Viewing archive of Friday, 20 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 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 232 Issued at 2200Z on 20 AUG 1999IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY WAS MODERATE. NEWLY NUMBERED REGION 8674
(S24E66) WAS BY FAR THE MOST ACTIVE REGION THIS PERIOD. THIS REGION
PRODUCED A LONG DURATION M1 X-RAY EVENT WITH MULTIPLE OPTICAL
SUBFLARES FROM 20/1236UT TO 20/1706UT. REGION 8674 ALSO PRODUCED AN
M1/SF ACCOMPANIED BY AN 180 SFU 10 CM BURST AND A WEAK TYPE II SWEEP
(400 KM/S) AT 20/1829UT AND A C7/SF AT 20/1927UT. AN 8 DEGREE
PROMINENCE ERUPTED ON THE NORTH-WEST LIMB (N47W74) AT 20/1530UT.
OTHER ACTIVE REGIONS WERE 8668 (N22W11), 8672 (N16W31), AND 8673
(S26E75) ALL OF WHICH PRODUCED OPTICAL SUBFLARES.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD WAS AT UNSETTLED TO MINOR STORM LEVELS. THE
SOLAR WIND VELOCITY DROPPED FROM 750 KM/S AT THE BEGINNING OF THE
PERIOD TO 550 KM/S AT THE END OF THE PERIOD. THE GREATER THAN 2 MEV
ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS AT HIGH LEVELS FOR MOST OF
THE PERIOD.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE THE NEXT 24 HOURS. AS THE SOLAR
WIND VELOCITY DROPS THE CURRENT DISTURBANCE SHOULD SLOWLY WEAKEN AND
UNSETTLED CONDITIONS CAN BE EXPECTED FOR THE REST OF THE FORECAST
PERIOD.
III. Event Probabilities 21 AUG to 23 AUG
| Class M | 60% | 60% | 60% |
| Class X | 05% | 05% | 05% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 20 AUG 152 Predicted 21 AUG-23 AUG 155/160/165 90 Day Mean 20 AUG 163
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 AUG 019/022 ESTIMATED AFR/AP 20 AUG 020/030 PREDICTED AFR/AP 21 AUG-23 AUG 018/025-015/020-010/015
VI. Geomagnetic Activity Probabilities 21 AUG to 23 AUG
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 01% | 01% | 01% |
| Minor storm | 01% | 01% | 01% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 01% | 01% | 01% |
| Minor storm | 01% | 01% | 01% |
| Major-severe storm | 01% | 01% | 01% |
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