[Bob Kuczewski]

UPDATE: This program is now on-line at:   https://ushawks.org/weather/BlobPlot.htm.

It's been nearly a year since I finished my "Blob Plot" Wind Visualization program, and I think it's about time to share it.

The attached file ("BlobPlot.htm.zip") is a ZIP file containing a single HTML file ("BlobPlot.htm"). You should be able to download it, unzip it, and double-click on it to bring up your web browser (Firefox, Chromium, Explorer, etc).

Initially, the plot will be empty, but if you select a site (such as Dockweiler in this example), then it should go to https://forecast.weather.gov to get the latest forecast as an XML file (assuming that you have an Internet connection). The program then parses the XML (shown in the first large text block), produces text versions of direction and speed (shown in last two text blocks) and draws a "blob plot" that looks something like this:

Dockweiler_2023_12_16.png (69.39 KiB) Viewed 14524 times

The plot typically shows the forecast for the next 7 days represented as a series of "blobs". The blobs are drawn to made it easy to visualize the wind at launch. Bigger blobs are stronger winds, and centered blobs show winds blowing directly in at launch. Blobs to the right of center show winds that would be arriving from the right of launch, and blobs to the left of center show winds arriving from the left of launch. The blobs are also color coded with green as most favorable, yellow as less favorable, and red as least favorable (usually not safe to launch at all). The forecast for the current date and time is at the top of the plot, and the most distant forecast (typically a week away) is at the bottom of the plot. Each date is listed, and a few times are also listed.

Because these plots are oriented to the launch direction at each site, you generally want to look for large green blobs near the center of the plot. For example, it's easy to see from a glance of the Dockweiler plot (above) that 2023-12-17 will have a light westerly wind in the afternoon and that 2023-12-18 will have a nearly perfect westerly wind in the late afternoon. You can see at a glance that rest of the week will have mostly strong winds from the south and southeast which are not generally flyable at Dockweiler (shown in yellow and red).

You can also zoom in by increasing the dimensions of the plot using the width and height selectors. These default to a size of 400 x 400 pixels, but that can be changed. The plot below shows the first two forecast days (2023-12-17 and 2023-12-18) with a vertical size of 2000 pixels.

Dock_2023_12_16_2000pix.png (23 KiB) Viewed 14520 times

That's the same data as the previous plot, but now it's expanded so you can see the individual blobs corresponding to the value of the forecast for each hour in the plot.

In addition to changing the plot size, you can also change the "Facing" direction. The default direction is the "normal" launching direction, but some sites have alternate launches. You can enter any heading to see the "blob plot" facing in that direction. All that does is shift the blobs (left or right). Feel free to experiment with it to see the results of facing different directions (try 0, 45, 90, 135, 180, 225, 270, 315, and 360).

You can change the site location by selecting from the list of sites and clicking the "Load" button. You can also visit the Google map by clicking the "Map" button (shown below for Dockwiler), and you can visit the forecast site (https://forecast.weather.gov) by clicking the "Weather" button.

Dockweiler_2023_12_16_map.png (387.5 KiB) Viewed 14520 times

Dockweiler_2023_12_16_forecast.png (89.32 KiB) Viewed 14520 times

You can add other sites, but you'll currently have to edit the actual program. If you look at the program in an editor, you should find the site dictionary that looks something like this:

var site_dict = {
  'Torrey': {'name':'Torrey', 'lat':32.890660, 'lon':-117.251772, 'faces':270,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.890660&textField2=-117.251772&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.890660&lon=-117.251772&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.890660,-117.251772,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Dockweiler': {'name':'Dockweiler', 'lat':33.920115, 'lon':-118.430178, 'faces':246,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=33.920115&textField2=-118.430178&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=33.920115&lon=-118.430178&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@33.920115,-118.430178,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Crestline': {'name':'Crestline', 'lat':34.236097, 'lon':-117.313265, 'faces':209,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=34.236097&textField2=-117.313265&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=34.236097&lon=-117.313265&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@34.236097,-117.313265,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Sylmar': {'name':'Sylmar', 'lat':34.333406, 'lon':-118.384389, 'faces':202,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=34.333406&textField2=-118.384389&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=34.333406&lon=-118.384389&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@34.333406,-118.384389,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Horse': {'name':'Horse', 'lat':32.774514, 'lon':-116.476846, 'faces':256,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.774514&textField2=-116.476846&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.774514&lon=-116.476846&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.774514,-116.476846,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Laguna': {'name':'Laguna', 'lat':32.938752, 'lon':-116.484360, 'faces':60,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.938752&textField2=-116.484360&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.938752&lon=-116.484360&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.938752,-116.484360,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Elsinore': {'name':'Elsinore', 'lat':33.629339, 'lon':-117.371037, 'faces':55,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=33.629339&textField2=-117.371037&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=33.629339&lon=-117.371037&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@33.629339,-117.371037,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Blossom': {'name':'Blossom', 'lat':32.874069, 'lon':-116.850217, 'faces':293,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.874069&textField2=-116.850217&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.874069&lon=-116.850217&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.874069,-116.850217,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Otay West': {'name':'Otay West', 'lat':32.573900, 'lon':-116.894152, 'faces':270,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.573900&textField2=-116.894152&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.573900&lon=-116.894152&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.573900,-116.894152,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Otay South': {'name':'Otay South', 'lat':32.573900, 'lon':-116.894152, 'faces':180,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.573900&textField2=-116.894152&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.573900&lon=-116.894152&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.573900,-116.894152,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Little Black': {'name':'Little Black', 'lat':32.987926, 'lon':-117.122285, 'faces':275,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=32.987926&textField2=-117.122285&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=32.987926&lon=-117.122285&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@32.987926,-117.122285,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Soboba': {'name':'Soboba', 'lat':33.825059, 'lon':-116.943961, 'faces':240,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=33.825059&textField2=-116.943961&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=33.825059&lon=-116.943961&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@33.825059,-116.943961,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},

