:Product: Weekly Highlights and Forecasts
:Issued: 1999 Oct 20 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
11 - 17 OCTOBER 1999

SOLAR ACTIVITY RANGED FROM LOW TO HIGH LEVELS. ACTIVITY WAS AT LOW
LEVELS THROUGH 13 OCTOBER DUE TO OCCASIONAL C-CLASS SUBFLARES,
MOSTLY FROM REGION 8731 (N12, L=292, CLASS/AREA FKC/1220 ON 17
OCTOBER). ACTIVITY ROSE TO HIGH LEVELS ON 14 OCTOBER DUE TO AN
IMPULSIVE X1/1N FLARE FROM REGION 8731 WITH ASSOCIATED TYPES II AND
IV RADIO SWEEPS, AND A 1000 SFU TENFLARE. THIS FLARE OCCURRED DURING
A PERIOD OF RAPID GROWTH WITHIN REGION 8731 WHICH INCLUDED THE
DEVELOPMENT OF A MAGNETIC DELTA CONFIGURATION NEAR REGION CENTER.
ACTIVITY DROPPED TO LOW LEVELS ON 15 OCTOBER AS THE REGION
STABILIZED  AS A LARGE F-TYPE SPOT GROUP WITH A COMPACT SPOT
DISTRIBUTION AND A COMPLEX MAGNETIC STRUCTURE. REGION 8751 REMAINED
LARGE AND COMPLEX FOR THE REMAINDER OF THE PERIOD, BUT PRODUCED ONLY
OCCASIONAL C-CLASS SUBFLARES.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD.
CORONAL HOLE EFFECTS WERE IN PROGRESS AS THE PERIOD BEGAN. SOLAR
WIND VELOCITIES INCREASED THROUGH 15 OCTOBER WITH PEAKS TO 800
KM/SEC, THEN GRADUALLY DECREASED DURING THE REMAINING DAYS.
DENSITIES WERE LOW, AS IS TYPICAL OF CORONAL HOLE WINDSTREAMS, AND
VARIED FROM 01 TO 06 P/CC. PHI DATA INDICATED AN AWAY (POSITIVE
POLARITY) SECTOR DURING THE ENTIRE PERIOD.

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

THE GREATER THAN 2 MEV ELECTRON FLUX WAS AT MODERATE TO HIGH LEVELS
DURING MOST OF THE PERIOD.

THE GEOMAGNETIC FIELD WAS DISTURBED DURING THE ENTIRE PERIOD DUE TO
THE EFFECTS OF A CORONAL HOLE WINDSTREAM (AS DESCRIBED ABOVE).
MIDDLE LATITUDES EXPERIENCED UNSETTLED TO MINOR STORM LEVELS DURING
THE DISTURBANCE WHILE HIGH LATITUDES SAW UNSETTLED TO MAJOR STORM
LEVELS.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
20 OCTOBER - 15 NOVEMBER 1999

SOLAR ACTIVITY IS EXPECTED TO BE AT LOW TO MODERATE LEVELS UNTIL
REGION 8731 DEPARTS THE WEST LIMB ON 24 OCTOBER. MOSTLY LOW ACTIVITY
IS ANTICIPATED DURING 25 OCTOBER - 05 NOVEMBER. THERE WILL BE AN
INCREASED CHANCE FOR MODERATE-LEVEL ACTIVITY BEGINNING 06 NOVEMBER
DUE THE RETURN OF (OLD) REGION 8731.

NO SIGNIFICANT 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 THROUGH 29 OCTOBER AND
AGAIN DURING 07 - 15 NOVEMBER. FLUXES ARE EXPECTED TO BE IN THE
NORMAL TO MODERATE RANGE DURING THE INTERVENING DAYS.

THE GEOMAGNETIC FIELD IS EXPECTED TO BE DISTURBED DURING 23 - 25
OCTOBER AND 06 - 13 NOVEMBER DUE TO RECURRENT CORONAL HOLE EFFECTS.
UNSETTLED TO MAJOR STORM LEVELS ARE EXPECTED DURING THESE
DISTURBANCES WITH THE MAJOR STORM PERIODS LIMITED TO HIGH LATITUDES.
QUIET TO UNSETTLED LEVELS ARE EXPECTED DURING THE REST OF THE
PERIOD.


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