Viewing archive of Monday, 19 April 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 Apr 19 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 109 Issued at 2200Z on 19 APR 1999IA. Analysis of Solar Active Regions and Activity from 18-2100Z to 19-2100Z SOLAR ACTIVITY REMAINED AT VERY LOW LEVELS. MINOR
GROWTH OCCURRED IN REGIONS 8517 (N22W63) AND 8518 (S14E40), BOTH OF
WHICH PRODUCED ISOLATED SUBFLARES. THE REMAINING REGIONS WERE EITHER
STABLE OR DECLINING. NEW REGIONS 8520 (N20E12) AND 8521 (N34W07)
WERE NUMBERED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGIONS 8517 AND 8518 MAY PRODUCE C-CLASS FLARES.
IIA. Geophysical Activity Summary 18-2100Z to 19-2100Z
GEOMAGNETIC FIELD ACTIVITY RANGED FROM QUIET TO ACTIVE LEVELS DURING
THE PERIOD. ACTIVE LEVELS WERE DETECTED AT ALL LATITUDES DURING
19/0900 - 1000Z. QUIET TO UNSETTLED LEVELS OCCURRED DURING THE
REMAINING HOURS.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT UNSETTLED TO MINOR STORM LEVELS DURING THE FIRST
TWO DAYS IN RESPONSE TO A PARTIAL-HALO CME OBSERVED ON 17 APRIL.
FIELD ACTIVITY IS EXPECTED TO DECLINE TO QUIET TO UNSETTLED LEVELS
ON THE FINAL DAY.
III. Event Probabilities 20 APR to 22 APR
| Class M | 10% | 10% | 10% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 19 APR 110 Predicted 20 APR-22 APR 110/110/105 90 Day Mean 19 APR 133
V. Geomagnetic A Indices
OBSERVED AFR/AP 18 APR 005/006 ESTIMATED AFR/AP 19 APR 008/008 PREDICTED AFR/AP 20 APR-22 APR 020/014-020/030-010/015
VI. Geomagnetic Activity Probabilities 20 APR to 22 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 40% | 40% | 25% |
| Minor storm | 20% | 20% | 10% |
| Major-severe storm | 05% | 05% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 45% | 45% | 30% |
| Minor storm | 25% | 25% | 15% |
| Major-severe storm | 05% | 05% | 01% |
All times in UTC
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