NOAA SEC Report of Solar-Geophysical Activity 25 Nov 2001
:Product: Report of Solar-Geophysical Activity :Issued: 2001 Nov 25 2200 UT # 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 329 Issued at 2200Z on 25 Nov 2001 IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: Solar activity was high. Region 9704 (S18W74) produced an impulsive X1 flare at 25/0951 UTC (optically correlated using SXI imagery). SOHO/LASCO imagery did not reveal a CME signature with this major flare, negating geoeffective potential. Even with the loss of the delta magnetic classification, this region remains the principle source of flare activity and produced numerous C-class flares during the period. Region 9715 (N06E58) has shown some growth in complexity over the period and produced several minor optical flares. New Region 9716 (S04E73) was numbered today. IB. Solar Activity Forecast: Solar activity is expected to be at low to moderate levels. Region 9704 remains capable of producing an isolated major flare before it transits the west limb. IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic field was at quiet to unsettled levels with an isolated period of active (24/2100-25/0000 UTC). The greater than 10 MeV proton event and associated polar cap absorption remained in progress at the end of the period (proton flux peaked to 18900 pfu at 24/0555 UTC). A moderate (10.2 percent based on the Thule neutron monitor) Forbush decrease began shortly after the beginning of forecast period and peaked near 25/0040 UTC, ended near 25/0300 UTC. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels through days one and two, becoming quiet to active on day three with the recurrence of a geoeffective coronal hole. The greater than 10 MeV proton event is expected to end late on the 26th, as it continues to slowly decrease. III. Event Probabilities 26 Nov-28 Nov Class M 40/40/40 Class X 10/10/10 Proton 95/50/10 PCAF in progress IV. Penticton 10.7 cm Flux Observed 25 Nov 170 Predicted 26 Nov-28 Nov 170/170/175 90 Day Mean 25 Nov 218 V. Geomagnetic A Indices Observed Afr/Ap 24 Nov 076/108 Estimated Afr/Ap 25 Nov 008/010 Predicted Afr/Ap 26 Nov-28 Nov 008/008-010/010-012/012 VI. Geomagnetic Activity Probabilities 26 Nov-28 Nov A. Middle Latitudes Active 15/20/30 Minor storm 05/10/10 Major-severe storm 01/01/05 B. High Latitudes Active 20/30/40 Minor storm 10/15/15 Major-severe storm 05/05/10
