Viewing archive of Wednesday, 21 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 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
:::::::::: CORRECTED COPY :::::::::: SDF Number 111 Issued at 2200Z on 21 APR 1999IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z SOLAR ACTIVITY INCREASED TO LOW LEVELS. ISOLATED,
OPTICALLY UNCORRELATED C-CLASS X-RAY FLARES OCCURRED. REGION 8517
(N24W88) PRODUCED A COUPLE SUBFLARES AS IT BEGAN TO CROSS THE WEST
LIMB. THE REMAINING REGIONS WERE STABLE. NO NEW REGIONS WERE
ASSIGNED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
THE GEOMAGNETIC FIELD WAS AT QUIET TO ACTIVE LEVELS. ACTIVE LEVELS
OCCURRED DURING 21/0900-1200Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT QUIET TO UNSETTLED LEVELS THROUGH THE PERIOD.
III. Event Probabilities 22 APR to 24 APR
| Class M | 10% | 10% | 10% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 21 APR 103 Predicted 22 APR-24 APR 105/105/105 90 Day Mean 21 APR 131
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 APR 015/021 ESTIMATED AFR/AP 21 APR 014/014 PREDICTED AFR/AP 22 APR-24 APR 010/010-007/007-007/007
VI. Geomagnetic Activity Probabilities 22 APR to 24 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 15% | 10% |
| Minor storm | 20% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 35% | 25% | 15% |
| Minor storm | 25% | 10% | 10% |
| Major-severe storm | 05% | 01% | 01% |
All times in UTC
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