Topband: Geomagnetic storms likely to commence on 9 December, reaching strong storm level on 10 December

[donovanf at erols.com]

Geomagnetic storm watches are in effect from 9-11 December , due to 
coronal mass ejection (CME) effects from a direct CME collision with 
the Earth's magnetosphere on 9-11 December. The CME eruption was 
associated with a C7 solar flare erupting from Sunspot Region 2790 
on 7 December. 


www.swpc.noaa.gov/news/geomagnetic-storm-watches-9-11-december-2020 


Arrival of a shock wave associated with the CME is possible late on 
9 December, initially resulting in a G1 level minor geomagnetic storm. 
As CME effects continue, geomagnetic disturbance is likely to increase, 
especially if the magnetic field carried with the CME rotates to a 
southward orientation, causing magnetic reconnection with the Earth's 
opposite polarity magnetosphere. 


The potential for strong storm levels exists and a G3 strong geomagnetic 
storm level w atch is in effect for 10 December. CME-related 
geomagnetic disturbances are forecast to continue through 11 December, 
likely resulting in G2 moderate geomagnetic storm levels - and another 
geomagnetic storm watch has been issued accordingly. 


While SWPC forecasters are fairly confident in CME arrival at Earth, 
timing and geomagnetic storm intensity are less certain. Continue to 
monitor the SWPC webpage for the latest conditions and forecast. 


www.swpc.noaa.gov/products/alerts-watches-and-warnings 


www.solarham.net/geo_forecast.htm 


www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction 


73 
Frank 
W3LPL