SOLAR ACTIVITY BECAME HIGH. REGION 8210 (S17E43) PRODUCED AN X1/2B AT 27/0920Z WITH A STRONG TYPE IV AND 950 SFU BURST AT 2695 MHZ. THIS MODERATE DURATION EVENT WAS ACCOMPANIED BY A CORONAL MORETON WAVE AND HALO CORONAL MASS EJECTION. REGION 8210 REMAINED A SMALL-MODERATE SIZE C-CLASS GROUP. HOWEVER, A MAGNETIC DELTA CONFIGURATION FORMED IN THE NORTHERN PORTION OF THE REGION AND LOCALIZED MAGNETIC GRADIENTS WERE HIGH. SMALL REGIONS WERE VISIBLE NEARING THE NORTHEAST AND SOUTHEAST LIMBS.

SOLAR ACTIVITY SHOULD BE LOW TO OCCASIONALLY MODERATE WITH REGION 8210 THE PROBABLE SOURCE REGION. OBVIOUSLY, X-CLASS EVENTS ARE POSSIBLE BUT NOT CONSIDERED LIKELY DUE TO THE SMALL AREAL COVERAGE OF THIS REGION IN WHITE LIGHT. CONTINUED INCREASES IN MAGNETIC COMPLEXITY COULD MODIFY THIS FORECAST.

THE GEOMAGNETIC FIELD RANGED FROM UNSETTLED TO MINOR STORM LEVELS. THE MOST DISTURBED PERIOD WAS FROM 27/0000-0300Z. THIS DISTURBANCE APPEARS TO BE CAUSED BY AN EXTENSION OF THE SOUTHERN POLAR CORONAL HOLE. ENERGETIC ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT WERE PREDOMINANTLY HIGH.

THE GEOMAGNETIC FIELD SHOULD BE UNSETTLED TO SLIGHTLY ACTIVE ON 28 APR AS THE END OF THE CORONAL HOLE STREAM ROTATES PAST THE EARTH DURING THAT PERIOD. UNSETTLED TO MINOR STORM CONDITIONS ARE PREDICTED FOR 29-30 APR IN RESPONSE TO THE X1 FLARE AND HALO CME MENTIONED ABOVE. ISOLATED PERIODS OF MAJOR STORMING ARE POSSIBLE AT HIGH LATITUDES. THE ARRIVAL TIME FOR THIS DISTURBANCE IS SOMEWHAT ADVANCED FROM PREVIOUS HALO CMES DUE TO A HIGH LAUNCH SPEED OBSERVED NEAR THE SUN.

  觀測的       27 APR 091
  預測的   28 APR-30 APR  092/094/096
  90天平均值        27 APR 104

OBSERVED AFR/AP 26 APR  021/031
ESTIMATED AFR/AP 27 APR  015/020
PREDICTED AFR/AP 28 APR-30 APR  010/015-020/020-020/020