KN4LF Daily LF/MF/HF/6M Frequency Radiowave Propagation Forecast Update #2008-17

Thomas Giella KN4LF <kn4lf@...>


Date Format is MM/DD/YYYY.

Published Monday 04/28/2008 at 1500 UTC

I'm sure that this is old news for most by now but I was so busy over the weekend I did not have a chance to report on the event until now.

On Saturday 04/26/2008 a solar filament collapsed near 8 degrees north and 8 degrees east and produced a small B3.8 class solar flare beginning at 1408 UTC. The solar flare produced a weak and slow (velocity 466 km/s) full halo coronal mass ejection (CME).

A solar filament is a relatively cool and dense ribbon of gas held together by solar magnetic fields. From Earth they usually appear as relatively dark lines across the face of the Sun. At times the magnetic lines holding the filament open up creating a tremendous eruption similar in size and impact of a coronal mass ejection (CME). The collapse of solar filament is virtually impossible to forecast.

The geoeffective (Earth facing) CME should begin impacting Earth's geomagnetic field on 04/29/2008 in the form of unsettled (Kp-3) to active (Kp-4) geomagnetic conditions. A brief and minor geomagnetic storm (Kp-5) is possible at high latitudes.

Normally I would not report on a weak event such as this but as we have not seen an Earth directed CME in a long long time it is newsworthy.

73 & God Bless,
Thomas F. Giella, KN4LF
Lakeland, FL, USA

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