Viewing archive of Sunday, 12 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 12 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 255 Issued at 2200Z on 12 SEP 1999IA. Analysis of Solar Active Regions and Activity from 11-2100Z to 12-2100Z SOLAR ACTIVITY INCREASED, BUT REMAINED IN THE LOW
CATEGORY. REGION 8699 (N21E15) GREW RAPIDLY DURING THE PERIOD AND
PRODUCED NUMEROUS SUBFLARES, A FEW OF WHICH REACHED C-CLASS. THIS
REGION DISPLAYED A MODERATELY COMPLEX MAGNETIC STRUCTURE, POSSIBLY
INCLUDING A DELTA MAGNETIC CONFIGURATION. REGION 8692 (S26E11)
SHOWED SOME POLARITY MIXING, BUT WAS STABLE MUCH OF THE PERIOD. IT
PRODUCED A SUBFLARE LATE IN THE DAY. A 20-DEGREE FILAMENT, LAST SEEN
CENTERED AT S20W31, ERUPTED EARLY IN THE PERIOD. A CORONAL MASS
EJECTION FOLLOWED THE ERUPTION, BUT DID NOT APPEAR TO BE
EARTH-DIRECTED. NEW REGION 8700 (N12E81) WAS NUMBERED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE AT
LOW TO MODERATE LEVELS. REGION 8699 MAY PRODUCE M-CLASS FLARES,
PARTICULARLY IF ITS PRESENT RATE OF GROWTH CONTINUES. THERE IS ALSO
A SLIGHT CHANCE FOR A MAJOR FLARE FROM THIS REGION.
IIA. Geophysical Activity Summary 11-2100Z to 12-2100Z
GEOMAGNETIC FIELD ACTIVITY INCREASED TO QUIET TO MINOR STORM LEVELS
WITH BRIEF MAJOR STORM PERIODS DETECTED AT HIGH LATITUDES. THE ACE
SPACECRAFT DETECTED AN INTERPLANETARY SHOCK PASSAGE AT L1 AT
12/0322Z FOLLOWED BY A SUDDEN IMPULSE AT EARTH AT 12/0400Z (21 NT,
AS MEASURED BY THE BOULDER USGS MAGNETOMETER). THIS ACTIVITY IS
LIKELY DUE TO A RECURRENT HIGH-SPEED CORONAL HOLE WIND STREAM.
IIB. Geophysical Activity Forecast
GEOMAGNETIC FIELD ACTIVITY IS
EXPECTED TO RANGE FROM UNSETTLED TO MINOR STORM LEVELS THROUGH THE
PERIOD AS CORONAL HOLE EFFECTS CONTINUE. THE GREATER THAN 2 MEV
ELECTRON FLUX, CURRENTLY AT NORMAL LEVELS, IS EXPECTED TO INCREASE
TO HIGH LEVELS DURING THE PERIOD.
III. Event Probabilities 13 SEP to 15 SEP
| Class M | 40% | 40% | 40% |
| Class X | 10% | 10% | 10% |
| Proton | 10% | 10% | 10% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 12 SEP 141 Predicted 13 SEP-15 SEP 150/155/160 90 Day Mean 12 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 11 SEP 008/010 ESTIMATED AFR/AP 12 SEP 018/015 PREDICTED AFR/AP 13 SEP-15 SEP 018/013-018/015-018/015
VI. Geomagnetic Activity Probabilities 13 SEP to 15 SEP
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 40% | 40% | 40% |
| Minor storm | 15% | 15% | 15% |
| Major-severe storm | 05% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 45% | 45% | 45% |
| Minor storm | 20% | 20% | 20% |
| Major-severe storm | 06% | 06% | 06% |
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