Geomagnetic Storm Watch Remains in Effect

NOAA’s Space Weather Prediction Center (SWPC) says a minor (G1) geomagnetic storm watch remains in effect for April 24-26, due to the continued influence of a large, recurrent, negative-polarity coronal hole high-speed stream (CH HSS). A coronal hole is an area of the Sun where the magnetic field folds back, and solar wind escapes. This follows on the heels of an unexpected coronal mass ejection (CME) impact on April 22.

Conditions on HF are no better than fair, with conditions on the higher bands (17 through 10 meters) deemed poor. A G1 warning had been in effect until 1500 UTC today.

The odds of a G1 storm are 50-50. The upside is that the CH HSS increases the chances of auroral displays at lower-than-typical latitudes. NOAA says migratory animals are affected at the G1 and higher levels, and aurora is commonly visible at high latitudes (northern Michigan and Maine).

A G1 storm can cause weak power grid fluctuations and possibly impact satellite operations. According to NOAA, during storms, the currents in the ionosphere, as well as the energetic particles that precipitate into the ionosphere, add energy in the form of heat. This can increase the density and distribution of density in the upper atmosphere, causing extra drag on satellites in low-Earth orbit.

The local heating also creates strong horizontal variations in the ionospheric density, which can modify the path of radio signals and cause GPS errors. Geomagnetic storms can generate harmful geomagnetic induced currents (GICs) in the power grid and in pipelines.