In the last chapter I introduced the concept of strategic weather analysis as an addition to the tactical version that most cruisers do, so if you missed that, please read it now.
In this chapter, and the next three, I'm going to get down into the actual details of how I receive and analyze weather on a day-to-day basis to plan our cruises as much as two weeks out. A system I have developed over 25 years of voyaging that I have recently updated, using the latest tools, over this summer's cruise to remote places.
First off, let's look at the gear and software I use.
Regarding your point, made in an earlier article, and again here, about precipitation: a potentially even more useful indicator of severe weather is CAPE (Convective Available Potential Energy). zyGrib can display it. I’ve not seen it in many other grib viewers.
zyGrib is more steak than sizzle, I admit. It was developed by engineers without the help of graphic designers. That makes it more “nerdy” perhaps, but I can ignore what it looks like. It’s a very powerful tool.
I agree that CAPE is useful, however, not “more useful” the two are different indicators and both are useful. Or to put it another way, I would not trade the rain parameter for CAPE. This is particularly true in the mid to high latitudes where CAPE can be quite low in a front, but precipitation will tell the tale.
As to zyGRIB, I’m sure you’re right about it’s power, but given that LuckGrib is, I think, equally able to display any parameters in an infinite and customizable ways, and is easier to install and use, I prefer it.
To be clear I said CAPE is more useful for identifying severe weather. There’s lots of non-severe weather that comes with precipitation.
Consider a weak cold front with rain showers and 20 kt gusts, compared to a cold front with of 50+ knot gusts, heavy lightening, driving rain, perhaps hail and supercells. The difference is usually the amount of CAPE. The former wouldn’t cause me to change my sailing plans but the latter is something I would prefer to avoid, so telling the difference between the two is very useful.
Sounds like you’re happy with LuckGrib. I would point out that your one complaint: that it doesn’t display H and L markers on local pressure maxima and minima. I can report that zyGrib can do this.
Like I said, no argument that CAPE is useful…but so is rain.
And to clarify, as I wrote in the post, LuckGrib can indeed mark lows and highs with H and L.
That said, if you are finding zyGrib great for you, that’s fine. As I said, it’s Frank Singleton’s favourite, so I’m sure it’s good.
CAPE is now in PredictWind Offshore app with thIs week’s update.
I must say, this is a pretty damn informative thread, not for the contention of the candidates for “most appropriate service”, which is always going to be a matter of taste and need, but to illustrate how the choice of download device, OS and file serving utility are closely linked and drive, to a degree, one’s options.
An added mix is the computational/predictive models on which the forecasts are based. A Canadian meterologist reported a couple of days ago how the U.S. models (GFS?) did not accurately predict Hurricane Irma’s track to the west side of Florida, but the European ones did to a better degree, and how this was causing consternation in her field. So I grasp why “what model does the app use?” would also enter into the decision-making. Me, I’m still reading the 500 MB book, which is worth it, but it’s like a uni course of the non-fluffy kind to wade through the concepts presented.
I was watching both the GFS and the European model predict Irma and really didn’t see any definitive superiority of either. Stepping back a bit, to me the thing that’s amazing is that both models had Irma’s track nailed as much as five days out with a very small margin of error, around 100 miles either side, if memory serves. The result being that probably thousands of lives were saved due to this advanced warning.
Every time I hear people, and particularly the popular press, bleating that a model messed up I’m reminded of a Louis CK rant: https://www.youtube.com/watch?v=q8LaT5Iiwo4 (Start at 3:00)
Well, I wasn’t really giving my own opinion but quoting a CBC meteorologist, Johanna Wagstaff. I concur 100 miles is pretty tight for five days. It makes me wonder why people who take Caribbean vacations in hurricane season get off complaining about having to stand around and wait. They could have bought insurance and they could have gotten on a plane. When Irma was still hours from Barbuda, it was pretty clear who was going to catch it. This ability to read the weather must surely play into decisions to go to sea under these circumstances. (I’ve already had this debate with Andy S. on Facebook). I’m wondering if you’ve had to use your weather knowledge to make that decision to stay put in a hurricane hole or to put to sea to get a couple of hundred miles in the right direction.
I can see very few situations where I would go to sea with a hurricane around. I guess the only exception would be if I were say in Antiqua and had at least four days ahead of any chance of hurricane arrival in which case I might head south to say Trinidad.
But I would need to think long and hard before even taking that step since a gear failure could result in getting caught at sea by the hurricane which would be almost certain death, whereas staying put and being sensible puts the boat at risk, but it’s unlikely we would die.
That said, this is academic since I would never be in the Caribbean during hurricane season.
And any thought of going to sea to ride out a hurricane, or “get a couple of hundred miles in the right direction” is just plain silly, and suicidal too. Even with today’s models, hurricanes are highly unpredictable so the right direction could rapidly become the wrong direction.
