Viewing archive of Saturday, 24 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 24 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 114 Issued at 2200Z on 24 APR 1999

IA. Analysis of Solar Active Regions and Activity from 23-2100Z to 24-2100Z

SOLAR ACTIVITY WAS VERY LOW. THE MOST IMPRESSIVE EVENT OF THE PERIOD WAS A LARGE CORONAL MASS EJECTION FROM BEHIND THE NW LIMB THAT PRODUCED A PROTON EVENT. EJECTA WAS FIRST OBSERVED AT AROUND 24/1230Z AND THE LIKELY SOURCE WAS OLD REGION 8517 WHICH ROTATED FROM VIEW EARLY ON 22 APRIL NEAR NORTH 20. THE REGION WAS DEVELOPING AS IT ROTATED THE LIMB. REGION 8522 (N16E50) THOUGH SMALL, PRODUCED THREE SUBFLARES WITH MINOR B-CLASS X-RAY BURSTS. NEW REGIONS 8523 (N32E42) AND 8524 (N22E53) WERE NUMBERED TODAY. REMAINING REGIONS WERE QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW.
IIA. Geophysical Activity Summary 23-2100Z to 24-2100Z
THE GEOMAGNETIC FIELD WAS QUIET WITH ISOLATED UNSETTLED PERIODS AT HIGH LATITUDES. A GREATER THAN 10 MEV PROTON EVENT BEGAN AT 24/1610Z AND IS CURRENTLY IN PROGRESS. THE 10 PFU THRESHOLD WAS CROSSED AT 24/1840Z AND CONTINUES TO INCREASE SLOWLY, REACHING A MAXIMUM OF 22 PFU LATE IN THE PERIOD. NO ENHANCEMENTS WERE OBSERVED YET ON THE GREATER THAN 100 MEV FLUX AND POLAR CAP ABSORPTION WAS JUST UNDER 1 DB AT ISSUE TIME.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD SHOULD REMAIN AT MOSTLY QUIET LEVELS. MATERIAL FROM THIS MORNING'S CME IS NOT EXPECTED TO IMPACT THE GEOMAGNETIC FIELD.
III. Event Probabilities 25 APR to 27 APR
Class M01%05%05%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       24 APR 101
  Predicted   25 APR-27 APR  105/110/115
  90 Day Mean        24 APR 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 23 APR  004/005
ESTIMATED AFR/AP 24 APR  007/007
PREDICTED AFR/AP 25 APR-27 APR  010/010-010/010-010/010
VI. Geomagnetic Activity Probabilities 25 APR to 27 APR
A. Middle Latitudes
Active15%20%20%
Minor storm05%05%05%
Major-severe storm01%01%01%
B. High Latitudes
Active20%25%25%
Minor storm05%05%05%
Major-severe storm01%01%01%

All times in UTC

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