:Product: Weekly Highlights and Forecasts :Issued: 2001 Nov 28 2212 UT Highlights of Solar and Geomagnetic Activity 19 - 25 November 2001 Activity alternated between low and high levels. High levels occurred on 22 and 25 November due to two major flares from Region 9704 (S18, L = 270, class/area Eki/610 on 22 November), which was the dominant flare producer of the period. The first was a M9/2n at 22/2330 UTC associated with a 9700 sfu Tenflare, several small filament eruptions, a full-halo coronal mass ejection (CME) and a proton event. The other major flare from Region 9704 was a very impulsive X1 at 25/0951 UTC with no significant radio emission. This region also produced frequent C-class flares throughout the period, most of which were impulsive with little or no significant radio emission; the exception being a long duration C4 X-ray flare at 21/1458 UTC associated with Type II and IV radio sweep events, a filament disappearance, and a full-halo CME. Region 9704 was large and magnetically complex but began to show signs of gradual decay late in the period as it approached the west limb. Another event of note was a M3/2b flare at 22/2036 UTC from Region 9698 (S24, L = 301, class/area Dso/130 on 17 November) associated with Type II and IV radio sweep events, a 630 sfu Tenflare, and a proton flux enhancement. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the period. Note: SWEPAM (velocity, density, and temperature) data were unreliable during approximately 23/0200 - 24/1800 UTC due to a solar proton event. However, the SOHO/MTOF sensor provided reliable data during this interval. A coronal mass ejection (CME) passed the ACE spacecraft beginning approximately 19/1740 UTC associated with increased velocities (peaks to about 610 km/sec), periods of increased southward IMF Bz (maximum deflections to minus 13 nT (GSM)), as well as modest increases in total IMF field intensity and density. These CME effects subsided early on 20 November. Another CME passage began at about 24/0539 UTC, then subsided on 25 November. This passage was associated with strong increases in velocity (peaks as high as 1000 km/sec) and density (peaks to around 90 p/cc), along with periods of strong southward IMF Bz with maximum deflections to minus 40 nT. A greater than 10 MeV proton event began at 19/1230 UTC, peaked at 20/0010 UTC (34 pfu), and ended at 20/1420 UTC. This event was likely due to a long-duration M2/1n flare from Region 9704 at 17/0525 UTC. Proton events at greater than 10 MeV and greater than 100 MeV occurred in the wake of the M9 flare of 22 November. The greater than 100 MeV event began at 22/2250 UTC, peaked at 23/0850 UTC (4.0 pfu), then ended at 24/1200 UTC. The greater than 10 MeV event began at 22/2320 UTC, reached a peak of 18,900 pfu at 24/0555 UTC, and was in progress and gradually decreasing as the period ended. The greater than 2 MeV electron flux at geosynchronous orbit was at normal to moderate levels during most of the period. Note: GOES electron flux data were unreliable during 23 - 24 November due to proton contamination. A weak geomagnetic field disturbance, due to a CME passage, occurred during 19/1800 – 20/0900 UTC with unsettled to active conditions detected. A severe geomagnetic storm occurred on 24 November due to a CME passage (most likely due to the M9 flare/halo CME on 22 November). The disturbance began with two back-to-back sudden impulses: 20 nT at 24/0500 UTC and 80 nT at 24/0555 UTC (as measured by the Boulder USGS magnetometer). Following the sudden impulses, field activity increased to minor to severe storm levels during 24/0600 - 1800 UTC. This disturbance subsided after 24/1800 UTC. Forecast of Solar and Geomagnetic Activity 28 November - 24 December 2001 Solar activity is expected to be at low to moderate levels throughout the period with isolated, low-level M-class expected. Isolated major flare activity will also be possible throughout the period. There will be a slight chance for a proton event during the forecast 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. The geomagnetic field is expected to be at quiet to unsettled levels during most of the period. .