:Product: Weekly Highlights and Forecasts
:Issued: 1999 Dec 28 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
20 - 26 DECEMBER 1999

SOLAR ACTIVITY RANGED FROM LOW TO HIGH LEVELS.  ACTIVITY WAS LOW
THROUGH 20 DECEMBER WITH ONLY C-CLASS SUBFLARES.  REGIONS 8806 (N19,
L=114, CLASS/AREA FHC ON 23 DEC) AND 8807 (N11, L = 111, CLASS/AREA
CAO ON 20 DEC) WERE THE MOST ACTIVE.  REGION 8798 (S13, L = 171,
CLASS/AREA DKC ON 17 DEC) WAS LARGE AND MAGNETICALLY COMPLEX AS WAS
REGION 8806.  BOTH SHOWED DELTA CONFIGURATIONS.  ON 21 DECEMBER
ACTIVITY INCREASED FROM LOW TO MODERATE DUE TO AN M1/1N AT
21/1719UT.   THE ACTIVITY LEVEL INCREASED TO HIGH ON 22 DECEMBER
WHEN REGION 8806 PRODUCED AN M5/1B EVENT AT 22/1904UT WITH A 280SFU
10CM FLARE.  REGION 8807 PRODUCED AN M1/2B WITH PARALLEL RIBBONS AT
22/0216UT AND WITH A TYPE II SWEEP EVENT.  THE LEVEL OF ACTIVITY
RETURNED TO LOW 23 THROUGH 26 DECEMBER.  MINOR C-CLASS FLARES
CONTINUED FROM REGIONS 8798, 8806, AND 8810.  REGION 8798 SLOWLY
DECAYED BEFORE IT ROTATED FROM VIEW ON DECEMBER 26.  REGION 8806 
HAS RETAINED A BETA GAMMA DELTA CONFIGURATION.  REGION 8810 (N35, L
= 024, CLASS/AREA EKO ON 26 DEC) ROTATED INTO VIEW ON 24 DECEMBER AS
A LARGE SPOT GROUP.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD. SOLAR
WIND CHARACTERISTICS COMMONLY ASSOCIATED WITH CME EFFECTS WERE
OBSERVED ON 24-25 DECEMBER WITH VELOCITIES AS HIGH AS 640 KM/SEC AND
SUSTAINED PERIODS OF SOUTHWARD IMF BZ WITH DEFLECTIONS TO MINUS 18
NT (GSM) EARLY ON 24 DECEMBER. SOLAR WIND FLOW RETURNED TO NOMINAL
CONDITIONS BY 26 DECEMBER.

NO PROTON EVENTS WERE DETECTED AT GEOSYNCHRONOUS ORBIT DURING THE
PERIOD.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS AT
NORMAL LEVELS MOST OF THE PERIOD.

THE GEOMAGNETIC FIELD WAS DISTURBED ON 24 AND 25 DECEMBER WITH BRIEF
ACTIVE TO MINOR STORM PERIODS DUE TO CME EFFECTS.  THE GEOMAGNETIC
FIELD WAS MOSTLY QUIET THE REMAINDER OF THE PERIOD.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
29 DECEMBER 1999 - 24 JANUARY 2000

SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS.
OCCASIONAL TO FREQUENT C-CLASS FLARES AND ISOLATED M-CLASS FLARES
ARE LIKELY THROUGHOUT THE PERIOD. REGION 8806 MAY PROVIDE A CHANCE
FOR AN ISOLATED MAJOR FLARE SOMETIME DURING THE FIRST PART OF THE
PERIOD UNTIL THE REGION ROTATES OFF THE DISK ON 31 DECEMBER.

THERE IS A CHANCE FOR A PROTON EVENT AT GEOSYNCHRONOUS ORBIT FROM
REGION 8806.

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 MINOR STORM
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.


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