1st December

Solar wind parameters, as measured at the ACE spacecraft, indicated the
onset of a positive polarity coronal hole high speed stream (CH HSS).
Solar wind speeds began to increase from initial values near 360 km/s at
the beginning of the period, and reached maximum values near 585 km/s
early in the new UTC day. Speeds eventually stabilized just below 500
km/s towards the end of the period. The IMF total field began the period
with minor fluctuations between 5 nT and 10 nT, then increased to just
below 14 nT near the end of the UTC day, before steadily decreasing to
finish the period near 9 nT. The Bz component of the IMF was variable
between +11 nT and -11 nT until the last few hours of the period, where
it remained positive to finish out the day. Phi angle was mostly
positive (away) throughout the period. ACE/EPAM data indicated an
enhancement of low energy particles, indicating the approach of a
possible transient that has the potential to give Earth a glancing blow.

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