Viewing archive of Tuesday, 21 April 1998

Solar activity report

Report of Solar-Geophysical Activity 1998 Apr 21 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 111 Issued at 2200Z on 21 APR 1998

IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z

SOLAR ACTIVITY WAS VERY LOW. THE ONLY ACTIVITY OF NOTE WAS AN ERUPTIVE PROMINENCE THAT OCCURRED ON THE WEST LIMB NEAR N30. NO OTHER ACTIVITY WAS NOTED WITH THIS ERUPTION. REGION 8205 (N21W53) DECAYED SLIGHTLY IN WHITE LIGHT AREA BUT IS STILL EXHIBITING OCCASIONAL PLAGE FLUCTUATIONS AND SURGING. THE REMAINING REGIONS HAVE BEEN QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW. REGION 8205 HAS POTENTIAL TO PRODUCE AN ISOLATED C-CLASS FLARE. STILL A SLIGHT CHANCE FOR FURTHER ACTIVITY NEAR THE SW LIMB - THE SOURCE OF YESTERDAY'S M1 X-RAY FLARE; HOWEVER, THE LIKELY SOURCE REGION HAS PROBABLY ROTATED ENOUGH TO ELIMINATE CONCERN. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 20/2100Z TO 21/2100Z: THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. THE GREATER THAN 10 MEV PROTON EVENT THAT BEGAN AT 20/1130Z IS STILL IN PROGRESS. A MAXIMUM VALUE OF 1700 PFU WAS REACHED AT 21/1205. THE EVENT APPEARS TO BE IN DECLINE NOW WITH A CURRENT VALUE OF 640 PFU. THE GREATER THAN 100 MEV EVENT PEAKED AT 7.4 PFU AT 21/1255Z AND IS CURRENTLY AT 2.5 PFU.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO CONTINUE AT QUIET TO UNSETTLED LEVELS. AN EXTENSION OF THE SOUTHERN CORONAL HOLE WILL MOVE INTO FAVORABLE POSITION FOR GEOEFFECTIVNESS ON DAY TWO AND THREE. EXPECT OCCASIONAL ACTIVE PERIODS DURING THIS PERIOD. THE PROTON EVENT IN PROGRESS IS EXPECTED TO LAST THROUGH TOMORROW.
III. Event Probabilities 22 APR to 24 APR
Class M 05%05%05%
Class X 01%01%01%
Proton05%05%01%
PCAFIN PROGRESS
IV. Penticton 10.7 cm Flux
  Observed       21 APR 92
  Predicted    22 APR-24 APR  092/090/090
  90 Day Mean        21 APR 104
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 APR  009/010
ESTIMATED AFR/AP 21 APR  007/010
PREDICTED AFR/AP 22 APR-24 APR  012/010-012/015-012/020
VI. Geomagnetic Activity Probabilities 22 APR to 24 APR
A. Middle Latitudes
Active15%30%30%
Minor storm 05%05%05%
Major-severe storm 01%01%01%
B. High Latitudes
Active20%40%45%
Minor storm 10%10%10%
Major-severe storm 01%06%06%

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