:Product: Weekly Highlights and Forecasts :Issued: 2001 May 22 2112 UT Highlights of Solar and Geomagnetic Activity 14 - 20 May 2001 Solar activity reached high levels during the period. Activity was low as the period began, then increased to moderate levels during 15 - 17 May by virtue of isolated, low-level M-class flares from Region 9455 (S17, l = 273, class/area Fai/230 on 17 May) (please refer to the Energetic Events list for flare specifics). Region 9455 was a moderate-sized spot group which changed little during the period, but maintained a minor degree of magnetic complexity until it crossed the west limb on 19 May. Activity decreased to low levels during 18 - 19 May with occasional C-class x-ray flares. Activity increased to high levels on 20 May with an M6 x-ray flare at 20/0603 UTC from beyond the southwest limb associated with a 360 SFU Tenflare, a Type II radio sweep, and a coronal mass ejection that did not appear to be Earth-directed. An M1 x-ray flare occurred at 20/0920 UTC associated with a Type II radio sweep. (Old) Region 9455 appeared to be the source for both of these flares. Region 9461 (N18, L = 161, class/area Dao/170 on 19 May) rotated into view on 15 May. It appeared to be the return of old Region 9433, which produced major flares during its previous two rotations. Region 9461 was a relatively simple D-type spot group with a mild mixing of polarities within its intermediate spots. It produced isolated C-class subflares during the period. Data were available from the Advanced Composition Explorer (ACE) spacecraft for most of the period. Periods of elevated solar wind speeds and proton temperatures, relatively low densities, and variable IMF Bz occurred during 14 - 16 May, suggesting high-speed streams associated with a negative-polarity coronal hole. A weak interplanetary structure passed the spacecraft beginning about 18/0900 UTC with effects extending into 19 May. The most notable change associated with this passage was a southward turning of IMF Bz during approximately 18/2000 - 19/0400 UTC with maximum deflections to minus 08 nT (GSM). No disturbances were detected during the rest of the period. There were no proton events detected during the period. However, proton flux enhancements at greater than 100 MeV and greater than 10 MeV began around 20/0700 UTC in the wake of the M6 x-ray flare mentioned above. The greater than 2 MeV electron flux at geosynchronous orbit ranged from normal to high levels. High flux levels occurred during 14 - 18 May. The geomagnetic field was disturbed during 14 - 15 May with intermittent active conditions and brief storm periods at high latitudes. This disturbance may have been due to coronal hole effects. Activity decreased to quiet to unsettled levels during 16 - 17 May. Quiet to unsettled conditions continued through most of 18 May. Activity increased to unsettled to active levels during 18/2100 - 19/0600 UTC, probably due to a weak interplanetary transient passage. Activity decreased to quiet to unsettled levels after 19/0600 UTC and remained so for the balance of the period. Forecast of Solar and Geomagnetic Activity 23 May - 18 June 2001 Solar activity is expected to range from low to moderate levels during the period. Isolated M-class flares will be possible during the period. No proton events are expected during the period. The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at normal to moderate levels during most of the period. However, high flux levels will be possible around 24 - 27 May and 12 - 15 June. The geomagnetic field is expected to be at quiet to unsettled levels during most of the period, barring an Earth-directed CME. However, active levels will be possible around 23 May and 11 June. .