:Product: Weekly Highlights and Forecasts :Issued: 1999 Dec 14 2112 UT HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY 06 - 12 DECEMBER 1999 SOLAR ACTIVITY WAS LOW THROUGH MUCH OF THE PERIOD WITH ISOLATED C-CLASS FLARES OBSERVED DURING MOST DAYS. HOWEVER, ACTIVITY BRIEFLY ROSE TO MODERATE LEVELS ON 07 DECEMBER BY VIRTUE OF AN M1/SN FLARE AT 07/2120UT FROM REGION 8791 (S14, L = 262, CLASS/AREA BXO/010 ON 09 DECEMBER). MOST VISIBLE REGIONS WERE SMALL AND SIMPLE, WHICH ACCOUNTED FOR THE RELATIVELY LOW ACTIVITY LEVELS. THE ANTICIPATED STRONG RETURN OF OLD ACTIVE REGIONS 8765 (S12, L = 234) AND 8766 (N18, L = 213) DID NOT MATERIALIZE AND APPEARED TO INTERRUPT THE RECURRENT PATTERN OF MODERATE TO HIGH ACTIVITY WITNESSED DURING THE LAST FEW SOLAR ROTATIONS. REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD. RECURRENT CORONAL HOLE EFFECTS WERE EVIDENT DURING 06 DECEMBER WITH ELEVATED VELOCITIES (PEAK 710 KM/SEC) AND LOW DENSITIES. THE SOLAR WIND FLOW WAS UNREMARKABLE DURING 07 - 11 DECEMBER. A CORONAL TRANSIENT PASSED THE SPACECRAFT LATE ON 12 DECEMBER ACCOMPANIED BY A SUDDEN VELOCITY INCREASE WHICH BRIEFLY PEAKED AT 820 KM/SEC, INCREASED IMF BZ VARIANCE WITH SOUTHERLY DEFLECTIONS TO MINUS 10 NT (GSM), AND A MINOR DENSITY INCREASE. EARTH WAS WITHIN AN AWAY (POSITIVE POLARITY) SECTOR THROUGHOUT THE PERIOD. NO PROTON EVENTS WERE DETECTED AT GEOSYNCHRONOUS ORBIT DURING THE PERIOD. THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS AT HIGH LEVELS FOR THE PERIOD. ACTIVE TO MINOR STORM LEVELS OCCURRED ON 06 DECEMBER DUE TO RECURRENT CORONAL HOLE EFFECTS. ACTIVITY DROPPED TO QUIET TO UNSETTLED LEVELS DURING 07 - 11 DECEMBER. ACTIVE TO MINOR STORM LEVELS OCCURRED ON THE LAST DAY OF THE PERIOD AS A CORONAL TRANSIENT IMPACTED THE GEOMAGNETIC FIELD. FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY 15 DECEMBER 1999 - 10 JANUARY 2000 SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS. OCCASIONAL C-CLASS FLARES ARE LIKELY WITH ISOLATED M-CLASS FLARES POSSIBLE SOMETIME DURING THE PERIOD. NO PROTON EVENTS ARE EXPECTED AT GEOSYNCHRONOUS ORBIT. THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ALTITUDE IS EXPECTED TO BE AT MODERATE TO HIGH LEVELS DURING 01 - 05 JANUARY. OTHERWISE, NORMAL TO MODERATE LEVELS ARE EXPECTED. THE GEOMAGNETIC FIELD IS EXPECTED TO BE AT UNSETTLED TO ACTIVE LEVELS DURING 31 DECEMBER - 03 JANUARY DUE TO RECURRENT CORONAL HOLE EFFECTS. QUIET TO UNSETTLED LEVELS ARE EXPECTED FOR THE REST OF THE PERIOD, BARRING ANY EARTH-DIRECTED CMES. .