  'Funston': {'name':'Funston', 'lat':37.713868, 'lon':-122.503116, 'faces':260,
   'wx':'https://forecast.weather.gov/MapClick.php?w3=sfcwind&w3u=1&AheadHour=0&Submit=Submit&FcstType=graphical&textField1=37.713868&textField2=-122.503116&site=all&unit=0&dd=&bw=',
   'wxml':'https://forecast.weather.gov/MapClick.php?lat=37.713868&lon=-122.503116&FcstType=digitalDWML',
   'map':'https://www.google.com/maps/@37.713868,-122.503116,688m/data=!3m1!1e3!5m1!1e4?hl=en&authuser=0'},
}

That's a standard Javascript dictionary, and the first 4 fields give the site name, site latitude, site longitude, and the direction that launch faces. It also gives links for viewing the actual forecast ("wx"), getting the XML from the forecast ("wxml"), and showing the map ("map"). You can add new sites, by simply duplicating one of those dictionary entries and changing the values. If you add new sites, please post them to this topic so everyone can benefit. I may make it easier to add new sites in the future, but this works for now.

Finally, I want to thank Eric for contributing to me posting this project. Eric has a great web site at:

      http://www.HangGlidingFlightSchool.com

I offered to add a few other flying club locations to Eric's database, and that reminded me that I had already looked up the locations for most of our San Diego day trip sites for the Blob Plot project. So I searched our forum for "blob plot" and found it here:

      https://ushawks.org/forum/viewtopic.php?f=44&t=2853&p=33140#p33140

I had intended to publish it back then (January of 2023), but I was still working on some details that I still haven't finished (never let the perfect be the enemy of the good). For example, this version shows the pretty ugly text boxes for the XML and the wind direction/speed that I used during debugging. I had intended to make them optional, but I never got around to it. Anyway, I hope you enjoy the program as it is, and please feel free to post any suggestions.

 
 
This file contains the actual Javascript program. It will need to be downloaded, "unzipped", and then opened with your web browser.

[Bob Kuczewski]

I've added BlobPlot to the weather section of the US Hawks to make it easier to find. It's at:

      https://ushawks.org/weather/BlobPlot.htm

I've also made the color scheme a little more conservative. It now shows:

Green: +/- 30 degrees
Yellow: 30 to 60 degrees
Red: Beyond 60 degrees

The previous ranges were 0-45, 45-90, and beyond 90.

The new version is currently at: https://ushawks.org/weather/BlobPlot.htm, and I've attached a zipped copy to this post if you want to run it locally.

[Bob Kuczewski]

I added a few more improvements, and they are enough to consider this one as BlobPlot 2.0.

BlobPlot_2026_02_17.png (41.15 KiB) Viewed 6189 times

This new version is currently at: https://ushawks.org/weather/BlobPlot.htm.

Rather than use fixed angle ranges for green, yellow, and red, it's now a user setting in the "+/-" field following the "Facing" field. It's currently defaulted to 15 degrees. That gives the following default angle ranges:

      Green: 0 degrees to +/- 15 degrees
      Yellow: +/- 15 degrees to +/- 30 degrees
      Red: above 30 degrees from either direction

You can change the ranges by changing the +/- field from 15 to whatever other angle you find appropriate for the site and your skill level.

This version also allows you to choose the number of forecast days to view. Choosing "1" will show the rest of the current day along with the next full day. Each additional number (2,3,4...) will show additional days. Note that this is very helpful to see the wind speed numbers which will often appear on top of each other when all 7 days are shown.

There are a few other minor improvements. Here's the current "Help" page:

BlobPlot shows forecast wind speed and direction as it might be observed on launch.

BlobPlot reads XML forecast data from weather.gov and parses it for display as a series of "blobs" showing the time (top to bottom), the direction (left to right) and the speed (size and value). These are displayed relative to the direction of launch for each selected launch site, so blobs at the center of the screen represent wind coming straight into launch. Blobs to the left of center represent wind coming from the left on launch, and blobs to the right of center represent wind coming from the right of launch. The size of the blobs show the forecast wind speed with larger blobs representing faster expected winds. The forecast speed is also shown as a small numeric value at the center of each blob.

---

Controls

• Site: Selects a flying site to view. This is the most important control, and it should generally be selected first.
  