The point being that the only time I would consider going to sea with a hurricane coming would be if I were near-certain that we would be in harbour and therefor able to get ashore to save our lives, if the hurricane struck our new location.
Bottom line, when you have lived most of your life, as I have, in the path of hurricanes, and experienced a bunch of them, you don’t take any chances.
Good to hear, now if we can just get them to provide the upper level stuff and GUST.
How quickly would you like to see Gust in PredictWind? Turns out it is in last week’s release as well. There are a good number of new features including being able to vary the speed of the running of the gribs displays over time. I too, being old school and having completed the Starpath trainer over a decade ago and having taught meteorology, would enjoy seeing the 500mb data in PredictWind but alas I think too many of today’s sailors are clueless about how to use it. I am surprised how few sailors I have met in the last two years of cruising the Caribbean full time have taken the time to learn the science of meteorology. Most just want to know “What Chris says” and some will look at a gribs or two. PredictWind seems to me, having used it for a few years now, as a good tool to help the cruising masses digest more data easily and get a reasonable view of the conditions over several days on their ipad or PCs. The Pro subscription satisfies my needs for lots of data (but I still look at 500mb faxes).
I just downloaded LuckGrib and it look s excellent. LuckGrib can download CAPE. Can you describe how and when to use CAPE, and what to look for? Thanks!
Glad you like LuckGrib. As to CAPE, since it has only recently become available when offshore I’m only just getting to grips with it’s use, so it may be a while before I can provide any really useful thoughts on it. That said, it’s most important use, I think, is as Jordan says further up the thread, to help indicate how violent fronts will be, and particularly what the risk of high energy local effects like thunder storms and tornados is going be.
That said, CAPE is not a panacea. For example we just had a nasty little low off Nova Scotia, caused by an upper level cut off low, that had winds over 50 knots and gusting higher but had very low CAPE readings.
CAPE is a measure of how unstable the atmosphere is. The more unstable the atmosphere is, the more convection you get. With small amounts of instability you git little fluffy cumulus clouds, with a little more cumulonimbus will start to form and you’ll get rain and gusts. As the amount of instability increases you’ll get strong squalls, lightening, hail, supercells (which cause tornados), microbursts, etc.
When a front is approaching, I like to see less than 1000 J/kg of CAPE in it, and I get concerned when I see more than 2000 J/kg. For reference these are the Storm Prediction Center values:
As John says in the sibling, convection isn’t everything. When it comes to the danger posed by weather at sea a primary concern is sustained surface level winds because they will have the most effect on sea state. Convection is a small contributor to sea state. Surface winds are driven by surface pressure gradients, so what you don’t want to see is tightly squeezed together isobars on the surface analysis, especially not ones with straight lines.
If this isn’t entertaining enough there’s another thing to consider with convection: wind shear. Wind shear occurs when air at different levels in the atmosphere blow in different directions. If you’ve ever seen fall streaks from cirrus clouds you’ve seen wind shear. When you have lots of wind shear you can have severe weather even with small CAPE. Here’s a diagram showing the relationship:
In zyGrib, you can investigate wind shear with a soundings diagram. To get it, you have to first download all the GFS altitude packages (second tab on the download menu). Then right click on the map where you want to see the soundings and select SkewT-LogP DIagram.
Just bought LuckGrib, opened the program, downloaded a grib with parameters I selected, and am enjoying the display. It was a snap to get started. Very intuitive. Now I will read manual/instructions to get more out of LuckGrib. Then LuckGrib can serve as an aid to self study and a weather course.
I have been using OpenCpn with the grib plug-in to view grib files I receive from sailmail. I had not gone to the trouble of setting up a dedicated grib viewer. LuckGrib appears far more powerful and was vastly easier to set-up. It makes acquiring the grib files a snap.
Thankfully I bought a refurbished MacBook Pro a couple of months ago in order to explore MacOS computing, so I was ready for LuckGrib when I read your article. LuckGrib requires OS X 10.11 or later (I had to upgrade but machine was fine). If someone is just getting started with grib file weather, even if they are a PC user like myself, I would suggest getting a Mac capable of running LuckGrib as the cost of LuckGrib and the hardware is well worth the savings in aggravation and technical learning required with alternatives.
Have you tried Squid? (http://www.squid-sailing.com/en/content/17-squid-marine-weather-software) I think it offers the most complete bunch of weather info in a very friendly interface ( includind sat images, observations, scat winds and of course a variety od models) subscription options are very attractive. It is in continuous development and is a standard tool for offshore racers now thanks to its user friendliness and integration with routing softwares. It also allows email requests.
No I have not tried Squid, but I did take a look at their web site.
