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 UTC
Prepared 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 1999

IA. 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 M40%40%40%
Class X10%10%10%
Proton10%10%10%
PCAFGREEN
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
Active40%40%40%
Minor storm15%15%15%
Major-severe storm05%05%05%
B. High Latitudes
Active45%45%45%
Minor storm20%20%20%
Major-severe storm06%06%06%

All times in UTC

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