:Product: Weekly Highlights and Forecasts
:Issued: 1999 Jun 01 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
24 - 30 MAY 1999

SOLAR ACTIVITY RANGED FROM LOW TO MODERATE LEVELS. LOW ACTIVITY
OCCURRED DURING THE FIRST TWO DAYS OF THE PERIOD DUE TO SEVERAL
SMALL C-CLASS SUBFLARES PRODUCED BY A FEW SMALL- TO MODERATE-SIZED
REGIONS. ACTIVITY INCREASED TO MODERATE LEVELS ON 26 MAY BY VIRTUE
OF AN IMPULSIVE M1/2N FLARE AT 26/1932UT FROM REGION 8552 (N19,
L=347, CLASS/AREA EKO/360 ON 27 MAY). ACTIVITY DECLINED TO LOW
LEVELS DURING 27 - 28 MAY. HOWEVER, A SERIES OF SYMPATHETIC FLARES
OCCURRED AROUND 27/0900UT FROM REGIONS 8551 (N32, L=021, CLASS/AREA
CSO/070 ON 24 MAY) AND 8554 (N26, L=355, CLASS/AREA CAO/060 ON 27
MAY) WHICH WERE FOLLOWED BY A TENFLARE AND TYPE II AND IV RADIO
SWEEPS. SOHO/LASCO IMAGES SHOWED A LARGE HALO CME BEGINNING AROUND
27/1330UT, BUT THIS WAS JUDGED TO BE A BACK-SIDE EVENT. ACTIVITY
ROSE TO MODERATE LEVELS AGAIN ON 29 MAY DUE TO AN OPTICALLY
UNCORRELATED M1 AT 29/0315UT WITH MODERATE DISCRETE FREQUENCY RADIO
BURSTS, A TYPE II RADIO SWEEP, AND A CME (NON-EARTH-DIRECTED). THIS
EVENT LIKELY ORIGINATED FROM BEYOND THE SOUTHEAST LIMB. ACTIVITY
DECLINED TO LOW LEVELS ON 30 MAY. HOWEVER, LONG-DURATION C-CLASS
X-RAY EVENTS WERE DETECTED AT 30/0338UT AND 30/1155UT. BOTH EVENTS
HAD ASSOCIATED CMES, BUT NEITHER APPEARED TO BE EARTH-DIRECTED. THE
PROVISIONAL INTERNATIONAL MONTHLY MEAN SUNSPOT NUMBER FOR MAY WAS
106.3. THIS WAS THE HIGHEST MONTHLY MEAN OBSERVED SO FAR THIS CYCLE.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD.
CORONAL HOLE EFFECTS WERE EVIDENT DURING 25 MAY WITH A VELOCITY
INCREASE FROM 400 - 600 KM/SEC, A BRIEF DENSITY INCREASE TO 23 P/CC
FOLLOWED BY A DROP TO 02 - 03 P/CC, AND SOUTHERLY IMF BZ DEFLECTIONS
TO MINUS 12 NT (GSM).

A SOLAR PROTON FLUX ENHANCEMENT AT GEO-SYNCHRONOUS ORBIT BEGAN AROUND
27/1130UT, PEAKED AT APPROXIMATELY 27/1230UT, THEN GRADUALLY
DECLINED TO BACKGROUND LEVELS BY MIDDAY, 29 MAY.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ALTITUDE WAS
AT NORMAL TO MODERATE LEVELS.

THE GEOMAGNETIC FIELD WAS DISTURBED DURING 25 MAY WITH UNSETTLED TO
MINOR STORM PERIODS. HOWEVER, THE MINOR STORM PERIODS WERE BRIEF AND
LIMITED TO THE HIGH LATITUDES. THIS DISTURBANCE APPEARED TO BE
CORONAL HOLE-RELATED. QUIET TO UNSETTLED CONDITIONS PREVAILED DURING
THE REMAINDER OF THE PERIOD.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
02 - 28 JUNE 1999

SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS.
ISOLATED M-CLASS FLARES ARE EXPECTED DURING THE PERIOD. THERE WILL
ALSO BE A SLIGHT CHANCE FOR A MAJOR FLARE SOMETIME DURING THE
PERIOD.

NO SIGNIFICANT PROTON FLUX ENHANCEMENTS ARE EXPECTED AT
GEO-SYNCHRONOUS ALTITUDE.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ALTITUDE IS
EXPECTED TO BE AT  NORMAL TO MODERATE LEVELS.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO INCREASE TO UNSETTLED TO
ACTIVE LEVELS AROUND 14 AND 21 JUNE DUE TO RECURRENT CORONAL HOLE
EFFECTS. OTHERWISE, THE FIELD IS EXPECTED TO BE AT QUIET TO
UNSETTLED LEVELS, BARRING ANY EARTH-DIRECTED CMES.

.