Viewing archive of Friday, 24 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 24 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 358 Issued at 2200Z on 24 DEC 1999

IA. Analysis of Solar Active Regions and Activity from 23-2100Z to 24-2100Z

SOLAR ACTIVITY WAS LOW. NUMEROUS C-CLASS FLARES WERE OBSERVED DURING THE PAST 24 HOURS. MOST OF THESE WERE FROM REGIONS 8798 (S13W73) AND 8806 (N20W14). THE LARGEST EVENT WAS A C8 AT 0934Z WHICH WAS NOT SEEN OPTICALLY. GOOD QUALITY OBSERVATIONS TODAY CONFIRM THE PRESENCE OF A DELTA CONFIGURATION IN THE CENTRAL PORTION OF REGION 8806, AN AREA OF STRONG AND APPARENTLY SHEARED MAGNETIC FIELDS. HOWEVER, THERE WERE NOT ANY DRAMATIC CHANGES OBSERVED IN THIS GROUP. AN ERUPTIVE PROMINENCE WAS OBSERVED FROM WEST LIMB AT N22 BETWEEN 1430-1511Z AND WAS ASSOCIATED WITH A C1 X-RAY EVENT. NEW REGION 8809 (N21E67) ROTATED INTO VIEW TODAY. LASCO DIFFERENCE IMAGE ANALYSIS OF THE CME ACTIVITY ON 22 DECEMBER SHOWS EVIDENCE OF A FAINT, 360 DEGREE HALO FOR BOTH EVENTS. THE BULK OF THE MATERIAL FROM BOTH CME'S APPEARED TO BE DIRECTED NORTHWARDS, IMPLYING ONLY A SMALL COMPONENT OF THE CME VELOCITY IN THE EARTHWARD DIRECTION.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGION 8806 IS LIKELY TO PRODUCE AT LEAST AN M-CLASS EVENT. THERE CONTINUES TO BE SOME CHANCE FOR A MAJOR FLARE OR PROTON PRODUCING FLARE FROM THE REGION SOMETIME OVER THE NEXT THREE DAYS.
IIA. Geophysical Activity Summary 23-2100Z to 24-2100Z
THE GEOMAGNETIC FIELD WAS MOSTLY QUIET. HOWEVER, A PERIOD OF UNSETTLED TO ACTIVE CONDITIONS WAS OBSERVED FROM 0600-1200Z. THE INCREASE WAS ASSOCIATED WITH A REVERSAL OF THE INTERPLANETARY SECTOR MAGNETIC POLARITY FROM A TOWARDS TO AN AWAY CONFIGURATION.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE MOSTLY UNSETTLED OVER THE NEXT TWO DAYS, BUT THERE IS A CHANCE FOR SOME ACTIVE PERIODS, ESPECIALLY IF THE CME'S OF 22 DECEMBER SHOULD HAPPEN TO HIT EARTH WITH A GLANCING BLOW. QUIET TO UNSETTLED CONDITIONS ARE EXPECTED ON THE THIRD DAY.
III. Event Probabilities 25 DEC to 27 DEC
Class M70%70%70%
Class X15%15%15%
Proton15%15%15%
PCAFYELLOW
IV. Penticton 10.7 cm Flux
  Observed       24 DEC 182
  Predicted   25 DEC-27 DEC  180/175/170
  90 Day Mean        24 DEC 174
V. Geomagnetic A Indices
OBSERVED AFR/AP 23 DEC  002/005
ESTIMATED AFR/AP 24 DEC  009/007
PREDICTED AFR/AP 25 DEC-27 DEC  010/015-012/020-005/010
VI. Geomagnetic Activity Probabilities 25 DEC to 27 DEC
A. Middle Latitudes
Active30%30%10%
Minor storm15%15%05%
Major-severe storm05%05%01%
B. High Latitudes
Active35%35%35%
Minor storm15%15%05%
Major-severe storm05%05%01%

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