Viewing archive of Thursday, 20 August 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 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 1998IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY HAS BEEN HIGH WITH A SINGLE X3.9 FLARE
AT 19/2145 FROM REGION 8307 (N32E60). THERE WAS AN ASSOCIATED TYPE
II AND IV SWEEP INDICATING A SHOCK WITH A SPEED OF 1400 KM/S +/-200
KM/S. REGION 8310 (N23E66) AND 8311 (N19E01) WERE NUMBERED TODAY.
REGION 8307 HAS MOVED FAR ENOUGH ONTO THE DISK THAT A RELIABLE
CLASSIFICATION HAS BEEN PERFORMED. IT IS CLASSIFIED AS A EKO BETA
DELTA WITH 8 SPOTS AND AN AREA OF 440 MILLIONTHS. THE MAGNETIC
CLASSIFICATION STILL NEEDS TO BE REFINED AS THE SPOT MOVES CLOSER TO
CENTER DISK.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE
MODERATE TO HIGH THROUGHOUT THE PERIOD.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD HAS BEEN UNSETTLED TO ACTIVE. DATA FROM THE
ACE SPACECRAFT INDICATE THAT A SMALL, SLOW SHOCK PASSED BY EARTH
OVER THE LAST 20 HOURS. ENHANCED DENSITY, SLOW BULK SPEED, AND
SEMI-SMOOTH TRANSITION OF BZ FROM NEGATIVE TO POSITIVE CONTRIBUTED
TO THIS CONCLUSION.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO ACTIVE WITH PERIODS OF MINOR STORM AT HIGHER
LATITUDES.
III. Event Probabilities 21 AUG to 23 AUG
| Class M | 75% | 75% | 75% |
| Class X | 40% | 40% | 40% |
| Proton | 15% | 15% | 15% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 20 AUG 139 Predicted 21 AUG-23 AUG 142/146/150 90 Day Mean 20 AUG 115
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 AUG 006/009 ESTIMATED AFR/AP 20 AUG 015/015 PREDICTED AFR/AP 21 AUG-23 AUG 025/020-020/018-015/010
VI. Geomagnetic Activity Probabilities 21 AUG to 23 AUG
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 20% | 15% |
| Minor storm | 10% | 10% | 05% |
| Major-severe storm | 05% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 30% | 25% | 20% |
| Minor storm | 15% | 10% | 10% |
| Major-severe storm | 05% | 05% | 05% |
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