Viewing archive of Tuesday, 21 April 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 Apr 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 111 Issued at 2200Z on 21 APR 1998IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z SOLAR ACTIVITY WAS VERY LOW. THE ONLY ACTIVITY OF NOTE
WAS AN ERUPTIVE PROMINENCE THAT OCCURRED ON THE WEST LIMB NEAR N30.
NO OTHER ACTIVITY WAS NOTED WITH THIS ERUPTION. REGION 8205
(N21W53) DECAYED SLIGHTLY IN WHITE LIGHT AREA BUT IS STILL
EXHIBITING OCCASIONAL PLAGE FLUCTUATIONS AND SURGING. THE REMAINING
REGIONS HAVE BEEN QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGION 8205 HAS POTENTIAL TO PRODUCE AN ISOLATED C-CLASS
FLARE. STILL A SLIGHT CHANCE FOR FURTHER ACTIVITY NEAR THE SW LIMB -
THE SOURCE OF YESTERDAY'S M1 X-RAY FLARE; HOWEVER, THE LIKELY SOURCE
REGION HAS PROBABLY ROTATED ENOUGH TO ELIMINATE CONCERN.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. THE GREATER THAN 10 MEV
PROTON EVENT THAT BEGAN AT 20/1130Z IS STILL IN PROGRESS. A MAXIMUM
VALUE OF 1700 PFU WAS REACHED AT 21/1205. THE EVENT APPEARS TO BE
IN DECLINE NOW WITH A CURRENT VALUE OF 640 PFU. THE GREATER THAN 100
MEV EVENT PEAKED AT 7.4 PFU AT 21/1255Z AND IS CURRENTLY AT 2.5 PFU.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO CONTINUE AT QUIET TO UNSETTLED LEVELS. AN EXTENSION OF
THE SOUTHERN CORONAL HOLE WILL MOVE INTO FAVORABLE POSITION FOR
GEOEFFECTIVNESS ON DAY TWO AND THREE. EXPECT OCCASIONAL ACTIVE
PERIODS DURING THIS PERIOD. THE PROTON EVENT IN PROGRESS IS EXPECTED
TO LAST THROUGH TOMORROW.
III. Event Probabilities 22 APR to 24 APR
| Class M | 05% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 05% | 05% | 01% |
| PCAF | IN PROGRESS | ||
IV. Penticton 10.7 cm Flux
Observed 21 APR 92 Predicted 22 APR-24 APR 092/090/090 90 Day Mean 21 APR 104
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 APR 009/010 ESTIMATED AFR/AP 21 APR 007/010 PREDICTED AFR/AP 22 APR-24 APR 012/010-012/015-012/020
VI. Geomagnetic Activity Probabilities 22 APR to 24 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 15% | 30% | 30% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 20% | 40% | 45% |
| Minor storm | 10% | 10% | 10% |
| Major-severe storm | 01% | 06% | 06% |
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