Wind barbs are well-defined symbols, but I noticed in my WX briefing that there are now occasional red barbs in the chart.
The red appears on both the 5kt and 10kt barbs, and sometimes for largest 10kt barb or the smallest 5kt barb.
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$\begingroup$ When I look very closely, I see that the red is actually an overlay, which hints that it might be related to gusts, but it's unclear how to interpret that overlay. $\endgroup$– Kenn SebestaApr 22, 2021 at 0:06
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1$\begingroup$ what about the red line underlying the direction? See the symbol in the center, east of Chicago $\endgroup$– EarlGreyApr 22, 2021 at 6:59
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1$\begingroup$ I'm pretty sure that's the wind overlay poking through. If you zoom in you can see it on all the wind barbs which have gust information. The degree to which it is evident is a function of the barb's angle. $\endgroup$– Kenn SebestaApr 22, 2021 at 10:23
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$\begingroup$ @Ron Beyer gives a great answer. The red is not an overlay on the black. But, it does indicate gusts. The body of the wind barb indicates the direction from which the wind is coming. Each fletching-like line at the end of the barb indicates 10 knots of wind. A half a line indicates 5 knots of wind. If the line is black, it indicates sustained winds. If the line is red, it indicates gusts. $\endgroup$– Dean F.Apr 22, 2021 at 17:17
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$\begingroup$ @EarlGrey - The red lines do not indicate direction. They indicate speed, only. The symbol you mentioned East of Chicago is two symbols. One is for a weather station on Lake Michigan. The other is for a weather station in the state of Michigan. They are just very close together. $\endgroup$– Dean F.Apr 22, 2021 at 17:21
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They do represent gusts:
Figure 1: Station Model PlotIn many cases, the data are plotted using standard symbols and plotting models. Fig. 1 shows the station model used in the METAR and TAF plots.
- Ceil - Ceiling height in hundreds of feet. This represents the height of the lowest broken or overcast cloud layer.
- Id - The 4 letter ICAO identifier for the site. KRFD is Rockford IL.
- Windbarb - The wind barb. The stick points in the direction the winds are coming from. Each full barb represents 10 knots of wind. Each half barb represents 5 knots. Red represents wind gusts. In this case, you have winds from the SSW at 25 knots with gusts to 30 knots.
So for example, these:
The one on the left represents wind of 15 knots gusting 20, and the one on the right is 15 knots gusting 25.
Odd ones like this:
Mean 5 knots gusting 10. Why they don't overlay I'm not sure.
answered Apr 22, 2021 at 0:45
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3$\begingroup$ In the case if the bottom graphic, why isn't that one "5 gust to 15"? How would 5G15 be represented? $\endgroup$– Ralph J ♦Apr 22, 2021 at 3:54
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1$\begingroup$ @GrzegorzOledzki - Great answer Ron. Wouldn’t 5G10 be a half one barb at the end of the windvane with half of it being black and half of it being red? $\endgroup$– Dean F.Apr 22, 2021 at 17:04
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$\begingroup$ @DeanF. Unfortunately I'm not entirely sure about this. I interpret it as a long line is always 10kts and a short one is always 5. You add up the long lines *10 and short *5 to get the speed. Black for steady, red for gusts... I can't find anything definitive when they are arranged like that. $\endgroup$ Apr 23, 2021 at 0:22
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$\begingroup$ My last comment was poorly worded on retrospection. My understanding of the gust and steady barbs would be black for steady and red for gusts. Just like you suggested. My understanding of the wind barbs is that you add all of the lines and flags together to get the top range of the winds (gusts) regardless of color. You only count the black lines and flags for the sustained winds. The red lines and flags are the gust factor. With that logic, one line on the windbarb that is half red and half black is a gust of 10 with sustained winds at 5 knots (gust factor of 5). $\endgroup$– Dean F.Apr 23, 2021 at 0:49