Viewing archive of Saturday, 11 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 11 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 254 Issued at 2200Z on 11 SEP 1999IA. Analysis of Solar Active Regions and Activity from 10-2100Z to 11-2100Z SOLAR ACTIVITY INCREASED TO LOW LEVELS BY VIRTUE OF AN
OPTICALLY UNCORRELATED C1 X-RAY FLARE AT 11/0631Z. ISOLATED B-CLASS
X-RAY FLARES WERE ALSO DETECTED, ONE OF WHICH WAS ASSOCIATED WITH A
SUBFLARE IN REGION 8690 (N14E06). REGION 8690 DISPLAYED A SMALL
INCREASE IN SPOT COUNT DURING THE PERIOD, BUT WAS OTHERWISE
UNREMARKABLE. NEW REGIONS 8696 (N14W48), 8697 (S20W06), 8698
(S16E64), AND 8699 (N21E29) WERE ASSIGNED TODAY. REGION 8699
APPEARED TO BE GROWING AT A MODERATE PACE AND PRODUCED A SMALL
SUBFLARE LATE IN THE PERIOD.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN
AT LOW LEVELS. REGIONS 8690, 8692, AND 8699 MAY PRODUCE C-CLASS
FLARES.
IIA. Geophysical Activity Summary 10-2100Z to 11-2100Z
GEOMAGNETIC FIELD ACTIVITY RANGED FROM QUIET TO ACTIVE LEVELS.
UNSETTLED TO ACTIVE LEVELS OCCURRED DURING 11/0100 - 0500Z FOLLOWING
A SOUTHWARD TURNING OF THE BZ COMPONENT OF THE INTERPLANETARY
MAGNETIC FIELD. FIELD ACTIVITY DECLINED TO MOSTLY QUIET LEVELS AFTER
11/0500Z.
IIB. Geophysical Activity Forecast
GEOMAGNETIC FIELD ACTIVITY IS
EXPECTED TO VARY FROM QUIET TO ACTIVE LEVELS. INTERMITTENT ACTIVE
PERIODS ARE EXPECTED IN RESPONSE TO RECURRENT CORONAL HOLE EFFECTS.
III. Event Probabilities 12 SEP to 14 SEP
| Class M | 25% | 25% | 25% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 11 SEP 123 Predicted 12 SEP-14 SEP 125/125/130 90 Day Mean 11 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 10 SEP 012/015 ESTIMATED AFR/AP 11 SEP 010/015 PREDICTED AFR/AP 12 SEP-14 SEP 015/015-015/015-015/015
VI. Geomagnetic Activity Probabilities 12 SEP to 14 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 35% | 35% |
| 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 | 05% | 05% | 05% |
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