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 UTCPrepared 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 1999IA. 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 M | 01% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
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 | |||
|---|---|---|---|
| Active | 15% | 20% | 20% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 20% | 25% | 25% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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