Viewing archive of Wednesday, 18 August 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 Aug 18 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 230 Issued at 2200Z on 18 AUG 1999

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

SOLAR ACTIVITY WAS LOW. A LONG-DURATION C7 EVENT WAS THE HIGHLIGHT OF THE PERIOD, BUT THE EVENT WAS NOT OPTICALLY OBSERVED. REGION 8668 (N22E15) REMAINS THE DOMINANT ACTIVE CENTER IN WHITE LIGHT AND H-ALPHA. NEWLY ASSIGNED REGION 8672 (N12E01) EMERGED JUST WEST OF 8668 AND PRODUCED A SUBFLARE AT 1154Z.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW. HOWEVER, REGION 8668 MAY PRODUCE AN ISOLATED M-CLASS EVENT DURING THE NEXT THREE DAYS.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
THE GEOMAGNETIC FIELD REMAINED AT ACTIVE TO MINOR STORM LEVELS. THIS DISTURBANCE, RELATED TO A HIGH SPEED SOLAR WIND STREAM, BEGAN IN THE EARLY PART OF 16 AUGUST. SPEEDS CONTINUED IN THE 600-700 KM/S RANGE MOST OF TODAY. THE GREATER THAN 2 MEV GEOSYNCHRONOUS ELECTRON FLUX ATTAINED HIGH LEVELS AROUND 1200Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE UNSETTLED TO ACTIVE ON 19 AUGUST. SOLAR WIND SPEEDS SHOULD DIMINISH TO A MORE NORMAL RANGE THEN, AND ACTIVITY SHOULD DECLINE. UNSETTLED CONDITIONS SHOULD PREVAIL AT THE END OF THE INTERVAL.
III. Event Probabilities 19 AUG to 21 AUG
Class M15%15%15%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       18 AUG 131
  Predicted   19 AUG-21 AUG  140/155/170
  90 Day Mean        18 AUG 163
V. Geomagnetic A Indices
OBSERVED AFR/AP 17 AUG  026/027
ESTIMATED AFR/AP 18 AUG  030/030
PREDICTED AFR/AP 19 AUG-21 AUG  015/020-015/015-015/010
VI. Geomagnetic Activity Probabilities 19 AUG to 21 AUG
A. Middle Latitudes
Active35%25%20%
Minor storm15%10%10%
Major-severe storm01%01%01%
B. High Latitudes
Active45%40%40%
Minor storm30%20%20%
Major-severe storm05%01%01%

All times in UTC

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