Solar wind parameters, as measured by the ACE spacecraft, began the
period under the influence of a weak, positive-polarity CH HSS. As the
day progressed, the strength and effects of the HSS steadily increased.
Wind speed began the period at 312 km/s, but began a steady rise at
21/1600 UTC, reaching 400 km/s by 21/1912 UTC. Speeds continued the slow
ascent, passing the 500 km/s mark at 22/0213 UTC, then 600 km/s at
22/0717 UTC. Speeds leveled off after reaching a peak of 628 km/s at
22/0744 UTC. The total interplanetary magnetic field (IMF) sporadically
ranged between +1/+13 nT the first half of the period, but later settled
into the +6/+8 nT (still enhanced) range by the end of the period. The
Bz component of the IMF also varied widely the first part of the
forecast period, ranging from +11 nT to a maximum southward deflection
of nearly -9 nT. By the end of the period, Bz had settled near -2 nT.
The phi angle was predominately positive (away) with a brief period of
negative (towards) sector reporting between 21/1450 UTC to 21/1910 UTC.