Friday, June 19, 2015

Atlantic and Pacific Weather Briefings

The Atlantic and Pacific weather briefing webpages are a unique service of the Ocean Prediction Center that are not as well known as they might be. These links are effectively the latest versions of all (or nearly all) of the maps available for each ocean displayed on a single webpage, in sequence.  We will recommend our own versions of these below, but here are links to the OPC versions:


The files they provide are gif format that show up in one long page of sequential pictures. Very nice for quick view on land but not useful underway in this presentation because of the large file sizes and low expensive bandwidth at sea.  Furthermore, we rarely need all of them at once

Needless to say, we can request any one of them individually by email request using the NWS's FTPmail or from Saildocs, but to do that, we need a custom request format and we need to know the actual file name for each one—there is also a unique file name for the latest version of each one, as opposed to, say, the file name for the map valid at 18z.

As it turns out, the NWS stores these maps in at least three different locations, and the file size for an identical map could be 300 kb one place, 85 kb another, and 27 kb in another. They also differ on the same site in size for a .gif file versus a .TIF file. As far as we can tell, the smallest ones are the .TIF files located at weather.noaa.gov/pub/fax  so we have used these.  We can find theses files of <30 kb for all of them, which is convenient as some comm sources have limits of 30 kb attachments.

One price we pay for minimum file size is the use of the .TIF format, which requires a graphics viewer, but these days all computers should have this. Also for some reason, some are stored in the wrong orientation, so we have to rotate them ourselves. Not a big deal.  (Also just a side note, that the .TIF format is not inherently the smallest file size from a technical point of view; it just happens that of the files we have access to, the smallest are in this format. We will ask the NWS to see if they might consider a directory with reduced file sizes that will be better suited for direct transmission via HF radio or Sat phone.)

Thus we have made a shortcut index to the briefing products that gives the user the opportunity to ask for individual products bypassing the need to first open an online index.  Our custom index is in the from of a pdf with active links within it. Thus with this pdf in your computer, you can just open the pdf and then select the link you want.... or mail the pdf to yourself and open it in your tablet or smartphone to get the products in those devices.

Another change we had to make from the standard Briefing presentation is to break up the surface analysis into two parts. This is done to keep the file size down. And the important adjustment is to ask for these from Saildocs, which offers the wonderful service of taking these 30 kb files and reducing them by 50% so we can get them at about 15 kb each, sometimes 10 kb.

You have a choice to download the image directly when using an Internet link, or choose the other link for each one that prepares the proper request from Saildocs to be send by your email.

The Internet request is straightforward (these will come directly from the NWS server), but there are nuances to the email link. Namely, when the link generates the email for you, you must be sure that there is no signature or anything else in the email. It must be a blank email with just the send command in the body.  The subject line does not matter.

Also, for this to work seamlessly, you will need to have your sat phone or pactor modem connected to the computer as well as being sure that the default email program for your computer is the same as you are using for high seas communications—google something like "setting default email on win7" for instructions on that. Note that we include a link to the list of file names, so you can request any of them directly from Saildocs as shown in any of the live links.

A sample element of the Briefings pdf looks like this:

This one is actually 13kb. The pic is outdated.
Our Briefings pdfs are about 2 MB, but they only have to be downloaded once to your computer from a land line. They are large so you can zoom into the outdated thumbnails to see what each map actually looks like.

We also include the update times and approximate file size. The sample shown above, for example, exists for both 00z and 12z valid times, but you would not get the latest 00z map till about 05z or 06z. The latest 12z map would first be available at about 17z to 18z.  Update times vary within these limits, but you might be able to pin it down more precisely. The file sizes may vary a few kb as well.

You can get the pdfs here:

Download custom Starpath Atlantic Maps Briefing pdf index

Download custom Starpath Pacific Maps Briefing pdf index.

Please give it a try and let us know how this works. This is a new idea, so we will need some in practice feedback to learn how to improve it. Please post your comments or questions in the comments section below.

Thanks.

We should add that what we offer above is a more convenient format for the maps briefings,  but there is also an OPC text briefings and these remain extremely valuable as they are.

OPC Atlantic Text Briefing             OPC Pacific Text Briefing.

Again, however, saildocs has an excellent presentation of these as well. We discuss these at this link


because these are extremely valuable, especially in the presence of tropical systems. As we show in that note, you simply cannot get adequate storm forecasting from any graphic map or grib file. We need these text reports.


Here is a related article about weather map file size and format.

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9 comments:

Yellow Pine said...

Can t open the TIF on my Android.

David Burch said...

Please google "tif viewer for android" to find several free apps that do this. I will try to do the same to test on an android tablet we have.