I guess the bottom line is that I’m just not really a fan of these all in one packages where someone else has decided what weather information I need and how I will view and use it. I just prefer to roll my own (more on that in the next two chapters) and use tools that I have found to be best in class for each function—UUplus for the download and LuckGrib or Viewfax for the analysis.
That said, to me the biggest benefit of these packages is that they give access to the European model, so I guess I might become interested in Squid if it let me do that at a better price than PredictWind.
I see your point, but maybe it deserves a try. For me its greatest advantage is that allows a straightforward overlay of sat images, grib data, scat winds and observations, which is very useful for assessing the models against “real data”, something not available with other viewers and still a bit cumbersome with Expedition or Adrena for instance. I used to georeference images in Expedition (in the case of sat pictures pre-processed with geosarsignal), but much easier with squid now. It also includes a routing module (only online) but for that Expedition and Adrena give much more powerful tools yet.
In any case I still use saildocs extensively specially with an iridium connection, using lists of links to specific met products, but when inmarsat fleet is available (frequent in offshore racing these days) squid saves a lot of time.
That makes sense. I have never felt the need for that level of overlaying, but that may be just me.
Re access to ECMWF: for several years I have used the paid service “Wetterwelt” from Kiel, Germany. They provide ECMWF with some secret sauce added. Currently it’s EUR 99/year including 19% German sales tax for the service which includes the software. A screenshot: It meets your requirements 1 and 4 but not 2 and 3. I briefly looked at Viewfax years ago and have been using zyGrib (my zyGrib doesn’t display H and L; I must have an older version). Of the three, I prefer Wetterwelt for its information display and useability (but wouldn’t call useability excellent). A feature that I like and sometimes use is to mark a route by clicking waypoints onto the chart and then add information like start time and average speed. After that a yellow marker shows up moving along the route in sync with the forecast date and time (the marker jumps as you click through the forecasts). The shading in the screenshot is for gusts but that can be customized (there was some bad weather here yesterday and the route is older. I wasn’t at sea yesterday). The available data is: Surface wind direction Surface wind speed Gusts Wave height Swell direction Wave period Surface pressure Weather Temperature (air) Don’t know if their grib files will open OK in another viewer. I have “the 500MB book” on my shelf and made it through the first 10 pages so far. Each fall, I again resolve to work through it this coming winter. I wouldn’t consider using a routing tool unless I were a race navigator, for which I have no plans. I like PC software vs. an app. I don’t like to see tablets being used widely because it directs development resources in the wrong direction (my opinion, and I’m not 80 years old either) but of course cannot help it. So I own a tablet as a cheap backup for the navigation software and computer and for reading magazines on the sofa (consuming, as you said). Mac software rules me out, at least so far. But I would much rather use a Mac computer than a tablet, either iOS or Android. I guess I will stick with zyGrib and not try Viewfax again as I already have used zyGrib, on and off, for several years. But I will get a current version. Re integrated know-all, have-all services I think that, to be safe and not suffer unnecessary, you have to “learn weather”. You can’t buy yourself free from it. And learning weather is a slow process. After 10 years of owning the boat, I am at best intermediate. Questions: 1. Why is H and L important? Lows are much smaller and the wind arrows tell for sure (not defending my current SW, just curious). 2. With 500MB display, how are the wind arrows for surface and 500MB level separated/identified? (maybe if I had finished “the book” I wouldn’t ask this) 3. I always thought that Gribs are for shorter term immediate route planning… Read more »
Lots of good observations in your comment, most of which I agree with.
One thing, I’m really, really sceptical of private companies that that promise “secret sauce”. Easy to say in marketing blurb, but I think pretty near impossible to do in reality.
More here: https://www.morganscloud.com/2016/02/05/five-tips-for-choosing-weather-information-to-believe-and-pay-for/
And here: https://www.morganscloud.com/2016/03/04/4-great-tips-from-a-professional-meteorologist/
As to the questions, I will cover all of that in the next two chapters. Spoiler: yes, I too use weather maps and agree with you about how important they are.
> (my zyGrib doesn’t display H and L; I must have an older version).
Go to the Isolines menu and check the “Pressure Low High” checkbox. I have version 6.2.3.
> 1. Why is H and L important?
You’re right that you can usually guess where the middle of the (anti)cyclone is by looking at the isobars and wind arrows, but why guess at it when you don’t have to?
> 2. With 500MB display, how are the wind arrows for surface and 500MB level separated/identified?
In zyGrib the wind arrows are only for the surface, but you can get see winds aloft by right clicking on the map and selecting “SkewP-LogP Diagram”
> 3. I always thought that Gribs are for shorter term immediate route planning and NOAA or UK Met Office meteorologist-produced weather charts for general outlook and overview (strategic weather analysis).
