Viewing archive of Tuesday, 28 December 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 Dec 28 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 362 Issued at 2200Z on 28 DEC 1999IA. Analysis of Solar Active Regions and Activity from 27-2100Z to 28-2100Z SOLAR ACTIVITY WAS MODERATE. REGION 8806 (N20W65)
PRODUCED AN M4/2B FLARE AT 28/0039UT. THIS EVENT WAS ACCOMPANIED BY
MODERATE RADIO EMISSIONS, INCLUDING A TYPE II SWEEP. REGION 8806
CONTINUES TO DECLINE AS IT APPROACHES THE WEST LIMB. ONLY MINOR
ACTIVITY WAS OBSERVED IN THE OTHER THREE SPOTTED REGIONS. THE
PROMINENCE THAT ERUPTED AROUND 27/2100UT APPEARS IN THE SOHO IMAGERY
TO COVER MUCH OF THE NORTHERN POLAR AREA.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE.
IIA. Geophysical Activity Summary 27-2100Z to 28-2100Z
THE GEOMAGNETIC FIELD WAS MOSTLY QUIET. A SHORT PERIOD OF UNSETTLED
CONDITIONS WAS OBSERVED AROUND 0300UT. THERE WERE ONLY MINOR
PARTICLE ENHANCEMENTS FOLLOWING THE 28/0039UT M4/2B FLARE.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED EARLY IN THE PERIOD. THE FIELD IS
EXPECTED TO BECOME DISTURBED STARTING ON 31 DEC AS A RESULT OF A
LARGE EQUATORIAL CORONAL HOLE EAST OF CENTRAL MERIDIAN.
III. Event Probabilities 29 DEC to 31 DEC
| Class M | 50% | 50% | 50% |
| Class X | 10% | 10% | 10% |
| Proton | 10% | 10% | 10% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 28 DEC 150 Predicted 29 DEC-31 DEC 145/140/135 90 Day Mean 28 DEC 176
V. Geomagnetic A Indices
OBSERVED AFR/AP 27 DEC 006/006 ESTIMATED AFR/AP 28 DEC 004/005 PREDICTED AFR/AP 29 DEC-31 DEC 005/005-008/010-012/012
VI. Geomagnetic Activity Probabilities 29 DEC to 31 DEC
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 10% | 15% | 15% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 20% | 20% |
| Minor storm | 05% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
Latest news
Monday, 1 December 2025
X1.9 solar flare, Coronal hole faces Earth
Friday, 14 November 2025
X4.0 solar flare
Tuesday, 11 November 2025
X5.1 solar flare, G4 geomagnetic storm watch
Latest forum messages
AR4294 / 4296 / 4298 355AR 4299 89AR4299 M8.1 CME 2025/12/06 70Growth of Cycle 25 975Incoming & Unnumbered Active Regions 21
More topicsSupport SpaceWeatherLive.com!
A lot of people come to SpaceWeatherLive to follow the Solar activity or if there is a chance to see the aurora, but with more traffic comes higher costs to keep the servers online. If you like SpaceWeatherLive and want to support the project you can choose a subscription for an ad-free site or consider a donation. With your help we can keep SpaceWeatherLive online!
Space weather facts
| Last X-flare | 2025/12/01 | X1.9 |
| Last M-flare | 2025/12/06 | M8.1 |
| Last geomagnetic storm | 2025/12/04 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| November 2025 | 91.8 -22.8 |
| December 2025 | 167.7 +75.9 |
| Last 30 days | 107.1 +13.7 |