Viewing archive of Thursday, 17 September 1998

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 1998 Sep 17 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 260 Issued at 2200Z on 17 SEP 1998

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

SOLAR ACTIVITY HAS BEEN VERY LOW FOR THE PAST 24 HOURS. TWO NEW REGIONS WERE NUMBERED: REGION 8339 (S17E42), A B-TYPE SPOT GROUP, AND REGION 8340 (N20E76), A SINGLE H-TYPE SPOT WHICH IS THE QUIET RETURN OF OLD ACTIVE REGION 8319. REGION 8319 PRODUCED FIVE M-CLASS FLARES DURING ITS LAST ROTATION. NUMEROUS TYPE III RADIO SWEEPS WERE REPORTED THROUGHOUT THE DAY, AS WELL AS A RADIO NOISE STORM AT 410 MHZ BEGINNING AT 1839 UT. MINOR SURGING ACCOMPANIED THE EAST LIMB APPEARANCE OF REGION 8340. THE REMAINDER OF THE LIMBS, AND THE DISK, WERE QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW BASED ON EXPECTATIONS OF C-CLASS FLARES FROM REGIONS DEVELOPING IN ACTIVE LONGITUDES IN THE EASTERN SOLAR HEMISPHERE. ISOLATED M-CLASS FLARES ARE POSSIBLE.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
THE GEOMAGNETIC FIELD HAS BEEN QUIET FOR THE PAST 24 HOURS.
IIB. Geophysical Activity Forecast
GEOMAGNETIC ACTIVITY IS EXPECTED TO PERSIST AT QUIET LEVELS TOMORROW, BUT INCREASE FROM QUIET TO UNSETTLED LEVELS IF THE SOLAR WIND CHANGES FROM ITS PRESENT STATE OF LOW SPEEDS, NORMAL DENSITIES, AND NORMAL MAGNETIC FIELD INTENSITIES. HIGHER SPEEDS AND FLUCTUATING MAGNETIC FIELDS ASSOCIATED SMALL DISAPPEARING FILAMENTS, OR FROM A POSITIVE NORTHERN CORONAL HOLE SHOULD ARRIVE AT EARTH DURING THE 3-DAY FORECAST PERIOD.
III. Event Probabilities 18 SEP to 20 SEP
Class M10%10%10%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       17 SEP 117
  Predicted   18 SEP-20 SEP  130/130/135
  90 Day Mean        17 SEP 127
V. Geomagnetic A Indices
OBSERVED AFR/AP 16 SEP  002/004
ESTIMATED AFR/AP 17 SEP  004/010
PREDICTED AFR/AP 18 SEP-20 SEP  005/010-010/012-010/012
VI. Geomagnetic Activity Probabilities 18 SEP to 20 SEP
A. Middle Latitudes
Active10%20%25%
Minor storm05%10%10%
Major-severe storm05%05%05%
B. High Latitudes
Active20%25%25%
Minor storm10%10%15%
Major-severe storm05%05%05%

All times in UTC

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