Viewing archive of Friday, 21 May 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 May 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 141 Issued at 2200Z on 21 MAY 1999IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z SOLAR ACTIVITY WAS LOW. REGION 8549 (N26W79) WAS VERY
ACTIVE, PRODUCING NUMEROUS OPTICAL SUB-FLARES. THE ONLY SIGNIFICANT
X-RAY EVENT WAS A LONG DURATION C2.4 FLARE. THE FLARE BEGAN AT
APPROXIMATELY 21/1715Z, REACHING A MAXIMUM AT 21/1949Z, AND WAS
STILL IN PROGRESS AT THE END OF THE PERIOD. REGION 8551 (N32E62)
WAS NUMBERED TODAY.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
WITH A SLIGHT POSSIBILITY OF ISOLATED M-CLASS X-RAY FLARES. REGION
8549 REMAINS ACTIVE WHILE ROTATING OFF THE DISK, AND REGION 8545
(N36W10) SHOWS SIGNS OF INCREASING MAGNETIC COMPLEXITY.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. THE GREATER THAN 2 MEV
ELECTRONS AT GEOSYNCHRONOUS ORBIT WERE AT MODERATE TO HIGH LEVELS.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO REMAIN QUIET TO UNSETTLED.
III. Event Probabilities 22 MAY to 24 MAY
| Class M | 25% | 25% | 25% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 21 MAY 140 Predicted 22 MAY-24 MAY 140/140/145 90 Day Mean 21 MAY 128
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 MAY 004/010 ESTIMATED AFR/AP 21 MAY 005/008 PREDICTED AFR/AP 22 MAY-24 MAY 005/008-005/010-005/010
VI. Geomagnetic Activity Probabilities 22 MAY to 24 MAY
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 10% | 10% | 10% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 25% | 25% |
| Minor storm | 05% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
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