Viewing archive of Tuesday, 21 December 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 Dec 21 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 355 Issued at 2200Z on 21 DEC 1999

IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z

SOLAR ACTIVITY WAS MODERATE. REGION 8806 (N19E24) PRODUCED AN M1/1N AT 21/1719UT. REGION 8806 IS THE LARGEST REGION ON THE DISK AND CONTINUES TO BE MAGNETICALLY COMPLEX. REGION 8798 (S13W33), THE SECOND LARGEST REGION ON THE DISK, HAS ONLY PRODUCED SMALL C FLARES. A CME WAS OBSERVED BY SOHO AROUND 1600UT ON THE 20TH, BUT APPEARED TO BE A BACKSIDE EVENT. THE OBSERVED 10CM RADIO FLUX REPORTED IN PART IV MAY BE FLARE ENHANCED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. THERE IS A FAIR CHANCE FOR MAJOR ACTIVITY FROM EITHER REGION 8798 OR REGION 8806.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
THE GEOMAGNETIC FIELD HAS BEEN BASICALLY QUIET.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE QUIET TO UNSETTLED.
III. Event Probabilities 22 DEC to 24 DEC
Class M50%50%50%
Class X15%15%15%
Proton05%05%10%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       21 DEC 217
  Predicted   22 DEC-24 DEC  200/195/190
  90 Day Mean        21 DEC 172
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 DEC  004/003
ESTIMATED AFR/AP 21 DEC  004/005
PREDICTED AFR/AP 22 DEC-24 DEC  007/010-007/007-005/007
VI. Geomagnetic Activity Probabilities 22 DEC to 24 DEC
A. Middle Latitudes
Active25%10%10%
Minor storm10%01%01%
Major-severe storm01%01%01%
B. High Latitudes
Active25%20%15%
Minor storm10%05%01%
Major-severe storm01%01%01%

All times in UTC

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