Viewing archive of Friday, 25 September 1998
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 1998 Sep 25 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 268 Issued at 2200Z on 25 SEP 1998IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z SOLAR ACTIVITY WAS LOW. ONLY 2 C-CLASS X-RAY FLARES
WERE OBSERVED DURING THE PERIOD. NOTABLE ACTIVE REGIONS WERE 8336
(S27W67), 8340 (N20W27) AND 8244 (S18W16), ALL OF WHICH PRODUCED
OPTICAL SUB-FLARES. PERHAPS THE MOST DYNAMIC REGION WAS REGION 8346
(S30E27) WHICH PRODUCED A B7/SF AND WAS SHOWING PLAGE FLUCTUATIONS
AS WELL AS POINT BRIGHTENINGS OF NEAR FAINT FLARE INTENSITY FOR MOST
OF THE PERIOD. THE REST OF THE DISK AND LIMB WAS STABLE AND MOSTLY
QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. REGIONS 8340, 8344 AND 8346 CAN BE EXPECTED TO PRODUCE
C-CLASS FLARES. IT IS ALSO POSSIBLE THAT THESE REGIONS COULD PRODUCE
AN ISOLATE M-CLASS EVENT.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
GEOMAGNETIC ACTIVITY WAS UNSETTLED TO SEVERE STORM LEVELS AT BOTH
MIDDLE AND HIGH LATITUDES. A GREATER THAN 10 PFU PROTON EVENT WAS
OBSERVED AT GEOSYNCHRONOUS ORBIT BETWEEN 25/0010UT AND 25/0230UT.
THE MAXIMUM OF 44 PFU WAS OBSERVED AT 25/0130UT. THE GREATER THAN
2MEV ELECTRONS AT GEOSYNCHRONOUS ORBIT REACHED THRESHOLD LEVELS AT
1605UT. THEY REACHED A PEAK AT AROUND 25/1830UT AND HAVE SINCE
DECLINED TO NEAR THRESHOLD LEVELS AT THE END OF THE PERIOD.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO MINOR STORM LEVELS. THIS WOULD BE
ATTRIBUTED TO THE CONTINUATION OF THE GEOMAGNETIC ACTIVITY OF 25
SEPTEMBER. THE GREATER THAN 2MEV ELECTRONS CAN BE EXPECTED TO
CONTINUE TO DECLINE.
III. Event Probabilities 26 SEP to 28 SEP
| Class M | 40% | 40% | 40% |
| Class X | 10% | 10% | 10% |
| Proton | 05% | 05% | 05% |
| PCAF | YELLOW | ||
IV. Penticton 10.7 cm Flux
Observed 25 SEP 139 Predicted 26 SEP-28 SEP 140/140/140 90 Day Mean 25 SEP 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 24 SEP 017/028 ESTIMATED AFR/AP 25 SEP 090/140 PREDICTED AFR/AP 26 SEP-28 SEP 040/050-025/025-015/015
VI. Geomagnetic Activity Probabilities 26 SEP to 28 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 50% | 30% | 25% |
| Minor storm | 30% | 10% | 10% |
| Major-severe storm | 05% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 60% | 50% | 40% |
| Minor storm | 30% | 20% | 15% |
| Major-severe storm | 05% | 05% | 01% |
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