Viewing archive of Tuesday, 21 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 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 355 Issued at 2200Z on 21 DEC 1999IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z SOLAR ACTIVITY WAS MODERATE. REGION 8806 (N19E24)
PRODUCED AN M1/1N AT 21/1719UT. REGION 8806 IS THE LARGEST REGION ON
THE DISK AND CONTINUES TO BE MAGNETICALLY COMPLEX. REGION 8798
(S13W33), THE SECOND LARGEST REGION ON THE DISK, HAS ONLY PRODUCED
SMALL C FLARES. A CME WAS OBSERVED BY SOHO AROUND 1600UT ON THE
20TH, BUT APPEARED TO BE A BACKSIDE EVENT. THE OBSERVED 10CM RADIO
FLUX REPORTED IN PART IV MAY BE FLARE ENHANCED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. THERE IS A FAIR CHANCE FOR MAJOR ACTIVITY FROM EITHER
REGION 8798 OR REGION 8806.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
THE GEOMAGNETIC FIELD HAS BEEN BASICALLY QUIET.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED.
III. Event Probabilities 22 DEC to 24 DEC
| Class M | 50% | 50% | 50% |
| Class X | 15% | 15% | 15% |
| Proton | 05% | 05% | 10% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 21 DEC 217 Predicted 22 DEC-24 DEC 200/195/190 90 Day Mean 21 DEC 172
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 DEC 004/003 ESTIMATED AFR/AP 21 DEC 004/005 PREDICTED AFR/AP 22 DEC-24 DEC 007/010-007/007-005/007
VI. Geomagnetic Activity Probabilities 22 DEC to 24 DEC
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 25% | 10% | 10% |
| Minor storm | 10% | 01% | 01% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 20% | 15% |
| Minor storm | 10% | 05% | 01% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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