Viewing archive of Tuesday, 18 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 18 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 138 Issued at 2200Z on 18 MAY 1999IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z SOLAR ACTIVITY WAS MODERATE. AN OPTICALLY UNCORRELATED
M1 X-RAY FLARE LED-OFF THE PERIOD FOLLOWED BY SEVERAL C-CLASS X-RAY
EVENTS. MOST OF THESE SMALLER EVENTS ORIGINATED FROM REGION 8541
(N21W53).
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
THE GEOMAGNETIC FIELD WAS QUIET TO ACTIVE WITH MINOR STORM CONDITIONS
SEEN IN THE HIGH LATITUDES FROM 18/06Z TO 18/09Z. THE DISTURBED
CONDITIONS WERE DUE TO THE EFFECT OF A RECURRENT CORONAL HOLE AND AN
ACCOMPANYING CO-ROTATING SHOCK.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE WITH POSSIBLE MINOR STORM
CONDITIONS. THESE CONDITIONS ARE FORECAST DUE TO THE CONTINUING
EFFECTS OF A CORONAL HOLE AS WELL AS THE IMPACT OF A CME ORIGINATING
FROM THE NW LIMB ON 17/05Z.
III. Event Probabilities 19 MAY to 21 MAY
| Class M | 20% | 20% | 20% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 18 MAY 141 Predicted 19 MAY-21 MAY 140/135/135 90 Day Mean 18 MAY 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 17 MAY 001/005 ESTIMATED AFR/AP 18 MAY 021/023 PREDICTED AFR/AP 19 MAY-21 MAY 020/020-010/012-008/010
VI. Geomagnetic Activity Probabilities 19 MAY to 21 MAY
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 50% | 30% | 30% |
| Minor storm | 25% | 10% | 10% |
| Major-severe storm | 05% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 50% | 40% | 40% |
| Minor storm | 30% | 15% | 15% |
| Major-severe storm | 15% | 05% | 05% |
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