Viewing archive of Friday, 17 September 1999

Solar activity report

Report of Solar-Geophysical Activity 1999 Sep 17 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 260 Issued at 2200Z on 17 SEP 1999

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

SOLAR ACTIVITY INCREASED TO MODERATE LEVELS. REGION 8690 (N16W74) SHOWED GRADUAL DECAY AS IT APPROACHED THE WEST LIMB. IT PRODUCED AN M2/SF AT 17/0120Z. REGION 8700 (N13E20) SHOWED SOME MIXED POLARITIES AS IT GRADUALLY DECAYED AND PRODUCED ISOLATED C-CLASS SUBFLARES. A PARTIAL-HALO CME WAS OBSERVED FOLLOWING YESTERDAY'S (16/1508 - 1615Z) 50-DEGREE DSF. NEW REGIONS 8702 (N22E15), 8703 (N21W92), AND 8704 (S21E63) WERE NUMBERED. REGION 8704 APPEARED TO BE THE RETURN OF OLD REGION 8674, WHICH PRODUCED MAJOR FLARES DURING ITS PREVIOUS ROTATIONS. THUS FAR, IT HAS BEEN A STABLE H-TYPE GROUP.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW WITH A SLIGHT CHANCE FOR AN M-CLASS FLARE FROM REGIONS 8690 AND 8700. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 16/2100Z TO 17/2100Z: THE GEOMAGNETIC FIELD WAS AT QUIET TO ACTIVE LEVELS WITH PERIODS OF MINOR TO MAJOR STORMING DETECTED AT HIGH LATITUDES. THE GREATER THAN 2 MEV ELECTRON FLUX REACHED HIGH LEVELS DURING THE PERIOD.
IIB. Geophysical Activity Forecast
GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO BE AT MOSTLY QUIET TO UNSETTLED LEVELS DURING THE FIRST DAY. ACTIVITY IS EXPECTED TO INCREASE TO ACTIVE TO MINOR STORM LEVELS LATE ON 19 SEPTEMBER DUE TO YESTERDAY'S DSF/CME. STORM LEVELS ARE EXPECTED TO CONTINUE THROUGH THE END OF THE PERIOD. THE GREATER THAN 2 MEV ELECTRON FLUX IS EXPECTED TO BE AT MODERATE TO HIGH LEVELS DURING THE PERIOD.
III. Event Probabilities 18 SEP to 20 SEP
Class M15%15%15%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       17 SEP 158
  Predicted   18 SEP-20 SEP  160/165/170
  90 Day Mean        17 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 16 SEP  018/032
ESTIMATED AFR/AP 17 SEP  012/020
PREDICTED AFR/AP 18 SEP-20 SEP  015/015-015/015-030/030
VI. Geomagnetic Activity Probabilities 18 SEP to 20 SEP
A. Middle Latitudes
Active30%50%50%
Minor storm10%30%30%
Major-severe storm05%10%10%
B. High Latitudes
Active40%50%50%
Minor storm15%30%30%
Major-severe storm05%10%10%

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