Viewing archive of Friday, 20 April 2001
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 2001 Apr 20 2200 UTCPrepared 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 2001IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity was moderate. The largest flare was an
M4/1F at 20/2004 UTC in Region 9433 (N17E52). This area also
produced an M1/1F at 20/0523 UTC. The region remains a
moderately-sized F-type sunspot group with some mixed polarities in
the central portions and a total area similar to yesterday's. Region
9432 (N08W06) also produced C-class subflares. Today's Penticton
F10.7 noon reading was taken during the M4, resulting in a
flare-enhanced value of 180 sfu.
IB. Solar Activity Forecast
Solar activity is expected to be
moderate. Additional M-class activity in Region 9433 is likely with
the possibility of an isolated major flare.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was quiet to unsettled. The greater than 10 MeV
proton event dropped below the 10 pfu event threshold at 20/1015 UTC
(start 18/0315 UTC and 321 pfu peak at 18/1045 UTC) and continues to
slowly decay.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be quiet to unsettled. A major flare in Region 9433
could generate another greater than 10 MeV proton event.
III. Event Probabilities 21 Apr to 23 Apr
| Class M | 75% | 75% | 75% |
| Class X | 10% | 10% | 10% |
| Proton | 05% | 05% | 05% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 Apr 180 Predicted 21 Apr-23 Apr 175/185/195 90 Day Mean 20 Apr 165
V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 005/007 Estimated Afr/Ap 20 Apr 008/010 Predicted Afr/Ap 21 Apr-23 Apr 005/010-005/010-010/010
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 10% | 10% | 10% |
| Minor storm | 05% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 15% | 15% |
| Minor storm | 10% | 10% | 10% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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