:Product: Weekly Highlights and Forecasts
:Issued: 1999 Aug 31 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
23 - 29 AUGUST 1999

SOLAR ACTIVITY RANGED FROM LOW TO HIGH LEVELS. REGION 8674 (S24,
L=246, CLASS/AREA FKC/770 ON 27 AUGUST) PRODUCED TWO MAJOR FLARES
AND ISOLATED M-CLASS FLARES. SIGNIFICANT DEVELOPMENT OCCURRED WITHIN
THE INTERMEDIATE AND TRAILER PORTIONS OF THE GROUP DURING 26 - 28
AUGUST, WHICH INCLUDED THE FORMATION OF TWO DELTA MAGNETIC
CONFIGURATIONS. THE FIRST MAJOR FLARE WAS AN M5/2N AT 27/1307UT WITH
RELATIVELY MODEST DISCRETE RADIO EMISSION. THE SECOND WAS AN X1/2N
AT 28/1805UT ASSOCIATED WITH A 1000 SFU TENFLARE AND A TYPE II RADIO
SWEEP WITH AN ESTIMATED. SHOCK VELOCITY OF 600 KM/SEC. ACTIVITY
DROPPED TO LOW LEVELS ON THE LAST DAY OF THE PERIOD AS REGION 8674
ENTERED A PERIOD OF SLOW DECAY. REGION 8681 (N21, L=207, CLASS/AREA
DAI/220 ON 29 AUGUST) EMERGED RAPIDLY ON 28 AUGUST, THEN CONTINUED
TO GROW THROUGH THE REST OF THE PERIOD WHILE PRODUCING OCCASIONAL
SUBFLARES.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD. IMF BZ
WAS MOSTLY SOUTHWARD DURING 23 - 24 AUGUST WITH MAXIMUM DEFLECTIONS
TO MINUS 14 NT (GSM), WHICH PROMPTED THE GEOMAGNETIC DISTURBANCE
DISCUSSED BELOW. DENSITIES WERE ENHANCED DURING 23 - 24 AUGUST AS
WELL, WITH A PEAK OF 17 P/CC NOTED ON 23 AUGUST. A CORONAL HOLE
SIGNATURE WAS OBSERVED DURING 25 - 29 AUGUST WITH INCREASED
VELOCITIES (PEAK AROUND 800 KM/SEC EARLY ON 27 AUGUST) AND LOW
PARTICLE DENSITIES (01 TO 02 P/CC). THE SOURCE OF THE HIGH-SPEED
STREAM APPEARED TO BE AN ISOLATED, NEGATIVE-POLARITY CORONAL HOLE
LOCATED ON THE SOUTHERN HEMISPHERE.

NO PROTON EVENTS WERE DETECTED AT GEO-SYNCHRONOUS ORBIT DURING THE
PERIOD.

THE GREATER THAN 2 MEV ELECTRON FLUX REACHED HIGH LEVELS ON 23 AND 28
- 29 AUGUST.

THE GEOMAGNETIC FIELD WAS DISTURBED DURING 23 - 24 AUGUST WITH ACTIVE
TO MINOR STORM PERIODS DETECTED AT ALL LATITUDES AND BRIEF MAJOR
STORM PERIODS DETECTED AT HIGH LATITUDES. ACTIVITY DECLINED TO QUIET
TO UNSETTLED LEVELS FOR THE REST OF THE SUMMARY PERIOD WITH BRIEF
ACTIVE INTERVALS RECORDED AT SOME HIGH LATITUDE STATIONS.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
01 - 27 SEPTEMBER 1999

SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS.
THERE WILL BE A CHANCE FOR MORE MAJOR FLARE ACTIVITY FROM REGION
8674 BEFORE IT DEPARTS THE VISIBLE DISK AROUND 02 SEPTEMBER. REGION
8681 MAY ALSO PRODUCE ISOLATED M-CLASS FLARES BEFORE IT DEPARTS THE
DISK AROUND 05 SEPTEMBER. CHANCES FOR MODERATE TO HIGH ACTIVITY ARE
ALSO EXPECTED TO INCREASE BEGINNING 16 SEPTEMBER WITH THE RETURN OF
(OLD) REGION 8674 TO THE VISIBLE DISK.

THERE WILL BE A SLIGHT CHANCE FOR A PROTON EVENT AT GEO-SYNCHRONOUS
ORBIT.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ALTITUDE IS
EXPECTED TO VARY FROM NORMAL TO HIGH LEVELS LEVELS DURING THE SECOND
HALF OF THE OUTLOOK PERIOD. OTHERWISE, NORMAL TO MODERATE FLUXES ARE
EXPECTED.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED INCREASE TO UNSETTLED TO
ACTIVE LEVELS AROUND 12 - 16 SEPTEMBER DUE TO RECURRENT CORONAL HOLE
EFFECTS. OTHERWISE, QUIET TO UNSETTLED CONDITIONS ARE EXPECTED,
BARRING ANY EARTH-DIRECTED CORONAL MASS EJECTIONS.


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