Viewing archive of Friday, 30 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 30 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 120 Issued at 2200Z on 30 APR 1999IA. Analysis of Solar Active Regions and Activity from 29-2100Z to 30-2100Z SOLAR ACTIVITY WAS LOW. CONTINUING DEVELOPMENT IN
REGION 8524 (N21W28) RESULTED IN ITS MERGER WITH NEARBY REGION 8522,
FORMING ONE LARGE BIPOLE. REGION 8524 PRODUCED A NUMBER OF C-CLASS
EVENTS, THE LARGEST BEING A C8/1F FLARE AT 1221Z. ONE NEW REGION,
8527 (N27E68), ROTATED FULLY INTO VIEW NEAR EAST LIMB, WHERE ANOTHER
REGION MAY BE SOON TO APPEAR NEAR S10. REGION 8525 (N16E59),
ALTHOUGH QUIET, HAS PATCHES OF BRIGHT PLAGE.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. REGION 8524 IS THE MOST PROMISING SITE OF M-CLASS
ACTIVITY. REGION 8525 MAY ALSO CONTRIBUTE SHOULD FURTHER DEVELOPMENT
OCCUR.
IIA. Geophysical Activity Summary 29-2100Z to 30-2100Z
THE GEOMAGNETIC FIELD WAS GENERALLY ACTIVE. A HIGH SPEED SOLAR WIND
STREAM, AT TIMES REACHING MORE THAN 650 KM/S AT THE ACE SPACECRAFT,
DROVE THE FIELD TO EPISODES OF MINOR STORM ACTIVITY DURING THE
PERIOD. THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT
ATTAINED HIGH LEVELS FROM ABOUT 1300 TO 2100Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT ACTIVE TO MINOR STORM LEVELS FOR THE NEXT THREE
DAYS. THE HIGH SPEED STREAM SHOULD ABATE BY THE LATTER PART OF THE
PERIOD. A CME, RELATED TO YESTERDAY'S M1 EVENT, MAY IMPACT THE FIELD
AT THE END OF THE FORECAST INTERVAL.
III. Event Probabilities 01 MAY to 03 MAY
| Class M | 30% | 30% | 30% |
| Class X | 05% | 05% | 05% |
| Proton | 05% | 05% | 05% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 30 APR 124 Predicted 01 MAY-03 MAY 130/135/140 90 Day Mean 30 APR 128
V. Geomagnetic A Indices
OBSERVED AFR/AP 29 APR 018/019 ESTIMATED AFR/AP 30 APR 023/025 PREDICTED AFR/AP 01 MAY-03 MAY 015/030-015/030-015/025
VI. Geomagnetic Activity Probabilities 01 MAY to 03 MAY
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 30% | 30% |
| Minor storm | 10% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 40% | 40% | 40% |
| Minor storm | 15% | 15% | 15% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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