Saturday, December 19, 2015

How to Find Archived Weather Maps

Normally we care about weather now, or even more often weather in the future, but it can happen that we want to know what took place sometime in the past.  You might, for example, want to review past weather data for the analysis of a voyage or yacht race, or maybe to look into sea and wind conditions from an event you see in the news. Schools like ourselves are often looking though archives for an example of a point we want to illustrate.... and indeed the example given below will answer one of our quiz questions, namely what was the wind speed and direction and the pressure at 30N, 130W on July 4, 2001?

Before addressing this specific question, I note that we are looking for archived data at random places, which often means we need to find the corresponding surface analysis maps. But if you happen to just need the data from a place that has an official reporting station, then the process is much easier.

Just find the station at the National Buoy Data Center and then at the bottom of the page find the link that goes to archived data.  Here is an example from our local West Point Lighthouse, station WPOW1: Historical Data & Climatic Summaries.

The less well known, but far more extensive, source we look at now is called the National Climatic Data Center (NCDC)—or to be more precise, that is what the agency used to be called. The NCDC has been incorporated into what is now called National Centers for Environmental Information (NCEI).  We can hope this frequent restructuring (a common practice in government agencies) is progress and not just job security. (The NCDC underwent a major restructure in how we access data just a few years ago.)

Neat new logo for the National Centers for Environmental Information (NCEI)

In any event, it is almost certain that had we known the new right place to look for what we want, it would take much longer to succeed.  In fact, we progress with our search below using the old name of the agency (NCDC), though it looks like Google does indeed know what NCEI stands for.  We will have to change our training materials to cover the new name.

Below is one path to the map we want for the Pacific surface analysis at 30N, 130W on July 4, 2001.

1) Google NCDC   NOAA   (Later we will look into a new route starting with NCEI.)

2) Find first link  (This will eventually be replaced, but is valid now.)

3) Click I want quick access to your products

4) Choose No. 9, scrolls you down to charts section.

5) Click Analysis and Forecast Charts

6) Select region and map type, i.e. Forecast or Analysis

7) For surface analysis maps, select Ocean Analysis, and click Continue

8) For our example select  Pacific East Surface Analysis, and click Continue

9) Note package limits given. For our example set beginning and end to 2001 07 04, click Continue

10) You will see a list of the 4 maps of that day. Click the .sfc.12 product (that will be the 12z map).

11) Right click and save the map, so you can view it better. They will be in the wrong orientation.

12) Then open it in a viewer of choice, rotate it, and look to 30N, 130W to find the answer.

That is the process and it will show you all the options you have for archived data as you play around with the site.

The video below illustrates the above, and then address the issue that once the map is in hand it might not give you what you want without further analysis, so we include that analysis as well in a second short video. 

The video below shows how to read the data we want from the map, once we have found it.

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