Meteorologist-created data is always much better than a GRIB. The advantage of GRIBs is that the forecast is updated as often as the model runs, and there’s much more detail than is usually available in official forecasts.
We have two more chapters to go, all will be revealed.
Hi John, As you specifically mention PredictWind in this article I would like to address some of your opinions. We acknowledge that everyone has their own way of using the weather options available, just like we all have our preferences on which boat designer/ sailmaker/ navigation software or deck hardware is best. Our goal is to provide and deliver the very best forecast data so sailors can make safe and informed decisions. We are all experienced offshore sailors ourselves and understand the requirements when sailing offshore, be it 1 day or 30 days at sea. Weather Models – Weather models are not “all the same under the hood”. We have expertise at running various weather models so have in depth knowledge in this area. – The ECMWF consistently gets the highest rating score. It is scientifically proven to be the best global model. – No single model is every correct 100% of the time, none. This is why PredictWind makes it very easy to compare 4 top models including the ECMWF and GFS – Comparing multiple models is common practice with all top navigators including Stan Honey, and all experienced navigators and meteorologists we have contact with. – We actually offer the ECMWF global GRIBs for Free on land based internet connections. This applies to all our models. -The Offshore App is free and can be used on Mac, PC, iOS and Android devices. Weather Routing -Manually doing weather routing is very time consuming, and error prone There is a lot of “fuss and fret” with this method, and unlikely to give you the best results. Why not make it fast and easy? Experienced sailor or not, most can see this routing tool as essential once they have experienced the benefits for themselves. – Possibly I think you miss the main point of the PredictWind weather routing service. The cloud based routing delivers the wind/wave/current from 4 models, in less than 1% of the equivalent GRIB file size. The data is also presented relative to your route, and the GRIB files. – The speed and simplicity is enough to convince most cruising sailors of the benefits The data download size (9kb maximum) for 4 atmospheric weather models, 2 wave models and 1 current model is appealing to all sailors. The results are in graph and table view and easily compared in a few minutes. – Yes, setting up Polars is very important to any weather routing . Most cruisers setup the Sail polars feature where they manually enter in their own upwind/reaching/downwind speed specifically for their boat. – Polar errors affect manual routing or the PredictWind routing in the same manner. – The departure planning tool calculates 4 routes, spaced 1 day apart and will summarize the results. This tool helps sailor being caught out, like your example of being caught out at sea by the passage ending up being a day or two slower. – Good seamanship is not getting caught out in bad weather. The weather routing &… Read more »
Thanks for a well reasoned defence of Predict Wind. I don’t agree with some or what you have written, but then I cover that in the post above, so no need to repeat myself.
The bottom line here is that a lot of this is a matter of opinion, and yours are certainly valuable to the debate.
That said, your crack about “teaching your child without H and L” did you no favours and is not the kind of debate we favour here at AAC.
Stepping back a bit, I guess by basic worry about Predict Wind is that I fear that many inexperienced users are regarding it, and particularly it’s routing and departure planning capabilities, as a substitute for going to the trouble to get a basic understanding of weather and safe route planning which I regard as a base skill that any voyager should have.
Incidentally, I have much the same worries about cruisers that delegate all their decisions, and most of their thinking too, to a weather router. More here: https://www.morganscloud.com/2008/05/01/weather-routing-and-the-skippers-responsibility/
So my hope is that this Online Book will encourage people to go through the weather analysis process manually, including looking at weather maps, and in so doing, get some basic understanding. If, after that, they decide Predict Wind is the way to go, I won’t argue.
We also have a piece coming from Andy, who is a huge fan of routing software, albeit a different package, so that should help provide a balanced look at the issues.
I just sent a small question to Craig from LuckGrib (at 11PM Friday night) and he replied in less than an hour!
Now that is service!
Yes, I have had the same experience.
