Viewing archive of Sunday, 20 December 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 Dec 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 354 Issued at 2200Z on 20 DEC 1998IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z SOLAR ACTIVITY WAS MODERATE. REGION 8415 (N20E38)
PRODUCED AN M1/1N FLARE AT 20/0900Z THAT WAS ACCOMPANIED BY MINOR
RADIO BURSTS. THIS REGION ALSO PRODUCED SEVERAL LOW TO MID C-CLASS
EVENTS DURING THE PERIOD. MIXED MAGNETIC POLARITIES REMAINED IN THIS
REGION BUT AREAL COVERAGE IN WHITE LIGHT DECREASED SLIGHTLY. A SMALL
CLASS C SUNSPOT GROUP ROTATED ONTO THE DISK NEAR N18E67 AND WAS
NUMBERED AS NEW REGION 8416. TWO LESSER REGIONS EMERGED ON THE DISK.
IB. Solar Activity Forecast
SOLAR ACTIVITY SHOULD BECOME GENERALLY
LOW FOR THE NEXT THREE DAYS. REGION 8415 IS CAPABLE OF PRODUCING
ISOLATED M-CLASS EVENTS.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
THE GEOMAGNETIC FIELD WAS PREDOMINANTLY UNSETTLED. DURING THE PERIOD,
SOLAR WIND VELOCITY INCREASED, DENSITY DECREASED, AND SEVERAL
INTERVALS OF PROLONGED SOUTHWARD BZ WERE OBSERVED.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
FORECAST TO BE QUIET TO UNSETTLED UNTIL THE LATTER HALF OF 21 DEC
WHEN A DISTURBANCE IS EXPECTED TO BEGIN. GENERALLY UNSETTLED TO
ACTIVE LEVELS ARE EXPECTED FROM THAT TIME THROUGH THE END OF 22 DEC.
DURING THIS DISTURBANCE, PERIODS OF MINOR STORMING ARE POSSIBLE AT
ALL LATITUDES WITH ISOLATED INTERVALS OF MAJOR STORMING POSSIBLE AT
HIGH LATITUDES.
III. Event Probabilities 21 DEC to 23 DEC
| Class M | 50% | 40% | 40% |
| Class X | 05% | 05% | 05% |
| Proton | 05% | 05% | 05% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 20 DEC 135 Predicted 21 DEC-23 DEC 130/128/129 90 Day Mean 20 DEC 133
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 DEC 006/007 ESTIMATED AFR/AP 20 DEC 012/012 PREDICTED AFR/AP 21 DEC-23 DEC 018/020-025/025-012/009
VI. Geomagnetic Activity Probabilities 21 DEC to 23 DEC
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 30% | 20% |
| Minor storm | 20% | 20% | 05% |
| Major-severe storm | 20% | 20% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 25% | 20% |
| Minor storm | 25% | 25% | 05% |
| Major-severe storm | 30% | 30% | 01% |
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