• Load: Forces loading of the XML for a flying site. This is generally done automatically when a new site is selected, but the load button forces a reloading in case the data has changed.
  
• Map: Shows a map of the flying site.
  
• Weather: Shows the Weather.gov forecast page.
  
• Facing: Shows the direction the site faces. For example, a site facing west will show 270. This value is generally set automatically when a site is selected. However, it can be manually changed for different launch directions or different launches near the same site.
  
• +/-: Sets the tolerance range for the green, yellow, and red blobs relative to ideal launch direction. For example, the value of 15 means that winds up to 15 degrees (left or right) of the ideal launch direction will be shown as green. Winds from 15 to 30 degrees will be shown as yellow. And winds beyond 30 degrees will be shown as red. This value can be changed to match your own preferred limitations and preferences. The appropriate value also depends on any unique terrain features at each site.
  
• Days: Sets the number of days forecast in advance. A value of 1 will just show the next day. A value of 2 will show 2 days. Weather.gov typically only forecasts up to 7 days in advance, so that's the highest value.
  
• Window Width: Sets the width of the graphics window on your page.
  
• Window Height: Sets the height of the graphics window on your page.
  
• Apply: Used to apply all values (including numbers entered into text fields).
  
• View Control: Used to select viewing of additional panels. The currently available panels are:
  
  
  • Help Panel - Displays helpful information (this panel)
    
  • Data Panel - Displays the actual data values (Raw XML, Wind Direction, Wind Speed). These can be selected, copied, and pasted into other documents and applications for further analysis.
    
  • No Panel - Shows no additional panel
• Show: This button forces the display of the selected view (sometimes needed when reloading).

BlobPlot 2.0

Here's the latest version:
 

[Bob Kuczewski]

Two minor improvements (now BlobPlot2a.htm):

• The Load button now forces a re-loading of the site's direction.
• The link to weather.gov is now fully specified.

Here's the latest version:
 

[Bob Kuczewski]

I've updated BlobPlot to version 2b which includes the ability to enter latitude and longitude directly for sites that aren't already included in the program. In order to select other sites, choose "Other" as the site, and then enter the latitude and longitude in the fields provided. Then click the "Load" button to load that site. Note that you should also change the direction that the site faces with the "Facing Field" (click the "Apply" button to apply the new facing direction).

You can run it directly from here:

      https://ushawks.org/weather/BlobPlot.htm

Here's the latest version for downloading:
 

[Bob Kuczewski]

I've updated BlobPlot to version 3 which includes gust rings around the sustained wind circles. Here are some forecast examples from today.

Dockweiler:

Dockweiler_2026-04-13_1620.png (44.37 KiB) Viewed 4458 times

Crestline:

Crestline_2026-04-13_1620.png (44.69 KiB) Viewed 4458 times

If you compare the two plots, you'll find that the sustained wind is predicted to be considerably higher at Dockweiler. But the gust rings around the Crestline blobs are relatively larger (compared to the sustained wind speeds) than the gust rings around the Dockweiler blobs. This shows the typically greater variability (gustiness) of inland sites.
 

[Bob Kuczewski]

Here's a comparison between the 7-day BlobPlot for Horse and the traditional 7-day weather graph (which typically requires scrolling to view all of the days):

Horse_BlobPlot_2026-04-13.png (77.51 KiB) Viewed 4451 times

Horse_Graphs_2026-04-13.png (136.5 KiB) Viewed 4450 times

It's the same data, but much easier to assess with the BlobPlot.

[Bob Kuczewski]

BlobPlot 4.0

BlobPlot now shows the forecast precipitation as shades of blue.

Prior to this version, BlobPlot only showed the wind speed and direction. That worked pretty well in southern California ... until the rains came! The latest version (4.0) now shows the forecast precipitation in shades of blue. The brighter the blue, the higher the chance of rain.

I had to go back to a Dockweiler forecast I had downloaded in mid-February to find one with significant and varied rain to use as an example. Here's the BlobPlot of that forecast from February 17th, 2026 (forecasting the conditions for February 18th and 19th):

Forecast_Dockweiler_2026-02-18.png (89.63 KiB) Viewed 4404 times

As you can see from the bright blue at the top of the plot, rain was very likely in the early morning hours of February 18th, 2026 (from midnight to 4am). If you look closely, you'll also see some very faint dark blue from 4am until 10am. That shows much less chance of rain during those hours. The plot background is nearly black the rest of the day which indicates nearly zero percent chance of rain.

Rain was also expected on the 19th. You can see there's a light chance of rain (dark blue) from 4am to 10am followed by a much stronger chance of rain (bright blue) between 10am and 4pm. Then the likelihood of rain is reduced (dark blue) between 4am and 10pm. Finally, the chance of rain after 10pm is very low (nearly black).

All of the other features of BlobPlot remain the same except for the addition of a new Test Panel. That panel has buttons that generate synthetic test data which can be used for testing without an internet connection. The Test Panel was mostly helpful during development, but it may have other uses. Here's a plot of some synthetic data with varying wind direction, varying wind speed, and varying probability of precipitation:

BlobPlot_SineTest.png (113.67 KiB) Viewed 4400 times