Hi John, Thank you for mentioning LuckGrib, I appreciate it. As you spend more time with the software, please let me know if you have any questions or suggestions. Having read over the comments I would like to add a couple of points. I have used ViewFax and zyGrib in the past, and generally liked them. The more options sailors have to download and view weather forecasts the better, in my opinion. I have had friends who have used PredictWind and liked it. My experience is that everybody who has used the other software and then used LuckGrib has preferred LuckGrib (If somebody doesn’t have this experience please email me as I would love to hear why.) Of course LuckGrib doesn’t do automated weather routing, and I generally agree with your reservations here, but if this was important to someone then they would need to look for additional software. CAPE has been mentioned several times. LuckGrib does indeed support downloading CAPE from several of the models it supports. It also supports CIN (convective inhibition) and LI (surface lifted index) which are all convection related. If anybody is interested in doing some research to see how these parameters relate and which ones are most useful and how they can be used I would like to hear about it. I have used the wind/pressure/rain combination with success in my sailing so far. On the discussion of the various models – its true that ECMWF seems to be the current champion these days, having higher skill scores on average than the other models, and that LuckGrib does not provide this model. Its my understanding that Hurricanes are difficult to forecast in detail, i.e. locating its center with extreme accuracy. I suspect that for sailors, any of the global models would have provided sufficient information to make your decisions – i.e. if I see a forecast with a hurricane passing anywhere near to me 6 days from now, I need to start planning, regardless of which side of the track I’m forecast to be on, etc. For hurricanes in North America, LuckGrib is able to provide access to several of the models that NOAA provides (for free), some of which are updated every hour. For example, HRRR is a high resolution (3km) model updated every hour and it incorporates high resolution radar imagery and so tends to be very accurate (but only for the 18 hours of forecast data it provides.) As an aside, HRRR would be an excellent resource for North American sailors to use when day sailing – high resolution and hourly updates. On the display of H and L for the sea level pressure – this has been generalized, so you are able to display the local maxima of wind speed or rain if you want. If you are viewing wind gusts, you could have a marker show the maximum wind gust location. H and L are simply local minima and maxima, LuckGrib allows you to view these for any of… Read more »
Welcome to AA and thanks for your overview and thoughts, very useful.
A couple of points to expand on what you said that may help others:
I would like clarify Craigs comment and I think John has mentioned this too. PredictWind does NOT add “secret sauce” to the ECMWF or GFS weather models to produce our proprietary global model outputs. The PWG and PWE forecasts area full global model calculation. Before a weather model is run it has an Initial Conditions file entered in to it. I think this is where the confusion can come from. We do use the ECMWF and NCEP (GFS) initial conditions files. To produce an initial conditions file is a big deal, but it is not a forecast, it is the snapshot in time for that day.
Once you have the initial conditions you add in a forecast model along with a huge amount of computing power, after this you get your global forecast model. For us this is PWG and PWE global models.
PredictWind ‘buys’ the computing power to do this for each model run, something that allows us to do something which is normally the domain of government agencies, being a private company we do it more efficiently. Many top navigators use our model outputs as they are very good and often times do a better job for them.
We actually ditched the GEM(CMC) model after years of complaints about its inaccuracy (anecdotal of course), this is when we replaced it with the ECMWF at the same time changing our initial conditions source for the PWE to ECMWF.
You can read more on this here https://www.predictwind.com/why-predictwind-forecast/
Hi John and all,
Much that has been written here is way above me, I suspect, in part, as I have had spotty internet this last decade or more and when I do have it, it is pay as you go, which inhibits poking around and exploring. So, I am personally unfamiliar with these routing programs that are being discussed. That said, I can’t imagine leaving passage/departure decisions up to a computer program. Working the weather data out as far as possible, working with your likely day’s mileage, anticipating the pros and cons of going above or below a great circle route, anticipating the effect of a low traveling faster or going farther north, etc. etc. puts me into the rhythm of a passage and facilitates making good decisions when things start to go a bit different than predicted, always likely.
My best, Dick Stevenson, s/v Alchemy
Great comment. I could not agree more on the importance of manual route planning and you explained the reasons really well. Thank you.
Just a reminder that there are two more chapters to come, the first of which we will publish in a few days, in which I will detail step by step how I analyze the weather. So please don’t assume things like, for example, that I only uses GRIBs from my above discussion of tools.
I am slowly working through the details of actually using much of the technology discussed in the postings and responses. While I really appreciate the integration and simplicity of PredictWind’s Offshore App, I also use LuckGrib while in WiFi range. It would be lovely for someone to detail the recipe of using UUPLUS with the GO! to download GRIBs offshore for display in LuckGrib… someone here must have done this successfully.
That’s my next chapter.
I too have been reading all of the chapters in this book. I’m new at using some of this technology but trying to figure it out. I downloaded LuckGrib (which is NOT free, as I think someone mentioned, and $20 as I think it’s author mentioned) and I’ve got an Iridium 9505 with which I can download GRIB files to view with ViewFax on the boat’s PC. But Ive used LuckGrib to view downloaded weather files and it seems so much better….BUTTTT, I’ve only been able to do this in a wifi environment. I cannot find a 9 pin to USB cable that works with the sat phone that my MAC can see!!! All the cables I’ve tried (four, and I’m pretty sick of it) only seem to work with Windows. LuckGrib does not run on Windows (and I’d rather use my Mac anyway. Any suggestions?
What software are you using on the Mac to get GRIBs? Note that you can’t use LuckGrib’s built in download, or at least not practically, with Iridium and SailMail does not run on Mac.
We recommend UUPlus for this function, plus it’s great for email and the guys at UUPlus will help you get it working including recommending a cable if required.
