Viewing archive of Sunday, 25 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 25 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 115 Issued at 2200Z on 25 APR 1999IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z SOLAR ACTIVITY WAS VERY LOW. REGIONS 8524 (N22E39) AND
8523 (N31E28) BOTH PRODUCED MINOR B-CLASS SUBFLARES. NEW REGIONS -
8522 (N17E38) AND 8524 WERE THE ONLY REGIONS ON THE VISIBLE DISK
THAT SHOWED ANY GROWTH. REMAINING REGIONS WERE EITHER STABLE OR
DECAYING.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGION 8522 AND REGION 8524 MAY SOON DEVELOP C-CLASS
POTENTIAL, ESPECIALLY CONSIDERING THEIR PROXIMITY TO EACH OTHER.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
THE GEOMAGNETIC FIELD WAS QUIET. A GREATER THAN 10 MEV PROTON EVENT
BEGAN YESTERDAY AT 24/1610Z ASSOCIATED WITH THE LARGE HALO CME FROM
BEHIND THE NORTHWEST LIMB AT AROUND 24/1230Z. THE 10 PFU THRESHOLD
WAS CROSSED AT 24/1840Z WITH A MAXIMUM OF 32 PFU OBSERVED AT
25/0055Z. THE FLUX DROPPED BACK BELOW THE 10 PFU LEVEL AT 25/1451Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED. NO GEOEFFECTIVNESS IS EXPECTED
FROM YESTERDAY'S CME. THE GREATER THAN 10 MEV PROTON FLUX IS
EXPECTED TO RETURN TO BACKGROUND LEVELS BY END OF PERIOD.
III. Event Probabilities 26 APR to 28 APR
| Class M | 05% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 25 APR 103 Predicted 26 APR-28 APR 110/115/115 90 Day Mean 25 APR 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 24 APR 005/007 ESTIMATED AFR/AP 25 APR 005/005 PREDICTED AFR/AP 26 APR-28 APR 010/010-010/010-010/010
VI. Geomagnetic Activity Probabilities 26 APR to 28 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 20% | 15% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 25% | 20% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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