:Product: 19970928RSGA.txt :Issued: 1997 Sep 28 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 271 ISSUED AT 2200Z ON 28 SEP 1997 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 27/2100Z TO 28/2100Z: SOLAR ACTIVITY WAS LOW DUE TO A C1/EPL ON THE SOUTHWEST LIMB (SW48) AT 28/1442Z. REGION 8088 (S29W41) IS THE ONLY SPOTTED REGION CURRENTLY ON THE VISIBLE DISK. THIS REGION HAS CHANGED LITTLE, MAINTAINING A MODERATELY SIZED D-CLASS SUNSPOT CONFIGURATION AND CONTINUING TO PRODUCE PLAGE FLUCTUATIONS ASSOCIATED WITH SMALL B-CLASS X-RAY OUTPUT. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW. THERE IS AN OUTSIDE CHANCE OF AN ISOLATED M-CLASS FLARE IN REGION 8088. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 27/2100Z TO 28/2100Z: THE GEOMAGNETIC FIELD RANGED FROM QUIET TO MINOR STORM. SOLAR WIND DATA DOES NOT CLEARLY INDICATE THE ARRIVAL OF A SHOCK FROM THE CME ACTIVITY OBSERVED ON 23-24 SEP. CURRENT GEOMAGNETIC ACTIVITY MAY BE RELATED TO THE EQUATORWARD EXTENSION OF A POLAR CORONAL HOLE. THE GREATER THAN 2 MEV ELECTRON FLUX CROSSED THE HIGH THRESHOLD AT 28/1643Z. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS EXPECTED TO BE UNSETTLED TO ACTIVE. A DISTURBANCE RESULTING FROM THE ACTIVITY OBSERVED ON 23-24 SEP IS BECOMING LESS LIKELY. III. EVENT PROBABILITIES 29 SEP-01 OCT CLASS M 10/10/05 CLASS X 01/01/01 PROTON 01/01/01 PCAF GREEN IV. PENTICTON 10.7 CM FLUX OBSERVED 28 SEP 087 PREDICTED 29 SEP-01 OCT 086/086/084 90 DAY MEAN 28 SEP 082 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 27 SEP 011/013 ESTIMATED AFR/AP 28 SEP 015/020 PREDICTED AFR/AP 29 SEP-01 OCT 020/020-015/012-010/010 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 29 SEP-01 OCT A. MIDDLE LATITUDES ACTIVE 30/30/15 MINOR STORM 15/15/05 MAJOR-SEVERE STORM 05/01/01 B. HIGH LATITUDES ACTIVE 30/30/15 MINOR STORM 15/15/05 MAJOR-SEVERE STORM 05/05/01