Viewing archive of Sunday, 25 April 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 Apr 25 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 115 Issued at 2200Z on 25 APR 1999

IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z

SOLAR ACTIVITY WAS VERY LOW. REGIONS 8524 (N22E39) AND 8523 (N31E28) BOTH PRODUCED MINOR B-CLASS SUBFLARES. NEW REGIONS - 8522 (N17E38) AND 8524 WERE THE ONLY REGIONS ON THE VISIBLE DISK THAT SHOWED ANY GROWTH. REMAINING REGIONS WERE EITHER STABLE OR DECAYING.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW. REGION 8522 AND REGION 8524 MAY SOON DEVELOP C-CLASS POTENTIAL, ESPECIALLY CONSIDERING THEIR PROXIMITY TO EACH OTHER.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
THE GEOMAGNETIC FIELD WAS QUIET. A GREATER THAN 10 MEV PROTON EVENT BEGAN YESTERDAY AT 24/1610Z ASSOCIATED WITH THE LARGE HALO CME FROM BEHIND THE NORTHWEST LIMB AT AROUND 24/1230Z. THE 10 PFU THRESHOLD WAS CROSSED AT 24/1840Z WITH A MAXIMUM OF 32 PFU OBSERVED AT 25/0055Z. THE FLUX DROPPED BACK BELOW THE 10 PFU LEVEL AT 25/1451Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE QUIET TO UNSETTLED. NO GEOEFFECTIVNESS IS EXPECTED FROM YESTERDAY'S CME. THE GREATER THAN 10 MEV PROTON FLUX IS EXPECTED TO RETURN TO BACKGROUND LEVELS BY END OF PERIOD.
III. Event Probabilities 26 APR to 28 APR
Class M05%05%05%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       25 APR 103
  Predicted   26 APR-28 APR  110/115/115
  90 Day Mean        25 APR 129
V. Geomagnetic A Indices
OBSERVED AFR/AP 24 APR  005/007
ESTIMATED AFR/AP 25 APR  005/005
PREDICTED AFR/AP 26 APR-28 APR  010/010-010/010-010/010
VI. Geomagnetic Activity Probabilities 26 APR to 28 APR
A. Middle Latitudes
Active20%20%15%
Minor storm05%05%05%
Major-severe storm01%01%01%
B. High Latitudes
Active25%25%20%
Minor storm05%05%05%
Major-severe storm01%01%01%

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