Viewing archive of Thursday, 16 September 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 Sep 16 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 259 Issued at 2200Z on 16 SEP 1999

IA. Analysis of Solar Active Regions and Activity from 15-2100Z to 16-2100Z

SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT THIS PERIOD WAS A C7/SF FROM REGION 8700 (N14E31). OCCASIONAL MINOR C-CLASS SUBFLARES WERE ALSO OBSERVED IN REGIONS 8699 (N22W39) AND 8692 (S26W41). AN IMPRESSIVE DARK, 50 DEGREE FILAMENT ERUPTED FROM NORTH-CENTER DISK. THIS FILAMENT WAS ACTIVE FOR MOST OF THE PAST 24 HOURS. ELEVATION WAS FIRST DETECTED AT AROUND 16/1230UT WITH THE TOTAL ERUPTION OF THIS TWO-PART FILAMENT OCCURRING AT 16/1620UT. THE EVENT WAS OBSERVED ON BOTH GROUND AND SPACE-BASED INSTRUMENTS WITH A LARGE CME OBSERVED BY LASCO.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO REMAIN LOW. SEVERAL EXISTING SUNSPOT REGIONS ARE CAPABLE OF PRODUCING C-CLASS ACTIVITY WITH AN ISOLATED CHANCE FOR A LOW M-CLASS.
IIA. Geophysical Activity Summary 15-2100Z to 16-2100Z
THE GEOMAGNETIC FIELD WAS AT QUIET TO MINOR STORM LEVELS WITH ISOLATED MAJOR STORMING PERIODS AT HIGH LATITUDES. A SUSTAINED PERIOD OF SOUTHWARD BZ AND A 600KM/S SOLAR WIND SPEED FOLLOWED A SUDDEN IMPULSE (SI) OBSERVED AT 15/2019UT.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE QUIET TO ACTIVE WITH OCCASIONAL MINOR STORMING MOSTLY AT HIGH LATITUDES. DAY TWO SHOULD BE LESS ACTIVE AS THE HIGH SPEED STREAM SUBSIDES, EXPECT QUIET TO OCCASIONAL ACTIVE. WE MAY SEE THE EFFECTS OF TODAY'S LARGE DSF ON DAY 3, LOOK FOR ACTIVE TO MINOR STORM CONDITIONS POSSIBLE BY LATE DAY 3.
III. Event Probabilities 17 SEP to 19 SEP
Class M15%15%15%
Class X05%05%05%
Proton05%05%05%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       16 SEP 158
  Predicted   17 SEP-19 SEP  160/165/170
  90 Day Mean        16 SEP 164
V. Geomagnetic A Indices
OBSERVED AFR/AP 15 SEP  021/032
ESTIMATED AFR/AP 16 SEP  025/030
PREDICTED AFR/AP 17 SEP-19 SEP  020/025-015/020-012/012
VI. Geomagnetic Activity Probabilities 17 SEP to 19 SEP
A. Middle Latitudes
Active50%40%50%
Minor storm30%20%30%
Major-severe storm10%05%10%
B. High Latitudes
Active40%40%50%
Minor storm50%25%30%
Major-severe storm10%05%10%

All times in UTC

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