Viewing archive of Saturday, 17 July 2004
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 2004 Jul 17 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 199 Issued at 2200Z on 17 Jul 2004IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z Solar activity was at high levels. Region 649 (S10E13)
continues to produce M and X-class flare activity. The largest
flare of the period was an X1/1f impulsive flare that occurred at
17/0757Z. Region 649 also produced an M2/1n event at 17/1651Z.
Minor radio bursts accompanied both flares. LASCO imagery shows
most of the CME plasma structure directed towards the eastern solar
hemisphere. Region 652 (N05E71) appears fairly ominous in white
light with 750 millionths of sunspot area. This region has produced
several C-class flares today and remains too close to the solar
eastern limb to determine accurate magnetic structure. Region 653
(S14E71) was numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be at
moderate to high levels.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic field ranged from quiet to major storm levels. ACE
data indicates that a shock passed the instrument at approximately
16/2100Z. This transient is believed to have been the result of the
weak signature, full halo CME activity seen on 13 July. Higher
latitudes experienced major storm conditions between 17/0000 and
0300Z.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be at predominantly unsettled levels. There is a chance
for isolated active to minor storm conditions with further transient
activity resulting from the multitude of major flares seen over the
past several days.
III. Event Probabilities 18 Jul to 20 Jul
| Class M | 80% | 80% | 80% |
| Class X | 40% | 40% | 40% |
| Proton | 20% | 20% | 20% |
| PCAF | Green | ||
IV. Penticton 10.7 cm Flux
Observed 17 Jul 149 Predicted 18 Jul-20 Jul 150/150/145 90 Day Mean 17 Jul 098
V. Geomagnetic A Indices
Observed Afr/Ap 16 Jul 008/012 Estimated Afr/Ap 17 Jul 024/025 Predicted Afr/Ap 18 Jul-20 Jul 012/015-012/015-012/015
VI. Geomagnetic Activity Probabilities 18 Jul to 20 Jul
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 25% | 25% | 25% |
| Minor storm | 15% | 15% | 15% |
| Major-severe storm | 10% | 10% | 10% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 35% | 35% | 35% |
| Minor storm | 20% | 20% | 20% |
| Major-severe storm | 10% | 10% | 10% |
All times in UTC
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