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Updated - Do forecast models consider solar eclipses?



There's been a lot of chatter in the misinformation network about this from aviators who are trying to figure out the best place to fly to view the eclipse. Not all numerical weather prediction models do consider solar eclipses in their computations. But NOAA's High Resolution Rapid Refresh (HRRR) model does take this into consideration and has done this even before the last total solar eclipse in August 2017 to affect the United States.


It's not all about weather forecasts either. According to Stan Benjamin a senior scientist at NOAA's Global Systems Laboratory (GSL), “this is important for the energy industry, allowing them to use NOAA’s weather model toward predicting solar and wind power generation even during rare but important eclipse disruptions.”


The eclipses were first incorporated into the then-experimental version of the HRRR model before the 2017 total solar eclipse. By the time a partial solar eclipse hit the Arctic in June of 2021, NOAA’s operational weather forecasts included eclipses. Now, the HRRR model is taking on, for the first time, an eclipse over the continental United States as it is no longer considered an experimental model.


During a solar eclipse, the moon passes between Earth and the sun, fully or partially obscuring the sun for very short period. In the areas where the shadow of the moon passes over Earth, it's likely that temperatures can drop between 4°F and 10°F. Given this, less solar radiation hits the Earth, and since spatial differences in solar radiation drive the motion of air in the atmosphere the winds will die down momentarily in this area like it does at night.


You may also notice this effect on a much smaller scale when there is a broken fair weather cumuliform cloud deck present on any given day. As the shadow of that cloud passes over you when standing on the surface, notice how the winds will change within that shadow. The same thing will be true during the eclipse, but at a greater scale.


For a few hours during the morning of the Great North American Eclipse of 2024, as the eclipse passes by and temperatures remain lower for longer, the turbulent eddies that normally mix up the boundary layer (the first few thousand feet of our atmosphere) will be less intense, which can greatly affect changes near the surface. Less turbulence can affect low-level clouds and some may dissipate before or after the eclipse, with further impacts on the amount of downwelling solar energy. But this will depend on many other factors including terrain.


Take a look at the hourly forecast for the town or city you are planning to visit for the eclipse...you might notice that the temps are being forecast to drop a few degrees during this time.


Most pilots are weatherwise, but some are otherwise™ 


Dr. Scott Dennstaedt

Weather Systems Engineer

Founder, EZWxBrief™

CFI & former NWS meteorologist

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