Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Aug 2004

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 Aug 18 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 231 Issued at 2200Z on 18 Aug 2004

IA. Analysis of Solar Active Regions and Activity from 17/2100Z
to 18/2100Z: Solar activity has been high. Region 656 (S15,L=87)
produced significant flare activity, including an X1.8/Sf at 18/1740
UTC. Region 661 (N09E06) exhibited gradual growth in size over the
period, and produced several C-class flares. New Region 662
(N12E28) was numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be low
to moderate. Region 661 may produce C- or M-class flares.

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field has been quiet to unsettled.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled all three days. Isolated active
conditions are possible on days two and three (20-21 Aug) from minor
effects of a small coronal hole that will reach geoeffective
position.

III. Event Probabilities 19 Aug-21 Aug

• Class M 40/20/15
• Class X 10/05/01
• Proton 05/05/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 18 Aug 140
• Predicted 19 Aug-21 Aug 115/115/110
• 90 Day Mean 18 Aug 109

V. Geomagnetic A Indices

• Observed Afr/Ap 17 Aug 009/011
• Estimated Afr/Ap 18 Aug 009/012
• Predicted Afr/Ap 19 Aug-21 Aug 008/010-008/015-005/010

VI. Geomagnetic Activity Probabilities 19 Aug-21 Aug

• A. Middle Latitudes
• Active 20/30/20
• Minor storm 01/05/01
• Major-severe storm 01/01/01

B. High Latitudes

• Active 30/35/30
• Minor storm 05/10/05
• Major-severe storm 01/01/01