Viewing archive of Thursday, 16 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 16 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 259 Issued at 2200Z on 16 SEP 1999IA. Analysis of Solar Active Regions and Activity from 15-2100Z to 16-2100Z
SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT THIS PERIOD
WAS A C7/SF FROM REGION 8700 (N14E31). OCCASIONAL MINOR C-CLASS
SUBFLARES WERE ALSO OBSERVED IN REGIONS 8699 (N22W39) AND 8692
(S26W41). AN IMPRESSIVE DARK, 50 DEGREE FILAMENT ERUPTED FROM
NORTH-CENTER DISK. THIS FILAMENT WAS ACTIVE FOR MOST OF THE PAST 24
HOURS. ELEVATION WAS FIRST DETECTED AT AROUND 16/1230UT WITH THE
TOTAL ERUPTION OF THIS TWO-PART FILAMENT OCCURRING AT 16/1620UT. THE
EVENT WAS OBSERVED ON BOTH GROUND AND SPACE-BASED INSTRUMENTS WITH A
LARGE CME OBSERVED BY LASCO.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN
LOW. SEVERAL EXISTING SUNSPOT REGIONS ARE CAPABLE OF PRODUCING
C-CLASS ACTIVITY WITH AN ISOLATED CHANCE FOR A LOW M-CLASS.
IIA. Geophysical Activity Summary 15-2100Z to 16-2100Z
THE GEOMAGNETIC FIELD WAS AT QUIET TO MINOR STORM LEVELS WITH
ISOLATED MAJOR STORMING PERIODS AT HIGH LATITUDES. A SUSTAINED
PERIOD OF SOUTHWARD BZ AND A 600KM/S SOLAR WIND SPEED FOLLOWED A
SUDDEN IMPULSE (SI) OBSERVED AT 15/2019UT.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO ACTIVE WITH OCCASIONAL MINOR STORMING MOSTLY
AT HIGH LATITUDES. DAY TWO SHOULD BE LESS ACTIVE AS THE HIGH SPEED
STREAM SUBSIDES, EXPECT QUIET TO OCCASIONAL ACTIVE. WE MAY SEE THE
EFFECTS OF TODAY'S LARGE DSF ON DAY 3, LOOK FOR ACTIVE TO MINOR
STORM CONDITIONS POSSIBLE BY LATE DAY 3.
III. Event Probabilities 17 SEP to 19 SEP
| Class M | 15% | 15% | 15% |
| Class X | 05% | 05% | 05% |
| Proton | 05% | 05% | 05% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 16 SEP 158 Predicted 17 SEP-19 SEP 160/165/170 90 Day Mean 16 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 15 SEP 021/032 ESTIMATED AFR/AP 16 SEP 025/030 PREDICTED AFR/AP 17 SEP-19 SEP 020/025-015/020-012/012
VI. Geomagnetic Activity Probabilities 17 SEP to 19 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 50% | 40% | 50% |
| Minor storm | 30% | 20% | 30% |
| Major-severe storm | 10% | 05% | 10% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 40% | 40% | 50% |
| Minor storm | 50% | 25% | 30% |
| Major-severe storm | 10% | 05% | 10% |
All times in UTC
Latest news
Friday, 28 March 2025
X1.1 solar flare
Monday, 24 March 2025
Coronal hole faces Earth
Saturday, 22 March 2025
Strong G3 geomagnetic storm watch for 23 March
Latest forum messages
We are launching a dating app! SpaceWeatherLove! Download it today! 6AR4048 80AR4046 151Deep Flare Net 2AR4049 2
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 | 2025/03/28 | X1.1 |
| Last M-flare | 2025/04/01 | M5.6 |
| Last geomagnetic storm | 2025/03/27 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| February 2025 | 154.6 +17.6 |
| Last 30 days | 128.5 -22.7 |