Geomagnetic storm / aurora (polar lights) watch – Saturday, April 20
A high latitude and mid latitude auroral activity watch is in effect from 12h UT today until 24h UT tomorrow. Geomagnetic field is expected to reach storm levels (G2, Kp=6) in response to impacts of two coronal mass ejections.
At Kp=6/G2 storm level, aurora may be visible approximately north of the line:
south Ireland – central Uk – northern Netherlands – northern Germany – nortern Poland – northern Belarus
In case of unusually strong substorming, aurora may briefly be visible south of this line.
NOAA SEC estimates 40% probabiliy of minor storm and 20% probability of major-severe storm at mid latitudes on April 20, with corresponding probabilities of 35% and 10% on April 21. High latitude major-severe storm probability is 75% on April 20 and 21. Peak Kp index of 6 is currently expected at 15-18h UTC, however, this time interval depends on the timing of CME impact. nThis watch will be upgraded to warning when solar wind parameters become favourable enough or allowed to expire after 24h UTC April 21.