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Modern Marine Weather,
3rd ed.


David Burch

ebook copies are available in various formats

Errata/Notes 3rd ed (first printing)

Errata 2nd ed (now out of date)

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There is no logic to the order of these items

Squall lines Great Lakes , H.M.S. Eurydice
Example of custom weather resources: Pacific, Puget Sound, Inside Passage, tropical Atlantic. Some of these may not be up to date.
Section of Dove's Law of Storms on Practical Matters (mostly of historical interest)
To get to NGA pubs use:   If that does not work try:  This is only here because it had historically been hard to get to, but it seems better these days.  "msi" stands for marine safety information.
We have greatly expanded the coverage of ASCAT in the 3rd ed, but here are a couple earlier articles (information in the book is much updated). Here is an index of sorts to the articles: Here is a magazine article from 2011, which is of interest only in that shows what we did not know was on the horizon in those days: ASCAT—Wind at Sea  In short, this is not a new resource at all, and we hope that the 3rd ed of our book will motivate more usage, as we propose more ways to get the data. Remember ASCAT and ship reports are the truth we need to rely on when interpreting any forecasts.

Other satellite wind data. The Navy also has satellite wind data called WindSAT. You can view the WindSAT descending passes and WindSAT ascending passes direct from the Navy, or as analyzed by the OSWT. We have not yet compared the results to ASCAT, which we will do and add here later. In many cases this looks like encouraging supporting data or even data where no ASCAT is available. But in other cases, we cannot quite understand what we are seeing.  So the role of the WindSAT is still an open question for us. We are looking into this.

Our earlier information on Ocean Currents is at Note we were more optimistic about the value of these predictions when the second edition was written than we are now. This is a work in progress.  The new book presents a broader look at this subject and we will update the online articles as soon as possible. We do have word from those close to this field that the models are getting better continually.

Links to Navy Gulf Stream Analysis maps. These were at one time linked at OPC, but on last look (Jul 30, 2018) they were gone. So we add them here. These maps remain the starting point for any analysis of the Gulf Stream. They are discussed in the text.
Northern region color
Northern region BW with digital temps
Southern region color
Southern region BW with digital temperatures

Resources for Barometer Use in Marine Navigation
Check out our Barometer Calibration page
Starpath Ship Reports free ship reports delivered to your email from within 300 nmi of your location at sea, anywhere in the world (
We have a greatly expanded discussion of models in the 3rd ed. For a concise description of available data see
How to combine GRIB files and when we need to do this.

To study past examples of tropical storms and hurricanes looking at archived values of all related products: analysis, forecast, and tropical cyclone warning maps, NHC Advisories, and archived GFS files, see these several links: and (354 parameters for whole globe, ~ 60 MB) and  You can view the large GFS files in LuckGrib (Mac or iPad only) or Panoply (PC or Mac). We do not know of other viewers capable of showing these large files with so many parameters.  Note: the usual way to access just the parts of a GRIB file we want is called OPeNDAP, but it seems NOMADS no longer (≥ 2018) offers this format for archived model predictions, hence we are left with downloading one valid time per file for the whole globe, covering all 354 parameters. We hope to add some videos on the use of Panoply when we can... there is a learning curve, because the types of files we want to see and how we want to see them for marine applications is not the typical use of this amazing program.

For a list of where archived data is listed in the text, see note below.

Below is a list of several veteran chart and navigation suppliers from around the country. Each of these outlets is a joy to visit for any navigator, but if they are not convenient to you, they can send you what you need. Needless to say, there are other fine chandleries and navigation supply stores around the country that might carry these publications or can get them for you; these are the ones we know by direct experience that stock all the crucial publications. There are certainly others.

• Baker, Lyman & Co., Metairie, LA,
• Binnacle, Halifax, Nova Scotia, Canada,
• Bluewater Books & Charts, Fort Lauderdale, FL,
• Captains Nautical Supplies, Seattle, WA,
• Landfall Navigation, Stamford, CT,
• Pilothouse Charts, Philadelphia, PA
• Safe Navigation, Long Beach, CA,
• Seabreeze Nautical Books and Charts,
• Starpath School of Navigation

Archived data are presented several places in the book. Use the index entry "archived data" to find links for specific products, which include: ASCAT, 185–186, climate, 237, currents, 73, hurricane data, 105, 120, 186, 203–204, 222, 254, model forecasts, 168–170, 186, 203–204, observations, 11, 39. pressure, 23, QuikSCAT, 236, weather maps, 101, 185, 203, weather radar, 251, yacht race routes, 241.  This index item is not in the first printing of the book.
The new (as of early 2018) 72-hr forecasts updated once a day at 12z are now in the FTPmail folder for access by email request. These are not yet on the radiofax broadcast schedules, although this is planned.

