Solar activity report

Viewing archive of Friday, 18 December 1998

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 1998 Dec 18 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 352 Issued at 2200Z on 18 DEC 1998

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

SOLAR ACTIVITY WAS HIGH. REGION 8415 (N19E61) PRODUCED A M8/2N EVENT AT 18/1722Z WITH AN ASSOCIATED TYPE II SWEEP. THE TYPE II SPEED WAS ESTIMATED AT 1200 KM/S. AN 880 SFU TENFLARE WAS ALSO DETECTED DURING THE M8 X-RAY EVENT. REGION 8415 ALSO PRODUCED NUMEROUS C-CLASS X-RAY EVENTS DURING THE PERIOD.

IB. Solar Activity Forecast

SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE WITH CONTINUED C-CLASS EVENTS AND THE LIKELIHOOD OF MORE M-CLASS X-RAY EVENTS FROM REGION 8415 OR REGION 8409 (S27W63).

IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z

THE GEOMAGNETIC FIELD WAS QUIET. A CME WAS OBSERVED FROM SOHO LASCO IMAGERY AT 18/1834Z IN ASSOCIATION WITH THE M8 X-RAY EVENT IN REGION 8415 EARLIER TODAY. LASCO AND EIT REPORTED A PARTIAL HALO.

IIB. Geophysical Activity Forecast

THE GEOMAGNETIC FIELD IS EXPECTED TO BE QUIET, BECOMING QUIET TO UNSETTLED DURING THE THREE DAY PERIOD. NO SIGNIFICANT GEOMAGNETIC EFFECTS ARE EXPECTED FROM THE X-RAY EVENT AT 18/1722Z UNTIL THE END OF THE PERIOD.

III. Event Probabilities 19 DEC to 21 DEC

Class M	50%	50%	50%
Class X	05%	05%	05%
Proton	01%	01%	01%
PCAF	GREEN

IV. Penticton 10.7 cm Flux

  Observed       18 DEC 155
  Predicted   19 DEC-21 DEC  150/145/140
  90 Day Mean        18 DEC 133

V. Geomagnetic A Indices

OBSERVED AFR/AP 17 DEC  000/002
ESTIMATED AFR/AP 18 DEC  002/003
PREDICTED AFR/AP 19 DEC-21 DEC  005/009-008/009-008/009

VI. Geomagnetic Activity Probabilities 19 DEC to 21 DEC

A. Middle Latitudes
Active	15%	15%	15%
Minor storm	01%	01%	01%
Major-severe storm	01%	01%	01%

B. High Latitudes
Active	15%	20%	20%
Minor storm	01%	05%	05%
Major-severe storm	01%	01%	01%

All times in UTC

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