Viewing archive of Tuesday, 17 August 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 Aug 17 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 229 Issued at 2200Z on 17 AUG 1999IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z SOLAR ACTIVITY WAS LOW. REGION 8668 (N21E28), THE MOST
PROMINENT ON THE DISK, HAD TWO LONG-DURATION C-CLASS FLARES. THE
FIRST, A C2/SF AT 1323Z, LASTED NEARLY 90 MINUTES. THIS EVENT WAS
FOLLOWED SOON AFTER BY A C5/SF AT 1602Z THAT ENDURED FOR NEARLY
THREE AND ONE HALF HOURS. BOTH OF THESE EVENTS WERE RICH IN DISCRETE
RADIO BURSTS ACROSS THE SPECTRUM. REGION 8662 (S16W90) IS SURGING AS
IT TRANSITS THE LIMB.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW.
REGION 8668 SHOULD CONTINUE TO PRODUCE C-CLASS FLARES. IF ADDITIONAL
GROWTH OCCURS THERE, M-CLASS EVENTS MAY EVENTUATE.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
THE GEOMAGNETIC FIELD WAS AT ACTIVE TO MINOR STORM LEVELS THROUGHOUT
THE PERIOD. A HIGH SPEED SOLAR WIND STREAM, REGISTERING BETWEEN 500
AND 700 KM/S, CONTINUES TO BUFFET THE MAGNETOPAUSE. THE FLUX OF
GREATER THAN 2 MEV ELECTRONS AT GEOSYNCHRONOUS ORBIT REACHED HIGH
LEVELS FROM APPROXIMATELY 1500 TO 1800Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE DURING THE NEXT 24 HOURS AS THE
EFFECT OF THE HIGH SPEED STREAM ABATES. CONDITIONS SHOULD CALM EVEN
FURTHER THEREAFTER, WITH STRICTLY UNSETTLED CONDITIONS PREVALENT BY
THE END OF THE INTERVAL.
III. Event Probabilities 18 AUG to 20 AUG
| Class M | 15% | 15% | 15% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 17 AUG 141 Predicted 18 AUG-20 AUG 150/155/165 90 Day Mean 17 AUG 163
V. Geomagnetic A Indices
OBSERVED AFR/AP 16 AUG 025/029 ESTIMATED AFR/AP 17 AUG 025/035 PREDICTED AFR/AP 18 AUG-20 AUG 015/017-010/012-010/008
VI. Geomagnetic Activity Probabilities 18 AUG to 20 AUG
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 25% | 20% |
| Minor storm | 10% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 45% | 30% | 25% |
| Minor storm | 10% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
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