I’m using UUplus on both the PC and the Mac. That is a great recommendation, btw. the software is not exactly “Apple intuitive” but the support from John and Jeremy has been nothing if not extraordinary. I’m all sorted out on the PC (which I couldn’t have done without help, as I wouldn’t have understood why ViewFax wouldn’t open the GRIB the first time, for example). Now it’s just a matter of using the software on a daily basis and I’ll get it down. That said, both UUplus and LuckGrib are working just fine on the Mac. The problem is I can’t find a cable that talks to both the Mac and the satphone. All the cables seem to have drivers for PC’s only. Any help with that? Thanks.
I’m still confused. I think I’m right in saying that the driver for Mac or PC is part of UUPlus, no added software driver is required. Also, you say that UUPlus is working fine on the Mac?
Are you perhaps referring to a USB to Serial converter box? As I remember, the Iridium handsets are serial not USB and Macs are USB, so maybe that’s what you require?
Anyway, since you are using UUPlus I think the best bet is to get with John and Jeremy to sort this out. I’m near-sure they will know of a box and or cable that works.
Hi John, I’ve been re-reading this book over the last couple of days. I appreciate your very experienced perspective. I think we were both weaned on raw surface and 500mb faxes on curly thermal paper. That experience never leaves us. I think though that the majority of cruising sailors today lack the kind of meteorology training and study we felt we needed many years ago. The “weather” discussions I hear at anchorage these days seems to be about “What Chris said”. I don’t hear people saying things like “did you see the omega block developing that will likely stall this system…” or other comments that indicate they have either seem the real weather data or had some understanding of what they saw. Now I don’t want to slight other sailors but this seems to be today’s, just add water, sailing community in oday’s instant information world where thinking for one’s self is rarely required. This of course goes to the first article in this series in which you share the timeless advice hat the only one responsible for the weather forecast is the captain of the boat. I agree with your comments on gribs viewing tools but I have a different perspective on where the PredictWind toolset fits in. Here is my perspective, for what it’s worth. 1) The routing and departure animation features in PredictWind are huge time savers. We managed to tune the polars derating for our boat after a few crossings to where these tools are very useful for us. Running departure scenarios first on 24 or 48 hour intervals (four departure time runs per download) then having the interval once he best window as found, and repeating a few times gives us great insights into to expected weather. This is also a huge time saver for me when planning passages. 2) I believe you wrote that you have not benefitted from the hi res downloads in PredictWind in the areas where you have been cruising. When I have used these in the Caribbean, I found them to offer a lot more detailed and accurate prediction particularly near land as they seem to consider more of the local effects such as downs open winds on steep shores. I have found the ECMWF hi res models to be best in this regard. Unfortunately, as you know, these hi res files are big and often too big for Iridium downloads. When we sail where there is no hi res dataset available, I really miss them. 3) All together, I see the PredictWind Offshore tools with the Pro subscription address a potential audience that wants to develop their understanding of the weather facing them but does not have that higher level of meteorology study that you and I grew up with. That said, I find the tools fulfill my needs though I join you in wanting to see the 500mb data too; and 4) I remain impressed with the continued work to enhance the PredictWind Offshore tools. This is not… Read more »
I agree completely with your base thesis that many, perhaps most, modern cruisers are not taking the time to get the sort of basic weather understanding that we consider vital. In fact, I guess basic weather understanding is what I’m campaigning for in this Online Book and with these recent updated chapters.
Or to put it another way, I’m just not willing to just settle for, “they don’t have the understanding, so give ’em Predict Wind”—just call me Don Quixote. Seriously, not just going along with the crowd’s easy way, is much of what AAC is about, even though I know it limits our audience.
As to Predict wind, I’m perfectly happy with it in the hands of someone like you that understands the basics and the limitations of automatic routing. That said, I prefer a more roll-my-own approach, but that’s just taste and not really important either way.
I tend to steer clear of weather discussions as I am not that knowledgeable about the subject but your comment about routing programs got me thinking. Your concern over taking the output of the program at face value is completely justified.
What I think is interesting with using routing is if you can run a sensitivity analysis. Just like weather forecasters look at “spaghetti plots”, you can look at what happens if the boat speed is slower or faster than what you have programmed in with your “nominal” polar that you create. By looking at these outputs, you can see what your margin is and what the consequences are of being a bit slow or fast (for example, you may find that there is one section where it is worth motoring for a few hours if your speed average drops even a tiny bit). You can obviously do this all manually but a computer can do it more quickly so you can run more scenarios and it often displays information in a better way.
Weather and routing programs are all changing relatively quickly and it has been a few years since I have done a passage where I have messed with this stuff so I can’t speak to what the automated versus manual capabilities are in current software platforms. What I do know is that I do sensitivity analysis regularly in my job from simple stuff like tolerance analysis in Enventive to much more complicated dynamic modeling in different programs and this analysis almost always is more informative than the nominal analysis on its own.
