Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Aug 2004

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

Updated 2004 Aug 21 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 234 Issued at 2200Z on 21 Aug 2004

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity was very low. Occasional brightness
fluctuations were noted, but no flare activity occurred. Region 661
(N07W33) contains minor magnetic complexity and white light area
coverage of over 450 millionths, but has been stable for the past 48
hours. Region 663 (N11E52) has rotated fully into view as an
elongated beta spot group with some minor magnetic mixing. Region
664 (S10E25) exhibited considerable growth this period and also
displays some minor mixing. No new regions were numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be very
low to low. Isolated C-class flares are possible.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was quiet to active with isolated minor storm
periods. The disturbed periods are due to a slightly elevated solar
wind speed (near 500 km/s) and predominantly southward IMF Bz.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to active with isolated minor storm periods.

III. Event Probabilities 22 Aug-24 Aug

• Class M 15/15/15
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 21 Aug 120
• Predicted 22 Aug-24 Aug 120/120/120
• 90 Day Mean 21 Aug 109

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Aug 009/014
• Estimated Afr/Ap 21 Aug 020/020
• Predicted Afr/Ap 22 Aug-24 Aug 015/015-012/015-012/015

VI. Geomagnetic Activity Probabilities 22 Aug-24 Aug

A. Middle Latitudes

• Active 30/25/25
• Minor storm 10/05/05
• Major-severe storm 01/01/01

B. High Latitudes

• Active 40/40/40
• Minor storm 15/10/10
• Major-severe storm 05/01/01