Viewing archive of Monday, 27 April 1998

Solar activity report

Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 1998 Apr 27 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 117 Issued at 2200Z on 27 APR 1998

IA. Analysis of Solar Active Regions and Activity from 26-2100Z to 27-2100Z

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.
IB. Solar Activity Forecast
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.
IIA. Geophysical Activity Summary 26-2100Z to 27-2100Z
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.
IIB. Geophysical Activity Forecast
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.
III. Event Probabilities 28 APR to 30 APR
Class M20%20%20%
Class X15%15%15%
Proton10%15%15%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       27 APR 091
  Predicted   28 APR-30 APR  092/094/096
  90 Day Mean        27 APR 104
V. Geomagnetic A Indices
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
VI. Geomagnetic Activity Probabilities 28 APR to 30 APR
A. Middle Latitudes
Active20%30%35%
Minor storm10%20%25%
Major-severe storm05%10%10%
B. High Latitudes
Active25%35%35%
Minor storm15%25%30%
Major-severe storm05%15%15%

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