Unknown said...

Thanks, looks pretty nice! 30 kb is much better, 1/8 size, I'll take it!

Biggest issue I have with saildocs links is the program that we use for our sat email doesn't register itself as an email program, so I can't set it as the default email application. Expedition software for example doesn't give you the text of the saildocs request, so it can only open in your default email program. Annoying crap like that!

David Burch said...

Several notes, and more to follow: First we have updated the Pacific Briefings to v3, which now has <15 kb file size, thanks to Saildocs. They offer the wonderful service of reducing these by 50%. Mail a sail has similar option but they do not have many maps when i looked last. Ocens also reduces them by 50%, but this commercial app is not legal for the Transpac.

The proper saildocs query query for the small ones is just ie Send PYBA90.TIF That is, omit the url to the source, they take care of that for us. They have all of them at reduced size except latest 500 mb and latest 24h 500 mb. I will contact them to ask about these two. And we have to check the Atlantic side, not done yet.

Also i am trying to learn more about how we might link this index to email programs used in sat com mail... and i will check Airmail and ViewFax which might already have this option. We have several of the standard sat com mail programs here to test. It this does not work, then there are many workarounds, as the subject does not matter and you can just put some description of the map you want in the subject line, then resend it as needed. You can still look at this index to see what the maps look like as they can be zoomed in for detail.

David Burch said...

I tried this and my first problem was getting the Briefings pdf into the android tablet. chrome and firefox would not download it. So then i went to an iphone 6+ and there it all worked fine in Safari. ie go to this page on the iphone safari, then download the briefings pdf, and then click any of the maps, using the Internet connection and even the tifs show up nicely in the phone. in fact in a 6+ the maps can be read very nicely.... but this is not your question. PS do not save the pdf as an ibook. it lets you do that, but shuts off the links.

So then i used the iPhone to mail the briefing pdf to a gmail account which i then opened in the android tablet (samsung). the file could then be downloaded, and it gets stored in the Downloads folder. you access this from the MyFiles app.

then navigate to the pdf in MyFiles/Downloads, highlight the briefing pdf, and i get the option to open several ways. Blue fire reader opens it, but shuts off the links. I also have an option to open it with Drive PDF Viewer, and that works fine and keeps the links.

With that you can see the index very nicely and zoom to see details of each type of map. then click one using Internet option. It downloads it but the screen goes blank. the file has been stored in that same Downloads folder (fine my files in the list of apps).

then find the tif file, and click it. you might get the message No apps can perform this action. you can get that message even when you have an app that will do it.

next get a tif viewer and install it. the free one from Play store that i used is called Multi-TIFF Viewer. download that and install it.

Then open that app, and it says Tap here to choose a tif. that opens my files, go to downloads, and tap the one you want to highlight it (unfortunately you have just the file name, not what it is) then press Select and it opens fine for good viewing.

Note you still get the no app msg when direct click of the file from MyFiles/downloads. Maybe other tif viewers will assign some file type recognition that will save a couple steps.

Not as slick as the iphone using Safari, but it does work. By the way, Firefox and chrome on the Iphone do not work... this is similar behavior to desk top macs.

Yellow Pine said...

Thanks!

So...is the future of marine nav on smartphones with.Apple as opposed to Android?

David Burch said...

I cannot say that. I think the result is a bit typical in that Apple has the interface pretty smooth. I do not have much experience with my Android so stumbled a bit, but i am sure with practice and knowing the right procedures and apps it would be just as smooth. Also there are frankly more nav and weather options on the Android than on the iOS, but that of course does not mean better quality. I think if we choose a platform and then stick to it, we would learn the best solutions. There are many attractive features to the Android OS.... we use the Apple as we must integrate Macs, tablets, and phones and Apple has this set up better than others. The other big difference is with Apple in charge they can set standards, whereas the standards are much looser in the Andrloid Google world. The other side, with Apple having such strict standards and limits on what programmers can access, there are corresponding limits on what can be achieved, which means you can have options in Android that you do not have in iOS.

Matt G said...

I'd love to see a comparable Briefing doc for the Great Lakes.

David Burch said...

I think the Atlantic Briefing we have provides the best graphic maps of the lakes that are available. One could do better, however, with the digital versions of these called NDFD, available in grib format from Saildocs or Ocens WeatherNet. Better still are the HRRR data, but this is for now just available from Ocens. We have a note in this blog on the NDFD, and will be adding one on soon on the HRRR. I think we have a video on the latter. I will try to get out video index up dated to include it. www.starpath.com/videos. We have now on the list to make a post here about GL WX sources. thanks for bringing this up.