Viewing archive of Tuesday, 20 April 1999

Solar activity report

Report of Solar-Geophysical Activity 1999 Apr 20 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 110 Issued at 2200Z on 20 APR 1999

IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z

SOLAR ACTIVITY REMAINED AT VERY LOW LEVELS. REGIONS 8517 (N22W77) AND 8518 (S15E29) PRODUCED ISOLATED B-CLASS SUBFLARES, BUT SHOWED NO SIGNIFICANT CHANGES IN SIZE OR STRUCTURE. THE REMAINING SPOT GROUPS WERE SMALL, STRUCTURALLY SIMPLE, AND STABLE. NO NEW REGIONS WERE ASSIGNED.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW. REGION 8518 APPEARS CAPABLE OF ISOLATED C-CLASS FLARE PRODUCTION. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 19/2100Z TO 20/2100Z: THE GEOMAGNETIC FIELD WAS AT UNSETTLED TO MINOR STORM LEVELS AT ALL LATITUDES.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO REMAIN AT UNSETTLED TO MINOR STORM LEVELS DURING THE FIRST DAY, THEN DECLINE TO QUIET TO UNSETTLED LEVELS FOR THE REMAINDER OF THE PERIOD.
III. Event Probabilities 21 APR to 23 APR
Class M 10%10%10%
Class X 01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       20 APR 105
  Predicted    21 APR-23 APR  105/105/105
  90 Day Mean        20 APR 132
V. Geomagnetic A Indices
OBSERVED AFR/AP 19 APR  010/013
ESTIMATED AFR/AP 20 APR  022/022
PREDICTED AFR/AP 21 APR-23 APR  020/030-010/010-007/005
VI. Geomagnetic Activity Probabilities 21 APR to 23 APR
A. Middle Latitudes
Active40%20%10%
Minor storm 30%10%05%
Major-severe storm 05%01%01%
B. High Latitudes
Active40%25%10%
Minor storm 40%15%10%
Major-severe storm 05%01%01%

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