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

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 261 Issued at 2200Z on 18 SEP 1998

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

SOLAR ACTIVITY WAS VERY LOW. REGION 8339 (S16E30) EXHIBITED SOME MINOR GROWTH AND PRODUCED SEVERAL SUBFLARES DURING THE LATTER HALF OF THE PERIOD. NO SIGNIFICANT X-RAY ENHANCEMENTS ACCOMPANIED THESE FLARES. REGION 8340 (N22E64) IS LIKELY THE MOST COMPLEX REGION ON THE VISIBLE DISK BUT ITS LIMB PROXIMITY IS STILL HAMPERING A DETAILED ANALYSIS. PERIODS OF SURGING WITH SEVERAL PLAGE FLUCTUATIONS WERE NOTED IN THIS REGION AND A SMALL FILAMENT ERUPTED LATE IN THE PERIOD. A PROMINENCE ERUPTED OFF THE SW LIMB AT 17/2250Z. THE REMAINING REGIONS WERE QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW. THOUGH NO FLARING HAS YET OCCURRED IN REGION 8340, ITS SIZE AND APPARENT COMPLEXITY WILL LIKELY PRODUCE ISOLATED C-CLASS FLARING.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
THE GEOMAGNETIC FIELD WAS QUIET UNTIL APPROXIMATELY 18/1100Z. A DISTURBANCE BEGAN AT THAT TIME PRODUCING UNSETTLED TO ACTIVE CONDITIONS WITH AN ISOLATED PERIOD OF MAJOR STORMING AT HIGH LATITUDES. PREDOMINANTLY UNSETTLED TO ACTIVE CONDITIONS HAVE BEEN OBSERVED AT ALL LATITUDES SINCE 18/1500Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO REMAIN UNSETTLED TO ACTIVE. A LARGE EXTENSION OF THE NORTHERN CORONAL HOLE WILL MOVE INTO FAVORABLE POSITION FOR GEOEFFECTIVENESS BY LATE TOMORROW. DISTURBED CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE EARLY PART OF NEXT WEEK.
III. Event Probabilities 19 SEP to 21 SEP
Class M10%15%15%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       18 SEP 123
  Predicted   19 SEP-21 SEP  125/130/130
  90 Day Mean        18 SEP 127
V. Geomagnetic A Indices
OBSERVED AFR/AP 17 SEP  005/007
ESTIMATED AFR/AP 18 SEP  017/010
PREDICTED AFR/AP 19 SEP-21 SEP  015/015-015/015-015/020
VI. Geomagnetic Activity Probabilities 19 SEP to 21 SEP
A. Middle Latitudes
Active35%35%35%
Minor storm10%10%10%
Major-severe storm05%05%05%
B. High Latitudes
Active45%45%45%
Minor storm20%25%25%
Major-severe storm05%10%10%

All times in UTC

<< Go to daily overview page

Latest news

Support SpaceWeatherLive.com!

A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!

SpaceWeatherLive Pro
Support SpaceWeatherLive with our merchandise
Check out our merchandise

Latest alerts

Get instant alerts!

Space weather facts

Last X-flare2024/12/08X2.2
Last M-flare2024/12/24M1.0
Last geomagnetic storm2024/12/17Kp5+ (G1)
Spotless days
Last spotless day2022/06/08
Monthly mean Sunspot Number
November 2024152.5 -13.9
December 2024110.7 -41.8
Last 30 days116.5 -41.7

This day in history*

Solar flares
12011M5.77
21998M1.83
32001M1.76
42001M1.41
52011M1.22
DstG
11988-85
21998-57
31978-57G2
42014-49
52002-39
*since 1994

Social networks