:Product: 19991230RSGA.txt :Issued: 1999 Dec 30 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 364 ISSUED AT 2200Z ON 30 DEC 1999 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 29/2100Z TO 30/2100Z: SOLAR ACTIVITY WAS LOW. ISOLATED MINOR C-CLASS EVENTS OCCURRED EARLY IN THE PERIOD. COMPLEX REGION 8806 (N22W96) PRODUCED A C2/SF WITH A LARGE BRIGHT SURGE AT 29/2151Z. THIS REGION HAS SINCE ROTATED FROM VIEW WITH JUST MINOR SURGING EVIDENT ON THE LIMB. REMAINING REGIONS WERE STABLE. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW. OLD REGION 8806 MAY STILL PRODUCE ISOLATED C-LEVEL X-RAY EVENTS AS IT ROTATES FURTHER AROUND THE WEST LIMB. REGION 8810 (N37E06), THOUGH STABLE, HAS POTENTIAL FOR ISOLATED C-CLASS EVENTS. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 29/2100Z TO 30/2100Z: THE GEOMAGNETIC FIELD WAS QUIET WITH UNSETTLED CONDITIONS BEGINNING LATE IN THE PERIOD. THE ONSET OF A HIGH SPEED CORONAL HOLE STREAM WAS OBSERVED AROUND 30/1530Z, AND ACCOUNTED FOR THE LATE-DAY DISTURBANCE. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS EXPECTED TO BE AT QUIET TO ACTIVE LEVELS WITH MINOR STORMING PERIODS LIKELY AT HIGH LATITUDES. THIS CORONAL HOLE RELATED DISTURBANCE WILL LIKELY PERSIST THROUGH THE NEXT THREE DAYS. III. EVENT PROBABILITIES 31 DEC-02 JAN CLASS M 20/10/10 CLASS X 05/05/05 PROTON 05/05/05 PCAF GREEN IV. PENTICTON 10.7 CM FLUX OBSERVED 30 DEC 136 PREDICTED 31 DEC-02 JAN 130/130/130 90 DAY MEAN 30 DEC 176 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 29 DEC 005/007 ESTIMATED AFR/AP 30 DEC 005/006 PREDICTED AFR/AP 31 DEC-02 JAN 015/015-020/025-020/025 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 31 DEC-02 JAN A. MIDDLE LATITUDES ACTIVE 60/65/65 MINOR STORM 20/25/25 MAJOR-SEVERE STORM 05/10/10 B. HIGH LATITUDES ACTIVE 60/60/60 MINOR STORM 30/30/30 MAJOR-SEVERE STORM 10/10/10