That’s an interesting thought. I guess I would be a lot happier about these programs if they added something like that, and even happier if it clearly demonstrated to the user that very small variances in the input data, as well as compliance with route, could result in nasty results.
Hi Jon, I’m new here – I only wish I had found you earlier. What an amazing mine of information! We have been full time live-aboards for 10 years but in rather less “rugged” waters than you and many of your other readers sail upon. We have spent all our time in the Mediterranean. The weather (at least in the summer) is reasonably predictable, the sea is warm, the distances are usually short and the cell phone network is close to ubiquitous. That said, the Med can be vicious and needs to be treated with great respect. The great god Poseidon is not a forgiving deity. I have been reading with great interest, your weather chapters. I hope you won’t mind me giving my perspective as one of the “modern cruisers” referred to rather disparagingly. I don’t have any formal weather training although I do have enough physics and engineering to understand your arguments, what a weather model is and what its limitations are. Most days, I only need to know what the weather will be like today and the following night so that: I have a gentle passage to a safe anchorage or mooring and a good night sleep. Or know that I’m better off staying put and possibly battening down the hatches. Or I change my plans and go somewhere else. I have seldom found that meteorologist-generated forecasts have been useful to me and are often seriously misleading – I have often been warned of high winds and/or thunder storms and then have had a clear blue sky and gentle breezes all day (although never the reverse). I guess this because they always forecast the worst anywhere in a large area and that is often a long way from me. In contrast, I have found, GRIB based forecasts to be much more reliable for a couple of days – even the Mistral, the Meltemi and usually the Bora seem well predicted. In the early days, I used raw low-res GRIB files and did my best to figure out the all important island and mountain-valley effects – with limited success. PredictWind with its high resolution accounting for terrain, was a revelation. Many times it has warned me of narrow high-velocity, streams of air – some of which might have been predictable with careful examination of the chart or Google Earth and others that were not. Several times I have warned other skippers in a Greek town quay or anchorage of a coming local blow which was predicted by nobody else. I find PredictWind much quicker and more reliable for this than doing it manually. The dual display of two different initialisations of the same model helps me to judge how likely the forecast is to pan out as predicted. In the Med, rain nearly always falls from cumulonimbus often with associated squalls – so I always check for rain predictions and assume that they have wind and lightening. My expectation was they would just be indications but to my… Read more »
All sounds good to me. As you say, your area is very different from mine and you have obviously thought about the way you approach weather analysis for your needs, and that’s really what matters, not the specifics.
Very glad to hear that the PW high resolution models provide value. As I said in the post, they don’t cover the areas I sail in at high res so I have not seen the topographic benefits that you are getting. Good to know.
Wondering if you have any comment on “GRIB Explorer Plus” by OCENS? I am looking at it because I bought my Iridium Go/service from them. And my general comment on this is I wish somebody would write “GRIB Analysis For Dummies”, because I really need it. I don’t even know what you are talking about with terms like “500mb”, “CAPE”, etc. (well I do now since I’ve googled it) but then I have to choose which model, and which data source, with absolutely no guidance from any GRIB software I have seen) – it is really intimidating.
I have looked at GRIB Explorer plus so I can’t opine on it. That said, I have not in the past been a fan of OCENS since they seem to charge a lot of money for data that we can get for free from SailDocs.
As to GRIBBs for Dummies, if you keep reading on through this Online Book I think you will find pretty much everything you need including step by step instructions on downloading and analysis, which GRIB readers I like and suggested models. You also might want to get a copy of Frank Singleton’s book. It’s a quick read and very well done.
Also, this page explains how to use our Online Books and you will find a table of contents for our Weather online book here.
Hi John and Colin. Have very much enjoyed your website since becoming a member earlier this year. Also enjoyed meeting Colin at East River Marine this summer. Here’s what caught my attention in this article:) Where do you get off using an expression like “sturm und drang”. Do you even know what that means?
Yes, I do. Not sure why you are upset or questioning my use in such an aggressive manner. To me it just enlivens the text a bit, much as savoir faire or carpe diam might in different circumstances.
I really can’t see anything to give offence in the Wikipedia listing either: https://en.wikipedia.org/wiki/Sturm_und_Drang
one nice feature of View Fax is the little boat which moves together with the time frame of the Grib model, indicating were you ought to be , approximately. I always find that quite useful! Saves me having to imagine where I will be in 3 days time.
Are you aware of any other grib viewer that does that?
Yes, LuckGRIB, my current favourite viewer, has that feature. That said it is only available for Mac and iPad.
John, have you an analysis of all the monthly subscriptions you pay for in regards to navigation and weather? I haven’t added them up but it feels like there are a lot of monthly charges/subscriptions for things. We are preparing to do some extended sailing and I have been contemplating signing up for some of the things like iridium go, a charting program such as navionics etc. but it seems like its getting out of reach when on a budget.
