Viewing archive of Thursday, 23 September 1999

Solar activity report

Report of Solar-Geophysical Activity 1999 Sep 23 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 266 Issued at 2200Z on 23 SEP 1999

IA. Analysis of Solar Active Regions and Activity from 22-2100Z to 23-2100Z

SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT OF THE PERIOD WAS AN IMPULSIVE C1/SF FROM 8706 (N20E25). REGION 8700 (N12W61) WAS THE MOST ACTIVE REGION THIS PERIOD AND PRODUCED SEVERAL MINOR SUBFLARES. A SIXTEEN DEGREE FILAMENT ERUPTED FROM NEAR S14W47 AT 23/1529Z. REMAINING REGIONS WERE MOSTLY QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN AT LOW LEVELS. ONLY ISOLATED C-CLASS X-RAY EVENTS ARE EXPECTED. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 22/2100Z TO 23/2100Z: THE GEOMAGNETIC FIELD WAS AT QUIET TO MAJOR STORM LEVELS. THE GEOMAGNETIC STORM THAT FOLLOWED YESTERDAY'S SUDDEN IMPULSE AT 22/1222Z, CONTINUED THROUGH EARLY THIS PERIOD. THE STORM SUBSIDED RATHER QUICKLY AFTER 23/0600Z AND THE FIELD HAS BEEN MOSTLY QUIET TO UNSETTLED SINCE.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE AT QUIET TO ACTIVE LEVELS. SOLAR WIND SPEED REMAINS ELEVATED FOLLOWING YESTERDAY'S INTERPLANETARY SHOCK. OCCASIONAL ACTIVE PERIODS ARE LIKELY DURING LOCAL NIGHTTIME HOURS ESPECIALLY AT HIGHER LATITUDES.
III. Event Probabilities 24 SEP to 26 SEP
Class M10%10%10%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       23 SEP 137
  Predicted   24 SEP-26 SEP  135/135/130
  90 Day Mean        23 SEP 163
V. Geomagnetic A Indices
OBSERVED AFR/AP 22 SEP  029/037
ESTIMATED AFR/AP 23 SEP  022/025
PREDICTED AFR/AP 24 SEP-26 SEP  012/015-010/012-010/010
VI. Geomagnetic Activity Probabilities 24 SEP to 26 SEP
A. Middle Latitudes
Active30%20%20%
Minor storm10%05%05%
Major-severe storm05%01%01%
B. High Latitudes
Active40%30%30%
Minor storm10%10%05%
Major-severe storm05%01%01%

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