:Product: Weekly Highlights and Forecasts
:Issued: 2000 Sep 26 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
18 - 24 SEPTEMBER 2000

SOLAR ACTIVITY VARIED FROM LOW TO HIGH LEVELS. ACTIVITY INCREASED
FROM LOW TO HIGH LEVELS ON 19 SEPTEMBER DUE TO AN M5/1N FLARE AT
19/0826 UTC FROM REGION 9165 (N14, L = 186, CLASS/AREA DKC/400 ON 15
SEPTEMBER). THE M5 FLARE, WHICH WAS ASSOCIATED WITH A TYPE II RADIO
SWEEP AND A 360 SFU TENFLARE, OCCURRED AS REGION 9165 GRADUALLY
DECAYED. REGION 9169 (N10, L = 078, CLASS/AREA FKC/2140 ON 19
SEPTEMBER) ROTATED INTO VIEW ON 18 SEPTEMBER AS A VERY LARGE,
MAGNETICALLY COMPLEX SUNSPOT GROUP. AT 2140 MILLIONTHS AREAL
COVERAGE, REGION 9169 WAS ONE OF THE LARGEST SUNSPOT GROUPS OBSERVED
THIS CYCLE. DESPITE ITS SIZE AND COMPLEXITY, IT PRODUCED ONLY
ISOLATED C-CLASS SUBFLARES TO DATE. ACTIVITY WAS AT LOW LEVELS
DURING MOST OF THE REST OF THE PERIOD DUE TO ISOLATED C-CLASS
SUBFLARES. HOWEVER, ACTIVITY ROSE TO MODERATE LEVELS ON 24 SEPTEMBER
DUE TO AN M4/2N FLARE AT 24/0338 UTC FROM REGION 9166 (S13, L = 123,
CLASS/AREA EKO/760 ON 21 SEPTEMBER), WHICH HAD BEEN SLOWLY DECAYING
AT THE TIME OF THE FLARE.

DATA WERE AVAILABLE FROM THE ADVANCED COMPOSITION EXPLORER (ACE)
SPACECRAFT FOR MOST OF THE PERIOD. A HIGH SPEED CORONAL HOLE WIND
STREAM WAS IN PROGRESS AT THE START OF THE PERIOD WITH VELOCITIES AS
HIGH AS 900 KM/SEC DETECTED ON 18 SEPTEMBER. VELOCITIES GRADUALLY
DECREASED DURING 19 - 20 SEPTEMBER AS CORONAL HOLE EFFECTS SUBSIDED.
ANOTHER HIGH SPEED STREAM BEGAN MIDDAY ON 24 SEPTEMBER AND WAS IN
PROGRESS AS THE PERIOD ENDED.

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

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS AT
MODERATE TO HIGH LEVELS DURING 21 - 24 SEPTEMBER.

GEOMAGNETIC FIELD ACTIVITY WAS AT ACTIVE TO MINOR STORM LEVELS ON 18
SEPTEMBER DUE TO CORONAL HOLE EFFECTS WITH MAJOR TO SEVERE STORM
PERIODS DETECTED AT HIGH LATITUDES. ACTIVITY GRADUALLY DECLINED
DURING 19 - 20 SEPTEMBER AS CORONAL HOLE EFFECTS SUBSIDED. QUIET TO
UNSETTLED LEVELS PREVAILED DURING 20/1500 - 24/1200 UTC. ACTIVITY
INCREASED TO UNSETTLED TO ACTIVE LEVELS AFTER 24/1200 UTC DUE TO
CORONAL HOLE EFFECTS.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
27 SEPTEMBER - 23 OCTOBER 2000

SOLAR ACTIVITY IS EXPECTED TO BE AT LOW TO MODERATE LEVELS. ISOLATED
M-CLASS FLARES ARE EXPECTED SOMETIME DURING THE PERIOD. THERE WILL
ALSO BE A CHANCE FOR AN ISOLATED MAJOR FLARE FROM REGION 9169 UNTIL
IT CROSSES THE WEST LIMB ON 1 OCTOBER.

A PROTON EVENT IS POSSIBLE AT GEOSYNCHRONOUS ORBIT UNTIL 1 OCTOBER.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS
EXPECTED TO BE AT MODERATE TO HIGH LEVELS THROUGH 28 SEPTEMBER.
MODERATE TO HIGH FLUXES ARE ALSO POSSIBLE DURING 15 - 17 OCTOBER.
NORMAL TO MODERATE FLUXES ARE EXPECTED FOR THE REST OF THE PERIOD.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO BE AT UNSETTLED TO ACTIVE
LEVELS DURING 27 SEPTEMBER. ACTIVE TO MINOR STORM LEVELS ARE
POSSIBLE DURING 14 - 16 OCTOBER. QUIET TO UNSETTLED CONDITIONS ARE
EXPECTED FOR THE REST OF THE PERIOD, BARRING AN EARTH-DIRECTED CME.


.