:Product: 20010516RSGA.txt :Issued: 2001 May 16 2200 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Environment Center and the U.S. Air Force. # Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 136 Issued at 2200Z on 16 May 2001 IA. Analysis of Solar Active Regions and Activity from 15/2100Z to 16/2100Z: Solar activity remained at moderate levels. Region 9455 (S17W52) produced an M1/Sf flare at 16/1042 UTC as well as isolated C-class subflares. Minor development was reported in the interior portion of this region, where a mild mix of polarities has persisted. Region 9454 (N13W08) also displayed a small degree of magnetic complexity, but was stable through the period. Region 9458 (S12W72) produced a C2/Sf flare at 16/1550 UTC as it approached the west limb. This flare was associated with a Type II radio sweep and a CME, which did not appear to be Earth-directed. Region 9461 (N16E63), which was the return of old Region 9433 (responsible for major flares during it previous two rotations), was relatively stable during the period. At present it is classed as a simple D-type group, but it is still too close to the east limb for a detailed analysis. No new regions were assigned. IB. Solar Activity Forecast: Solar activity is expected to be at low to moderate levels with a fair chance for an isolated M-class flare from Region 9455. There is also a slight chance for an isolated M-class flare from Region 9454. At present, it is difficult to gauge the flare potential of Region 9461, given its proximity to the east limb. However, given its rich history of flare production, it cannot be counted out as a source for energetic flare activity. IIA. Geophysical Activity Summary 15/2100Z to 16/2100Z: Geomagnetic field activity ranged from quiet to unsettled levels. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels during the period. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at mostly quiet to unsettled levels with a chance for active periods at high latitudes. The greater than 2 MeV electron flux may reach high levels during the first half of the forecast period. III. Event Probabilities 17 May-19 May Class M 40/40/40 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 16 May 138 Predicted 17 May-19 May 145/150/155 90 Day Mean 16 May 167 V. Geomagnetic A Indices Observed Afr/Ap 15 May 010/016 Estimated Afr/Ap 16 May 012/015 Predicted Afr/Ap 17 May-19 May 012/020-012/020-010/015 VI. Geomagnetic Activity Probabilities 17 May-19 May A. Middle Latitudes Active 30/30/20 Minor storm 10/10/05 Major-severe storm 01/01/01 B. High Latitudes Active 35/35/25 Minor storm 15/15/10 Major-severe storm 01/01/01