Viewing archive of Saturday, 18 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 18 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 261 Issued at 2200Z on 18 SEP 1999

IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z

SOLAR ACTIVITY WAS LOW. REGION 8700 (N13E07) PRODUCED THE LARGEST FLARE SINCE YESTERDAY, A C8/2F AT 17/2212UT. SEVERAL SUBFLARES AND FLARE-BRIGHT PLAGE FLUCTUATIONS ALSO OCCURRED IN THIS REGION. 8700 SUNSPOTS CONTINUE TO EXHIBIT MIXED POLARITIES. REGION 8699 (N22W65) ALSO PRODUCED C-CLASS ACTIVITY, THE LARGEST BEING A C2/SF AT 18/1821UT. NEW REGION 8705 (S11E28) EMERGED ON THE DISK.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. C-CLASS ACTIVITY IS EXPECTED IN REGIONS 8699 AND 8700. AN ISOLATED M-CLASS FLARE IS POSSIBLE IN REGION 8700.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
THE GEOMAGNETIC FIELD RANGED FROM QUIET TO ACTIVE. ACTIVITY LEVELS CONTINUED TO FLUCTUATE IN RESPONSE TO SIMILAR SOLAR WIND (HIGH SPEED AND VARIABLE BZ) EXPERIENCED FOR THE PAST FEW DAYS. THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS HIGH.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO REMAIN QUIET TO UNSETTLED FOR THE NEXT SEVERAL HOURS. ACTIVE TO STORM CONDITIONS ARE POSSIBLE LATE ON THE 19TH, CONTINUING THROUGH THE 20TH, DUE TO THE CME/DSF DETECTED ON THE 16TH. THE GREATER THAN 2 MEV ELECTRON FLUX SHOULD REMAIN MODERATE TO HIGH.
III. Event Probabilities 19 SEP to 21 SEP
Class M15%15%15%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       18 SEP 152
  Predicted   19 SEP-21 SEP  155/160/165
  90 Day Mean        18 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 17 SEP  009/015
ESTIMATED AFR/AP 18 SEP  015/015
PREDICTED AFR/AP 19 SEP-21 SEP  015/015-030/030-015/015
VI. Geomagnetic Activity Probabilities 19 SEP to 21 SEP
A. Middle Latitudes
Active50%50%30%
Minor storm20%30%10%
Major-severe storm05%10%05%
B. High Latitudes
Active50%50%30%
Minor storm20%30%10%
Major-severe storm05%10%05%

All times in UTC

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