Viewing archive of Monday, 20 September 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 Sep 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 263 Issued at 2200Z on 20 SEP 1999IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY WAS LOW. REGION 8699 (N24W88) PRODUCED
THE LARGEST FLARE, A C9/1F AT 19/2312UT. REGION 8700 (N12W19) ALSO
PRODUCED SMALL C-CLASS FLARES. REGION 8700 CONTINUES TO SLOWLY
DECAY. REMAINING DISK REGIONS ARE SMALL AND SIMPLE.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. C-CLASS ACTIVITY IS EXPECTED TO CONTINUE, PRIMARILY IN
REGION 8700. THE LIKELIHOOD OF M-CLASS ACTIVITY IS DIMINISHING WITH
THE DEPARTURE OF REGION 8699 AND THE DECAY IN REGION 8700.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. THE GREATER THAN 2 MEV
ELECTRON FLUX WAS MODERATE TO HIGH.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED. A SOLAR WIND SIGNATURE FROM THE
SEP 16 CME/DSF EVENT HAS NOT YET BEEN SEEN AND ITS ARRIVAL IS
BECOMING LESS LIKELY.
III. Event Probabilities 21 SEP to 23 SEP
| Class M | 10% | 10% | 10% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 20 SEP 145 Predicted 21 SEP-23 SEP 142/140/138 90 Day Mean 20 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 SEP 009/010 ESTIMATED AFR/AP 20 SEP 010/010 PREDICTED AFR/AP 21 SEP-23 SEP 010/015-010/012-010/010
VI. Geomagnetic Activity Probabilities 21 SEP to 23 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 10% | 05% |
| Minor storm | 05% | 01% | 01% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 20% | 10% | 10% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
Latest news
Thursday, 21 November 2024
Major far side eruption, S1 radiation storm
Monday, 11 November 2024
Coronal hole faces Earth
Friday, 1 November 2024
X2.0 solar flare
Latest forum messages
Filaments and prominences 532AR 13901 111Strong far side CME 225AR 13903 1Incoming & Unnumbered Active Regions 1246
More topicsSupport SpaceWeatherLive.com!
A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!
Space weather facts
| Last X-flare | 2024/11/06 | X2.39 |
| Last M-flare | 2024/11/20 | M1.1 |
| Last geomagnetic storm | 2024/11/10 | Kp5+ (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| October 2024 | 166.4 +25 |
| November 2024 | 142.7 -23.8 |
| Last 30 days | 156.1 +4.7 |