Viewing archive of Saturday, 17 April 1999

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 1999 Apr 17 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 107 Issued at 2200Z on 17 APR 1999

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

SOLAR ACTIVITY WAS VERY LOW. TWO NEW REGIONS WERE ASSIGNED TODAY: REGION 8518 NEAR S16E66 AND REGION 8519 NEAR N17W33. TWO FILAMENTS ERUPTED DURING THE PERIOD: AN 8 DEGREE FILAMENT NEAR S19W08 BETWEEN 16/2144UT AND 17/1116UT AND A 20 DEGREE FILAMENT NEAR S32W15 BETWEEN 17/1640-1830UT.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW FOR THE NEXT THREE DAYS.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
THE GEOMAGNETIC FIELD RANGED FROM UNSETTLED TO MAJOR STORM LEVELS. A GEOMAGNETIC DISTURBANCE THAT BEGAN WITH A SUDDEN IMPULSE YESTERDAY AT 16/1126Z INTENSIFIED INTO A GEOMAGNETIC STORM. MID-LATITUDES WERE AT MINOR TO MAJOR STORM LEVELS ON THE 17TH FROM 00-09UT AND HIGH LATITUDES WERE AT MAJOR TO SEVERE STORM LEVELS DURING THE SAME TIME INTERVAL. THE DISTURBANCE SUBSIDED AFTER 0900Z WITH PREDOMINANTLY UNSETTLED CONDITIONS PREVAILING FROM 1200 TO THE END OF THE DAY.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE MOSTLY UNSETTLED FOR THE NEXT 24 HOURS, AND IS EXPECTED TO BE QUIET TO UNSETTLED FOR THE SECOND AND THIRD DAYS.
III. Event Probabilities 18 APR to 20 APR
Class M15%15%15%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       17 APR 116
  Predicted   18 APR-20 APR  114/112/110
  90 Day Mean        17 APR 134
V. Geomagnetic A Indices
OBSERVED AFR/AP 16 APR  013/014
ESTIMATED AFR/AP 17 APR  035/045
PREDICTED AFR/AP 18 APR-20 APR  010/010-005/010-010/012
VI. Geomagnetic Activity Probabilities 18 APR to 20 APR
A. Middle Latitudes
Active20%15%15%
Minor storm10%10%10%
Major-severe storm05%01%01%
B. High Latitudes
Active35%25%20%
Minor storm15%10%10%
Major-severe storm10%05%05%

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