12z Atlantic 72hr surface forecast: PPAK98.TIF
12z Atlantic 72hr wind/wave forecast: PJAK88.TIF

12z Pacific 72hr surface forecast: PPBK98.TIF
12z Pacific 72hr wind/wave forecast: PJBK88.TIF

12z Alaska 72hr surface forecast: PPCK98.TIF
12z Alaska 72hr wind/wave forecast: PJCK88.TIF

These are in the radiofax format, not the color versions we see at OPC. They are available from FTPmail, but not yet from saildocs, unless you make a direct request with the full URL. (If not familiar with the file names, read the various rfax***.txt files at the fax links above.)

Note that there are 72hr tropical maps of the Pacific, but these are not new.

00z Pacific Tropics 72h forecast PYFK83.TIF
12z Pacific Tropics 72h forecast PYFK84.TIF
Latest Pacific Tropics 72h forecast PYFK10.TIF
GFS model runs now include forecasts every 1h to h120, 3h to h240, 12h to h384. It will take a while for 3rd party providers to accommodate these new intervals; most offer every 3h to h48, 6h to h96, 12h to h384. The latest version of LuckGrib incudes hourly GFS and FV-GFS out to 18hr.
The HRRR model, which previously updated every hour, extending out to h18, now has modified that schedule to extended to h36 on the specific runs made at HH. That is, the 00, 06, 12, and 18z runs of HRRR extend out to h36, but all of the other 20 runs each day still extend out to h18.  We do not know of any automated source of this data that offers the extended forecasts, but they are available by direct download as explained in the text.  This update is even harder for providers to implement, so we wait and see what becomes available, or download it directly ourselves.

As of mid March 2018, the OPC has discontinued showing past or future tracks of both Lows and Highs. They will only show a projected Low position providing it has gale or more winds, or other significant weather associated with it, such as potential for vessel icing due to freezing spray in northern systems. See OPC discussion of this online. This appears to be primarily a budget issue, as they do not have the manpower to add the tracks and still do new things they want to do such as the 72-hr forecasts. On the other hand, we do get this information from global model forecasts, and these changes do clean up the maps, which is in the right direction. We have to wait and see if the new 72-hr forecasts balance out the loss of track data on the surface analysis maps.

Marine Weather Information Guide.  New from VOS program, it appears to be a good first step toward a print source of info that was on the Marine Weather Services Charts. You can supplement the forecast zone identifications with their internal document MARINE AND COASTAL AREAS OF RESPONSIBILITY, which has better pictures of the zones than they do online. Nevertheless, we are proud of our own rendition of these zones and how to use them that appears in the text.
Contact the Author
Read about our Online Marine Weather Course
Description of our expanded ship reports service. How to get near-live reports by email request.
Our main source is the weather articles at Later we will focus here on ones referenced in the book. Below are just a few suggested ones, but see first the Marine Weather Check List and overview of Marine Weather.
We have added to the textbook discussion of weather by satphone in two articles in our nav blog: Nuts and Bolts of Sat Phone Usage and Weather by Sat Phone.  The book updates these.
Two new articles related to converting station pressure to sea level pressure: Point Four Four per Floor—QFE to QNH to QFF and Mean Sea Level, Tides, and Barometers
True Wind Revisited which are updated notes on computing True Wind from Apparent Wind when COG ≠ Heading... again, our treatment of accurate true wind computations is greatly expanded in the text.
Comparison of tropical storm statistics from 1977 to 2017
Notes on HF use in South Pacific and other places by MetBob Article 1 and follow up Article 2, also tells how to receive Bob's valuable weekly reports by email request to saildocs. Must have for SPAC sailing.
Hurricanes on the Route to Hawaii — Weather vs. Climate.  Summary: we do not have to change anything we have been teaching on this for the past 20 years.
Effect of Leeway on Knotmeter Speed   ... a follow up on a point only mentioned briefly in the book.   
See  (we will itemize these later)
An example of the corner effect, which we just annotated with our new favorite way to predict where this effect will occur in the Northern Hemisphere: with your back to the wind, expect enhanced winds off large low corners on your right hand side.  Start with the Buys-Ballot law for finding direction to lowest pressure (left hand in NH), which puts the wind on your back. Then corner effect is on your right. So the Buys Ballot law gives you two things: direction to low pressure on your left, and potential corner effect winds on your right. Both directions are reversed in the SH. We have other ways to predict this in the book, but this is probably an easier way to remember it.

Using Buoy Data and BuoyCAMs to study Passing Storms.  This is an article on the subject with links to several related videos. (This is an update to earlier links that have been removed because they are outdated now that the Hurricane Florence has gone ashore.)

To see the corresponding ASCAT wind measurements along the East Coast of the US you can use these links. Then look at Ascending and Descending separately. East Coast Ascending.kml and East Coast Descending.kml There has to be two links so they work in a phone as well as a computer. These KML do not have to be updated. They should last to cover the next East Coast storm, or to use anytime you want to check the winds. The data shown will the the latest available whenever you open Google Earth.


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