:Product: 19990823RSGA.txt :Issued: 1999 Aug 23 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 235 ISSUED AT 2200Z ON 23 AUG 1999 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 22/2100Z TO 23/2100Z: SOLAR ACTIVITY WAS LOW. AS REGIONS 8673 (S19E32) AND 8674(S25E35) ROTATE ONTO THE DISC IT BECOMES APPARENT THAT THE TWO REGIONS MAY MERGE INTO ONE SINGLE COMPLEX REGION. IMAGES FROM THE EIT/SOHO SPACE CRAFT SHOW INDICATIONS OF AN ACTIVE REGION JUST OVER THE NORTHEAST LIMB THAT WILL SOON BE ROTATING ONTO THE DISC. AN 11-DEGREE DISAPPEARING SOLAR FILAMENT (N60E33) WAS NOTED AT 23/1404UT. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGIONS 8673 AND 8674 ARE BOTH CAPABLE OF PRODUCING ISOLATED M-CLASS EVENTS AT ANY TIME. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 22/2100Z TO 23/2100Z: THE GEOMAGNETIC FIELD WAS UNSETTLED TO MINOR STORM CONDITIONS WITH ONE PERIOD OF MAJOR STORMING OCCURRING AT HIGH LATITUDES FROM 03-0600UT. THE CAUSE OF THIS GEOMAGNETIC ACTIVITY IS INDETERMINATE AT THIS TIME BUT MAY HAVE BEEN THE EFFECTS FROM THE M9.8/1N FLARE IN CONJUNCTION WITH A TYPE II SWEEP THAT OCCURRED ON 20/2310UT. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS EXPECTED TO BE QUIET TO UNSETTLED. III. EVENT PROBABILITIES 24 AUG-26 AUG CLASS M 60/60/60 CLASS X 10/10/10 PROTON 01/01/01 PCAF GREEN IV. PENTICTON 10.7 CM FLUX OBSERVED 23 AUG 188 PREDICTED 24 AUG-26 AUG 190/195/200 90 DAY MEAN 23 AUG 164 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 22 AUG 007/011 ESTIMATED AFR/AP 23 AUG 020/035 PREDICTED AFR/AP 24 AUG-26 AUG 015/015-010/012-015/017 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 24 AUG-26 AUG A. MIDDLE LATITUDES ACTIVE 10/05/10 MINOR STORM 05/05/05 MAJOR-SEVERE STORM 01/01/01 B. HIGH LATITUDES ACTIVE 20/15/20 MINOR STORM 10/05/10 MAJOR-SEVERE STORM 01/01/01