NOAA Changes Course
A message from Chris Parker of Marine Weather Center regarding the changes being planned by NOAA:
In late 2017, early 2018, and in the fairly near future, NOAA's OPC (Ocean Prediction Center) is shifting resources away from some existing graphical products (images, such as charts depicting weather features) - and devoting more resources to gridded products plus a new 72-hour image forecast.
I agree with Lee Chesneau that these changes are not without consequence for the mariner. Here's a summary of the changes and why they're important:
FIRST MAJOR CHANGE...While NOAA added a suite of 72-hour forecast images (synoptic charts for 500mb and surface, as well as wind/wave forecast), they removed 72-hour details from the 96-hour products.
This sounds complicated, but I prefer the legacy product, and here's why:
Previously, the 48hr forecast image included 24hr, 48hr, and 72hr location and strength of every significant weather feature (Low and High pressure system)...while the new product removes the 24hr prediction (there is a separate 24hr forecast image). In addition, the 72hr forecast is only provided for strong Low pressure systems (GALE Force or stronger)...so the 48hr forecast image lacks a 72hr forecast for lesser (but still significant) features.
The 96 hour forecast image previously included 72hr, 96hr, and 120hr location and strength of every significant weather feature (Low and High pressure system)...while the new product removes the 72hr prediction (there is a new separate 72hr forecast image). In addition, the 120hr forecast is only provided for strong Low pressure systems (GALE Force or stronger)...so the 96hr forecast image lacks a 120hr forecast for lesser (but still significant) features.
While these changes simplify the images, there are 2 big problems:
1. in order to have a reasonable day-to-day forecast, I now need 4 charts, where before I only needed 2 charts. These are image products, which take a long time (and often lots of electricity and/or satellite or HF radio email time) to access.
2. it is easier to get a sense of weather patterns by analyzing on a single image how features evolve over 3 days rather than only 2 days.
SECOND MAJOR CHANGE...upper-air troughs are no longer drawn on 500mb charts.
This is a big problem. There are at least several ways of determining the presence and characteristics of a 500mb trough (inflections of 500mb height, 500mb temperature, and 500mb wind speed/direction).
The new 500mb forecast images contain only 500mb iso-height contours and very limited 500mb wind speed/direction. So the tools are partly missing which a self-sufficient mariner might use to identify the inflections and hence the presence and characteristics of a 500mb trough.
Removing the depiction of upper-air troughs from the 500mb forecast image means mariners may fail to realize there's an approaching upper-air feature which could influence his/her weather.
WHAT ABOUT THE IMPROVEMENTS?:
While the new images are easier to read, and there are more images, needing to receive and analyze 4 large images instead of 2 is a drawback - not a benefit.
Additional geographic areas will be covered by NDFD (forecaster verified) GRIB (gridded) forecasts. This is a benefit for those who use NDFD GRIBs, but I'll make 2 observations:
A. NDFD GRIBs predict only gradient wind speed/direction and height of waves 0 they do not weight in on squalls or many small scale (in time and/or size) events, upper-air/500mb weather, ocean swells, and the direction/interval of the significant wave.
B. In order to use these raw data products, I must either be connected to the Internet (to use an online viewing tool), or use a combination of a special data delivery tool and special data viewing software (these are readily available at little or no cost, but require mastering the special tools).
So NDFD GRIBs are good for some mariners, but not for all, and do not include everything a prudent mariner should know about upcoming weather.
I hope this explains the changes and their consequences for Cruisers in as straightforward a manner possible.
I agree with Lee Chesneau the changes are on-the-whole bad for Cruisers, and I already signed Lee's petition. Feel free to quote me.
Chris Parker
Marine Weather Center
If you wish to sign Lee Chesneau's Petition, you will find it HERE.