Solar activity was moderate. Todays activity was dominated by a very long-duration M1 flare that occurred between 1203-1904Z with maximum at 1715Z. The source region appeared to primarily be Region 1520 (S17W75), although it appears that Region 1521 (S19W85) was involved in the early phase and may have been the initial trigger for the overall event. An associated, bright CME was observed off the southwest limb beginning at 1400Z; the leading edge plane-of-sky speed was estimated to be about 960 km/s in the LASCO C3 field of view. The proximity of Regions 1519 (S17 just past west limb), 1520, and 1521 to the west limb hindered analysis of the spot groups. New Region 1524 (S18E52) was assigned and is a simple C-type sunspot group. An additional new spot group appeared to be emerging just south of Region 1524.

Solar activity is expected to be moderate for the next 24 hours with 1520 and 1521 as the most likely source regions. Activity and background levels are expected to decrease significantly by the second and third days as these regions rotate beyond west limb.

The geomagnetic field ranged from active to quiet levels with some isolated minor and major storm intervals at high latitudes. Unsettled to active levels prevailed duing the earlier part of the period and quiet to unsettled levels dominated from 17/0900Z through the end of the day. Solar wind observations from the ACE spacecraft showed continued influence of the 12 July CME from the beginning of the period through about 17/0600Z. The z-component of the interplanetary magnetic field was initially negative and reached a peak negative value of about -9 nT during this latter phase of the CME passage. Nominal solar wind conditions prevailed from 17/0600Z through the end of the day. A greater than 10 MeV proton event began at 17/1715Z in response to todays long-duration M1 and associated CME event. The peak value observed so far was 87 PFU at 17/2030Z. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels during the period.

The geomagnetic field is expected to be quiet for the next three days. Model results for todays CME from the west limb indicate an interplanetary disturbance that is too far west to produce geomagnetic activity. The greater than 10 MeV proton event is expected to continue through part of the first day (18 July).

  Pozorováno       17 Jul 128
  Předpovězeno   18 Jul-20 Jul  115/105/095
  90 denní průměr        17 Jul 129

  Pozorováno Afr/Ap 16 Jul  027/040
  Odhadovaný     Afr/Ap 17 Jul  015/020
  Předpovězeno    Afr/Ap 18 Jul-20 Jul  006/005-007/005-006/005