Viewing archive of Tuesday, 25 May 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 May 25 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 145 Issued at 2200Z on 25 MAY 1999IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z SOLAR ACTIVITY WAS LOW. THE PERIOD WAS CHARACTERIZED
BY A NUMBER OF VERY WEAK C-CLASS X-RAY AND OPTICAL FLARES. TWO
REGIONS WERE NUMBERED TODAY. THE FIRST, REGION 8553 (N25W02) ,
BEGAN THE PERIOD AS A SOUTHWEST EXTENSION TO REGION 8551 (N32E10).
THE SECOND, REGION 8554 (N27E39), FORMED OVERNIGHT.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN
LOW WITH A SLIGHT CHANCE FOR AN ISOLATED M-CLASS X-RAY FLARE.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
THE GEOMAGNETIC FIELD RANGED FROM QUIET TO MINOR STORM LEVELS. THE
MOST ACTIVE CONDITIONS WERE SEEN OVERNIGHT AND IN THE EARLY MORNING
HOURS. THESE CONDITIONS WERE DUE TO THE EFFECT OF A SMALL CORONAL
HOLE AS WELL AS THE IMPACT OF A TRANSIENT FEATURE THAT BROUGHT A
SUSTAINED PERIOD OF SOUTHWARD BZ.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED. AS THE EFFECT OF THE CURRENT
CORONAL HOLE DIMINISHES, ANOTHER RECURRENT HOLE IS EXPECTED BY THE
SECOND DAY OF THE FORECAST PERIOD.
III. Event Probabilities 26 MAY to 28 MAY
| Class M | 30% | 30% | 30% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 25 MAY 143 Predicted 26 MAY-28 MAY 145/145/150 90 Day Mean 25 MAY 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 24 MAY 011/011 ESTIMATED AFR/AP 25 MAY 015/019 PREDICTED AFR/AP 26 MAY-28 MAY 012/012-010/010-010/010
VI. Geomagnetic Activity Probabilities 26 MAY to 28 MAY
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 20% | 20% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 25% | 25% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
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