:Product: Weekly Highlights and Forecasts
:Issued: 1999 May 12 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
03 - 09 MAY 1999

SOLAR ACTIVITY RANGED FROM LOW TO HIGH LEVELS. THE PERIOD BEGAN WITH
ACTIVITY AT MODERATE LEVELS BY VIRTUE OF AN M4/2N FLARE AT 03/0602UT
FROM REGION 8525 (N17, L=299, CLASS/AREA FSO/290 ON 02 MAY) WITH
ASSOCIATED TYPE II AND IV SWEEPS AND A HALO CME. ACTIVITY DROPPED TO
LOW LEVELS DURING 04 - 06 MAY WITH ISOLATED C-CLASS SUBFLARES, MOST
OF WHICH WERE OPTICALLY UNCORRELATED. ACTIVITY INCREASED TO MODERATE
LEVELS DURING 07 - 08 MAY WITH ISOLATED M-CLASS FLARES INCLUDING AN
M4/1F AT 08/1440UT WITH TYPE II AND IV RADIO SWEEPS FROM REGION 8526
(N21, L=340, CLASS/AREA DAO/100 ON 06 MAY). ACTIVITY ROSE TO HIGH
LEVELS ON 09 MAY AS REGION 8527 (N19, L=331, CLASS/AREA EAO/230 ON
08 MAY) PRODUCED AN M7 X-RAY FLARE AT 09/1807UT AS IT CROSSED THE
WEST LIMB.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD. A WEAK
INTERPLANETARY SHOCK PASSED THE SPACECRAFT AROUND 05/1500UT
ACCOMPANIED BY MINOR INCREASES IN SOLAR WIND VELOCITY AND IMF BZ
VARIABILITY (MAXIMUM SOUTHERLY DEFLECTIONS TO MINUS 08 NT (GSM)).
DENSITIES BRIEFLY INCREASED TO 30 P/CC AS WELL. THIS SHOCK WAS
LIKELY ASSOCIATED WITH THE HALO-CME THAT FOLLOWED THE M4/2N FLARE OF
03 MAY.

A GREATER THAN 10 MEV PROTON ENHANCEMENT AT GEO-SYNCHROMOUS ALTITUDE
BEGAN EARLY ON 04 MAY FOLLOWING THE M4/2N FLARE OF 03/0602UT. FLUXES
REMAINED ENHANCED THROUGH 04 MAY, THEN INCREASED TO EVENT LEVELS AT
05/1820UT (MAXIMUM FLUX WAS 014 PFU AT 05/1955UT) FOLLOWING A WEAK
INTERPLANETARY SHOCK PASSAGE. THE PROTON EVENT ENDED AT 06/0550UT.
ANOTHER PROTON ENHANCEMENT BEGAN AROUND 09/2100UT FOLLOWING THE M7
FLARE AT 09/1807UT.

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

THE GEOMAGNETIC FIELD WAS AT QUIET TO UNSETTLED LEVELS. A WEAK SUDDEN
IMPULSE OCCURRED AT 05/1542UT (08 NT, BOULDER USGS MAGNETOMETER),
BUT WAS NOT FOLLOWED BY A SIGNIFICANT DISTURBANCE.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
12 MAY - 07 JUNE 1999

SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS.
THERE IS ALSO A FAIR CHANCE FOR AN ISOLATED MAJOR FLARE SOMETIME
DURING THE PERIOD.

THERE WILL BE A FAIR CHANCE FOR A SOLAR PROTON ENHANCEMENT OR EVENT
AT GEO-SYNCHRONOUS ALTITUDE SOMETIME DURING THE PERIOD.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ALTITUDE MAY
REACH HIGH LEVELS THROUGH 20 MAY AND AGAIN DURING 27 - 31 MAY.
OTHERWISE, NORMAL TO MODERATE LEVELS ARE EXPECTED.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO INCREASE TO UNSETTLED TO
ACTIVE LEVELS DURING 12 - 13, 16 - 17, AND 25 - 28 MAY DUE TO
RECURRENT CORONAL HOLE EFFECTS (BRIEF STORM PERIODS MAY ALSO OCCUR
AT HIGH LATITUDES). QUIET TO UNSETTLED CONDITIONS ARE EXPECTED
DURING THE REST OF THE PERIOD, BARRING ANY EARTH-DIRECTED CMES.


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