Viewing archive of Monday, 20 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 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 110 Issued at 2200Z on 20 APR 1998IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY BECAME MODERATE. A LONG DURATION M1
X-RAY EVENT AND TYPE II SWEEP OCCURRED AT 20/1021UT. THE LIKELY
SOURCE FOR THE FLARE WAS BEHIND THE SW LIMB. SPACE-BASED SENSORS
INDICATE STRONG EMISSIONS ON THE LIMB ALONG S25. A LARGE CME WAS
ALSO OBSERVED OFF THE W-SW LIMB. FAINT POST FLARE LOOPS WERE ALSO
EVIDENT. REGION 8205 (N21W40) CHANGED VERY LITTLE IN THE PAST 24
HOURS, AND MAINTAINS IT'S DSO BETA CONFIGURATION. THE REMAINING
REGIONS HAVE BEEN QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGION 8205 HAS SMALL POTENTIAL TO PRODUCE A C-CLASS
FLARE. FURTHER ACTIVITY ALONG THE SW LIMB IS POSSIBLE BUT UNLIKELY
AS POSSIBLE SOURCE REGION ROTATES FURTHER BEHIND THE LIMB.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO ACTIVE. A GREATER THAN 10 MEV
PROTON EVENT BEGAN AT 20/1130Z, PASSED THE 10 PFU THRESHOLD AT
20/1400Z, AND IS CURRENTLY STEADY AT A MAXIMUM OF 330 PFU. THE
GREATER THAN 100 MEV PROTON FLUX IS AT 2.3 PFU AND STILL RISING
SLOWLY. POLAR CAP ABSORPTION IS CURRENTLY AT A MAXIMUM OF 6.4 DB.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO CONTINUE AT QUIET TO ACTIVE LEVELS. MOST OF THE MATERIAL
FROM THIS MORNING'S ACTIVITY APPEARS WESTWARD BOUND, THUS, NO
SIGNIFICANT IMPACT IS EXPECTED ON THE GEOMAGNETIC FIELD. THE 10 AND
100 MEV PROTON EVENTS ARE EXPECTED TO CONTINUE THROUGH TOMORROW.
III. Event Probabilities 21 APR to 23 APR
| Class M | 10% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 10% | 05% | 01% |
| PCAF | IN PROGRESS | ||
IV. Penticton 10.7 cm Flux
Observed 20 APR 098 Predicted 21 APR-23 APR 096/094/092 90 Day Mean 20 APR 104
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 APR 002/004 ESTIMATED AFR/AP 20 APR 010/012 PREDICTED AFR/AP 21 APR-23 APR 010/010-012/012-010/012
VI. Geomagnetic Activity Probabilities 21 APR to 23 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 15% | 25% | 25% |
| Minor storm | 05% | 10% | 10% |
| Major-severe storm | 01% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 20% | 30% | 30% |
| Minor storm | 05% | 15% | 10% |
| Major-severe storm | 05% | 11% | 11% |
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