindSat and ASCAT disagreed in any circumstance, most meteorologists would go with the ASCAT.

May 21 — Challenges ahead

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

The main challenge at the moment is getting south of LiHou Reef, or deciding very soon to turn and follow the wind over the top. Jacob is fighting hard at the moment to keep the track south of west. Recall his boat Emerson is big (28ft x 5 ft), and in strong wind (he has sustained 20 kts +, often a steady 25 kts, sometimes approaching 30, from the SE) it is very difficult to control the boat. He is in huge trade wind seas as well to deal with.

The situation is discussed in the video below. This morning there are signs he could turn south a bit so that is very good.  The meteogram of forecasts is below, showing there is some slight improvements on Thursday and Friday, but Wed, tomorrow, still is a big challenge. The winds pick up to solid 25, which we also see in the ASCAT, and even veer a bit more to the SE.  So the key now is getting past Wed.

We have a new KML file with chart segments loaded.  Also found this very nice link to Sat images over AU. http://satview.bom.gov.au/

AU tides for this region are also online. There is a station at the top of the reef. Tide range is about 6.5 feet in this area. Tides affect not just the depth, but also the currents running between the cuts or passes in the reefs.

Progress now is judged not day by day, but hour by hour.  The KML file is updated hourly.

Update 1640z tuesday last 4 hours very good course to the south.

Below is the GFS ensemble model, which outputs a standard deviation (SD).  we expect 67% of all winds within 1 SD, but deviation could be higher or lower than mean. we see see SD about 1 for Tuesday meaning forecasts 18±1 kt, then 1.5 on wed and thurs is more uncertain with ± 2kts, then strangely Friday is back to ± 1.5. Generally the SD just gets bigger with time.  Average pressures gradually falling with back to about 1015± 1 on Thursday Friday.

I think this is all pretty normal for a normally good forecast. When the forecast is bad, the SDs can get very large. For TC Ann sometimes the SDs equaled the wind speeds!

this plot is from present position on a heading of 266 T at 1.6 kts.  Possible routes do not affect this too much, but as all is better to the south, the winds are also a bit lighter to the south as well.

This is from LuckGrib, which has a nice option to display the SDs.

May 12 -— A Brush with a Tropical Storm

Background: Notes here on our Google Earth tracking of Jacob Adoram

                                 Index of Google Earth overlays.  Download the KLM file.

Main news is the loose cannon Low that has been in and out of the picture is back in and just 90 nmi to the SE of Jacob with winds of 50+ kts, but it seems that is the closest it will get.  For now he can take advantage of the strong N winds behind it as it moves west to make good progress to the south.

We see favorable currents on the horizon, which he might be able to reach.

An ASCAT pass shows real wind speeds. Purple is 50+. This storm is moving quickly to the west, toward about 290 T.  It had come down from the north, then stopped, then turned and went West.  It was first forecasted to cross the rhumbline and keep going to the southeast. Then it was forecasted to dissipate at the rhumbline, then a day or so ago the track got better... but the wind speed forecasts did not.

Compare that to the GFS forecasts below of 30 kts. This and other issues are discussed in the video link below.

May 8 — Major Milestones Achieved; Still Challenges Ahead

Background: Notes here on our Google Earth tracking of Jacob Adoram

Index of Google Earth overlays.  Download the KLM file.

I started this on May 2, when it was true that: After covering 5,400 nmi made good across the globe from Neah Bay to his present position, accomplished by actually rowing a staggering 8,500 nmi (over one third of the earth's circumference) along the twisted course dictated by wind, waves, and current.
Jacob is now well past the 1,000 miles to go mark.  This morning he is 961 miles from Cairns and making good progress.  Conditions look good for the next 4 days, but there is a storm on the horizon that he will have to negotiate.

____

It is now May 8, and a lot has happened. First he is well into the past 1,000 mile mark and getting closer to approaching another milestone of 800 nmi off.  This leaves just one more of our 400 nmi range rings to cross.

He has also set the milestone in that there is just one more island group (Coral Sea Islands) to get past before Cairns. He is essentially past the dangerous Indispensable Reefs, with open water for about 600 nmi till the Coral Islands Group.  We may need to do some digging to get charts of these reefs.

The real challenge at hand has been a loose cannon storm that has been since May 3rd a classic case of impossible to forecast.  He will start to feel the winds of this tomorrow, one way or the other, but it could get deeper. I illustrate present and past forecasts of this in the video below, but need to make a better demo of just how wrong the forecasts have been.