Viewing archive of Thursday, 23 September 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 Sep 23 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 266 Issued at 2200Z on 23 SEP 1999IA. Analysis of Solar Active Regions and Activity from 22-2100Z to 23-2100Z SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT OF THE PERIOD
WAS AN IMPULSIVE C1/SF FROM 8706 (N20E25). REGION 8700 (N12W61) WAS
THE MOST ACTIVE REGION THIS PERIOD AND PRODUCED SEVERAL MINOR
SUBFLARES. A SIXTEEN DEGREE FILAMENT ERUPTED FROM NEAR S14W47 AT
23/1529Z. REMAINING REGIONS WERE MOSTLY QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN
AT LOW LEVELS. ONLY ISOLATED C-CLASS X-RAY EVENTS ARE EXPECTED.
IIA. Geophysical Activity Summary 22-2100Z to 23-2100Z
THE GEOMAGNETIC FIELD WAS AT QUIET TO MAJOR STORM LEVELS. THE
GEOMAGNETIC STORM THAT FOLLOWED YESTERDAY'S SUDDEN IMPULSE AT
22/1222Z, CONTINUED THROUGH EARLY THIS PERIOD. THE STORM SUBSIDED
RATHER QUICKLY AFTER 23/0600Z AND THE FIELD HAS BEEN MOSTLY QUIET TO
UNSETTLED SINCE.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT QUIET TO ACTIVE LEVELS. SOLAR WIND SPEED REMAINS
ELEVATED FOLLOWING YESTERDAY'S INTERPLANETARY SHOCK. OCCASIONAL
ACTIVE PERIODS ARE LIKELY DURING LOCAL NIGHTTIME HOURS ESPECIALLY AT
HIGHER LATITUDES.
III. Event Probabilities 24 SEP to 26 SEP
| Class M | 10% | 10% | 10% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 23 SEP 137 Predicted 24 SEP-26 SEP 135/135/130 90 Day Mean 23 SEP 163
V. Geomagnetic A Indices
OBSERVED AFR/AP 22 SEP 029/037 ESTIMATED AFR/AP 23 SEP 022/025 PREDICTED AFR/AP 24 SEP-26 SEP 012/015-010/012-010/010
VI. Geomagnetic Activity Probabilities 24 SEP to 26 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 20% | 20% |
| Minor storm | 10% | 05% | 05% |
| Major-severe storm | 05% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 40% | 30% | 30% |
| Minor storm | 10% | 10% | 05% |
| Major-severe storm | 05% | 01% | 01% |
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