Live Weather Waldorf
This guide shows how to pull real-time live data from NOAA for mapping weather phenomena.
We're going to use RTMA, or Real-Time Mesoscale Analysis. The resolution of this data is 2.5km, and focused on the contiguous U.S.
You can view the general page for RTMA here, which also includes links to Hawaii, Alaska, and Puerto Rico. You can also find this dataset via Google Earth Engine.
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First go to this FTP website: https://nomads.ncep.noaa.gov/pub/data/nccf/com/rtma/prod/
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Look for the folders that start with:
rtma2p5_ru.2021XXYY. The XX will be month, YY day, and you should see the past 10 days here. For the day's data you're after, click into its corresponding folder. -
More mystery files! The ones you'll be interested in here are gonna be:
rtma2p5.tXXz.2dvaranl_ndfd.grb2_wexp. In this case, the XX corresponds to the hour IN GMT. You can subtract four hours from that to get the ET time.This is near real-time data, so if you're pulling data for today, you might have to wait for it show up. Good news is that it only lags by about an hour or so.
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Good news – QGIS can open up this monstrosity. Kick it into QGIS. This geotiff has data for multiple weather phenomena baked into it in separate bands. However, because QGIS only loves NOAA so much, you can't read the metadata of the each band to decipher what's what. Here's a quick guide:
| Name | Units | Min | Max | Description |
|---|---|---|---|---|
| HGT | m | -81* | 4226* | Model terrain elevation |
| PRES | Pa | 60848* | 105183* | Pressure |
| TMP | °C | -43.2* | 43.73* | Temperature |
| DPT | °C | -81.41* | 30.92* | Dew point temperature |
| UGRD | m/s | -32.93* | 34.04* | U-component of wind |
| VGRD | m/s | -28.44* | 39.21* | V-component of wind |
| SPFH | kg/kg | 0* | 0.02* | Specific humidity |
| WDIR | deg true | 0* | 360* | Wind direction (from which blowing) |
| WIND | m/s | 0* | 42.46* | Wind speed |
| GUST | m/s | 0* | 58.02* | Wind speed (gust) |
| VIS | m | 0* | 20000* | Visibility |
| TCDC | % | 0* | 100* | Total cloud cover |
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For this tutorial, we're going to focus on temperature. From your Style Panel, choose Singleband pseudocolor, and then Band 03.
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Now, using the table above we can see this layer is in Celsius. You can make your ramp whatever you'd like to accommodate that, but I've got one pre-baked for you right here to use. Just save that file, and then open it up in style panel – via clicking that folder icon next to the big ol' Classify button.
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Hit Apply and head off to the races!