:Product: 19990731RSGA.txt :Issued: 1999 Jul 31 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 212 ISSUED AT 2200Z ON 31 JUL 1999 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 30/2100Z TO 31/2100Z: SOLAR ACTIVITY WAS LOW. SEVERAL C-CLASS FLARES WERE PRODUCED BY REGION 8651 (N25E23). THE LARGEST WAS A C5/SF AT 30/2335Z. THIS REGION REMAINS THE LARGEST REGION ON THE DISK AND IS AN E-TYPE GROUP WITH A WHITE LIGHT AREA OF AROUND 730 MILLIONTHS. THE SECOND MOST INTERESTING GROUP IS REGION 8645 (S25W16) WHICH ALSO PRODUCED SEVERAL C-CLASS FLARES. THIS REGION HAS MAINTAINED A WHITE LIGHT AREA OF AROUND 600 MILLIONTHS AND IS A F-TYPE GROUP. NEW REGION 8654 (N19W18) WAS NUMBERED TODAY. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGIONS 8645 AND 8651 HAVE THE POTENTIAL FOR PRODUCING ISOLATED M-CLASS EVENTS. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 30/2100Z TO 31/2100Z: THE GEOMAGNETIC FIELD WAS AT QUIET TO SEVERE STORM CONDITIONS. MAJOR TO SEVERE STORMS WERE PRESENT EARLY IN THE PERIOD WITH UNSETTLED TO ACTIVE LEVELS PREDOMINATE TOWARD THE END. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS EXPECTED TO BE UNSETTLED WITH PERIODS OF ACTIVE CONDITIONS THE FIRST DAY OF THE FORECAST. THE SECOND AND THIRD DAYS ARE EXPECTED TO RETURN TO QUIET TO UNSETTLED CONDITIONS. III. EVENT PROBABILITIES 01 AUG-03 AUG CLASS M 80/80/80 CLASS X 15/15/15 PROTON 10/10/10 PCAF YELLOW IV. PENTICTON 10.7 CM FLUX OBSERVED 31 JUL 201 PREDICTED 01 AUG-03 AUG 195/190/190 90 DAY MEAN 31 JUL 162 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 30 JUL 041/036 ESTIMATED AFR/AP 31 JUL 018/020 PREDICTED AFR/AP 01 AUG-03 AUG 015/012-008/008-008/008 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 01 AUG-03 AUG A. MIDDLE LATITUDES ACTIVE 25/15/15 MINOR STORM 05/05/05 MAJOR-SEVERE STORM 01/01/01 B. HIGH LATITUDES ACTIVE 30/20/20 MINOR STORM 10/05/05 MAJOR-SEVERE STORM 05/01/01