Viewing archive of Saturday, 20 February 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 Feb 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 051 Issued at 2200Z on 20 FEB 1999IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY WAS LOW. REGION 8458 (S22W74) PRODUCED A
C8/SF WITH TYPES II AND IV SWEEP AT 0406Z. THIS EVENT IMMEDIATELY
FOLLOWED ANOTHER C8 AT 0310Z THAT WAS NOT OBSERVED FROM THE GROUND.
OF THE OTHER C-CLASS EVENTS OCCURRING, THE C4/SF AT 1519Z, ALSO FROM
8458, HAD A TYPE II SWEEP. NEW REGION 8468 (N35W66) EMERGED AT A
HIGH LATITUDE. THE OTHER SIX SPOT GROUPS WERE STABLE.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO PERSIST
AT LOW LEVELS.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO VARY FROM QUIET TO ACTIVE LEVELS OVER THE NEXT 3 DAYS. A
HIGH-SPEED STREAM FROM A WELL-POSITIONED CORONAL HOLE MAY AFFECT
THE NEAR-EARTH ENVIRONS IN THE NEXT 48-72 HOURS.
III. Event Probabilities 21 FEB to 23 FEB
| Class M | 20% | 20% | 20% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 20 FEB 157 Predicted 21 FEB-23 FEB 150/145/140 90 Day Mean 20 FEB 147
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 FEB 024/038 ESTIMATED AFR/AP 20 FEB 003/010 PREDICTED AFR/AP 21 FEB-23 FEB 005/010-005/017-015/012
VI. Geomagnetic Activity Probabilities 21 FEB to 23 FEB
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 10% | 15% | 30% |
| Minor storm | 05% | 05% | 10% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 10% | 20% | 40% |
| Minor storm | 05% | 05% | 15% |
| Major-severe storm | 01% | 01% | 01% |
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