I haven’t, but adding it up in my head I would say about $250 a month when actively offshore cruising. That includes Iridium unlimited data, UUplus, and keeping all my charts up to date. When coastal cruising we drop the Iridium, so about half that. (That does not include the cost of cell phone data, since we need that anyway.)
And yes, it sounds like quite a bit of money. On the other hand, having really good weather information can save us a lot of money.
I have tried to illustrate how the different equipment/application presented in this book would fit on my boat where i am already riding the devil with a Windows navigation computer running TimeZero linked to the Furuno Navnet, radar, chartplotter, autopilot. Last year i purchased an old Sirius XM weather receiver for 100 US and it displays nice wind, fronts, lighting on the chartplotter but this is just valuable for coastal cruising. I already have a WeatherFAX/Navtext and an ICOM 802 SSB with pactor. Using Winlink for the moment. So i plan to add an Iridium GO and engage with Sailmail and perhaps also PredictWind…
Comments are welcomed. An image is worth a thousand words…
I tried to take a look, but got a 404 error. Could you please check the URL, particularly since I think it’s a worthy idea.
Helping my daughter’s engineering class launch a high altitude weather balloon. I found this site that is really fun to play with and may even have some useful properties!https://earth.nullschool.net/
Do you have a primer on how to calculate and tweak polars? There are none published for my vessel.
I’ve been playing with OpenCPN lately and downloaded some GRIBS into their weather module. Any comments on the OpenCPN viewer?
I don’t. The problem is that if you don’t have an accurate set of polars developed by a naval architect there is not a lot we amateurs can do to get them accurate enough to make automatic weather routing useful or even safe. And even if you have said polars, adjusting them to reflect the actual sailing capabilities for a cruising boat with an aging crew, old sails, and maybe a less than clean bottom is near impossible.
I know that’s not what the vendors like Predict Wind say, but they are selling a product and service.
Bottom line, the use of automated weather routing as a substitute for really learning how to route an ocean passage safely by hand scares the living crap out of me.
As to OpenCPN, I have not used it, but I do have an article that explains how to evaluate a GRIB viewer yourself: https://www.morganscloud.com/2017/09/12/strategic-weather-analysis-hardware-and-software/
I’ve just started playing with TZ on boot camp, but have previously enjoyed getting to know luckgrib, which lives in the other side of a reboot. So I wonder what you think of the weather program in TZ? If it worked well enough that would certainly be convenient.
Yes, good point, going back and forth from luckgrib to TZ is a pain in the neck. I’m lucky in that because of my work here at AAC I always have two Macs aboard, so it works for me. That said I have always found the weather part if TZ kind of limiting and not a patch on LuckGRIB. You might want to have a look at PredictWind. Last time I looked LuckGRIB was miles ahead, at least to me, but that may have changed and many people like PW a lot.
Thanks so much John, I’ve played with it on an iPad but at the time I didn’t like it like I do luckgrib, but I’ll take a look at the windows version, since it would be great to simplify sharing of waypoints etc.
As always so much good information and experience to digest. Thank you all.
It may be of interest to anyone wanting to try out LuckGrib ( which l recommend) that your Mac OS version may be a limiting factor.
Having tried the 14 day free trail on my iPhone l thought splash out and buy the version for my trusty old MacbookPro late 2012.
Ok stop laughing 😝 everyone, at least l can take mine apart and insert memory etc 👍
But, a big but, will my present OS run the latest version on the OS App Store.
It’s indicating that it needs Big Sur to download. Not to be put off l tried on one of my old Mac Pro towers running High Sierra again nope it wouldn’t download.
At this point l must point out l’m retired from the world of video editing hence my trusty Macs (vintage!)
I’ve been in touch with Craig McPheeters who has been very helpful, credit to the man and good YouTube videos to watch and evaluate the program.
If anyone has recently downloaded LuckGrib onto a Mac what OS were you running at the time and did you notice on the App Store what OS requirements did it need.
Thank’s for the heads up on that. I’m running LuckGrib on a 2016 Macbook Pro and also on a 2013 one running Monterey and the other High Sierra, without issues. As I remember everything changed in the Macbook Pro over the 2012/13 time frame and pre 2013 units have trouble running a lot of modern software including latest operating systems, but with units after 2013 all is good.
Sorry, none of that helps your situation much. One thought that might be more useful: now that so many people are upgrading to Apple silicon based Macs, refurbished Intel macs built after 2013 can be bought quite inexpensively and will still run Monterey. I think the sweet spot might be a unit from around 2018-2019
Of course the next shoe to drop will be when Apple stops updating Intel based Macs, but I expect that will be a while.